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Dredged sediments used as novel supply of raw material to produce Portland cement clinker
Abstract
The maintenance of waterways generates large amounts of dredged sediments that are an environmental issue. This paper focuses on the use of fluvial sediment to replace a portion of the raw materials of Portland cement clinker, which would otherwise come from natural resources. The mineralogy of the synthetic cement was characterised using X-ray diffraction and scanning electron microscopy and its reactivity was followed by isothermal calorimetry. Comparisons were made to a commercial ordinary Portland cement (CEM I 52.5). Compressive strength measurements were conducted on cement pastes at 1, 2, 4, 7, 14, 28 and 56 days to study strength development. The results showed that Portland cement clinker can be successfully synthesised by using up to 39% sediment. The compressive strengths developed by the cement made from sediment were equivalent to those obtained with the reference at early ages and 20% higher at long term.
... Different types of wastes have been studied in the literature in order to produce cement, and mainly Buildings 2022, 12, 1421 2 of 12 OPC cement. Aouad et al. used sediment from the north of France to produce OPC cement [13]. Their results showed that 39% of sediment can be added to the raw meal, and the compressive strength of sediment-based cement is equivalent to the reference cement (without sediment) and exceeds it by 20% in the long term. ...
... The characterization of COx argillite realized in different studies shows the presence of three main components: clay, calcite and quartz [17,[22][23][24][25]. These phases are essential to produce clinker in the cement industry [13,26,27]. The main objective of this paper is to investigate the possibility of using COx argillite as part of the meal blend to produce ordinary Portland cement. ...
... Figure 7 shows the calorimetric curve for COx cement paste. The shape of the curve is similar for an ordinary Portland cement presented in previous studies [13,[36][37][38]. A first peak in phase I is formed after water addition and the anhydrous grain dissolution. ...
Excavated soils and rocks are materials obtained in construction works that could represent an ecological issue if a durable and efficient reuse process is not set. The radioactive waste disposal planned by the French National Radioactive Waste Management Agency will generate large quantities of excavated soil (mainly as Callovo-Oxfordian argillite). The re-use of excavated soils is a recent question. There is a lack in the literature concerning the recycling of such materials. Therefore, this paper aims to investigate the possibility of using Callovo-Oxfordian argillite (COx argillite from the French URL) as a raw material for Portland cement clinker production. COx argillite was first characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) then a Portland cement clinker was synthesized at laboratory scale. The produced clinker was characterized to verify the chemical and mineralogical composition. After adding gypsum, the reactivity of the resulting cement was assessed by setting time and isothermal calorimetry measurements. The compressive strength was assessed on standard mortar prisms at 1, 14 and 28 days. The results show that a Portland cement clinker containing 64% C3S, 14% C2S, 10% C4AF, 7% C3A and 1% CaO can be produced when 22.24% of raw meal was substituted by the COx argillite. The setting time and isothermal calorimetry results show that the produced cement shows an equivalent reactivity to conventional ordinary Portland cement. The compressive strength at 28 days is 56 MPa, showing that the produced cement can be considered as CEM I 52.5 N Portland cement.
... Aouad et al. [20] used the fraction of polluted sediment with particles size smaller than 2 mm from the Scarpe Canal, located in the industrial basin of the North of France, to produce clinker/cement in the laboratory with a 39.1 wt% substitution rate of sediment. The authors showed that the four mineral phases of the cement were obtained without the appearance of secondary phases. ...
... The preparation process of the cement paste in this part is similar to that in the analysis of the degree of hydration. Based on previous studies [20,43,47], the compressive strength was measured on 6 samples after 2, 15 and 28 days performing at a constant stress of 0.3 MPa/s. ...
... The result shows that the chemical composition of the principal oxides of OPC 97 cement is comparable to that of OPC 97 TM cement. However, it is important to note that the amount of zinc in OPC 97 is 10 times higher than that in Ordinary Portland Cement [20]. ...
Around 56 million m³ of sediments are dredged in France per year to maintain the access to ports and waterways. Sediments are considered as waste regarding regulations and cause environmental, ecological and economic issues. This paper aims to use dredged sediments as raw material to replace traditional materials in Portland clinker production. Two clinkers are produced at the laboratory scale: a reference with chemical reagents CaCO3, SiO2, Al2O3 and Fe2O3 and a second clinker with sediment as a partial substitution for chemical reagents while controlling all the three cementitious modulus.
The synthetized cements were characterized by X-ray diffraction; X-ray fluorescence and scanning electron microscopy in order to identify their mineralogical and chemical composition as well as their microstructure. The reactivity of the synthesized cements was followed by isothermal calorimetry and the mechanical strength of cement pastes was measured at 2, 15 and 28 days. The CEMHYD3D code was used to numerically modelling the hydration of synthesized cements in order to follow the evolution of phases and to predict the properties of hydrated cements.
The results demonstrate the potentiality of reuse sediments in the cement manufacturing with a high rate of sediment incorporation without affecting the phase assemblage.
... According to certain regulations (European Directive 2008/98/CE), sediments extracted from watercourses (eg. in a reservoir) is considered as waste [1]. Work carried out by EDF manager of approximately 220 dams in France on raw dam sediments, allowed to determine five relevant sectors for the valorisation of this material [2]: the production of ceramic materials [3][4][5][6][7], the confection of road layers [8][9][10][11][12], the incorporation in mortar composition as a mineral addition [3,[12][13][14], the agronomical use [15,16], and the production of clinker [7,[17][18][19][20][21]. ...
... Aouad et al. [19] used fluvial sediment to replace a portion of the raw materials of Portland cement clinker. They demonstrated that Portland cement clinker could be successfully synthesised by using up to 39% sediment. ...
Siltation is a permanent threat to the operation of dams since it reduces its storage capacity. In Tunisia, the annual siltation of dams is estimated at 22 Mm3 / year. Sediments currently cover 20% of the total capacity of the reservoirs, which could be a national water security issue in the years to come. Considering that sediments contain the oxides, SiO2. Al2O3. Fe2O3 and CaO, as main chemical constituents, a partial replacement of the raw materials in the cement production is suggested. This work concerns dam sediments from different regions in Tunisia. Characterisation results show that studied sediments are suitable for a beneficial reuse in the clinker production. However, according to the chemical composition, the incorporation rate of sediments in the raw mix varies from one sediment to another but still relatively important, ranging between 9 and 27 wt%. The characterization of produced clinkers show that mineralogy depends on minor oxides contents, especially SO3. MgO and equivalent Na2O. It has been proven that it is possible to substitute natural materials with 27.4 %SS sediment. The obtained clinker is characterized by the presence of M1 C3S and orthorhombic C3A. The high free lime content associated to incomplete alite formation can be surmounted by increasing slightly the clinkerization temperature.
... Various treatments and reuse possibilities are available, such as brick production [5][6][7][8] or to replace a portion of raw materials in the production of Portland cement clinker [9,10], sometimes after applying an effective treatment, such as the Novosol process. Aouad et al. [9] showed comparable compressive strengths of a commercially produced Portland cement and a manufactured cement based on sediment. ...
... Various treatments and reuse possibilities are available, such as brick production [5][6][7][8] or to replace a portion of raw materials in the production of Portland cement clinker [9,10], sometimes after applying an effective treatment, such as the Novosol process. Aouad et al. [9] showed comparable compressive strengths of a commercially produced Portland cement and a manufactured cement based on sediment. ...
In a context of sustainable development, civil engineering must increasingly use recyclable materials to preserve natural resources. Sediments could be a solution in the context of their recovery in several areas. Uncontaminated marine sediments were used to partially substitute sand aggregate in the formulation of mortars. Five mortars were manufactured with different percentages of sand substitution. Physical, chemical, mineralogy, and mechanical characterization were carried out in order to investigate their possible use and impact in cemented-based materials. The mechanical strengths and the elastic modulus of mortars were analyzed. The hydration kinetics of the mortars were studied at different temperatures. The acceleration of the chemical reactions was also assessed through the determination of the apparent activation energy of mortars. Finally, the microstructure of two formulations of mortars was observed by Scanning Electron Microscope (SEM). Results show a drop of the mechanical properties with the increase of the percentage of substitution. This can be attributed to the natural composition of sediments and to the increase of the total porosity of the mixtures. The measured heat released of mortars increase with the increase of sediment content. This result suggests an additional chemical activity linked to the presence of sediments within the matrix.
... wet weight of fully immersed permeable brick m 22 : dry weight of permeable brick V : ...
... Zhu et al. [15] used the tailings mined by the mine as the binder, and melted the tailings waste at 1180-1200°C for 45 min to prepare the permeable brick with a permeable rate of 3 Â 10 À2 cm=s, with 20 wt% tailings; Xie et al. [16] prepared permeable brick with permeable rate of 1:08 Â 10 À2 cm=s at 1150°C, using sludge from waterworks as binder and sand with particle size range of 1.0 mm-1.4 mm for 1 h; Shi et al. [17] used the mixture of sodium silicate solution, fly ash and quartz sand as cementitious material, and added the feldspar quartz tailing with the particle size of 7 mm-10 mm as aggregate to prepare the permeable brick with the permeable rate of 2:44 Â 10 À2 cm=s; He et al. [18] used P•O 42.5R ordinary portland cement and polycarboxylic acid water reducing agent and steel slag aggregate with a particle size of 4.75 mm-7.1 mm to prepare permeable brick with permeability coefficient of 4:2 Â 10 À2 cm=s, but the strength development of cement-based materials requires sufficient hydration of the cement. Only after curing to a certain age can the strength that meets the performance requirements [19][20][21][22]. Therefore, cement as a binder material for porous materials still has certain disadvantages. ...
... In the literature, several reuse options for fine sediments were considered such as (i) construction of functional soils [6,7], (ii) sub-base layers in road or pavement construction [8][9][10], (iii) raw material for traditional ceramic bricks manufacturing [11][12][13] and (iv) partial replacement of sand in concrete production [14][15][16][17]. Beneficial reuse of fine sediment as a raw material to produce clinker was also investigated by different authors [18][19][20]. Aouad et al. [18] worked on a contaminated sediment from a waterway in Northern France. They obtained a satisfying clinker by introducing this sediment with a mass ratio of 39.1 wt%. ...
... Beneficial reuse of fine sediment as a raw material to produce clinker was also investigated by different authors [18][19][20]. Aouad et al. [18] worked on a contaminated sediment from a waterway in Northern France. They obtained a satisfying clinker by introducing this sediment with a mass ratio of 39.1 wt%. ...
The accumulation of fine sediments (<200 µm) occurs in hydroelectric dams due to watershed erosion and solid transport. A rigorous and sustainable sediment management is required. Although most of these materials are transferred into the watercourse downstream, a significant quantity might have to be managed as on-land waste in the future. Considering that sediments contain silica, alumina, calcia and iron oxide as main chemical constituents, they could be useful candidate raw materials in the cement industry for the manufacture of clinker. This work concerns sediments from French dams. Whatever their origin, each sediment is suitable for a beneficial reuse as silico-aluminous raw material for clinker production. The characteristics of the raw sediments can lead to specific microstructures in the clinkers. However, clinker characteristics can still be controlled by adjusting raw mix proportions, maintaining a rather high sediment content in the mix (between 10 and 15 wt%).
... Some authors studied the use of contaminated sediment to replace a portion of raw materials in the production of Portland cement clinker [32,33]. Aouad et al. showed that the laboratory manufactured cement based on the sediment produced the equivalent compressive strengths to those commercially produced Portland cement [32]. ...
... Some authors studied the use of contaminated sediment to replace a portion of raw materials in the production of Portland cement clinker [32,33]. Aouad et al. showed that the laboratory manufactured cement based on the sediment produced the equivalent compressive strengths to those commercially produced Portland cement [32]. Dang et al. investigated the new blended cements made of a mixture of Portand cement and 8%, 16% and 33% of thermally treated sediment at 650°C and 850°C. ...
... Among these, all producing/manufacturing techniques were involved with high-temperature treatment and thus were energy-intensive and costly [2]. Innovatively, dredged fluvial sediments were utilized as a novel supply of raw material to make Portland cement clinker; Portland cement clinker is very finely ground to produce Portland (hydraulic) cement [90]. The results indicated that Portland cement clinker can be synthesized by using up to 39% sediment. ...
