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Thermal insulators made with rice husk ashes: Production and correlation between properties and microstructure

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Abstract

Extruded and pressed thermal insulators were obtained with the utilization of rice husk ashes, which is a residue from the beneficiation process of rice with high silica content. The thermal insulators were characterized both chemically (composition) and physically (particle size, porosity, density and thermal conductivity), and their properties were correlated to their microstructure. The thermal conductivity of these insulators was determined by the hot plates method, according to the ASTM-E 1225-87 Standard, and the measured values were then compared to a commercial thermal insulator made from diatomaceous silica. The morphology of the preset phases (solid and porous), as well as their distribution, was determined by means of scanning electron microscopy.

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... Although it can be used to produce various useful products such as activated carbon, sodium silicate [32,33], silicon carbide [34], or silicon nitride [35], its practical utilization is limited due to economic reasons. If unused, rice husk needs to be landfilled, where it can self-burn and create a problem for the environment [36]. ...
... Other concrete properties such as thermal conductivity and autogenous shrinkage were also investigated when RHA was incorporated in the concrete mix [36,100]. Although the thermal conductivity of the RHA insulators was found lower, it was still higher than a commercial thermal insulator made from diatomaceous silica, used as reference [36]. ...
... Due to such properties, sugarcane bagasse ash can be used for temperature control in mass concrete. Other concrete properties such as thermal conductivity and autogenous shrinkage were also investigated when RHA was incorporated in the concrete mix [36,100]. Although the thermal conductivity of the RHA insulators was found lower, it was still higher than a commercial thermal insulator made from diatomaceous silica, used as reference [36]. ...
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Concrete production utilizes cement as its major ingredient. Cement production is an important consumer of natural resources and energy. Furthermore, the cement industry is a significant CO2 producer. To reduce the environmental impact of concrete production, supplementary cementitious materials such as fly ash, blast furnace slag, and silica fume are commonly used as (partial) cement replacement materials. However, these materials are industrial by-products and their availability is expected to decrease in the future due to, e.g., closing of coal power plants. In addition, these materials are not available everywhere, for example, in developing countries. In these countries, industrial and agricultural wastes with pozzolanic behavior offer opportunities for use in concrete production. This paper summarizes the engineering properties of concrete produced using widespread agricultural wastes such as palm oil fuel ash, rice husk ash, sugarcane bagasse ash, and bamboo leaf ash. Research on cement replacement containing agricultural wastes has shown that there is great potential for their utilization as partial replacement for cement and aggregates in concrete production. When properly designed, concretes containing these wastes have similar or slightly better mechanical and durability properties compared to ordinary Portland cement (OPC) concrete. Thus, successful use of these wastes in concrete offers novel sustainable materials and contributes to greener construction as it reduces the amount of waste, while also minimizing the use of virgin raw materials for cement production. This paper will help the concrete industry choose relevant waste products and their optimum content for concrete production. Furthermore, this study identifies research gaps which may help researchers in further studying concrete based on agricultural waste materials.
... Therefore, 1000 kg of paddy grain produces about 200 kg (20%) of RH, and when it is burned to generate energy, about 50 kg (25%) of RHA is generated, a volume containing around 45 kg (85-95 %) of amorphous silica. The properties of RHA depend on the ecological circumstances of its origin as well as the process applied for burning the husk [23]. It has a high silica content in the amorphous form, which has broad applicability in industries including ceramics, construction, chemicals and electronics among others [24]. ...
... RHA containing silica is amorphous, however, which causes it to act as a nonheat conducting ingredient in refractories [53]. RHA insulation refractories are fabricated by mixing of different flux contents (as binder), plasticizers (due to the lack of plasticity of RHA) and pore-forming agents (to increase the porosity of final products) [23,35,54]. Air is entrapped in the pores of refractories, a characteristic which is attributed to lower values of κ, because entrapped air acts as a barrier to the flow of heat. ...
Article
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Use of waste or byproducts from different industries and the agricultural sector has acquired increasing attention in the scientific, technology, ecological, economic and social spheres in recent years. Rice husk (RH) is a byproduct of rice milling and rice husk ash (RHA) is generated by combustion in a separate boiler. Both RH and RHA are abundantly accessible in rice growing countries such as China, India, Brazil, the US, and Southeast Asia. RH has therefore been recycled by burning it for energy production. This generates RHA, which contains a huge quantity (85-95%) of amorphous silica. Over the past two decades, RHA has been used extensively in numerous fields for manufacturing of different silicates, zeolites, catalysts, nanocomposite, cement, lightweight construction materials, insulators, and adsorbents. This paper presents a comprehensive overview on the processing of nano silica from RH/RHA. It tries at the same time, to present a critical review of the application of RHA as an ingredient for the production of various ceramic materials, e.g., refractory, glass, whiteware, oxide and non-oxide ceramics, silica aerogel and SiO2/C composites. In summary, amorphous silica derived from RHA or RH provides a potential alternative to conventional silica sources (e.g., quartz) for the manufacture of value-added ceramics for practical applications.
... Characteristics of RHA depend on environmental circumstances of its origin as well as the route acquired during burning conditions of the husk [31]. It contains 80-97% of amorphous silica and this silica shows better reactivity than crystalline silica present in quartz [32]. Different studies are performed in order to utilize the RHA silica for preparation of different ceramics i.e. glazes preparation [33], borosilicate [34], cordierite [35], mullite [36], forsterite [37], silicon carbide [38] and refractory bricks [39]. ...
... When temperature is increased from 800 to 1000 • C, geopolymerisation reaction takes place [19]. RHA contains amorphous silica that is more active, this silica starts diffusion reaction with others grains when increasing the firing temperature than 800 • C [32]. This diffusion of grains and geopolymerisation reaction are eliminates the pores between grains, aid the decreases of porosity and increases in bulk density with increasing temperature. ...
Article
The main objective of this study is to evaluate the use of different wastes as a raw materialin the fabrication of insulation refractory. These wastes are fly ash, rice husk (RH), rice huskash (RHA) and fired refractory grog. Various samples are prepared with different composi-tions based upon partial and fully replacement of clay by FA. Rice husk is used as an additiveto produce the pores in the matrix. The specimens are prepared by semi dry process andsintering is performed at 800-1000?C in air atmosphere. Numerous physical, mechanicaland thermal characterizations like apparent porosity (AP), bulk density (BD), cold crush-ing strength (CCS), linear shrinkages, X-ray diffraction (XRD), scanning electron microscope(SEM) and thermal conductivity measurements of fired samples are done. The results showthat the use of waste materials decreases the thermal conductivity and bulk density ofthe insulation refractory. Cold crushing strength of the 100 wt.% waste materials sample isaround 15 MPa. This promising characteristic suggests that these wastes materials may leadto be used as a potential material for the preparation of insulation refractories. The use ofwaste materials may be economically attractive and technically feasible.
... Among these impurities in rice husk ash are heavy metals, which could pose, environmental and health hazards to ecosystems and humans [2]. The properties of rice husk ash are affected by the method applied in burning the rice husk and the ecological factors surrounding its origin [3]. ...
... Thus, the authors are pleased to state that this is the first study of its kind reported in the literature with regards to rice husk ash and this has been the motivation for this work. 3 The sample collection and preparation have already been outlined in [2]. For this study, the concentrations of the metals Ti, Cr, Ni, Cu, Zn and As were taken from Table 1 in [2] and used for the computations in this paper. ...
