Alaa M. Rashad

Alaa M. Rashad
College of Engineering Shaqra University and Housing & Building National Research Center (HBRC)

Professor

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164
Publications
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9,242
Citations

Publications

Publications (164)
Article
Sodium tripolyphosphate (STPP) is commonly employed as a retarder and a supplementary component in superplasticizers within Portland cement (PC) systems and serves as a dispersant in the ceramic industry. To date, there has been a lack of comprehensive research on the effect of STPP on the corrosion resistance of rebars embedded in alkali-activated...
Article
Fly ash (FA) geopolymer is widely used due to its friendly environmental and prospective properties in mechanical and durability issues. After initial heat curing, this system may be cured in air (which is most common) or in water. Unfortunately, there is a deterioration in its compressive strength when cured in water compared to air curing. In thi...
Article
Natural talc (T) is an abundant material on Earth. Due to its seductive properties, it is commonly used as a filler in various applications. In the construction field, it can be used in polymers, paints, ceramics, and various cementitious materials. Oppositely, in alkali-activated materials (AAMs), there are shortcomings in talc applications. Thus,...
Article
High-volume slag (HVS) is often used to produce environmentally friendly building materials. However, HVS suffers from low strength at an early age. To overcome this problem, for the first time, the amorphous phase of natural volcanic glass powder (VGP) and the crystalline phase of natural quartz powder (Q.P) were individually used to enhance the s...
Article
Chrysotile, the most common serpentine polymorph, represents one of the most hazardous mine wastes known for its associated health risks. For the first time, chrysotile mine waste combined with barite was recycled to produce radiation shielding concrete (RSC) with promising mechanical and radiation attenuation properties. Chrysotile concrete (CC) w...
Chapter
The incorporation of metakaolin (MK) as a part of precursor may have a positive or a negative effect on the mechanical properties of geopolymers. This typically depends on testing age, activator type/concentration, Si/Na ratio, Si/Al ratio, MK ratio/fineness, type of precursor, precursor fineness and curing condition. When slag was used as the main...
Chapter
Metakaolin (MK) is widely used as a part of precursor. The incorporation of MK in the geopolymer mixture can affect its fresh properties such as workability and setting time. The incorporation of MK in the geopolymer mixture may have a positive effect or a negative effect on workability. This mainly depends on the type of precursor, Si/Na ratio, ac...
Chapter
The incorporation of metakaolin (MK) as a part of precursor may affect the physical properties of geopolymers. The density of the geopolymer may increase or decrease with the introduction of MK. This mainly depends on the type of precursor and MK amount. There are contradictory findings about the effect of MK on the water absorption and porosity of...
Chapter
The incorporation of metakaolin (MK) as a part of the precursor may have a positive or a negative effect on the durability of geopolymers. The findings on the effect of MK on carbonation depth and fire resistance are inconclusive. The incorporation of a suitable ratio of MK into geopolymers has a positive effect on surface resistance, sulphate resi...
Chapter
In this chapter, the general effects of metakaolin (MK) on the properties of different types of geopolymers mentioned in the previous chapters such as workability, setting time, water absorption, porosity, shrinkage and different durability aspects were summarized and compared. In addition, some statistics about the compressive strength, type of pr...
Article
Full-text available
As known, calcium oxide (CaO) is an alkaline material, which can be used widely to increase the clay-containing soils load carrying capacity, to produce aerated concrete and calcium aluminate cement. In the last few years, introducing CaO into alkali-activated materials (AAMs) became a hot topic and attained more attention than other times. General...
Article
Enormous amounts of ceramic and fly ash (FA) wastes are generated annually by ceramic industries/demolition/rejected units and thermal power plants. To preserve virgin natural resources, limit disposal amounts, and limit environmental pollution, these wastes can be applied in the construction field as a binder material after alkali activation. This...
Chapter
The incorporation of foaming or blowing agent in the geopolymer can produce porous microstructure, which improves the effectiveness of its thermal insulation. Improving the thermal insulation effectiveness can save energy and absorb acoustic. The target of this part is to review, summarize and analyse the past studies focused on the effect of SF, a...
Chapter
As known, NaOH and sodium silicate are widely used as alkaline activators for preparing geopolymers due to better obtained strength. Unfortunately, the manufacture of these activators is somewhat costly and requires a lot of energy. This is particularly true for sodium silicate, which is made by melting sodium carbonate and sand at 1350–1450 °C, th...
Chapter
Herein, the incorporation of SF as a part of a precursor, as a part of activator and as a foaming agent for geopolymers has been comprehensively reviewed, summarized and analysed. The main outcomes can be briefed as follows.