This study systematically examined dredged materials from various aspects, including their sources, the volume generated annually, beneficial uses, and the management processes currently practiced. In addition, this paper presents the relevant policies governing the dredging, reuse, and disposal of dredged materials in the United States. A summary of various sources, types/classifications, and the physical and chemical properties of dredged materials used by various researchers are presented. This paper also summarizes the innovative techniques for the beneficial reuse of dredged materials in a wide range of applications in concrete materials, construction products, roadway construction, habitat building, landfill liner/cap, agriculture soil reconstruction, and beach nourishment. Further, limitations and corresponding solutions related to the beneficial use and management of dredged materials were provided in the end.
... De nombreuses études internationales indiquent diverses réutilisations bénéfiques des sédiments de dragage comme matière première dans la construction, à savoir : la construction de routes [78][79] , a production de ciment [80] [95]. À notre connaissance, il n'existe pas d'études qui se sont intéressés à proprement dit, à l'incorporation des sédiments de dragage marins en remplacement du sable dans les béton mousse. ...
L’utilisation de matériaux recyclés dans les bétons en remplacement du sable permet de répondre à un double enjeu : la nécessité de préserver la ressource naturelle menacée d’épuisement et la possibilité de régler la problématique de l’accumulation des déchets. L’étude, réalisée en partenariat avec le laboratoire de génie civil et géo-environnement, a pour objet d’évaluer l’effet de trois matériaux recyclés sur les propriétés du béton mousse en substitution au sable. Ces trois matériaux recyclés sont les sédiments marins issus du dragage, les mâchefers d’incinération des déchets ménagers, et la fibre de verre recyclée. Le choix s’est porté sur le béton mousse car il permet de réaliser des économies en énergie et en coût. En effet la présence de volumes d’air créés par la mousse, lui confère une faible densité, des propriétés d’isolation thermique et une bonne ouvrabilité. L’objectif attendu de ce travail est de déterminer comment les matériaux recyclés impactent les propriétés du béton mousse et de montrer s’ils peuvent constituer des alternatives intéressantes au sable. Pour cela, il a été choisi d’adopter une approche analytique consistant à étudier chaque élément séparément et à observer son effet sur les autres éléments. L’étude a été menée en deux temps : - une étude préalable des propriétés des matériaux et de leur interaction avec la mousse. - une analyse comparative des propriétés des bétons mousse dans laquelle le taux de substitution et la teneur en mousse ont été variés. L’effet des matériaux seul sur le mélange, l’effet de la mousse seule sur le mélange et enfin l’effet des matériaux sur le mélange avec mousse ont été étudiés.L’expérimentation a montré que les sédiments peuvent constituer d’une très bonne alternative au sable. Ils présentent en effet de bien meilleures performances mécaniques, une meilleure ouvrabilité, un meilleur rapport résistance/densité, et ce sans altération des propriétés d’isolation thermique, leur permettant une utilisation plus structurelle. Une modélisation des effets et une optimisation de la formulation ont été proposées. Les résultats des mâchefers se sont révélés concluants. Les bétons mousse obtenus ont présenté des propriétés variables selon le taux de substitution adopté. Cela a permis de conclure qu’ils pouvaient se substituer parfaitement au sable pour diverses applications. Il serait intéressant d’expérimenter un plus grand nombre de formulations de béton mousse à comme cela a été fait pour les sédiments. Les résultats sur la fibre de verre recyclé sont intéressants mais moins concluants que les sédiments et les mâchefers. Les bétons mousse obtenus sont plus légers et plus isolants pour des taux de substitution supérieurs à un certain seuil. Cependant les fibres ne semblent pas constituées un renfort et présenter de bénéfice mécanique.
... There exist already some fields of application where sediments are currently being recycled, such as road and road underlays construction [2] and bricks production [3][4][5][6]. Recently, studies have been focusing on reusing sediments as alternative materials in concrete to reduce the environmental impact resulting from cement manufacturing and limit the consumption of natural resources for concrete production [1,[7][8][9][10][11][12]. These studies have shown that incorporating sediments in cement, mortar, and concrete is very promising. ...
Due to the large volumes of sediments dredged each year and their classification as waste materials, proper management is needed to efficiently dispose of or recycle them. This study aimed to recycle flash-calcined dredged sediment in the development of an eco-friendly 3D-printable mortar. Mortars with 0, 5, 10, 15, 20, and 30% of flash-calcined sediment were studied. Two tests were carried out to determine the printability of the mixtures. First, a manual gun device was used to examine the extrudability, then a modified minislump test was conducted to assess the buildability and shape-retention ability of the mixtures. Furthermore, the flow table test and the fall cone test were used to evaluate the workability and structural buildup, respectively. The compressive strength was also evaluated at 1, 7, and 28 days for printed and nonprinted mortar specimens. In addition, isothermal calorimetry measurements were conducted on corresponding cement pastes. The results showed that it was possible to print mortars with up to 10% of flash-calcined sediment with the preservation of extrudability and buildability. The results showed that flash-calcined sediment shortened the setting time, decreased the flowability, and enhanced the shape-retention ability. Nonprinted samples with 5% and 10% of flash-calcined sediment showed a similar to higher compressive strength compared to that of the reference mortar. However, printed samples recorded an equal to lower compressive strength than that of nonprinted samples. In addition, no significant change in the hydration process was detected for blended cement pastes compared to the reference cement paste.
... A practical replacement of 3-6% of total feedstock material (dry mass basis) was recommended considering the factors of chloride scaling and SiO 2 burning. Aouad et al. (2012) [52] investigated the feasibility of DMs as novel supply of the raw material to produce clinker. The XRF analysis showed that cement made from DMs (39 wt.%) had a comparable chemical composition to OPC. ...
... Several studies have been demonstrated the feasibility of sediments reuse in different applications as the new materials for the road construction sector [13,14], mineral admixture in the mortars and concretes [12,[15][16][17] and raw materials for the cement manufacture [18][19][20]. The previous studies [18,20,21] indicated that the chemical composition of sediments principally consisted of four main oxides as SiO 2 , CaO, Al 2 O 3 and Fe 2 O 3 . In addition, their mineral composition contained the major phases as quartz (SiO 2 ), calcite (CaCO 3 ) and the minor clays phases as Illite, Kaonilite. ...
The dredged sediment has been used as an alternative material in the construction sector. However, it’s often necessary to apply the specific treatments in order to improve their reactivity and performance. The papar aims to investigate the pozzolanic reactivity of a river sediment treated by flash calcination method at calcination temperatures 650, 750, and 800 °C respectively to develop a novel pouzzolanic admixture for blended cement. The pozzolanic reactivity of flash calcined sediments was evaluated by using numerous analysis such as Fratini test, isothermal calorimetry analysis, lime consumption analysis and compressive strength development. The results clearly showed the detrimental effect of raw sediment on the cement hydration, resistance development and microstructure of mortars. However, flash calcined sediments clearly exhibited pozzolanic reactivity and considerably improved the microstructure, mechanical performance with a same substitution rate. The results demonstrated that flash calcination could be used as a suitable treatment method to produce a new supplementary cementitious materials of low—CO2 blended cement.
Graphical Abstract
... The beneficial uses of dredged sediments in construction materials have been discussed in many forums. Dredged sediments have been successfully valorized in the manufacturing of Portland cement [11][12][13], aggregates [14], as well as in bricks production [15][16][17][18][19], and roads [20]. ...
The valorization of dredged sediments is a promising solution to reduce the strain on natural resources, which is in line with sustainable development goals. This study aims to evaluate the potential valorization of dredged sediment in manufacturing compressed earth blocks (CEBs). The CEBs were stabilized by a combination of fly ash (FA) with sodium hydroxide (NaOH). The stabilization was achieved by partial substitution of sediment for fly ash with six different percentages 10, 20, 30, 40, and 50% by weight. The CEBs samples were characterized in terms of structural, microstructural, mechanical, and thermal properties. The results showed that increasing FA content significantly improves the mechanical strength of CEBs, dry compressive strength ranges from 2.47 MPa to 9 MPa, whereas wet compressive strength ranges from 0.95 MPa to 6.9 MPa. The mechanical performance is related to the amount of alkali-activated fly ash gels, which bind the sediment grains and makes the CEBs more compact and resistant. The optimal dosage of alkali-activated fly ash to replace the sediment was between 10 and 20%. In this substitution range, mechanical performance and physical properties improved significantly. In addition, the thermal properties varied slightly with alkali-activated FA content.
... Focusing on environmental problems, some Algerian scholars have tried to use the sludge dredged from dams, particularly the K'sob dam, as a cost-effective natural binder compared to Portland cement, the yield of which is subjected to production conditions in cement plants [8,9]. Other researchers emphasized on the strength and durability after a portion of Portland cement is replaced with the sludge dredged from dams [10,11]. ...
This paper attempts to simulate the use of green materials from the silt in a dam, and reduce the harmful impacts of siltation on Algerian dams affected by frequent droughts and irregular rainfalls, which are resulted from climate change. These harsh weather conditions are the main cause of water erosion in Algeria, leading to a high silting level in many dams across the country. Therefore, it is necessary to dredge the considerable volumes of sludge in the dam areas. This paper treats the sludge dredged from the K’sob dam, and adds the treated sludge into cement, creating a hybrid binder that can be used in composition of cementitious materials. Specifically, the sludge extracted from the K’sob dam was characterized chemically, physically, mineralogically, and mechanically, and introduced both as a substitute of cement and a component in the mixture of ordinary concrete/mortar. The sludge was firstly activated through calcination, and added to cement at the mass dosages of 10%, 15%, and 20% separately. The mechanical behavior, especially that under compression, of cementitious materials (concrete/mortar) based on the treated sludge was studied through lab tests. The test results show that this technical innovation gives the finished product three major properties, namely, high strength, economy, and a beneficial ecological impact. The results obtained are encouraging and promise an optimal exploitation of the sludge from similar dam areas.
... These drugged harbour sediments have mineral compositions similar to the raw material, which could be a resource used in construction materials with or without treatment (Charlier et al. 2002). A possible application for recycled dredged material is as a raw material for construction materials such as road construction (Achour et al. 2014;Zentar et al. 2009), mortar production (Couvidat et al. 2016;Zhao et al. 2018), Portland cement clinker production (Aouad et al. 2012;Dalton et al. 2004), concrete production (Rozière et al. 2015;Junakova et al. 2015). ...
The aim of this study was to recycle dredged sediments as an alternative raw material in the production of ceramic tiles. The effect of the substitution of kaolin by raw sediment (HDS) and calcined sediment (HDSC) in the mixture of the ceramic tile samples sintered at 1100 and 1200 °C was studied. The samples were prepared with different proportions of HDS and HDSC (0, 10, 20 and 30 wt.%) substituting kaolin. The mineralogical analysis of the samples shows that mullite phase disappears in the samples incorporating raw sediments (HDS) and fired sediments (HDSC) leading to the formation of new crystalline phases such as anorthite and diopside.Moreover, ceramic tile samples with 20 wt.% of calcined sediment improve its densification and hence the compressive strength (171 MPa) and thermal conductivity (0.555 W/mK). An evaluation of the leaching was carried out in the ceramic samples, finding that the concentrations of heavy metals in the leachate were within the safety limit established by the USEPA. The heavy metals were immobilised in the ceramic matrix. Therefore, the results showed that dredged sediment (HDS) and calcined sediment (HDSC) could be used as substituent of kaolin to produce eco-friendly ceramic building materials as floor tile ceramics.
... Geleneksel bertaraf yöntemlerin çevresel etkileri, çevre koruma düzenlemelerinin getirdiği sınırlamalar ve 2016 yılından beri Türkiye'nin taraf olmaya başladığı Londra Sözleşmesi gereğince dip tarama malzemesi atık olarak değil bir kaynak olarak görülmeye başlanmıştır [1,6]. Dip tarama malzemeleri inşaat mühendisliğinde çimento üretimi [7][8][9], agrega üretimi [10][11][12], beton üretimi [13,14], tuğla üretimi [15,16], yol alt yapı tabakalarında kullanımı gibi faydalı kullanım alanları belirlenerek çalışmalar yapılmaktadır. Geçmişte Türkiye'nin Barselona (1976) ve Bükreş (1982) Sözleşmelerinin gerekliliklerini yerine getirmesi zorunlu olduğu halde mevcut ulusal yönetmelikler dip tarama malzemelerinin atık yönetimi kriterlerinin belirlenmesi açısından yetersiz kalmaktadır. ...