Article
In a previous study by the authors [2], the concentrations of heavy metals in Izzi CP, Ikwo CP and Izzi R8 were reported to be quite high. As an extension of the previous work, in the present work, pollution of rice husk ash (RHA) of Izzi CP, Ikwo CP and Izzi R8 rice species due to heavy metal contamination was assessed using various pollution indices. The results of the study showed that all the samples indicated ultra-high contamination level due to the heavy metals as indicated by the modified contamination degree (mCd) values. Also, the results showed that in the Izzi CP, the order of contamination factor is Cu<Zn<Cr<Ni<As, Cr<Zn<Cu<Ni<As for Ikwo CP and Cr<Cu<Zn<Ni<As for Izzi R8. For all the samples Cr and As showed the lowest and highest enrichment respectively of all the metals. The values of the geoaccumulation index, Igeo, for Ni and As suggested extremely polluted conditions for all the samples and the highest ecological risk is from Arsenic (As). Furthermore, it was observed that Izzi CP is the most contaminated of all the samples and that the major contributor to this contamination is Arsenic (As).
... The investigation of material's properties and microstructure "in operando" are 396 supposed to provide also important information for practical applications. For example, at 397 temperatures above 800 °C, large pores are known to promote heat transfer by thermal radiation due 398 to reflection of the incident radiation on their internal surface ( Gonçalves and Bergmann 2007). In 399 the present approach, this aspect could not be investigated, therefore "in situ" tests will be considered 400 in the future. ...
... The investigation of material's properties and microstructure "in operando" are supposed to provide also important information for practical applications. For example, at temperatures above 800 °C, large pores are known to promote heat transfer by thermal radiation due to reflection of the incident radiation on their internal surface ( Gonçalves and Bergmann 2007). In the present approach, this aspect could not be investigated, therefore "in situ" tests will be considered in the future." ...
Article
The behavior of a composite material, consisting of metakaolin-based alkaline aluminosilicate binder, granules of the same initial composition used as a swelling agent, and calcium carbonate, was studied during firing in the temperature range 25°C–1,000°C. A combination of techniques was used to investigate its microstructure, composition, and properties. The material developed porosity at 200°C, largely contributed by water loss from the swelling agent, resulting in expansion and decrease in thermal conductivity and mechanical strength. Between 400°C and 800°C the thermal insulation characteristics further improved. At 1,000°C, crystallization of new phases with a decrease in the amorphous content produced a small contraction and increased thermal conductivity and mechanical strength. The material exhibited good stability with appropriate characteristics for use as intumescent coating for fire protection of structural elements. Modification of the binder:granules ratio may allow producing composites for specific applications.
... It has been reported that geopolymerization reaction takes place between fly ash containing active alumina and silica when the temperature is increased from 800 to 1000 °C [16] and clays generally go into vitrification at around 850-950 °C [47]. RHA contains amorphous active silica which is responsible for diffusion reaction with other grains while increasing the sintering temperature above 800 °C [48]. The diffusion of grains, vitrification of clay minerals and geopolymerization reaction of fly ash eliminate the pores between the grains. ...
Article
This study aims to investigate the use of different wastes as raw materials in the fabrication of sustainable, eco-friendly fired building bricks. Wastes such as demolished bricks, fly ash and rice husk ash (RHA) are used for the development of fired building bricks. Based upon partial replacement of clay by demolished brick waste (5–25 wt%), various samples are prepared with different compositions and the total waste is kept up to 80 wt%. The effect of glass cullet addition on the sintering temperature and properties of fired bricks are also studied. The samples are prepared by the semi-dry process and fired at different temperatures, i.e., 800, 900 and 1000 °C in air atmosphere. All the fired specimens are characterized mainly by physical, mechanical and thermal characterizations. The compressive strength and water absorption are compared with their respective American society for testing materials (ASTM) standards. Results exhibit that 10 wt% glass cullet and 70 wt% other waste demonstrate better properties at 800 °C. These promising results suggest that this study will be open a new window to brick industry for utilization of demolished bricks in commercial production of fired bricks.
... Goncalves and Bergmann [121] have utilized the rice husk ashes to produce thermal insulators. The thermal insulators were characterized both chemically and physically, and their properties were correlated to their microstructure. ...
... On the other hand, as amorphous silica is a reactive material, it can be used as pozzolan in cement industries and producing low-cost building block [42,43], as cement additive in solidification of hazardous wastes [44,45], in cement, alkali-activated materials (AAMs), geopolymer, and construction industries [46], as filler in polymer, plastic, rubber industries [47,48]. However, resistance against fire is one of the special features of crystalline silica which is the reason for using it in thermal insulators, ceramic production, steel industry, and refractory brick [49][50][51]. ...
Article
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The incineration of agricultural wastes (agro wastes) as a fuel, solid fuel, and/or for the same purposes, resulting in landfilled ash that in most cases makes an environmental problem due to disposal. These landfilled most of the time contain valuable elements such as silica and alumina which are promising alternatives to be used in value-added engineering products. With this regard, the optimal use of these wastes has always been a concern for researchers, and the utilization of them for different purposes is an effective way of management. Although in recent years, the beneficial use of agro waste ashes has been considered by many researchers in different engineering fields, according to the preparation conditions and activation techniques, different kinds of ashes are produces. Therefore, according to the composition of final product, various applications are considered including wastewater treatment, additive for cement industry, and alkali-activated materials, as an additive for production of glass, silicate, pure silica, silicon carbide, refractory materials, as filler in thermoplastics and rubbers, reinforcing agent, and adsorbent in polymer composites and epoxy thermostable polymers, for producing advanced materials such as Silicon nitrite (Si3N4) and magnesium silicide (Mg2Si), and many more. The present paper surveys the preparation steps and techniques for activation of rice husk ash as one of the most used agro waste ash and its applications in engineering fields.
... It may occur due to a decrease in the porosity of samples as the unit weight increased and crystalline hydration products also improve through this addition of OPC; which is conforms by Figs. 12( [56,57]. It is also seen that the j values increased with the increasing measurement temperature of conductivity. ...
Article
This work aims to evaluate the feasibility of using seashell and fly ash as ingredients for fabrication of the sustainable ceramic board. The multi-phase ceramic powder (MCP) formulation was done through the mixing of 1:1 weight ratio of fly ash and heat-treated seashell as ingredients and calcined at 1100 °C. Larnite (Ca2SiO4) was a major phase, and minor phases obtained in MCP were mullite (Al4.56Si1.44O9.72), calcium aluminate (Ca3Al2O6), and anorthite (CaAl2Si2O8). Ceramic board (CB) samples were prepared by simple room temperature curing (without autoclave) process with the mixing of a different portion of unground rice husk ash (URHA), rice husk (RH) and a small amount (10 wt%) of Ordinary Portland Cement (OPC). Several physicals, mechanical and thermal characterizations especially X-ray diffraction (XRD), scanning electron microscope (SEM), water absorption, bulk density (BD), expansion in water, bending strength, compressive strength, thermal conductivity, and humidity effect of the cured specimen were analyzed. The obtained results show that the addition of URHA, RH, and OPC with MCP influence all the properties of CB. The wastes derived CB exhibits good properties than a standard internationally calcium silicate board’s technical data, i.e., low density (<1000 kg/m³), good bending strength (>6 MPa) and low thermal conductivity (<0.22 W/m-K). It suggests that these wastes derived sustainable CB can be used for the internal lining of the building for thermal insulation.