Chapter
Due to the prospective properties of silica fume (SF), it is frequently used in Portland cement (PC) systems as a supplementary cementitious ingredient to improve the mechanical and durability properties. In recent developments, numerous studies have been implemented to obtain superior properties of various types of geopolymer by incorporating SF....
Chapter
In spite of silica fume (SF) can be incorporated into different geopolymer types as a part of precursor, as a part of activator or as a foaming agent, most of the earlier studies employed SF as a part of cementitious material (as a part of precursor or an additive) (~ 74.1%), whilst employing it as a part of activator came in the second place (14.8...
Article
For the first time, the hazardous chrysotile was valorized as an aggregate in radiation shielding concrete (RSC). This was accomplished through its amalgamation with two different ratios of boric acid (H3BO3) by 1 and 3% of cement mass to produce CR1, and CR2 concrete mixtures, respectively, in comparison with zero H3BO3 in the control concrete (CC...
Article
Full-text available
Currently, the introducing of basalt and natural fibers into different geopolymer swift growth of geopolymers. Despite of geopolymers have good properties such as fire resistance, flame resistance, higher compressive strength and higher durability, they suffer from low tensile strength and flexural strength. Different types of fibers were used to i...
Article
As known, the earth crust is rich with limestone. The limestone powder (LSP) accounts for about 75 % of the composition of Portland cement (PC). It can be used as cement replacement and in other fields and applications such as agriculture field, metal refining field, gaseous effluents field, production of glass, ceramic, mineral wool, pulp and pape...
Article
This study is the first attempt to investigate the possibility of recycling carbonated lime residue (CR) (a by-product from the sugar beet-making industry) as a foaming agent. For this purpose, phosphoric acid (H3PO4) was used as an activator for metakaolin (MK) to obtain MK geopolymer pastes. Subsequently, the MK was partially replaced by CR at ra...
Article
Full-text available
Alkali-activated slag (AAS) cement is one type of alkali-activated binders free from Portland cement. The main problems of this type of cement are its high drying shrinkage and low carbonation resistance that hinder its wide use. In the current paper, the authors tried to suppress this high drying shrinkage and enhance the carbonation resistance of...
Article
In this work, for the first time, the possibility of employing nano-lead oxide (nPbO) in alkali-activated slag (AAS) mortar as a modifier agent for its properties was studied. Different ratios of nPbO (0 wt.%, 1 wt.%, 3 wt.% and 5 wt.%) were added to the plain AAS mortar. The influences of these ratios on flowability, mechanical strength, water abs...
Article
Full-text available
Herein, the possibility of including recycled glass powder as a promising material in amalgamation with slag to produce new binder materials activated by sodium silicate solution capable to resist high temperatures was studied. Slag was partially replaced with glass powder (GP) at ratios in the range of 0–15%, by weight, with a step of 5%. The powd...
Article
Recently, freshwater is under stress due to population growth, change of climate, urbanization and industrialization. World Meteorological Organization expected that 5 billion people will be in a shortage of even freshwater for drinking. In fact, it is difficult to get freshwater in some areas. In the construction field, concrete consumes about 2 b...
Article
Natural aggregate is commonly used in mortar and concrete. In some places in the world, the natural aggregate may no longer reach the construction demands in terms of quality or/and quantity. Hence, alternative resources should be searched. On the other hand, the disposal of steel slag (SS) resulting from the refinement of pig iron by electric arc...
Article
The increasing requirement for indoor thermal comfort in the building sector leads to an increased demand for new thermal insulating materials. Developing materials capable to meet technical and environmental requirements are a hot topic. Thus, in this study, the authors tried to manufacture an insulating binder free from Portland cement (PC) or fo...
Article
Full-text available
The influence of lightweight expanded clay aggregate (LECA) on the physico-mechanical properties and microstructure of geopolymer mortar containing slag binder alkali-activated with sodium silicate solution before and after exposure to thermal loads was investigated. In the current procedure, siliceous sand was partially substituted with LECA fine...
Article
This study aims to solve the perpetual problem of imperative use heat curing for fly ash (FA) geopolymer cement to obtain reasonable strength, especially at the early ages by using calcinated carbonation lime residue (CCR). The carbonation lime residue is a waste resulting from the sugar beet industry. For this purpose, FA was partially replaced wi...
Article
In general, building materials exposed to the marine environment are more prone to deteriorates than others. There are three main zones of the marine environment named atmospheric zone, tidal zone and submerged zone. This article investigated the effect of different curing conditions named water curing, air curing, seawater curing and wet/dry curin...