Günümüzde, çeşitli amaçlarla gerçekleştirilen deniz tarama uygulaması sonucunda elde edilen malzemeler artık atık olarak görülmemekte ve farklı alanlarda yeniden kullanım potansiyelleri araştırılmaktadır. Bu çalışmada, denizlerde yürütülen tarama işlemleri sonucunda elde edilen malzemelerin çimento ve kireç katkısı ile iyileştirilerek, mühendislik özelliklerinde ki değişimler incelenmiş ve bu iyileştirme sonucunda dip tarama malzemesinin yol altyapı tabakalarında yeniden kullanım potansiyeli irdelenmiştir. Saf halde bulunan ve hazırlanan karışımlar üzerinde Kıvam limit deneyleri, minyatür kompaksiyon ve serbest basınç deneyleri uygulanmıştır. Serbest basınç deneyi 1,7 ve 28 gün gün kür koşulları için tekrarlanmıştır. Yapılan deneyler sonucunda, eklenen çimento ve kireç oranının artmasıyla numunelerin plastik limitlerinin arttığı ile buna bağlı olarak plastisite indislerinin azaldığı tespit edilmiştir. Tüm oranlardaki çimento ve kireç katkıları ve artan kür süresi, malzemenin serbest basınç dayanımını arttırmıştır. Yapılan çimento ve kireç katkısı ile zemin özelliklerinin iyileştiği ve yol altyapı tabakalarında kullanıma uygun olduğu tespit edilmiştir.
... Based on previous studies [23,[26][27][28][29], the compressive strength of the cement paste was measured on the cube of dimension 1×1x1 cm 3 under a constant stress of 0.3 MPa/s using a uniaxial press at 2, 15 and 28 days of hydration. For each measurement, 6 samples were tested. ...
Cement paste hydration is a complex physical-chemical process. The aim of this paper is to use three approaches to determine the degree of hydration: portlandite quantification, scanning electron microscopy and bound water quantification. In order to investigate the physical-chemical and mechanical properties, as well as the hydrates generated. Portland cement was synthesized and characterized in the laboratory. At all hydration durations, the portlandite quantification method and SEM-BSE image analysis show similar results. The method of SEM images analysis requires time to gather and process images, but is unaffected by the type of hydrates produced. The bound water quantification method gives a lower degree of hydration than two other methods at all hydration times. To test the reliability of these procedures, the compressive strength was calculated based on the degree of hydration. The results indicate that the portlandite quantification method and SEM-BSE image analysis are more accurate than the bound water quantification approach in terms of reproducing the experimental results.
... In the last decade, dredged sediments have been considered as a waste, but they are no longer stored or landfilled and they can be used as a commercial material in many cases. Several studies have investigated the use of dredged sediment as civil engineering materials : brick [3][4][5], lightweight aggregates [6,7], supplementary cementitious material for blended cement [8][9][10], Portland clinker [11], stabilized road-base [12][13][14], paving blocks [15,16], etc. ...
A very significant quantity of sediments are dredged all over the world. Many previous studies demonstrate that this materials can be used as a cementitious supplementary material. In this paper, the raw sediments were dried, sieved, and thermally treated in order to eliminate organic matter and activate the minerals. The physical, chemical, and mineralogical properties were determined for the raw and treated sediments. Blended self-compacting mortars were formulated by substituting partial Portland cement with sediments. The compressive and bending strength, and dynamic modulus of elasticity were tested for different deadlines (7, 28, 60, and 90 days). The fresh properties of the pastes were investigated as well. The results shows that sediments can be used as a replacement of cement up to 12% of the volume of cement while maintaining the fresh compactibility properties.
... This replacement allows not only to preserve the natural resources and to recover wastes, but also to reduce the CO 2 emissions. Different types of wastes have been studied in the literature in order to produce cement, and mainly OPC cement, such as red mud [10], steel slag [11], sediments [12,13], recycled concrete aggregate [14], oil based mud cutting [15], oyster and scallop shell [16] etc. ...
The amount of bottom ashes generated from the municipal solid waste incineration is increasing considerably. Therefore their recycling is necessary in order to limit the landfilling that presents environmental issues. The aim of this paper is to recycle Municipal Solid Waste Incineration Bottom Ash from the north of France; as a secondary raw material for Portland cement clinker production. In this order Municipal Solid Waste Incineration Bottom Ash is characterized and then used to substitute raw materials for clinker production at laboratory scale. Substitutions rates up to 12.4% have been tested. The produced clinkers have been characterized by X-Ray Diffraction and the crystalline phases were quantified by Rietveld analysis. The microstructure has been studied by scanning electronic microscopy. After adding gypsum, the compressive strengths of the corresponding cements were measured at 1, 7 and 28 days. The mineralogical composition of the 28 days hydrated cement pastes were studied by X-Ray Diffraction. The results show that up to 12.4% of Portland cement raw materials can be replaced by the Municipal Solid Waste Incineration Bottom Ash without changing the mineralogical composition. In addition the compressive strengths of the cement pastes produced with Municipal Solid Waste Incineration Bottom Ash are equivalent to the one without bottom ash.
... En outre, ils ont démontré qu'une teneurélevée en chlorure de sédiments marins n'augmente pas la teneur en chlorure de produit final. Aouad et al. [36] ont travaillé sur un sédiment fluvial. Les résultats ont montré que le clinker de ciment portland peutêtre produit en utilisant 39% de sédiments (la température maximale de calcination est de 1450°C). ...
Les sédiments de dragage, classés aujourd'hui comme déchets, semblent être une alternative prometteuse aux matériaux conventionnels. Les opérations de dragage, réalisées par la Direction Territoriale du Bassin de la Seine (DTBS), génèrent un volume annuel des sédiments d’environ 150 000 m3. Dans cette thèse, nous nous intéressons tout d'abord au potentiel de valorisation de ces sédiments en tant qu'alternative aux granulats ou au ciment (comme addition). Pour ce faire, une étude de variabilité du gisement francilien et de son effet sur les propriétés du béton est réalisée. La compilation des propriétés du gisement montre que 30 % du volume dragué pourrait être considéré comme une source stable et propre de granulats, alors que les sédiments non inertes ne représentent que 6 %. L'étude expérimentale montre que la substitution de 30 % en volume des granulats ou la substitution de 10 % en volume de ciment respectivement par des sédiments grossiers ou par des sédiments fins affecte que légèrement la cinétique d'hydratation, la résistance à la compression et le retrait. Ensuite, nous avons approfondi l’effet de la matière organique des sédiments sur les propriétés rhéologiques, physico-chimiques (hydratation et retrait) et mécaniques d’une pâte de ciment. Les résultats obtenus montent que les substances humiques, matières organiques présentes dans les sédiments, ont un effet analogue à celui des lignosulfonates de calcium, un plastifiant, tant sur la cinétique d'hydratation que sur la rhéologie de la pâte cimentaire. La dernière partie de la thèse traite de l’effet de l’incorporation des coquillages sur les propriétés mécaniques et de durabilité du béton. Cette partie est scindée en deux volets ; un volet expérimental et un volet numérique. Le premier a comme objectif d’évaluer l’effet de l’incorporation des coquillages, comme graviers, sur les propriétés macroscopiques des bétons (propriétés mécaniques et propriétés de durabilité). Les résultats expérimentaux montrent qu'il n'y a aucun effet de l'incorporation des coquillages sur l'affaissement, le retrait et les propriétés de durabilité (la porosité, la diffusion des ions chlore et la carbonatation) du béton pour des substitutions inférieures à 20 %. En revanche, les propriétés mécaniques diminuent avec l'augmentation du taux de substitution; pour une substitution volumique de 20 %, la résistance à la compression et le module élastique diminuent respectivement de 20 % et 17 %. Le volet numérique a pour objectif de construire un outil numérique cohérent permettant de prédire les propriétés mécaniques et de diffusion d'un béton en fonction de sa composition et des paramètres physiques et géométriques de la microstructure. Par des observations microscopiques (MEB) et en modélisant les coquillages comme des inclusions plongées dans une matrice cimentaire, nous montrons que l'adhésion entre le coquillage et la matrice est limitée, et doit être prise en compte pour estimer les propriétés des bétons à base de coquillages
... In a preservation context of natural raw resources, marine sediments are positioned as potential alternative mineral granular resources for construction. Most studies have been led on the use of treated sediments in cementitious matrices (Aouad et al. 2012). A literature review on sediment recovery in SCC shows that the thermal treatment of sediment has several advantages (removal of the organic matter part, improvement of the rheological properties of SCC, removal of sediment agglomerates during mixing, activation of long-term pozzolanic properties, stabilization of heavy metals, etc.) (Safhi et al. 2019). ...
Environmental and ecological issues have led to the development of new sustainable channels for the recovery of dredged sediments. One of the major difficulties of sediment valorization lies in particular in its very heterogeneous composition. For example, the presences of heavy metals and organic matter have a significant influence on the environmental impact of materials formulated with sediment. Some heavy metals such as antimony, mercury, lead, and cadmium in high concentrations are dangerous to the body. Trace metals trapped in sediments are transformed through complex biogeochemical processes. They subsequently associate with organic matter to form clay-humic groups that define the degree of sediment pollution. The Harbour Dredging Sediments (HDSs) used were classified as non-hazardous waste in accordance with Directive 12/12/14/EC. The purpose of this study is to evaluate the environmental impact of the use of HDS from active lagoon in the formulation of self-compacting concrete (SCC) with the objective of incorporating a high sediment content, obtaining materials with a low environmental impact and ensuring compressive strength of a C25/30 class concrete. Three HDSs are being studied that have a significant impact their difference by their fines content at 125 μm. Sediments recovered from the active lagooning process have not undergone any physical, chemical, or thermal treatment. The DMDA (Densified Mixture Design Algorithm) method is used to optimize the composition of “sediment” SSCs. The communication focuses on mortars equivalent to these “sediment” SCCs (SCMs). Sediment represents about 20% of the granular composition with a sediment-to-cement ratio of 80%. Compressive strengths are greater than 25 MPa and tensile strengths are in the range of 3 to 8 MPa at 28 days of curing. From an environmental point of view, all heavy metals are stabilized except nickel. In particular, there has been a considerable decrease in the levels of sulfate, total organic carbon, and chloride. The different SCMs are classified as inert, clinker hydration produces hydrates that capture and stabilize heavy metals in the cementitious matrix. The results obtained show that HDSs could be used as a secondary raw material in the formulation of self-compacting concretes.
... Light-burned MgO cement, also referred to as carbon negative cement uses light-burned MgO obtained by calcining magnesium carbonate at low temperatures below 1000 °C. This is the primary raw material and is capable of absorbing carbon dioxide during the curing process (Harrison 2001 (Chui, Liu and Tang 1992), approximately 450 °C lower than the 1450 °C (Puertas et al. 2008;Chen et al. 2010;Aouad et al. 2012) used for OPC. As a result, the environmental impact of burning fossil fuels can be reduced (Dung and Unluer 2016). ...
Light-burned MgO cement has a lower calcination temperature than ordinary Portland cement. It has been widely studied as a measure to reduce carbon dioxide because of its property of absorbing carbon dioxide during curing. This study investigated the effects of calcination temperature on the physical properties of light hydrated magnesium carbonate and calcined MgO hydrated in moisture and CO2 at 25 °C and 60 °C. The crystal size of light-burned MgO increased with increasing calcination temperature, and carbonates were formed through carbonation curing. Further, nesquehonite and hydromagnesite were formed in the 25CC and 60CC specimens, respectively, and the carbonate formation reduced with increasing crystal size. The highest compressive strength of 3.5 MPa was obtained for the 25CC specimen in which nesquehonite was formed; however, hydromagnesite exhibited better CO2 sequestration capacity.