... On the other hand, the incorporation of URHA in the composition does not have a significant effect on the Ä values. It may be happened due to lower Ä values of amorphous RHA silica (0.140 W/m K), which also acts as a barrier to the flow of heat and attributes to the lower value of Ä [54]. ...
Article
The present investigation aims to estimate the feasibility of using eggshell and rice husk ash (RHA) as ingredients to produce calcium silicate board (CSB). The solid-state route was used to prepare the calcium silicate (CS) powder through the mixing of heat treated RHA (∼93% SiO2) and calcined eggshells (∼99% CaO) at 1050 °C. CSB specimens were prepared at room temperature by simple curing process followed by mixing of different proportions of CS powder, ordinary portland cement (OPC) and unground rice husk ash (URHA). Several physicals, mechanical and thermal characterizations of the cured specimens were performed. The addition of OPC and URHA with CS were significantly influenced all the properties of CSB. The wastes derived CSB was exhibited low density (
... The RHA is an agricultural waste, which is generally used as ameliorants to break up clay soils and improved soil structure but is also used for the production of silica. The properties of RHA depend on the ecological circumstances of its origin as well as the process applied for burning the husk [5]. Silica which is the constituents of silicon and oxygen has the molecular formula SiO 2 . ...
Article
Full-text available
Nanotechnology is the most emerging field in the area of different scientific research. Various methods of synthesis of nanoparticles are available. The wet chemical synthesis method is applicable in the extraction of silica nanoparticles from Rice Husk Ash (RHA). Rice husk is a form of waste product from the rice milling industries which is produced in an abundance amount in and around the country. Rice husk which is generally left on the field as a waste contains 60% silica content and can be economically viable raw materials for the extraction of silica [1-2]. Initially, Rice husk was burnt to obtain its ash. Then, a simple bottom-up approach, the sol-gel method was applied, and fine powder silica in the nanoscopic range was extracted. After extraction of it, internal arrangement and average particle size were recognized by XRD while molecular components and structure present in silica were identified by FTIR. The obtained silica was then used in making of ceramics matrix nanocomposites (particularly silica-sand cement block), and its mechanical properties were identified by compressive strength test using Instron testing machine which was found to be increased in comparing with the compressive strength of ceramics composite (Sand cement block) prepared in the same ratio and same size of mold as that of ceramics matrix nanocomposites. The ceramics matrix nanocomposites acquiring higher mechanical strength than Ceramics composite occurred due to the incorporation of Silica nanoparticles.
... The crystalline form of silica can be applied in the production of ceramic [96,97], thermal insulator [98], and refractory brick [99] because of its high resistance to burning. Also, it has been used as a substitute for commercial silica in glassmaking [100]. ...
... Upon incineration, RH generates new waste in the amount of around 18-25 wt.%, namely rice husk ash (RHA), which causes environmental pollution as well as disposal problems, since only a small quantity of RHA, is used in agriculture and the brick industry. RHA is composed primarily of silica at greater than 92 wt.%; its characteristics depend on the ecological circumstances of its origin as well as the combustion conditions [19]. This silica has a large spectrum of applicability in industries, including chemicals, electronics and others [20]. ...
Article
Full-text available
The aim of this study is to fabricate synthetic wollastonite from chicken eggshells (CES) and rice husk ash (RHA) through an economical solid-state route. Wollastonite was formulated with a stoichiometric amount of calcined eggshells (~99% CaO) and heat-treated RHA (~93% SiO2) as ingredients and calcined at 1000, 1100, 1150 and 1200°C for 120 min. The XRD spectrum revealed single-phase para-wollastonite (monoclinic, P21/a) after annealing at 1100°C and 1200°C with calcined powder contents comprising mainly a phase of pseudo-wollastonite (anorthic, C-1). For dielectric measurement, only the para- and pseudo-wollastonite pressed powder was sintered at 1100 and 1200°C for 240 min. The obtained results showed a stable, low dielectric constant (ε׳) of about 4.5 to 6, losses (tanδ) of about 0.0026 to 0.00361 and resistivity of around 6-9×10⁸ (Ώ-cm) at 100 kHz. These are highly promising characteristics which suggest that waste-derived synthetic wollastonite may be useable as an ingredient in electrical porcelain applications.
... tonnes production of rice straw in a year [4]. This residue occupies large areas, where it can self-burn, spreading the ashes and causing tremendous harms to the nature [5]. During silicates from the soil and accumulate it into their structures. ...
Article
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Clay has been used as main material in fabrication of bricks however the use of waste materials in brick manufacturing has been introduced for conservation of dwindling clay resources, as well as preventing environmental and ecological damages caused by quarrying and depletion of raw materials. Bricks that available in some regions have poor quality, low compressive strength, higher water absorption and uneven surfaces Therefore in this study, rice husk ash has been utilized for the preparation of bricks in partial replacement of clay. The specimens were cast with different replacement levels of clay varying as 0%, 5%, 10%, 15%, and 20% with rice husk ash. The specimens were tested for water absorption and compressive strength accordingly to Malaysian Standard EN 1008:2010 for 2 hours. Experimental shows that excessive addition of rice husk ash has higher water absorption and low compressive strength as rice husk ash percentage increases rice husk ash characteristics predominate. The bonding between the clay particle and the rice husk ash particles is weak. By adding 10% of rice husk ash by weight is the best brick properties which 6.80 MPa of compressive strength and 16.30% of water absorption. The water absorption of RHA brick developed did not exceed 20% hence promoted to be partial replacement of clay.
... Conversely, it is slightly diluted the mechanical strength of the bricks compared with the commercially available insulation bricks. Low σ value (0.140 W/m·K) and amorphous silica containing RHA make useful as an ingredient for the fabrication of insulation refractory [34]. The RHA containing insulation bricks are prepared by the mixing of binder (fluxing materials), plasticizers (no plasticity of RHA) and pore former with RHA [35][36][37]. ...
Article
Full-text available
Wastes from different manufacturing processes and energy generation unite are attributed to the ecological and health issues. Instead of land-filling, the waste can be recycled or reused to convert marketable value-added products with high ecologic and economic interest. Ceramics are attracting particularly in waste recycling perceptions. From this eco-friendly propensity, in the last two decades, an increasing number of studies have demonstrated the possibility to use alternative ingredients in the place of conventional raw materials (e.g., most common ternary clay-quartz-feldspar system) for the fabrication of ceramics. Researchers are trying to incorporate the wastes and industrial by-products like fly ash (FA), rice husk ash (RHA), blast furnace slag (BFS), sludge, glass waste, polished tile waste, eggshell and others for making different ceramics. The present review is aimed to provide an up-to-date overview of the recent waste-derived ceramics including refractories, glasses, whitewares, oxide and non-oxide ceramics with the correlation of waste incorporation limits, manufacturing routes, and properties of the ceramics. The investigation reveals that ceramic industries have huge potential to utilize the wastes as substitution of the natural raw materials. The waste to value-added ceramics conversion not only solves the disposal problems but also conserves the natural resources.
... Thus, RHA is utilized as an alternative to ordinary portland cement (OPC) to increase the performance and the durability as well as to decrease the costs and for environmental reasons [12]. Furthermore, it is used for coatings in epoxy paints [13], as insulating material on account of its low thermal conductivity [14] or as filling material in rubbers [15,16]. The porous nature of the biogenic silica paired with the high specific surface area suggests a use in inexpensive biocide delivery systems (BDS) for controlled, sustained biocide release for crop and wood protection [17,18]. ...
Article
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Biomasses are a sustainable, CO2 neutral source used in biorefning. Si-accumulating plants can be used for the production of biogenic silica in a biomass valorisation process. This study examines the production of high-grade porous silica from different plant parts like rice, oat and spelt husk, rice straw and horsetail using a generalized procedure for all. The silica materials were produced by a 2-step method. First, the biomasses were pretreated with water and then subjected to leaching with citric acid. As a second step, a sequential burning program was applied. The characterization of the untreated biomasses was carried out by X-ray fluorescence (XRF) analysis and thermal analysis (TG–DTA). The biogenic silica samples were subjected to XRF, carbon content analysis, low temperature nitrogen physisorption, scanning and transmission electron microscopy as well as X-ray diffraction. Independent of the initial composition of the plant part, the established method resulted in amorphous, biogenic silica with up to 99.7% purity, mesopores between 2 and 30 nm with pore volumes of up to 0.46 cm3 g−1 and specifc surfaces of up to 303 m2 g−1. It was shown that the generalized method developed works not only for all the biomasses separately, but also if treated in the same batch. The produced biogenic silica can be considered as sustainable alternative to other silica products like precipitated silica, silica gel and fumed silica which are produced in highly energy consuming processes.
... The properties of rice husk ash are shown in Table 3. The composition presented in this Table were taken from studies reported by the following authors (Aprianti et al., 2015;Gonçalves and Bergmann, 2007;Khan et al., 2012). ...
Article
In oil-well cementing, Portland cement is commonly used as a binder in cement slurry formulations. However, a significant amount of CO2 is released into the atmosphere during the production of clinker, the main in-process materials in cement manufacturing. Again, the use of non-renewable resources in cement production makes the process unsustainable. Over the years, chemical and physical analyses of some industrial and agro wastes have revealed characteristics that make them useful as supplementary cementitious materials. Some of these byproducts contain chemicals that can be extracted to modify the fresh and hardened properties of cement-based materials. These materials include coal fly ash, ground granulated blast furnace slag (GGBFS), silica fume, granite waste powder (GWP), rice biomass, palm oil biomass, sugarcane biomass, wood biomass, coconut biomass, and corn biomass. The purpose of this study is to investigate the industrial and agro wastes that were used in cement-based materials and make recommendations for future applications of these materials in oil-well cementing. An overview of experimental procedures and conclusions from laboratory and field studies conducted to evaluate the performance of such materials as cement admixtures is presented. A summary of key findings has also been reported. We recommend extensive evaluation of GWP as a filler/pozzolanic material or alternative to silica flour as an anti-strength retrogression agent. Secondly, we recommend an investigation into the use of other waste materials such as RHA as fillers in cement formulations to enhance the early-age strength development of fly ash and GGBFS oil-well cement systems, especially at low-temperature conditions. Finally, we recommend an assessment of POFA as an extender and the evaluation of both POFA and RHA as anti-strength retrogression agents in oil-well cement formulations.
... The RHA in its amorphous form it is already known as an alternative source of silica since assumes pozzolanic properties [7,8]; it is resistant to chemical corrosion, temperature variations and presents low thermal conductivity, high melting point, low bulk density and high porosity. These characteristics make it an excellent co-product to be introduced in several spheres of industry such as electronics, cement and ceramics [3,9,10]. Regard to ceramic materials, the waste amount of any kind that can be used almost never transpass 10% by weight and the most notable effect besides the energy saving during the burning process are a bigger porosity, mechanical and shrinkage properties reduction [3]. ...
Article
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The main objective of this work was to evaluate the effects of rice husk ash and wollastonite microfibers incorporation, added per clay partial substituition, on physical and thermal properties of refractory ceramic composites. The raw materials characterization occurred with respect to their chemical composition (XRF), phase composition (XRD) and granulometry by laser. The composites were avaluated by physical properties - apparent porosity, bulk density, water absorption, linear retraction after sinterization and mass variation - and thermal properties - thermal conductivity and thermal shock. The rice husk ash used in the present work proved to have potential as a ceramic precursor in the development of refractories. The clay substitution per ash and the microfiber different percentages resulted in an increase in water absorption and apparent porosity and a reduction in the linear retraction. The increase in porosity suggests that the mullitization was insufficient. Regarding the thermal performance, the thermal conductivity was inversely proportional to the porosity and the microfiber percentage. In addition, the higher the thermal-shock temperature gradient the lower was the number of cycles resisted by the composites.
... The ecological circumstances of its origin and the process applied for burning the husk influences the properties of RHA [6]. Burning RH produces high ash content, ranging from 13 to 29% depending on the rice variety, climate and geographical location. ...
Article
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Heavy metals such as Cr, Zn, As, Pb and Cu can be hazardous to health and the environment. The focus of this study is to investigate the trace metal constituents of rice husk ash (RHA) from Ikwo and Izzi rice clusters. RHA of Izzi CP, R8 and Ikwo CP rice husk species were sampled. Elemental characterization was done using X-ray fuorescence method. A total of 14 elements (K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Rb, As, Br, Sr and Ga) were detected in the rice husk species except in Izzi CP where Ga was not detected. The concentration of these elements in weight percent (wt. %) were compared with literature. Elements like, K, Ca, Fe, and Mn were found to be in negligible concentrations in all the samples while Ga, Rb, Cu, Cr, Zn, As and Ni were found to be well above the literature values. The X-ray fuorescence analysis of the samples showed that some toxic heavy metals like Cr, As, Ni, and Cu were of high concentrations compared to literature which for health reasons are not advisable to have long term exposure.
... As shown in Table 1, RHA was mainly composed of silica along with major oxides of potassium, calcium and magnesium. Similar observations were reported in previous studies [17]. ...
Article
Rice Husk (RH) is an agricultural waste which is produced in huge amounts from the milling process of paddy rice. Rice Husk Ash (RHA) is a by-product material obtained from the combustion of rice husk. The amorphous silica-rich RHA (84-90 wt%) has a wide range of applications. This research focused on the possibility of utilizing RHA in the process of developing a mortar with low thermal conductivity to enhance the thermal comfort in concrete and masonry buildings. The thermal conductivity of mortar was determined by Lee’s Disc method, and the results were compared to the data for conventional mortar as well as commercial thermal insulation materials. The results indicate a significant reduction in thermal conductivity in the mortar developed with RHA
... Moreover, it is also being used in low-permeable, high-performance, and high-strength concrete mixtures in the construction of bridges, marine environments, and nuclear power plants. One thousand kilograms of rice can produce almost 45 kgs of RHA which exhibits high surface area, significant pozzolanic properties, and high silica content (∼95%) [205]. RHA mixed GPC could minimize the temperature effects that arise due to the hydration of cement. ...