... Pour cela, le recyclage des déchets, des résidus et des sousproduits naturels ou industriels sont devenues un enjeu clé pour la réduction de la consommation des matières naturelles. Ces matériaux peuvent êtres valorisés selon plusieurs voies : soit en remplaçant une partie des matières premières pour fabriquer le ciment, soit en remplaçant les agrégats pour la formulation des bétons et des mortiers.De nos jours, les sédiments constituent des matériaux de plus en plus étudiés pour des utilisations en Génie Civil[12,15,17,18,108,109]. La plupart de ces études s'accordent sur la faisabilité de cette valorisation. ...
Sedimentation at the bottom of rivers and ports exposes an economic and environmental problem. Strict regulations on environmental protection lead managers to find alternative solutions to conventional methods of stockpiling or immersion of dredged sediments. The work in this thesis focus on the use of combined marine sediments and oyster shell as a construction material to make new composite cement that can be used industrially. After identification of the physicochemical characteristics, the raw materials are treated at high temperature to remove all organic compounds and activate clay minerals. The treated materials were then mixed in order to obtain a composition close to that of Portland cement. New blends are selected to replace 8, 16, and 33% by weight of Portland cement CEM I 52.5. Bearing in mind the hydraulic, physical, and mechanical characteristics, the durability of new binders under the influence of carbonation and chloride diffusion was also investigated. According to the EN 197-1 standard, new binders could be used up to 16% for 52.5 Class cement and 33% for 42.5 Class cement. The addition of new binders influences on the microstructure of the cement matrix and contributes to improve the transport properties. However, the use of these binders requires a longer curing time for the best hydraulic, mechanical, and transport properties.
... To reduce the damage to the surrounding environment, the cement industry is experimenting with methods for using byproducts and wastes as alternative materials for cement manufacturing. Such materials may replace silicon-aluminum (Aouad et al., 2012;Canpolat et al., 2004;Puertas et al., 2008;Tsakiridis et al., 2004), iron (Cao et al., 2019;Lin et al., 2018;Popescu et al., 2003;Tsakiridis et al., 2008;Young and Yang, 2019), and conventional raw materials in the cement. However, these waste products have limitations on their reuse proportion as supplementary materials in cement-clinker production; thus, it is necessary to find alternative materials to replace limestone and thereby reduce environmental pollution. ...
... In cement mortars manufacturing [15][16][17], the objective of these studies is to investigate the effect of the partial substitution of sand or cement by dredged sediments on the mechanical behaviour of cement-based building materials, the results of strength and durability tests concluded that these sediments could be used as raw construction materials. As artificial aggregates [18], the objective is to manufacture artificial aggregates from dredged sediments to stabilize coastal erosion by reloading beaches. ...
Bricks manufactured, based on dredged sediments extracted from Tangier and Larache ports in Morocco were investigated. Chemical, physical, geotechnical, mineralogical and environmental characterizations studies of ports dredged sediments were performed. Partial substitution of natural clay by dredged sediments was achieved with different substitution rates by weight (20%, 40%, 50%, 60% and 70%) to manufacture brick samples at the laboratory scale. The compressive strength was the factor determining the optimal substitution rate of the natural clay. Compressive strength values of fired bricks with different rates of sediments incorporated show that the manufactured bricks have mechanical characteristics relatively close to natural clay until 60% substitution for Larache port dredged sediment (SL) and until 50% for Tangier port dredged sediment (ST). The results in this study confirm that dredged sediments from the ports of Tangier and Larache can be used as an alternative raw materials resource for the manufacturing of fired bricks.
... In addition, thermal treatment at 650e850 C would transform the clay in sediment into calcined clay and decompose the calcium carbonate into calcium oxide which would contribute to the hydration (Dang et al., 2013). For instance, Aouad et al. (2012) reported the utilization of MDS to produce cement clinker considering lime saturation factor, silica ratio and alumina ratio following the traditional procedure of producing cement clinker. Another representative pre-treatment method is Novosol® process featured by stabilization of heavy metals by phosphatation and destruction of organic materials by calcination (Dia et al., 2014;Zoubeir et al., 2007). ...
In this paper, the properties of concrete made with marine dredged sediment (MDS) were investigated both qualitatively and quantitatively with an emphasis on the strength. Annually, a huge amount of marine sediment is dredged and disposed of largely as waste, causing serious environmental problems. To minimize such disposal, the use of MDS for in-situ concrete production is a promising solution. However, the properties of marine sediment concrete (MSC) so produced is still not easy to predict up to now. To make full use of MDS and better understand MSC for more viable mix design, this study reviewed the properties of MDS and MSC and discussed a broad range of influencing factors from which key factors were identified using the data of 112 mixes in the literature. Moreover, the key factors were quantitatively correlated to strength and such correlation yielded a prediction equation with fairly high accuracy. This study on the use of MDS with the least pre-treatment shall advance the design of in-situ MSC to meet specific engineering requirements and enhance the sustainability.
... Many international studies indicate various beneficial reuses of dredged sediments as a raw material in construction, namely: road construction (Kamali et al., 2005(Kamali et al., , 2008Scordia, 2008), cement production (Aouad et al., 2012;Benzerzour et al., 2017;Dalton et al., 2004;Dang et al., 2013;Du and Pang, 2018), and aggregate replacement for mortar or concrete manufacturing (Agostini et al., 2007;Ben Fraj et al., 2012;Limeira et al., 2011;Mymrin et al., 2017;Said et al., 2015;Wang et al., 2017Wang et al., , 2018. Reusing sediments as concrete aggregates offers both economic and environmental prospects. ...
Dredged river sediments may potentially be reused as aggregate in concrete production. The variability of dredged sediments has been quantified by measuring their concentrations of heavy metals, several distinct pollutants, specific granular fractions and organic content at various locations in the Seine River watershed over three years (2015–2017). It has been shown that the sediment deposit does not significantly change from one year to the next, while the organic content, which delays cement hydration, concentrates in the finest fraction removable by sieving. Moreover, 30% of sediment volume is mainly sand and readily reusable in the form of concrete aggregate. Various sediments have thus been sieved to coarse aggregates, sands and fines in order to formulate concretes. Substituting 30% of aggregate volume by the resulting coarse aggregates or sands, once depleted of silt and organic matter: marginally affects hydration, extends setting time to just under 3 h, decreases compressive strength by 10%, and increases shrinkage strain by 15%. In contrast, the finest part of the sediment significantly alters these properties, owing to its soluble organic matter and silt contents.
... Such valorization includes the fabrication of bricks (Samara et al., 2009), ceramic products (Xu et al., 2014), lightweight aggregates (Liu et al., 2018), and road construction materials (Kasmi et al., 2017). Recent studies have demonstrated that thermally treated sediments can render the sediments more reactive and that treated sediments can be useful for clinker production (Aouad et al., 2012;Faure et al., 2017) or as SCM. Dang et al. (2013) designed a new blended cement containing 8%, 16%, and 33% of treated sediments from the trap Lyvet on the Rance River in France. ...
Several studies have proven the use of dredged sediments as supplementary cementitious materials (SCMs), but limited information is available on the effect of such treated sediments on self-consolidating concrete performance. The main objective of this study was to evaluate the performance of self-consolidating concrete (SCC) fabricated with treated sediments. The sediments were thermally treated at 800 °C for 1 h. The packing density of the granular skeleton was optimized to reduce the paste content and produce SCC with relatively low binder content. Three different SCC mixtures were prepared with 0%, 10%, and 20% cement replaced with treated sediments by mass. Key fresh, physical, hardened, and microstructural properties of the investigated SCC mixtures subject to different curing regimes were evaluated. The test results showed that the optimized SCC mixtures exhibited adequate self-consolidation characteristics. The particle size and high chemical activity of the sediments led to pore refinement of micro-pores, increased density, improved microstructure, and reduced micro-cracks of the investigated SCC mixtures. Furthermore, the use of up to 20% of treated sediments resulted in a compressive strength of 66 ± 1 MPa at 91 days, which is comparable to that of the reference mixture made without any sediments. Leaching test results confirmed the ecological potential of producing SCCs based on sediments, which could be an interesting alternative of using local materials to reduce the high demand of cement, thus further reducing the CO2 footprint of concrete structures.
... Such materials can be considered as promising alternative for conventional agregates in the construction sector. To date, research on sediments reuse in cementitious materials either as aggregates [1][2][3][4][5][6][7] or as alternative for cement [8][9][10][11][12][13] dealt with treated sediments by: neutralization, washing, heat treatment or bio-remediation to eliminate the harmful effects of pollutants such as organic matter. Indeed, European Standard EN12620 + A1 requires limiting the proportion of aggregate containing organic matter so that the setting time of the control mortar does not exceed 120min and the reduction of the compressive strength of the reference mortar remains lower than 20% at 28-day [14]. ...
Dredged river sediments may contain various types of organic matter that can affect the properties of a cement matrix, with the most representative part of such organic matter consisting of humic substances (HS). This work seeks to investigate the effects of humic substances on the rheology, the hydration and the strength development of a cement paste with different curing times, ranging from 1 to 90 days. Results show that adding organic matter to the cement paste offers greater workability by decreasing the yield stress. This addition also serves to retard the hydration of cement particles. Setting times increase to beyond one week when raising the amount of humic substances in the mixture, while the released heat ultimately reaches values comparable to those of the reference cement paste. Therefore, the addition of organic matter negatively affects strength development of the paste, especially at an early age; no resistance at 1-day has been noticed for HS content greater than 1%. Nevertheless, there was no significant reduction in the compressive strength up to 20% for HS content less than 1% at 90-day. In parallel, a study on pastes containing calcium lignosulfonate (water reducer) is carried out and the same effects are observed.
... Production of bricks has been successfully demonstrated in several cases [1][2][3]. Also use as resource for lightweight aggregates [4], stabilised road-base [5,6], Portland clinker [7] and supplementary cementitious materials (SCM) for blended cements [8,9] have been investigated. Clearly, use as resource for construction materials is a preferred application route. ...
This paper aims to assess the influence of flash calcined dredging sediments (CFC), having pozzolanic reactivity, on the early-age hydration and autogenous deformation behaviour of blended cements, where cement is replaced by 20, 30 and 40% of CFC. The results indicate that the early-age hydration behaviour of a CFC blended cement is similar to the early-age hydration behaviour of a fly ash blended cement. Furthermore, CFC acts as an SCM that decreases autogenous shrinkage. This is attributed to an increased early-age swelling, and to the dilution effect and formation of different hydration products. The observed swelling is most probably due to the increased ettringite content and higher sulphate to alumina ratio, ensuring a crystallisation pressure as a result of supersaturation of the pore solution towards ettringite formation. Besides its pozzolanic reactivity, the decreased autogenous shrinkage that CFC is generating in blended cements, is encouraging for its use as a novel SCM that reduces early-age cracking risk of concrete, hereby improving concrete durability.
... Dredged sediments have been considered as waste [6]. However, several studies have investigated the beneficial reuse of sediments in the field of civil engineering: in bricks [7], as lightweight aggregates [8], supplementary cementitious material for blended cement [9], Portland clinker [10], stabilized road-base [11], in paving blocks [12], etc. Due to the importance of this topic, several research and industrial programs on sediment management have been launched: PRISMA Self-compacting concrete (SCC) is a recent generation of concrete developed in Japan in the 80's. It was designed to facilitate the placement of concrete in heavily reinforced forms without vibrating the mixture. ...
This paper deals with the prospect of recycling dredged sediments in self-compacting mortars (SCM) and their impact on the fresh and hardened properties of SCC pastes/mortars. The raw sediments were dried, sieved to 120 μm, and then thermally treated at 850 °C for one hour. Physical, chemical and mineralogical properties were determined for all materials. Fifteen mortars/paste mixes were prepared using the response surface methodology, based on the variation of three independent parameters: water-to-binder, sediments-to-cement, and volume-of-binder-to-total-volume ratios. The responses were the workability and fluidity of the self-compacting pastes, and the mechanical properties of the self-compacting mortars (compressive, bending strength, and dynamic modulus of elasticity). A numerical optimization was used to select the optimal mixture with the maximum amount of treated sediments, while maintaining self-compactibility properties.
... In the cement industry, finding a less expensive binder using wastes and natural resources, such as silt from sediments dredged from dams (Benamara et al. 2013;Bourabah et al. 2015;Remini and Bensafia 2016;Remini 2017), particularly Chorfa dam (western Algeria), has become a major concern in facing the shortage in the production of Portland cement (Lin and Lin 2005;Ouhba and Benamara 2009;Aouad et al. 2012). ...