... RHA presents silica in distinct phases that is; amorphousquartzcrystobalite -tridymite which is a gradual transition from one phase to the other as the burning time and temperature increases. Gonzalves and Bergmann (2007) showed that the properties of the RHA depend on the ecological circumstances of its origin (soil chemistry, fertilizer applied, type of rice) as well as the burning process. This study is aimed at analyzing the chemical and physical properties of the RHA in Kenya; a case study on Mwea RHA produced under controlled burning with burning temperature as the only variable. ...
Research
Rice husk is an agriculture by-product obtained from theprocessing of food crop of paddy, with no major alternative use. Research publications have concluded that rice husk ash possesses pozzolanic properties and that these properties vary very much with locality and depend on the manufacturing process including the burning and grinding process. Use of pozzolanic alternative or cement replacement materials is expected to reduce construction costs as well as reduced carbon emissions resulting from cement manufacturing process. In addition pozzolanas increases compressive and flexural strengths, reduces permeability and boosts resistance to chemical attack in concrete. The scope of the research in this paper covered an experimental analysis of the physical and chemical properties of the rice husk ash produced from a controlled burning of rice husk sourced from Mwea Irrigation Scheme, Kenya. Prior to the experimental analysis, controlled burning of the rice husks was conducted at a temperature range of 300-500°C; 500-700°C and 700-900 °C each with a 3-hour soaking time. The resulting ash samples were then characterized using energy dispersive x-ray spectroscopy, atomic absorption spectroscopy, loss of ignition, color, specific gravity, particle size distribution and fineness. The results show that, the rice husk ash had distinct color variation at each burning temperature. The amount of silica present in the rice husk ash varied with the burning temperature, approximately in the range of 80% to 89% taking more than 50% of the total elemental composition. Rice husk ash indicated higher, loss of ignition when produced at lower temperatures. It was established that amorphous rice husk ash in a controlled burning could be produced at temperature range of 500-700 0 C.
... The properties of RHA most often rely on the sort of rice plants, as well as on the process of heat treatment of the RiH. [17]. Besides, the properties of reactive silica present in the RHA may also vary depending on the heat treatment temperature time. ...
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In the last few decades, the demand for cement production increased and caused a massive ecological issue by emitting 8% of the global CO2, as the making of 1 ton of ordinary Portland cement (OPC) emits almost a single ton of CO2. Significant air pollution and damage to human health are associated with the construction and cement industries. Consequently, environmentalists and governments have ordered to strongly control emission rates by using other ecofriendly supplemental cementing materials. Rice husk is a cultivated by-product material, obtained from the rice plant in enormous quantities. With no beneficial use, it is an organic waste material that causes dumping issues. Rice husk has a high silica content that makes it appropriate for use in OPC; burning it generates a high pozzolanic reactive rice husk ash (RHA) for renewable cement-based recyclable material. Using cost-effective and commonly obtainable RHA as mineral fillers in concrete brings plentiful advantages to the technical characteristics of concrete and to ensure a clean environment. With RHA, concrete composites that are robust, highly resistant to aggressive environments, sustainable and economically feasible can be produced. However, the production of sustainable and greener concrete composites also has become a key concern in the construction industries internationally. This article reviews the source, clean production, pozzolanic activity and chemical composition of RHA. This literature review also provides critical reviews on the properties, hardening conditions and behaviors of RHA-based concrete composites, in addition to summarizing the research recent findings, to ultimately produce complete insights into the possible applications of RHA as raw building materials for producing greener concrete composites-all towards industrializing ecofriendly buildings.
... O restante (20-30%), compreende elementos minerais formando sílica, álcalis e oligoelementos (Sarangi et al., 2009). A cinza de casca de arroz (CCA) obtida pelo processo de queima da casca de arroz (CA) tem em torno de 85-95% de sílica amorfa, é as suas propriedades dependem principalmente do processo aplicado no processo de queima a casca (Gonzalves & Bergmann, 2007). Tornado o uso de CCA, foco de investigações para identificar e conhecer os eventuais benefícios das aplicações nos cultivos. ...
... After combustion, rapid or slow cooling process is performed. It gives rice husk ash with the presence of amorphous silica (85-90%) [73][74][75]. Zain et al. [73] described a different method for treating RHA with firing of raw form at the rate of 10°C till the temperature reaches 700°C. After reaching, it has been kept for 6 h. at the same temperature. ...
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Increase in urbanization is the reason for the inadequacy of building development materials. The systematically increasing interest in evolving building development materials, there is a need to hold an ability for good decisions and, update standard procedures with accessible near materials. Agro-mechanical and alternative robust waste transfer is another important issue of worry in making nations. This paper investigates the potential utilization of agro-squander as a substitute for possible building materials. The present study also emphasizes over the use of agro-squander material without their conversion to ash. As the development of ash particles involves the emission of carbon dioxide.
... Thermal conductivities and densities of conventional and unconventional thermal insulation materials[83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101]. ...
Article
The carbon footprint of buildings is mainly attributed to the embodied carbon of building materials and their hygrothermal performance. In recent years, the search for materials with low gray energy and better hygro-thermal performance has increased. Foamed geopolymers are among the materials that are attracting a lot of attention. Their high hygrothermal performance and the fact that they can be synthesized from abundant earth elements at ambient hygrothermal conditions are the main reasons for their growing popularity. Foamed geo-polymers can also be produced from commonly available industrial wastes providing new opportunities for a circular economy. Many studies have been done to engineer these materials for specific applications in water purification, catalysis, thermal insulation, hazardous waste encapsulation, and acoustic isolation. Several recent papers have been discussing the mechanical features of geopolymers. Recent reviews also focus on the processing , applications, and properties of foamed geopolymers. However, a review about the impact of manufacturing parameters on porosity, pore nucleation, and pore parameters is still missing. These parameters determine the intrinsic and extrinsic thermal isolation properties of foamed geopolymers. This article aims to address this research gap. The effects of pore-forming agents, molar ratios of oxides, water, curing temperature, and pH on the microstructure of foamed geopolymers are discussed in this paper. The influences of these factors on intrinsic and extrinsic pore parameters are presented.
... Based on these report, corncob ash has the potential source of silica. Silica is a chemical compound with the formula SiO 2 molecule (silicon dioxide) which can be obtained from mineral silica, vegetable (natural material) and synthesis (Bragmann and Goncalves, 2007). ...
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In this study, a simple method to obtain silica from corncob ash has been investigated using a nonthermal and thermal method. The Nonthermal method was done by various acid treatment with HCl, HBr and citric acid at room temperature. Thermal method was performed for HCl-leached, HBr-leached, and citric acid-leached corncob in the furnace at 750 ºC for 5 hours. Corncob ash was characterized by Energy Dispersive X-ray fluorescence spectroscopy (EDXRF), Fourier transforms infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and Scanning electron microscope-electron dispersive X-ray (SEM-EDX). In this study silica content increase after acid treatment (leaching) and combustion at high temperatures. The result established that silica is most obtained with HCl treatment that is equal to 79,95% with lower metallic oxide impurity content. The FTIR spectra with different intensity shows silanol group at 1636 – 1641 cm-1, whereas siloxane group at 1037 – 1106 cm-1, 616–797 cm-1, and 459–469 cm-1. X-Ray diffractogram shows silica transition pf amorphous (2θ = 21 - 25º) to quartz crystalline (2θ = 26.66º) phase. The surface morphology of silica that characterized with SEM-EDX shows amorphous and crystalline silica corresponds to XRD result. The high intensity spectra of Si and O in EDX shows the presence of silica in corncob ash.
... The concentrations vary from region to region, and other elements may also appear to differentiate a particular harvest. The Rio Grande do Sul state, the author's location, is the most rice-productive region in Brazil [11], and it has been reported that the RHA from this region typically also contains small percentages of manganese oxide (II) [14]. The presence of transition metal oxides and how they react and oxidize in the melt (ie., Mn 2+ /Mn 3+ and Fe 2+ /Fe 3+ ratio) can affect the transparency of the glass, giving colored hues to the final material [15,16]. ...
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Glass is a familiar material that requires abundant mineral sources, with devastating consequences for the environment. Rice husk ash (RHA) presents a very high silica content (>95%) and it can be a very promising alternative source for silica in silica-based glass. However, impurities like manganese and iron, which depend on the rice harvest, might limit RHA use, particularly in the production of optical transparent glasses. In this work, we discussed how Mn and Fe can affect the coloring of the produced glass, and how the effect of these impurities can be removed. First, the RHA was treated with acid solutions, leading to the production of a soda-lime glass with similar transparency to commercial glass (>70%). Secondly, another simpler approach was studied: a small amount of antimony oxide was added in the composition of the glass, obtaining a transparent glass (>80%, same thickness) with RHA.
... Moreover, it is also being used in low-permeable, high-performance, and high-strength concrete mixtures in the construction of bridges, marine environments, and nuclear power plants. One thousand kilograms of rice can produce almost 45 kgs of RHA which exhibits high surface area, significant pozzolanic properties, and high silica content (~95%) [205]. RHA mixed GPC could minimize the temperature effects that arise due to the hydration of cement. ...
Article
The rise in population and improvement in the lifestyle of human beings has caused a rapid increase in energy demands for buildings in the present day. An upsurge in energy demand, lack of fossil fuels, and environmental issues provide a crucial motive to the development of sustainable and viable infrastructure. Geopolymer (GP) composite free from cement, made from various waste materials with a high amount of Al2SiO3 and Na2SiO3/NaOH (alkali-activated silica) is evolving as an eminent material for sustainability purposes. They are also preferred due to the lesser emission of greenhouse gases as compared to ordinary Portland cement (OPC). This paper aims at presenting a sustainable domain and state of the art review of GP composite. The properties of composites made from various geopolymeric waste binders are presented. Besides, the microstructure and chemical characterization of GP composites are also discussed. The durability of GP composite is also highlighted considering its deterioration in various aggressive environments. In the end, a global warming potential (GWP) assessment was conducted and the practical applications of GP composites in the building industry are also provided.
Chapter
This study reports on an ongoing research project aimed at producing sustainable construction material for the precast concrete industry. This chapter studies the physical and chemical properties of materials, compressive strength, flexural strength, water absorption and porosity of multi-blended cements under different curing methods. Fly ash (FA), palm oil fuel ash (POFA) and rice husk ash (RHA) were used to replace 50% ordinary Portland cement by mass. Specimens were cured in water (WC), air under room temperature (AC), the combination of hot water at 60 °C for 24 h and curing in water (HWC) and air (HAC). The results showed that HAC could be an effective curing method with higher compressive and flexural strengths and lower water absorption and porosity for blended cement mortars. Mortars containing ground granulated blast furnace slag (GGBFS) in binder had higher enhancement of compressive strength under early hot-water curing, while at 24 h hot-water curing, mortar containing ordinary Portland cement (OPC)–RHA–FA binder showed better performance in properties compared to the other binders.
Article
Fulgurite is a natural glass created by lightning. Naturally it can be found at beaches or in deserts. Artificial fulgurite is created by immersing high-voltage electrodes in a tab of sand. Commonly, fulgurite is of interest among geoscientists, but its applications are still unknown. In the present paper, the concept of natural fulgurite generation is simulated to induce artificial fulgurite. Instead of lightning, a high-power laser beam is used as a source of transient heating. Syntactic sand from agrowaste is used as target material. Artificial fulgurite is generated after transient heating from a laser beam. The benefit of this finding can be used to extract silica from rice husk ash using laser technology.
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Mining and production of mineral fertilizers and transport across continents is vastly energy-inefficient, expensive and produces greenhouse gases. More viable plant nutrition strategies as alternatives for the prevailing use of mineral fertilisers, mainly produced by direct or indirect exploitation of non-renewable natural resources, are urgently needed. In face of growing world population and the limited area of productive agricultural land, this is one of the big challenges during the next decades. Use of recycling fertilisers based on industrial or municipal waste could be a promising perspective in this direction. On the other hand, the industrialization of society, the introduction of motorized vehicles, and the explosion of the human population, have caused an exponential growth in the production of goods and services. Coupled with this growth has been a tremendous increase in wastes. The question is: what is the possible way of reuse of these wastes? In general, it is obvious that the intensification of agricultural production triggers continuous increase in CO2 emission due to the larger volumes of materials used in production, because artificial fertilizers and other chemicals can be produced only in process of high energy input. Because of the rising energy demand, the costs of production are also mounting, which results in environmental problems. The goal of our work was to present the alternative way of the recycling of industrial wastes and by-products. The use of these by-products in agriculture offers us the possibility to moderate the quantities of expensive mineral fertilizers used in agriculture. As a side effect, CO2 emission could be decreased, as well. We show the two possible ways of the utilization of wastes and by-products: 1) use as waste and deposit, 2) reuse as plant nutrition materials.
Conference Paper
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Sustainable source of energy is one of the great challenges in generating clean power. There are several energy sources available for this purpose, such as photovoltaic, wind and geothermal. An emerging technology for sustainable energy harvesting is thermoelectricity, whereby temperature gradients in a structure are used to directly power thermoelectric generators (TEGs). For example, in South Texas, the asphalt pavement surface temperature in the summer is as high as 55°C due to solar radiation while Soil temperatures below the pavement, are roughly constant (i.e., 27°C to 33°C) at relatively shallow depths (150 mm). In such cases, there is around 20oC of thermal gradient available throughout most of the year. This thermal gradient can be used to drive TEG (typically 5mm in thickness) to produce electricity. This study describes the development of prototype using TEG to harvest this thermal energy and convert it into electric power. The objective of this study is to design a prototype that optimizes the temperature gradients available for thermoelectric power generation and evaluate the prototype under laboratory and field conditions.
Conference Paper
In this study, rice husk ash (RHA) and RHA derived silica aerogel were prepared and incorporated into low density polyethylene (LDPE) as a filler (0-10%) forming a composite and the performance of both fillers were compared. The composites were prepared by melt-blending and compression moulding. The effect of differing filler weight percentage on the thermal properties was also determined. Characterization of the fillers was done using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and a thermal conductivity meter. The prepared composites were characterized using FT-IR and thermal analysis was done using TGA, DSC and a thermal conductivity meter. Both fillers show improvements in terms of the thermal stability of the composite when compared to unfilled LDPE but comparisons between the silica aerogel and RHA shows that silica aerogel’s performance slightly edges the performance of RHA. The incorporation of silica aerogel as filler shows better thermal stability when compared to RHA with a slight increase in onset degradation temperature as the filler percentage increases. In terms of thermal conductivity, the addition of silica aerogel as filler shows an increase in thermal insulation strength of the composite with a reading in the range of 0.0926-0.1820 W/m.K compared to RHA at 0.3275-0.3532 W/m.K and unfilled LDPE samples at 0.3889 W/m.K.