Hydraulic facilities are subjected to significant siltation which, in a very short period of time, can render them unusable. In Algeria, the silting-up of a great number of dams, built for drinking water needs and for irrigation, implies the necessity and urgency to take action. Therefore, the maintenance work, which leads to dredging the deposited silt, constitutes an unbearable obligation for the preservation of the environment. Chorfa dam (western Algeria) may be mentioned as a concrete example. This study is part of a long research whose objective is to contribute to the valorization and the optimization of the formulations economically that are easy to implement and which enable to use the dredged materials in the formulation of ordinary concretes by partial substitution to cement (10, 20 and 30%) of dredged sediments, after calcination at 750 °C to make them active. Tests were carried out on concrete that was vibrated in the fresh state (setting time) and hardened state (compressive strengths and durability of concrete exposed to sulfuric acid attack) in order to determine their characteristics. The results obtained confirmed the possibility to develop concretes containing calcined silt, with proportions up to 30%, and which can meet the economic, ecological and technological objectives.
... Based on very low leaching of heavy metals and arsenic the product was found safe for the humans and the environment. Aouad et al. [17] have used the river sediments (up 39%) in the mixture for the production of clinker and cement. The resulting new cement had a 20% higher compressive strength in comparison to the conventional Portland cement (CEM I 52.5). ...
The purpose of this study was development of the optimal conditions for the inertization of the polluted marine sediments using groundwater treatment sludge highly enriched in iron and aluminum. For that purpose fine-grained sediment (>85% clay and silt fraction) highly enriched in copper and zinc was amended with the waste sludge (from 10% to 50%). The sample with the optimum percentage of the waste sludge was further subjected the thermal treatment at 200–800°C. The efficiency of the treatment was determined by the leaching tests and toxicity testing using Hordeum vulgare L. as biosystem. The percentage of the seed germination, the root elongation, and the germination index before and following the treatment were determined. Untreated sediment leachate caused significant arrest in the percentage of the seed germination (6.7 ± 6.7%), the root elongation (1.9 ± 2.2%), and the germination index (0.2 ± 0.3%) with EC50 of 24.9%, suggesting a significant toxic potential of the sediments. After amendment with 30% of the waste sludge the concentrations of the considered micropollutants decreased below regulated values while all three toxicological parameters showed no significant difference compared to the negative control. The toxicity of the sediment was completely removed following the thermal treatment at 400°C.
... Rozière et al. [14] used 7.9 dwt% (percentage of total dry mass) of pre-treated sediments (thermo-chemical treatment) as filler in self-consolidating concrete. Aouad et al. [15] incorporated 25.74 dwt% of sediments to be introduced into the kiln for Portland cement clinker production. After a thermo-chemical pre-treatment, Lafhaj et al. [16] produced clay bricks substituting clay by pretreated sediments (from 25 to 45 dwt%). ...
Sediments valorization (recycling) has revealed limitations due to different restrains and practical difficulties. When it comes to different recovery methods, the possibility of valuing diverse types of sediments still needs to be defined. Using a statistical approach, the present study aims to quantitatively estimate the mechanical resistance of stabilized sediments. A database that included 22 fine sediments is selected and assembled from the literature. These sediments were treated with distinct types and quantities of additives (fillers and/or binders). The present study includes two parts. On one hand, using multivariate linear regression tool of XLstat software, an analytical model that highlights the effects of various parameters influencing the mechanical resistance of treated sediments after 28 days is obtained. This model showed that organic matter content and plasticity index are the most significant factors of sediments characteristics, while cement is the best mechanical strength booster. On the other hand, the evolution of treated sediments mechanical resistance over time is modelled by an exponential relationship using a least square regression method. Both models showed acceptable accuracies compared to a panel of selected experimental values.
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... Such a huge amount of dredged soils can be reused as an alternative to natural soil resources in civil engineering. The application domains of dredged soils include road base materials (Wang et al. , 2013a, embankments (Levacher and Sanchez 2011), brick production (Hamer and Karius 2002;Samara et al. 2009), cement production (Dalton et al. 2004;Aouad et al. 2012), concrete production (Chen et al. 2012a), and aggregate production (Wei et al. 2011;Chen et al. 2012b). It should be emphasized that the authors have conducted a systematic research on the beneficial reuse of dredged Dunkirk soils and proven the feasibility of stabilized soils as road base materials by an in situ test road (Zentar et al. 2008;Siham et al. 2008;Dubois et al. 2009;Zentar et al. 2012;Miraoui et al. 2012;Wang et al. 2012aWang et al. , 2013aAchour et al. 2014). ...
Very few studies have been carried out to investigate the durability and swelling behavior of dredged marine materials. To tackle this issue, this study mainly considers the influence of water immersion and thawing-freezing on the stress-strain characteristics and swelling property of 16 designed soil mixes with cement, lime, and Class-F fly ash. The unconfined compressive strength, failure strain, deformation modulus, and their quantitative corelationships are discussed in detail to evaluate the mechanical performance of stabilized materials damaged by water immersion and thawing-freezing. The result reveals that binder type and binder content have an important influence on the position and shape of stress-strain curves, compressive strength, deformation modulus, failure strain, and failure mode. The derived relationships between unconfined compressive strength and deformation modulus/failure strain are quantified, taking into account ageing effects. To quantitatively estimate the strength degradation, a coefficient of strength loss is defined for evaluating the effect of thawing-freezing and water immersion on compressive strength. Moreover, three-stage modes are proposed for depicting satisfactorily the stress-strain curves and swelling-time curves. A combination of relative swelling percent and absolute swelling amount, which can be reduced by chemical stabilization, is used to reasonably describe the swelling potential of stabilized soils.
Nearly 170 million tons per year of waste rice husks are produced worldwide, which pollutes the environment and poses health risks. RHA has become a potential threat to the ecosystem and needs real solutions. The direct disposal of RHA into open land or water bodies causes environmental pollution. One of the possible solutions is to utilize RHA additive to cement, lime, basalt fibers, Carbide slag, etc. This paper summarized the fundamental properties of soil and rice husk ash and its application in ground improvement and environmental protection. A comprehensive review of the literature available on RHA-soil mixture was performed to identify the gaps in understanding the behavior of the mix in terms of mechanical properties, durability, environmental impact, and internal mechanism. The results showed that adding RHA may significantly improve the soil's compressive strength, shear strength, and CBR value, which would be advantageous for both the economy and the environment.
Additionally, it can significantly enhance soil performance in terms of shrinkage cracking. Generally, the full use of RHA as an addition for cement/lime, etc., in-ground improvement is promising since it can result in energy savings, low carbon emissions, and sustainable development. However, using control burned RHA with high amorphous silica content, conducting soaked CBR tests, consolidation tests, and freezing/thawing tests to analyze the effects of RHA on the geotechnical properties of soil still need to be studied further.
The construction industry is one of the main sectors responsible for today’s climate change as well as the extraction of large volumes of raw materials for concrete manufacturing. At the same time, significant volumes of sediments are being dredged each year (in France, nearly 60 M m3), and given their waste status these materials are barely or not at all being reused. This industry is the primary target chosen by sediment managers to ensure a viable and sustainable reuse stream. More specifically, pervious concrete is considered as a green infrastructure solution for urban areas. In this work, sediments dredged from the Seine Basin in Paris (France) were used to produce a cleaner pervious concrete. Two sets of pervious concretes were prepared, the first based on sandy sediments by fully substituting the conventional sand, while the second set of concretes was based on fine sediments by partially substituting the cement. Slump, fresh density, hydration, porosity, permeability, compressive strength, tensile splitting strength and thermal conductivity were all evaluated through testing. Results show that the incorporation of sediments delayed, albeit marginally, the cement hydration (by less than 3 h) due to the presence of organic matter. The properties of pervious concrete are affected by the grain size of the incorporated sediment. The finer the sediment, the more compact the concrete structure, hence generating less porosity in the mixture, lower permeability and higher compressive strength. The thermal conductivity and volumetric heat of these pervious sediment-based concretes were also comparable to measures of the control concrete yet lower than those of ordinary concrete.
Worldwide, the preservation of non-renewable resources and recycling waste materials in the potential applications are gaining global attention. In this context, rigorous research studies focus on finding solutions to reuse and recycle various waste materials. Among the different types of waste materials, the dredged sediments are one of the valuable resources having potential to replenish the depletion of natural resources by reusing and recycling as secondary raw material in various applications. The process of sediments dredging is an essential and routine activity for ports and harbors to maintain sustainable navigation systems in the sea and river environment; on the other hand,
continuous accumulation of contaminated dredged sediment harms the environment, ecology, and marine ecosystems. Managing the dredging process and dredged sediment is a fundamentally important aspect of marine and river ecosystems. The technology development to recycle dredged sediments as secondary raw materials can supplement natural resources and it would be a viable solution to eliminate environmental pollution, alleviate the problem of land scarcity for waste dumping, and partially can meet the demand of resource gap. This article presents the state of the art of recycling and valorization opportunities of dredged sediments, which leads to replenishing the depletion of natural resources and increasing global sustainability.
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In this study, effect of partial replacement of cement by waste sludge from water supply plant on compressive strength and water absorption of hardened concrete was investigated to evaluate potential use of such waste for concrete production. After drying at 110 °C in a laboratory oven, the sludge was grounded and sieved to have a particle size of less than 0.14 mm to partially replace cement at levels of 0, 10, 20, and 30% by mass. Mixture proportion of reference concrete with 0% sludge replacement in which a desired slump and compressive strength at 28 days were 6 ± 2 cm and 45 MPa, respectively was designed according to Bolomey-Skramtaev method. All concretes with a water-to-binder ratio of 0.53 were prepared. The results showed that the waste sludge decreased slump of fresh concrete when the mixing water amount of all concrete mixture proportions was kept constant. The higher the waste sludge replacement, the lower the slump of fresh concrete. The partial replacement of cement by waste sludge in a range of 10–30% decreased the compressive strength of hardened concrete by 15.10–47.17% when compared with the reference concrete at the age of 28 days. The sludge replacements at 10 and 20% by mass increased the water absorption by 3.82 and 93.51%, respectively. Consequently, replacing 10% of cement with the sludge for concrete production was beneficial in terms of not only ensuring designed slump, compressive strength, and water absorption at the age of 28 days but also decreasing carbon dioxide emission from cement production and utilizing the waste sludge from the water supply plants towards sustainable development.KeywordsCement replacementCompressive strengthHardened concreteWaste sludgeWater absorption
The effect of substituting coarse aggregates with Corbicula shells on the mechanical and durability properties of concrete is evaluated by combining experimental investigations and micromechanical modeling. While substituting 20% of the aggregate volume with Corbicula shells does not affect slump, porosity, carbonation or chloride diffusion, a total replacement decreases slump, increases porosity and carbonation depth. Regarding mechanical properties, Young’s modulus and compressive strength decrease linearly with the incorporation rate of Corbicula shells. The shells are then modeled as non-spherical inclusions surrounded by an interfacial transition zone and embedded in a cementitious matrix, so that micromechanical models provide estimates of mechanical and diffusion properties. Combining the model and experimental results reveals that the low stiffness and drop in compressive strength of the concrete are explained by a weak adhesion between the shells and the cementitious matrix.
At present, a large amount of land is occupied and the environment is polluted due to the production and accumulation of massive dredged sediment. At the same time, the construction of “sponge cities” is imminent, wherein there is a great demand for permeable brick. Here, a kind of eco-friendly non-sintering dredged sediment permeable brick (DSPB) was developed from wrap-shell lightweight aggregates (WSLAs). To improve the performance of DSPB, polypropylene fibers (PPFs), carbon fibers (CFs) and glass fibers (GFs) of low content were added to it separately, and the optimum type, content, and mixing ratio for fibers were determined by evaluating the compressive strength, water permeability coefficient and strength loss rate of fibers-laden DSPB. It was found that GFs significantly improve the performance of DSPB. When the GFs content was 2.0 kg/m³ and the mixing ratio was 3:7 (GFs in WSLAs shell: GFs in cementitious material), the compressive strength, water permeability coefficient and strength loss rate of GFs-laden DSPB were 16.4 MPa, 0.202 mm/s and 9.76%, respectively. The above test results met the requirement of Chinese National Standards (CJ/T 400–2012). Compared with the unreinforced ones, the permeability coefficient of the GFs-laden DSPB remained unchanged with compressive strength 30.2% higher, and the strength loss rate was reduced by 23.1%. The point-to-point connection structure in GFs-laden DSPB was observed by scanning electron microscope (SEM) and polarizing microscope (PM). GFs play a crack resistance effect at point-to-point connection zone and in WSLAs shell, which is beneficial to improve the overall strength and frost resistance of DSPB. The addition of GFs at a low content has significantly improved the performance of DSPB in this study, and this method can be applied in pavement and further shed light to the new way of production of economical, non-sintering and high-strength building materials.