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El gránulo de kéfir de agua es consumido a nivel local debido a su potencial probiótico asociado a su contenido de bacterias ácido lácticas (BAL). Con el fin de explorar su potencial antioxidante, se propuso el uso de concentrado de mucílago de café (CMC) y la panela como sustratos en el proceso de fermentación de un consorcio de gránulos de kéfir de agua, cuya identificación metataxonómica indicó como predominantes los géneros: Lactobacillus sp y Saccharomyces sp. La concentración máxima de CMC que puede ser empleada sin alterar la viabilidad del gránulo y su metabolismo fue 10%, y combinada con panela en una concentración de 100 g/L produjo 45,17 g/L de masa seca y una productividad volumétrica de 0,15 g secos /L*día. Por otro lado, mediante un diseño multifactorial, donde se evaluaron las variables de concentración de panela (Cpanela), porcentaje de CMC y pH inicial, se observó que el crecimiento del kéfir de agua en presencia de CMC al 10% a pH 7,0 es similar a la concentración de CMC de 0% (Pvol:0,91±0,11; Xf: 27,3±3,2 y Pvol:1,01±0,13; Xf: 30,7±3,8, respectivamente) y de panela de 100g/L. Sin embargo, la mayor concentración de polifenoles totales fue obtenida en presencia de panela 100g/L y CMC al 10% a un pH de 7,0, con un valor de 187,0±6,0 mgGAE/100g, siendo esta la mejor combinación de factores. Estos hallazgos sugieren que el CMC puede ser utilizado junto con la panela como sustratos promisorios, con potencial antioxidante, en el proceso de fermentación usando el gránulo de kéfir de agua.
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Thermoelectric (TE) technology enables the efficient conversion of waste heat generated in homes, transport, and industry into promptly accessible electrical energy. Such technology is thus finding increasing applications given the focus on alternative sources of energy. However, the synthesis of TE materials relies on costly and scarce elements, which are also environmentally damaging to extract. Moreover, spent TE modules lead to a waste of resources and cause severe pollution. To address these issues, many laboratory studies have explored the synthesis of TE materials using wastes and the recovery of scarce elements from spent modules. For example, utilization of Si slurry as starting materials, development of biodegradable TE papers and bacterial recovery and recycling of Tellurium from spent TE modules. Yet, the outcomes of such work have not triggered sustainable industrial practices to the extent needed. This paper provides a systematic overview of the state-of-the-art with a view to uncovering the opportunities and challenges for expanded application. Based on this overview, it explores a framework for synthesizing TE materials from waste sources with efficiencies comparable to those made from raw materials.
Article
In this study, light-weight insulation materials were prepared with calcined flint clay as the main material and sawdust was infused by sols as a pore forming agent. Micro-porosity and properties of the prepared insulation materials were investigated and were found to have better comprehensive properties. Apparent porosity, bulk density and cold crushing strength of the compositions containing 40 wt% calcined flint clay, fired at 1400°C for 3 h, were found to be 71%, 0.85 g.cm–3 and 2.65 MPa, respectively. Thermal conductivity of the material was 0.133 W.m–1.K –1 at 300°C. When sawdust was soaked by 0 wt% sol, microstructure of the materials showed irregular pores. When sawdust was infused with 7 wt% alumina sol, the micropores were wrapped with larger pore. Meanwhile, the original pore was refined, and cold crushing strength and thermal conductivity were also optimized. When the sawdust was soaked in alumina sol, the cold crushing strength increased to 3.3 MPa and the thermal conductivity decreased to 0.116 W.m–1·K–1 at 300°C. Grey correlation method indicated that the pore size of <2 µm, 2-6 µm and 18-26 µm had more significant influence on cold crushing strength and thermal conductivity.
Chapter
Every year million pounds of rice husk ash (RHA) is produced in the United States. A majority of the RHA is being burnt to produce electricity, which is not a sustainable practice. This chapter focuses on the use of RHA as a supplemental cementitious material (SCM) in producing fresh concrete. Based on the information available in the literature and laboratory test results, processed fine RHA (150 microns) is found to be a viable SCM for producing regular concrete. On the other hand, coarse RHA can be used for producing flowable fill concrete (FFC). The findings of this study are expected to help industry professionals in using RHA as an SCM of concrete.
Chapter
Industrialization has led to consumption of fossil fuels, causing a sharp increase in greenhouse gas emissions. Finding alternative energy resources is crucial and energy storage systems have emerged as a solution. Fluctuating energy production of renewable energy sources dictates utilization of energy storage systems connected to them. The arising problem with energy storage systems is their high cost, limiting widespread usage. Thus, finding cost-effective resources and production methods is of major importance. In this view, solid waste materials (SWMs) emerge as a potential solution due to their diversity, tailorable nature to produce energy storage materials. Based on this perspective, this article deals with reviewing utilization of SWMs in electrochemical and thermal energy storage systems.
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EFEITO DA APLICAÇÃO DA CINZA DA CASCA DE ARROZ SOBRE ATRIBUTOS DE SOLO SOB PASTAGEM RESUMO: A aplicação de materiais carbonizados em solos pode resultar em melhoria de seus atributos químicos, físicos e físico-químicos. Entretanto, trabalhos que foquem sobre o efeito da aplicação da cinza da casca de arroz em solos ainda são escassos na literatura. Este estudo teve por objetivo avaliar os efeitos da aplicação da cinza de casca de arroz sobre os atributos químicos, físicos, e físico-químicos do solo. Foram coletadas amostras de solo (Luvissolo) sob pastagem em Dom Pedrito, RS. A amostragem foi feita em topossequência nas seguintes condições: i) pastagem com aplicação de cinza da casca de arroz (4,8 Mg ha-1) e; ii) pastagem sem aplicação de cinza. Posteriormente, foram determinados atributos químicos, físicos e físico-químicos de solo. Através dos resultados, averiguou-se que o uso da cinza no solo tem a capacidade de diminuir a acidez, aumentar a disponibilidade de nutrientes e melhora as condições estruturais dos perfis de solo analisados. PALAVRAS-CHAVE: Resíduos Industriais, Fertilidade do Solo, Matéria orgânica do solo, Acidez do solo. APPLICATION EFFECT OF RICE HUSK ASH ON SOIL ATTRIBUTES UNDER GRASSLAND ABSTRACT: Application of pyrolized materials to soils may result in improvement of their chemical, physical and physicochemical attributes. However, studies focusing on the effect of applying rice husk ash to soils are still scarce in the literature. This study aimed to investigate the application effects of rice husk ash on the chemical, physical and physicochemical soil attributes. Soil samples were collected (Luvisol) under Grass in Dom Pedrito-RS. The soil samples were collected in toposequence under the following conditions: i) Grassland with rice husk ash application (4.8 Mg ha-1) and; ii) Grassland without ash application. Subsequently, chemical, physical and
Conference Paper
Rice husk ash (RHA) has been considered as an agricultural by-product in the United States as well as all over the world. The chemical composition of the RHA particle makes it a potential supplementary cementitious material. This study investigates the potential uses of RHA as a supplementary cementitious material (SCM) in the preparation of flowable fill concrete (FFC). Flowable fill is defined as a self-compacting material, which has been used for different aspects such as backfilling, utility trenches, bridge abutments, pile excavations, and retaining walls. In this study, two different types of RHA samples (600-RHA: 600 µm, and 150-RHA: 150 µm) with two different particle sizes were utilized to evaluate their application in producing low strength FFC. The evaluation process of RHA modified FFC mixtures includes determination of strength, flowability, unit weight, and air content of modified FFC mixtures through different laboratory experiments. Fresh FFC test result showed that RHA modified FFC mixtures required higher amounts of water to maintain a desired level of consistency. Laboratory experiments on hardened FFC mixtures prepared using coarse RHA particles resulted in lower strength properties compared to the regular FFC where medium-fine RHA particles in FFC mixers were found to be effective in increasing the strength properties. Two field demonstrations have been conducted to evaluate the workability, placement, and in-service performance of RHA modified FFC in field conditions. The findings of this study are expected to help the transportation and construction agencies in finding an alternative construction material.
Book
This book comprises the select proceedings of the International Conference on Future Learning Aspects of Mechanical Engineering (FLAME) 2020. This volume focuses on several emerging interdisciplinary areas involving mechanical engineering. Some of the topics covered include automobile engineering, mechatronics, applied mechanics, structural mechanics, hydraulic mechanics, human vibration, biomechanics, biomedical Instrumentation, ergonomics, biodynamic modeling, nuclear engineering, and agriculture engineering. The contents of this book will be useful for students, researchers as well as professionals interested in interdisciplinary topics of mechanical engineering.
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كتاب المؤتمر الدولي المغاربي الأول لمستجدات التنمية المستدامة "الو اقع والمأمول
Article
This paper evaluates the synergistic influence of utilizing agricultural wastes i.e. rice husk ash (RHA) and coarse recycled concrete aggregates (CRCA) on the properties of recycled aggregate concrete (RAC). The RAC mixes were made with 0%, and 100% substitution of coarse natural aggregates by CRCA. Cement is further substituted by RHA at 0%, 5%, 10%, 15%, 20%, 25% and 30% to understand the influence of RHA on the fresh and hardened properties of RAC. The mechanical properties were investigated through compression, tension and flexure test at various ages such as 7, 28 and 56 days and other hardened properties like the water penetration resistance and the dry density were also studied. The various properties of the RAC were found to be improved as the RHA quantity is raised till 25% and further decreased when RHA content is increased to 30%. The use of RHA has proved to be very effective as the compressive strength improved by about 26% at 25% RHA. The correlation among the different strength parameters in the RAC mixes has also been established. The water permeability of the concrete mixes got reduced and the dry density increased with the increase in RHA content due to the reduced porosity. This was possible because of the pozzolanic reaction of amorphous silica present in RHA. Hence, the short comings of RAC can be overcome with the use of low end pozzolanic materials like RHA and can be used for retaining the performance of concrete containing 100% RCA.
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Fibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.
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The present work aimed to develop epoxidized natural rubber/thermoplastic polyurethane thermoplastic vulcanizates (ENR/TPU TPVs) having some specific properties, i.e., good processability and dynamic properties, and excellent heat and oil resistances. A comparative study on the effects of rice husk ash (RHA) and commercial siliceous earth (SE) as reinforcing fillers on alteration and enhancement of TPV properties was performed. It was found that the RHA-filled ENR/TPU TPVs showed an improvement of thermoelastic properties with outstanding thermal resistance relative to the pure TPU. This might be attributed to the synergistic effects of the dispersed vulcanized ENR domains and the RHA particles in the TPVs. Furthermore, the RHA-filled ENR/TPU TPVs had rather similar performance, processability and physical properties to the SE-filled ENR/TPU TPV. This indicates that the RHA has great potential as a filler in thermoplastic vulcanizates, in particular with ENR that is a renewable green resource.
Article
Biogenous silicic acids, known in everyday language as 'rice husk ashes', represent an interesting, growing and available raw material potential for insulating, shaped and unshaped refractory materials. The thermal decomposition of the precursor 'rice husks' makes the simultaneous attainment of energy and biogenous silicic acid possible. Thermal decomposition of rice husks is essentially done gradually with delivery of carbon monoxide and methane up to 500°C. The 'intermediate product' is black X-ray amorphous rice husk ashes with fixed carbon. Above 725°C the silicic acid begins to considerably crystallize into cristobalite. The crystallizations rate increases exponentially up to 1600°C. The fixed carbon content can be removed, if required, by adding oxygen and gasification. The test results form the basis for the industrial production of rice husk ashes with specific and reproducible product properties according to a thermal two-step process with corresponding firing units. Up to now, both products - Orylex R - which use rice husk ashes in insulating lightweight bricks for the preheating zones of cement rotary kilns and the tundish powder Nermat/Silimat R for distributor containers for the continuous casting of steel, make use of this raw material's potential on a quantitatively significant scale.
Article
A study is presented on the economic evaluation of a small energy system based on the availabity of natural energy sources in the agrarian state of Rio Grande do Sul of Brazil. A combined energy system run by burning the rice husks as a by-product and the energy a available from the windy sites, especially during the irrigation period, could be a viable proposition to meet the constant deficiency of power supply in the region. The electricity generating cost from the rice husks could be as low as US$ 34.03/MWh, whereas from wind energy it could cost US$ 67.79 and 112.98/MWh at places where the annual average wind speed is 6 and 5 m/s, respectively. On average, the combined system could produce electricity at US$ 62.21/MWh based on a 7% interest rate on the investment.
5a and b show the apparent density, porosity and compressive strength of both RHA Ex and RHA Pr ther-mal insulators. Plotted values are a mean of 20 measure-ments, and they are self-correlated. As it can be seen from Fig. 6a, thermal insulators made from RHA have low apparent density
  • Density
Density, porosity and mechanical strength Figs. 5a and b show the apparent density, porosity and compressive strength of both RHA Ex and RHA Pr ther-mal insulators. Plotted values are a mean of 20 measure-ments, and they are self-correlated. As it can be seen from Fig. 6a, thermal insulators made from RHA have low apparent density (350–850 kg/m References
Aproveitamento energé da casca de arroz. Programa energia
  • Cunha Jcc
  • Canepa
  • Em
Cunha JCC, Canepa EM. Aproveitamento energé da casca de arroz. Programa energia. Research Project Report, Fundatec, Porto Alegre, RS; 1986.
Estudo da viabilidade técnica e econômica do aproveitamento da cinza de casca de arroz como material pozolânico. Masters Degree Dissertation
  • L O Guedert
Guedert LO. Estudo da viabilidade té e econô mica do aprove-itamento da cinza de casca de arroz como material pozolâ. Masters Degree Dissertation, UFSC, PPGEPS, Florianó polis, SC; 1989.
Aproveitamento energético da casca de arroz
  • Jcc Cunha
  • E M Canepa