Phosphogypsum (PG) is a type of synthetic gypsum generated during the production of phosphoric acid. Each ton of phosphoric acid generates 5 tons of phosphogypsum. This industrial process has caused significant environmental problems worldwide. After an extensive literature review, it was possible to verify that both sedimentary and igneous PG can be used as in materials building components. The use of PG up to 50% meets the limits required for index I, with a radioactivity equivalent to radio-226 and a concentration of radon-222. The data found on bricks (0,11-0,41 Bq m⁻² h⁻¹) and plate (0,16-0,41 Bq m⁻² h⁻¹) show a lower exhalation rate. It is also found that calcination contributes to the reduction of PG impurities and to the of mechanical strength increase. Mortars and concretes produced with PG-based cementitious systems cementitious systems based on PG achieve high strength (60 MPa, 70 MPa, 80 MPa) and meet the technical feasibility criteria of European standards EN 998-1, EN 998-2, EN 13813, Eurocode 1992 and the American standard ASTM C270. The setting time is influenced by the mineral phase of the PG. It is concluded that cementitious materials produced from phosphogypsum are technically viable and achieve a satisfactory performance. It is possible to advance the following lines: PG-based concrete with high performance, PG-based hydration cement, stabilized mortar, PG-based concrete with high workability and studies about chloride ingress, carbonation, sulfate attack and acid attack in PG-based concrete.
La demande en matériaux de construction a considérablement augmenté, dont la grande majorité est d’origine naturelle. Etant donné que ces matériaux ne sont pas renouvelables, il est essentiel de trouver des matériaux alternatifs. Les études récentes menées à l’IMT Lille Douai ont montré que les matériaux issus de dragage possèdent des propriétés pouzzolaniques intéressantes et peuvent être utilisées comme ajouts cimentaires alternatifs ou comme filler. Vu le volume important dragué annuellement, cette valorisation aura des impacts environnementaux et économiques très positifs.Les objectifs visés dans cette recherche portent sur : la valorisation des sédiments du Grand Port Maritime de Dunkerque (GPMD, France) dans les bétons autoplaçants (BAPs) comme ajouts cimentaires ; la valorisation des sédiments fluviaux du Château l’Abbaye (France) dans des mortiers comme ajouts cimentaires afin d’évaluer la mobilité et la stabilité des éléments traces métalliques ; la solidification des sables dragués des Iles-de-la-Madeline (Québec) par liant hydraulique afin de produire des roches artificielles.Dans l’ensemble, les résultats de ce travail sur les sédiments mettent en exergue la contribution substantielle de ces matériaux à l’amélioration des performances des bétons et supportent leur emploi comme ajouts cimentaires. Ces résultats contribuent à réduire l’empreinte du CO2 dans le béton, ainsi que les exploitations minières. Ils permettent de mieux comprendre le comportement des sédiments dans les bétons à partir de certaines analyses et traitements, et d’identifier les milieux agressifs convenables à l’utilisation des sédiments.
According to current legal regulations, bottom sediment in watercourses containing heavy metals are considered dangerous to the environment and should be properly managed after extraction. Due to the well-known excellent ability of the products of cement hydration to immobilize heavy metals, the possibility of utilizing this type of waste products in cement composites was preliminary tested. For this purpose, basic research was carried out on the technological and mechanical characteristics of binders containing sediment from one of the rivers located in Lesser Poland. Standard mortars made of Portland cement CEM I and river sediment dried at 105°C were used for the tests. This supplement replaced cement in the amount of 10%, 20%, 30% and 40% by weight. The technological properties such as: water demand, setting time, consistency and mechanical properties were verified. Compressive and tensile strength at bending of hardened mortars were tested at different curing periods, i.e. after 14, 28 and 90 days. The obtained test results confirm that the fraction of river sediment in the binder in the amount of 10% generally does not adversely affect the properties of mortars, however, its greater amount is reflected in changes in the technological features and in a clear reduction of mechanical properties of the tested mortars.
The demand for building materials has increased enormously, and the vast majority are of natural origin. Since these materials are not renewable, it is essential to find alternatives. Recent studies at the IMT Lille Douai have shown that dredged materials have interesting pozzolanic properties and can be used as alternative cement additions or as filler. Given the large volume dredged annually, this recovery will have very positive environmental and economic impacts. The objectives of this research relate to: (1) The recycling of sediments from Grand Port Maritime de Dunkerque (France) in self-consolidating concrete (SCCs) as Supplementary cementitious materials (SCMs); (2) The recycling of fluvial sediments of Château l’Abbaye (France) in mortars as SCMs in order to assess the mobility and stability of heavy metal elements; (3) The solidification of the dredged sands of Iles-de-la-Madeline (Quebec) by hydraulic binder in order to produce artificial rocks. Overall, the results of this work on sediments highlight the substantial contribution of these materials to improving the performance of concrete and support their use as SCMs. These results contribute to reducing the footprint of CO2 in concrete, as well as mining. Also, contributes to understanding the behavior of sediments in concrete from certain analyzes and treatment. Thus, identify aggressive environments suitable for the use of sediments.
The current investigation proposes modifications in a clinker making process to separate calcination reaction from fuel combustion in the calciner, resulting in pure carbon dioxide production. Very hot stream of pure carbon dioxide or a mixture of carbon dioxide and steam is used as the heat carrier to supply required energy for endothermic calcination reaction. The proposed designs which internally separate 90 wt% carbon dioxide from limestone decomposition are environmentally and economically compared to the integration of a clinker making and a MEA carbon dioxide capture process as the conventional scenario. Results show that the proposed modifications significantly reduced carbon dioxide emissions, energy consumption and the cost of carbon dioxide capture in clinker making process.
Une réutilisation des sédiments issus du dragage en tant que matière première dans la fabrication d’un béton directement sur le site du dragage est une voie de valorisation économique et écologique. La présente étude a pour but de valoriser la partie fine des sédiments qui ne trouve pas de solutions de valorisation efficaces. En effet la structure en feuillet de l’argile la rend sensible aux conditions hydriques et lui confère une importante capacité de rétention des polluants. Afin d’optimiser les volumes à valoriser, le béton est envisagé en substitution totale des granulats par la fraction fine des sédiments. Les résultats apportés par la littérature tendent à privilégier une application en remblai tels que le remplissage entre deux rideaux de palplanches, un remblaiement géotechnique ou de carrières. Un procédé d’incorporation d’une mousse à base de protéine animale lors de la fabrication du béton est utilisé dans le cadre de cette étude pour alléger le matériau (densité comprise entre 1,1 et 1,3). Ce type de matériau fait donc partie de la catégorie des bétons légers de mousse plus communément appelée LWFC (LightWeight Foamed Concrete). Dans cette étude le matériau est désigné par le sigle BAMS (Béton Allégé par l’incorporation d’une Mousse et à base de Sédiments). L’étude a été réalisée sur un sol modèle constitué de 80% de bentonite et de 20% de sable correcteur de diamètre 0,125mm. La méthode de formulation est basée sur la limite de liquidité du sol afin de prendre en compte l’absorption de l’eau. La caractérisation du BAMS se scinde en trois parties ; La première partie correspond à la caractérisation à l’état frais du BAMS. Elle met en exergue une optimisation de l’abaissement de la densité à partir d’une certaine quantité d’eau apportée par rapport à la limite de liquidité du sol. L’allégement du matériau par l’incorporation d’une mousse modifie les propriétés du matériau à l’état frais ; elle améliore la fluidité et retarde la prise du ciment. La deuxième partie correspond à la caractérisation mécanique du BAMS ; l’eau apportée pour optimiser l’allégement du matériau impacte la résistance mécanique qui est jugée acceptable à partir de 0,5MPa. Celle-ci peut être améliorée en augmentant la quantité de ciment qui doit cependant rester faible pour rentabiliser la voie de valorisation. Il y a donc un compromis inévitable entre résistance mécanique et densité. Les combinaisons (densité ; résistance mécanique) possibles et les paramètres de formulations permettant de les atteindre ont été étudiés. Des essais non-destructifs sont effectués afin de contrôler la résistance mécanique in situ. L‘étude du retrait linéaire indique une variation dimensionnelle importante du BAMS de l’ordre du cm/m qui peut être divisé par 100 avec une cure humide. La troisième partie correspond à la durabilité par l’étude des propriétés de transfert du BAMS dont les résultats mettent en avant une accessibilité partielle du réseau poreux crée par la mousse incorporée.Le relargage des polluants dans les sédiments est évalué par un essai de lixiviation effectué sur un sol modèle pollué artificiellement (cas non-immergeable). Cet essai permet de valider l’efficacité de leur inertage par le traitement au ciment et l’utilisation du matériau sans impact environnemental selon le critère PH14.
Beneficial use of sediments is known as a sustainable and environmentally friendly alternative to confined disposal facilities and open water disposal. Since most of the geotechnical engineering applications such as roads, backfills, berms, and in situ capping require a large amount of material in their construction, the beneficial use of dredged materials in geotechnical engineering applications is a promising implementation. In this study, sediment dredging and management are introduced. The beneficial use of dredged materials in geotechnical engineering applications is reviewed, and the necessary requirements for their beneficial use in these applications are addressed.
The Boukhadra’s iron deposit supplies the El–Hadjar, the largest ironwork in the country located in the northeast of Algeria. The quality of the iron ore affects negatively the ironwork production, therefore a beneficiation of the iron ore by magnetic separation is considered as an appropriate solution. However, this technique is known for the generation of important quantities of nonmagnetic parts considered as rejects. The treatment or stock of these rejects is likely to have an important cost and creates environmental problems. In this study, the beneficiation process by magnetic separation of the Boukhadra’s iron ore and the valorization of the rejects from this beneficiation process as raw materials for Portland cement production are presented. Three rejects from the different beneficiation processes were mixed separately with marl and limestone from the same deposit of Boukhadra for the elaboration of three Portland cements.The mineralogical compositions of the raw materials and the produced clinkers in addition to the hydration products of the harden paste were studied by X-rays diffraction. The chemical composition of the clinker and raw materials was determined using X-rays fluorescence. The burnability of the clinkers has been characterized on the basis of the free lime content and the degree of crystallization of the clinker phases. The proportion of the different phases has been determined using Bogue calculation and Rietveld method. The compressive strength and setting time were determined according to French standards. The obtained clinkers are composed from Alite, Belite, Ferrite and Aluminate. The proportions of these phases are in abdication with the composition of regular Portland cements. These phases showed a good crystallization at 1400 °C. The obtained cements have mechanical and chemical proprieties that meet the requirements for Portland cement Class 42.5 according to NF P 15-301 which is an ordinary Portland cement. The results of this study conclude that the rejects used during this work are compatible with a valorization as raw materials for the fabrication of Portland cement.
J.C. TOURAY Professeur, Ecole Supérieure de l'Energie et des Matériaux, Orléans Directeur de thèse
G. DURAND Professeur, Ecole Centrale de Paris Rapporteur
J.P. OLLIVIER Professeur, Institut National des Sciences Appliquées, Toulouse Rapporteur
C. DEFOSSE Directeur environnement, Ciments Calcia Italcementi Group Examinateur
I. SERCLERAT Responsable Section Analyses Environnementales, CTG Italcementi group Examinateur
J. CHOISNET Professeur, Ecole Nationale Supérieure d'Ingénieur, Caen Examinateur
C. PROUST Maître de Conférence, Ecole Supérieure de l'Energie et des Matériaux, Orléans Examinateur
The feasibility of partial replacement of siliceous raw material for cement production with water purification sludge (WPS) was investigated by X-ray diffraction, free-lime analysis, compressive strength testing and toxicity characteristics leaching procedure (TCLP). It is found that WPS has no negative effects on the consumption of free lime and the formation of clinker minerals. The samples with WPS from 4 to 10wt.% have higher 3days and 7days strengths than the control. After 28days, however, only WPS replacements
Volcanic soil can be used to remove metals from wastewaters. Once used, it is disposed in landfills. The utilization of this material in the cement industry as an alternative raw material was evaluated using life cycle assessment (LCA) methodology. This possibility has been studied from an environmental point of view in a Chilean cement facility, representative of the current operation state of art, including both technical and economic analysis. Two scenarios were compared: Scenario 1, which corresponds to the existing cement production process, and Scenario 2, which represents cement production using spent volcanic soil. With the exception of the categories of carcinogens (C) and minerals (M), the comparative results are favourable to Scenario 2, specially regarding to the category of ecotoxicity (E), mainly due to the avoided landfilling emissions of the volcanic soil. When considering the damage assessment, damage to human health (HH), ecosystem quality (EQ) and resources (R) are lower in Scenario 2. In addition, sensitivity analyses were performed to study the influence of particular parameters (i.e., transport of spent volcanic soil, CO2 emissions from the clinkerization process and heavy metals leaching from the spent volcanic soil) on the results of the assessment. The use of alternative raw materials (in this case, spent volcanic soil), which present the advantage to be wastes from other technical systems, appear to allow the development of cement production in a more sustainable way, slightly improving the economy of the process. The spent volcanic soil can be treated with zero cost for the wastewater treatment plant with savings of 0.23€ for each tonne of clinker production. Establishing a sound management way for the spent volcanic soil could foment its possible use as mineral adsorbent in industrial wastewater treatment facilities.
Red mud from HINDALCO (Hindustan Aluminium Corporation) Industries Limited, Renukoot, India, contains significant quantities of alumina, iron oxide and silica. Presence of the said constituents makes it a suitable ingredient for the preparation of special cements. Preparation of three varieties of cements was investigated, namely: (a) aluminoferrite (C4AF)-belite (β-C2S) using lime + red mud + fly ash; (b) aluminoferrite-ferrite (C2F)-aluminates (C3A and C12A7) utilising lime + red mud + bauxite; and (c) sulfoaluminate (C4A3S̄)-aluminoferrite-ferrite using lime + red mud + bauxite + gypsum. The effects of composition (proportions of lime, red mud, fly ash, bauxite and gypsum), firing temperature and duration on the properties of cements produced were studied in detail. Cements made from lime + red mud + bauxite or lime + red mud + bauxite + gypsum exhibit strengths comparable or superior to ordinary Portland cement (OPC). On the other hand, those prepared using lime + red mud + fly ash did not have sufficient strength. Moreover, it was not possible to replace bauxite by fly ash (as a source of alumina) in any significant quantity.††The following notation has been used, throughout the text: A: Al2O3, C: CaO, F: Fe2O3, H: H2O, S: SiO2, S̄: SO3, T: TiO2.
Hundreds of millions of cubic meters of contaminated sediments are dredged from US harbors and waterways annually for maintenance of navigation, environmental remediation, or both. In recent years, inexpensive ocean dumping has been largely eliminated as a disposal alternative causing a crisis in the management of sediment. This paper presents a new beneficial use alternative for contaminated dredged material, which is to use dredged material as a feedstock in the conventional manufacture of Portland cement. The paper demonstrates the efficacy of the process at the bench and pilot scales, and presents a summary of practical and economic considerations. A bench scale manufacture was carried out with feedstock mixtures containing 1–12% dredged material from the New York/New Jersey (NY/NJ) harbor. The clinkers were quantitatively analyzed with X-ray powder diffraction and differences in phase concentrations were observed in the clinker samples manufactured with dredged material (decreased alite and increased belite) suggesting that additional burn time was needed to account for the quartz present in the sediments. The free chloride concentrations in the clinker samples were below ACI limits for cement used with reinforcing steel; however, the chloride in the dredged material remains a manufacturing concern and is expected to increase annual maintenance costs. A pilot scale manufacture was carried out in a batch rotary kiln; X-ray diffraction analysis and ASTM tests for strength, soundness, and setting time suggested that with better optimized burning conditions, dredged material can be successfully incorporated into full scale manufacture.
The cement industry has for some time been seeking procedures that would effectively reduce the high energy and environmental costs of cement manufacture. One such procedure is the use of alternative materials as partial replacements for fuel, raw materials or even clinker. The present study explores the reactivity and burnability of cement raw mixes containing fired red or white ceramic wall tile wastes and combinations of the two as alternative raw materials.The results showed that the new raw mixes containing this kind of waste to be technically viable, and to have higher reactivity and burnability than a conventional mix, providing that the particle size of the waste used is lower than 90 μm. The mineralogical composition and distribution in the experimental clinker prepared were comparable to the properties of the clinker manufactured with conventional raw materials. Due to the presence of oxides such as ZnO, ZrO2 and B2O3 in tile glazing, the content of these oxides was higher in clinker made with such waste. The mix of red and white ceramic wall tile waste was found to perform equally or better than each type of waste separately, a promising indication that separation of the two would be unnecessary for the purpose described above.
Concrete and mortars are porous composite materials resulting of a mix of cement, aggregates and water. Addition of an organic additive, currently used as grinding aid (Triisopropanolamine named TIPA), generates a mechanical strength increase of concrete and mortars with respect to samples hydrated without additive. The physico-chemical study we have carried out in order to explain this macroscopic observation has lead us to dismiss the assumption of a possible increase of the cement paste hydration degree despite a soluble complex formation between TIPA and iron hydroxide. A modification of the cement paste - aggregate interface in presence of TIPA has to be tacking into account as a result of mechanical compressive tests made on pure cement pastes and mortars.
The systems CaO-ZnO-Al2O3 (C-Z-A) and CaO-ZnO-Fe2O3 (C-Z-F) have been studied and their phase relationships established. Two hitherto unreported phases, Ca3ZnAl4O10 (C3ZA2) and Ca6Zn3Al4O15 (C6Z3A2) were characterized in the system C-Z-A: their X ray diffraction patterns were obtained and indexed. No new phases were discovered in the system C-Z-F. Phase coexistence has been established in both systems. C6Z3A2 is of particular interest to clinkering because it coexists with alite, belite and a clinker liquid phase. This is confirmed both by laboratory experiment and its identification in white and grey clinkers, made from industrial raw meals doped with 1·0 and 2·0 wt% of zinc oxide.
Soluble zinc salts added to cement mix water are generally agreed to retard hydration. The role of zinc in clinker is, however, less well-established. Experiments are reported on clinker stimulants and real industrial clinker meals, the latter doped with 1.5 wt% ZnO. Contrary to findings in the literature, relatively little zinc goes into solid solution in the main clinker phases: much is present in the interstitial phases as a solid solution based on 6CaO·3ZnO·2Al2O3. Supplementary studies of the CZA system disclose the existence of two ternary phases: C6Z3A2 and C3ZA2. Both are cementitious in combination with Ca(OH)2 or gypsum, or with both. ZnO at 1.5 wt% clinkered in industrial meal, does not affect set times but enhances the rate of strength gain. Zinc remains relatively insoluble, with aqueous Zn concentrations of stimulants not exceeding 2.2 ppm.
Construction materials account for a significant proportion of nonfuel materials flows throughout the industrialized world. Hydraulic (chiefly portland) cement, the binding agent in concrete and most mortars, is an important construction material. Portland cement is made primarily from finely ground clinker, a manufactured intermediate product that is composed predominantly of hydraulically active calcium silicate minerals formed through high-temperature burning of limestone and other materials in a kiln. This process typically requires approximately 3 to 6 million Btu (3.2 to 6.3 GJ) of energy and 1.7 tons of raw materials (chiefly limestone) per ton (t) of clinker produced and is accompanied by significant emissions of, in particular, carbon dioxide (CO2), but also nitrogen oxides, sulfur oxides, and particulates. The overall level of CO2 output, about 1 ton/ton clinker, is almost equally contributed by the calcination of limestone and the combustion of fuels and makes the cement industry one of the top two manufacturing industry sources of this greenhouse gas. The enormous demand for cement and the large energy and raw material requirements of its manufacture allow the cement industry to consume a wide variety of waste raw materials and fuels and provide the industry with significant opportunities to symbiotically utilize large quantities of by-products of other industries.This article, the second in a two-part series, summarizes some of the environmental challenges and opportunities facing the cement manufacturing industry. In the companion article, the chemistry, technology, raw materials, and energy requirements of cement manufacture were summarized. Because of the size and scope of the U.S. cement industry, the article relies primarily on data and practices from the United States.
The feasibility of municipal solid waste incineration (MSWI) ash utilized as the replacement of raw mix in cement production is investigated. Result shows that sieving, self-grinding, and magnet separation processes are necessary to remove the debris, salt, and metallic contents that existed in the MSWI ash. By using the pretreated MSWI ashes, the produced cement specimens were in compliance with the unconfined compression strength (UCS) standard in Taiwan at small replacement percentage (< 5%). When ash replacement percentage is large (more than 10%), the strength development of specimens would be hindered due to the deficient formation of the calcium silicate. Calculation on lime saturation factor (LSF) also shows a descending trend in consequence of the increase in replacement percentage. Thus, compositional effect should be taken into consideration for promoting the calcium silicate formation at the case of large ash replacement. In this research, adjustment of chemical composition was achieved by adding 183 g calcium oxide per kilogram of cement raw mixture with 15% ash replacement. After adjustment, the produced cement could develop seven- and fivefold increase on UCS compared with those without calcium oxide supplement at 3 and 7 days of curing, respectively. Results concluded that the MSWI ash was suitable in reuse for cement production under a well-conditioned situation.
The paper presents the results of research on the utilization of phosphogypsum produced as the waste of phosphoric acid manufacture. Phosphogypsum is a fine powder with high calcium sulfate content. The phosphatic and fluoride impurities present in phosphogypsum cannot be removed completely either by washing or chemical treatments. However, phosphogypsum, when heated at elevated temperature, produced an anhydrite and the impurities become inert. The formation of anhydrite cement was examined by microscopy and X-ray diffraction. Data showed that a stable anhydrite can be produced by heating phosphogypsum at 1000°C. The effects of different chemicals on setting and hardening of anhydrite cement and its hydration characteristics were studied. Results show that with the use of sodium sulfate and ferrous sulfate activators, maximum attainment of strength can be achieved. A correlation was established between hydration and chemically combined water. Microscopic studies revealed that formation of euhedral prismatic and rhombic shaped gypsum crystals govern high strength development in the anhydrite cement. Manufacture of anhydrite cement from phosphogypsum is recommended because of its lower energy requirements than the traditional building materials.
Burning of industrial wastes in cement kilns has an increasing environmental importance, brought about by the incorporation of potentially hazardous elements into clinker crystalline phases and partial substitution of primary fuel and raw materials. In this study, experimental clinkers were synthesized, with the addition of V, Zn and Pb to a standard raw meal, from which a control clinker was obtained for comparison. The three metals were chosen as they are present in the alternative fuel petcoke (V) and in industrial wastes (Zn, Pb) commonly burned in cement kilns. Electron microprobe and scanning electron microscope analysis revealed the preferential partition of these metals among the clinker crystalline phases. It was observed that V has shown a preferential partition towards C2S. Zn appears in higher amounts in periclase, and C3S has higher Zn contents than C2S. Pb concentrates in minute spherules and partitions toward C3S in small amounts.
Cement paste hydration is delayed by zinc which changes fundamental hydrates forming a thin layer of amorphous zinc hydroxyde around anhydrous particles. Evolution of this compound depends on pore solution composition of cement paste. In this paper, the authors study the influence of the amount of sulfate. Samples of cement paste used are prepared with adding to one clinker increasing amounts of gypsum. With small proportions of sulfate, C3A hydration is accelerated by zinc. On the contrary, if SO3 is more than 2.5 %, zinc delays C3A hydration. C3S hydration is always delayed and with 4 % in SO3, setting does not occur.
The retarding effect of a zinc addition on the hydration of Portland cement is investigated by calorimetry. A small amount of zinc powder leads to a variation of the first peak maximum, an extension of the dormant period and a change of the second calorimetry peak. These effects are due to the formation of a primary zinc hydroxide and its conversion later on into crystalline zinc hydroxide. The evolution of the thermograms is also studied as a function of zinc percentage.
Hydraulic (chiefly portland) cement is the binding agent in concrete and mortar and thus a key component of a country's construction sector. Concrete is arguably the most abundant of all manufactured solid materials. Portland cement is made primarily from finely ground clinker, which itself is composed dominantly of hydraulically active calcium silicate minerals formed through high-temperature burning of limestone and other materials in a kiln. This process requires approximately 1.7 tons of raw materials per ton of clinker produced and yields about 1 ton of carbon dioxide (CO2) emissions, of which cal-cination of limestone and the combustion of fuels each con-tribute about half. The overall level of CO2 output makes the cement industry one of the top two manufacturing industry sources of greenhouse gases; however, in many countries, the cement industry's contribution is a small fraction of that from fossil fuel combustion by power plants and motor vehicles. The nature of clinker and the enormous heat requirements of its manufacture allow the cement industry to consume a wide variety of waste raw materials and fuels, thus providing the opportunity to apply key concepts of industrial ecology, most notably the closing of loops through the use of by-products of other industries (industrial symbiosis).In this article, the chemistry and technology of cement manufacture are summarized. In a forthcoming companion ar-ticle (part II), some of the environmental challenges and op-portunities facing the cement industry are described. Because of the size and scope of the U.S. cement industry, the analysis relies primarily on data and practices from the United States.
This study compares two methods to immobilise the same amount of Zn in cement paste. In the first method, Zn is introduced into the raw material before clinkerisation, whereas in the second process, Zn is introduced in the liquid phase used to make the cement paste, which is often referred to as solidification/stabilisation. In laboratory-made clinker, Zn was mainly fixed within a new compound (Ca6Zn3Al4O15). Also, Zn was observed in tricalcium silicate (C3S) and in the interstitial phase (C3A and C4AF) with the exception of dicalcium silicate (C2S). In the present study, the threshold limit value corresponds to the maximum amount of Zn that could be incorporated without the stability of the clinker phases being modified. This threshold was reached when a decrease in C3A content and/or the presence of Ca6Zn3Al4O15 were observed by X-ray diffraction. The threshold limit of Zn in the studied clinker was established at 0.7% by weight. The reactivity of synthesised cement doped with Zn was studied by isothermal calorimetry measurements. These tests revealed that the incorporation of Zn had no effect on calcium silicate hydration (C3S and C2S), even if the Zn content exceeded the threshold limit value, i.e., 1%. These results were compared with those obtained through the solidification/stabilisation treatment of Zn in a cement paste. In these experiments, a Zn content of 0.7% induced a significant delay in the cement hydration. This difference in behaviour is due to the slower flow of zinc ions released in solution when it is incorporated in the clinker phases. Thus, the immobilisation during clinkerisation is a good alternative to treat waste with a high Zn content in Ordinary Portland Cement (OPC) without causing the well-known, deleterious effect on cement setting time.
The use of Cl- and SO3-containing by-products from chemical industries for manufacturing Portland cement clinker using a wet process was examined. The chemical and mineralogical compositions of the by-products and raw materials were determined. Homogeneous raw mixes containing different concentrations of by-products (5–30%) were prepared and the influence of the by-products on all steps of burning the mixes in a kiln to form a cement clinker was investigated. It was shown that introducing Cl- and SO 3-containing by-products to the raw mixes significantly changes all the cement clinker producing stages and changes the chemical and mineralogical compositions at all intermediate stages and in the finished products, forming new minerals containing Cl and SO3 [CaOX (SiO2)y CaCl2] or [CaOx (SiO2)y CaSO4] and increasing the amount of well-known intermediate minerals. The presence of the chlorides and sulfates in the cement clinker burning processes removes alkali from the raw mixes, turning them to volatile forms, accelerating the raw mineral decomposition processes and accelerating the formation processes of cement minerals (C2S, C12A7, C4AF) and formation of chloride and sulfate cycles in the kiln, forming clinker liquids and decreasing the formation and growth of the main cement minerals (C 3A, C3S). The cement clinker contains some quantity of minerals with Cl or SO3. Their presence in the final product decreases cement quality by reducing the amount of active CaO (C) and reducing the active CaO/SiO2 ratio.
The influence of high intakes of Cr, Ni, and Zn on the burning process and the formation of clinker phases is described. Three different raw meals were used and were burned with the metal oxides in four concentrations from 200 to 25,000 ppm. The resulting clinker was analysed for the content of free lime and X-ray diffraction analysis was done. Some of the clinker material was crushed and polished, and quantitative point counting was performed to provide the content of the different clinker phases. These samples were also analysed by scanning electron microscope connected with an energy-dispersive X-ray-spectrometer to detect the composition of the clinker phase. The results show that only very high intakes of heavy metals have measurable effects on the formation and composition of the clinker.
Incineration ash of municipal solid waste accounts for a great portion of the matter in landfills, and minimization of resource consumption and recycling of waste are important factors for ensuring the future welfare of humankind. The study presented in this paper reports a technology for producing cement from incineration ash of municipal solid waste, incineration ash of sewage sludge and other wastes such as aluminium dross and copper slag. As incineration ash of municipal solid waste contains chlorine, special attention should be paid to fixing the chlorine within the cement. It was verified that proper treatment (formation of calcium-chloroaluminate) is capable of fixing the chlorine. In order to confirm the efficacy of this technology before it is used on an industrial scale, a pilot-scale test (50 tons/day) was conducted. The quality of the resulting cement is sufficient to enable the cement to be put to practical use. Furthermore, the tested process does not cause secondary pollution. Consequently, 50% of raw materials for cement production can be obtained from incineration ash of municipal solid waste.
The disposal of contaminated dredged material has become an economical and environmental issue. Firstly, this study presents the Novosol® process which was used for the treatment of polluted sediments. This process is based on the stabilisation of heavy metals and on the thermal elimination of organic matter. A physical characterization of the processed material reveals high porosity (60%) and water absorption (45%). Moreover, the treated sediment aggregate (TSA) has a relatively low strength and a high content of fine particles.Secondly, an experimental study on the feasibility of TSA introduction in cement-based materials was performed. Three mortars for which a given sand volume was replaced by the same sediment volume (33%, 66% and 100%) were designed. A strong increase of drying shrinkage was observed (up to 10 times higher, when compared to a reference mortar). Permeability remained virtually constant, though. There was a significant increase in strength for low to moderate substitution, while high incorporated quantity of sediment led to a strength on the same order of that of the reference mortar.
The maintenance of waterways generates large amounts of dredged sediments, which are deposited on adjacent land surfaces. These sediments are often rich in metal contaminants and present a risk to the local environment. Understanding how the metals are immobilized at the molecular level is critical for formulating effective metal containment strategies such as phytoremediation. In the present work, the mineralogical transformations of Zn-containing phases induced by two graminaceous plants (Agrostis tenuis and Festuca rubra) in a contaminated sediment ([Zn] = 4700 mg kg−1, [P2O5] = 7000 mg kg−1, pH = 7.8), untreated or amended with hydroxylapatite (AP) or Thomas basic slag (TS), were investigated after two yr of pot experiment by scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS), synchrotron-based X-ray microfluorescence (μ-SXRF), and powder and laterally resolved extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. The number and nature of Zn species were evaluated by principal component (PCA) and least-squares fitting (LSF) analysis of the entire set of μ-EXAFS spectra, which included up to 32 individual spectra from regions of interest varying in chemical composition. Seven Zn species were identified at the micrometer scale: sphalerite, gahnite, franklinite, Zn-containing ferrihydrite and phosphate, (Zn-Al)-hydrotalcite, and Zn-substituted kerolite-like trioctahedral phyllosilicate. Bulk fractions of each species were quantified by LSF of the powder EXAFS spectra to linear combinations of the identified Zn species spectra.
The feasibility of the replacement of raw material for cement production by heavy metal-containing sludge from surface finishing and electroplating industries was investigated. The effect of heavy metal content in the cement raw mix on the crystalline formation in cement production was also examined by XRD analyses. It was found that both sludges were applicable for the replacement of raw mix for cement production by moderate conditioning of the sludge compositions with several compositional parameters. As the replacement of raw mix by sludge was within 15%, the formation of tricalcium silicate (C3S) phase in cement would be enhanced by the introduced heavy metals. While owing to a high level of heavy metals concentration (> 1.5%) in cement raw mix, C3S crystalline in cement would be inhibited by a large sludge replacement (> 15%). During the sintering process, over 90% of the high volatile elements such as Pb would evaporate in high temperature, yet 90% of the less volatile elements such as Cu, Cr and Ni would be trapped in clinkers. Most of all, the results of leaching test shows that the trapped elements in hydrated samples would not leach out under acidic conditions. The reuse of heavy metal-containing sludges as cement raw material would not cause leaching hazard from sintered clinkers. Heavy metal-containing sludges thus should have the potential to be utilized as alternative raw materials in cement production.
The slags from blast furnace (iron making ) and converter (steel making) after magnetic separation are mixed with limestone of six different compositions. The ground materials are fired in a pilot plant scale rotary kiln to 1350 °C for 1 h. The clinker is cooled, crushed, mixed with 3% gypsum, and ground to fineness of more than 3300 cm2/g. Initial and final setting times, consistency of standard paste, soundness, free CaO, and compressive and fractural strengths after 3, 7, and 28 days are measured. Samples with higher lime saturation factor developed higher C3S content and better mechanical properties. Blending 10% extra iron slag to a cement composed of 49% iron slag, 43% calcined lime, and 8% steel slag kept the compressive strength of concrete above standard values for type I ordinary Portand cement.
Rivers flowing through urbanized and industrial areas are usually greatly damaged by anthropogenic activities discharging contaminants. Characterizing the spatial distribution of pollutants in sediments is of high importance for selecting a suitable remediation operation, but is a complex task because this spatial variability is the result of various physical and chemical mechanisms occurring at different scales. Factorial Kriging Analysis (FKA) was applied on data collected in a canalized river (Scarpe, France) for that purpose, because this geostatistical technique allows to decompose a given variable into components of different spatial correlations and map them separately. This decomposition is meaningful provided that it can be related to physical phenomena occurring at the identified spatial scales. FKA applied to Cd and Zn concentrations in sediments of the Scarpe river proved to be effective, allowing their mapping to be decomposed in a first map related to a short-range spatial correlation corresponding to hot spots interpreted as the impact of industrial and urban inputs located along the canal, and a second map related to a long-range spatial variability associated with long pollutant plumes interpreted as the effect of one major upstream pollutant input.
The results of model calculations carried out to identify and quantify the input pathways of trace elements into cement and concrete and to estimate the extent to which trace element concentrations in cement may change due to waste utilization are presented. As expected, primary raw materials represented the most important input pathway for trace elements into cement, but the contribution from wastes was not negligible. The use of waste led to a slight increase of the concentrations of cadmium, antimony and zinc in cement. For cobalt, lead and vanadium, this increase was less distinct and for all other trace elements considered, the effect of the use of wastes on trace element concentrations in cement could not be demonstrated clearly. The trace element content of concrete was governed by the aggregates for most elements considered. However, for arsenic, cadmium, lead and zinc, both cement and the additive coal fly ash contributed noticeably to the total trace element concentration in the concrete.
Valorization of phosphogypsum as mineralizer in the burning of Portland cement clinker was studied in our laboratory. X-ray fluorescence, optical microscope technique and powder X-ray diffraction were then used to characterize the synthesized clinker and its raw mixture in terms of chemical composition and clinker mineralogical composition. The effects of phosphogypsum on structural and morphological properties of clinker minerals and on the presence of alite were followed by scanning electron microscopy combined with microprobe analysis. The addition of phosphogypsum to the cement raw mixture shows that the burning temperature decreases and therefore improves the production process of clinker. The addition of 10% phosphogypsum permits a complete clinkerization at low burning temperature (1200 degrees C), instead of 1470 degrees C, which increases the cement factory efficiency by 25% and extends the service life of furnace fire brick. Structural and morphological analysis of clinker produced under the new conditions show that phosphogypsum preserve perfectly the crystalline structure of silicate phases, which leads to the improvement of physical and mechanical properties of cement.
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