Article
In the current paper, an attempt has been done to produce insulating materials based on alkali-activated slag (AAS) mortars, free from any foaming/blowing agent, with a good balance between suitable compressive strength and low thermal conductivity. Due to its prospective properties, expanded perlite (EP) was used as a lightweight fine aggregate. F...
Article
Full-text available
Due to the high increase in the consumption of building energy in the world, it is urgent to develop and use thermal insulation materials to limit the demand of energy. In this article, the possibility of producing thermal insulation plasters from common cementitious materials such as fly ash (FA), metakaolin (MK), and silica fume (SF) without empl...
Article
The precursors of alkali-activated materials (AAMs) have major effects on their properties. More attention was paid to using by-product precursors such as slag and fly ash (FA) for AAMs, whilst less attention was paid to using another by-product precursor such as electric arc furnace slag (EAFS). The use of EAFS as a geopolymer precursor is still u...
Article
As known, Class F fly ash-based geopolymer system needs heat curing to obtain good properties. The heat curing of this system hinders its wide applications especially in the case of cast of situ. Thus, it is important to improve this system to be suitable for curing at room temperature. In this article, for the first time, the possibility of employ...
Article
Full-text available
The global consumption of river sand as a fine aggregate in the production of concrete and mortar is very high. Unfortunately, in the last 20 years, the obtainability of river sand is reducing and several countries have problems in supplying. One option to solve the scarcity of river sand is to use sea sand in the construction field. In the current...
Article
The behavior of high-volume fly ash (HVFA) cement pastes modified with metakaolin (MK), quartz powder (Q-P) and their combination in the marine environment was studied. HVFA pastes were manufactured by partially replacing Portland cement (PC) with 70% fly ash (FA). To develop the mechanical performance of this mixture, HVFA was modified by partiall...
Article
This study is the first attempt to investigate the possibility of incorporating nano-activated carbon (nAC), prepared from residual biomass of olive trees, on the properties of alkali-activated slag (AAS) pastes. After suitable preparation of nAC, it was added into AAS-pastes at various levels starting from 0.5 to 3.5, by weight. The results of wor...
Article
This article outlines the contribution of various precursors named ground-granulated blast furnace slag (slag) and metakaolin (MK) as a binary blend (s70m30) as well as slag, MK and fly ash (FA) as ternary blends on the properties and corrosion behaviour of geopolymer pastes. Different mixtures were activated with an alkaline activator solution and...
Article
In this paper, a simple eco-sustainable approach was applied to synthesize unfired building bricks, in which cement kiln dust (CKD), red clay brick waste (RCBW), and silica fume (SF) were the main ingredients. The CKD-RCBW-SF composite was adjusted at different weight ratios of 50-50-0, 50-40-10, 50-30-20, and 50-20-30 wt.%. The fabrication process...
Article
Full-text available
Pumice stone is a natural sponge-like lightweight aggregate formed during the rapid cooling and solidification of molten lava. After suitable preparation, it can be used as an aggregate to produce lightweight concrete or as a cementitious material to produce blended cement or geopolymer. This article focused on the influence of pumice powder (PP) o...
Article
At present, the need to include waste materials such as waste rubber as a part of building materials is getting more attention rather than any other time. The incorporation of waste rubber as a part of building materials decreases the landfills and reduces the consumption of virgin raw materials. Most of the previous studies incorporated waste rubb...
Article
Full-text available
This paper aims to study the effect of different particle sizes of granulated blast-furnace slag (GBFS) as a partial or full natural fine aggregate substitution in concretes with different water/cement (w/c) ratios. Natural sand fine aggregate was substituted with GBFS at ratios ranging from 25% to 100%, by weight. Two different particle sizes of G...
Article
To highlight the impact of barite and hematite addition on selected physical, mechanical, and radiation attenuation properties of serpentine concrete (A), different replacement ratios of barite and hematite aggregates (25, and 50% by volume) were used separately. The physico-mechanical properties of the prepared serpentine-barite (AB25, 50) and ser...
Article
This work is the first attempt to study the possibility of incorporating three different types of Egyptian serpentine aggregates (antigorite, lizardite and chrysotile) with different serpentinization grades as fine and coarse aggregates for normal concrete production. The results of physical and mechanical tests for each type of aggregate were comp...
Article
This work is the first attempt to study the possibility of incorporating three different types of Egyptian serpentine aggregates (antigorite, lizardite and chrysotile) with different serpentinization grades as fine and coarse aggregates for normal concrete production. The results of physical and mechanical tests for each type of aggregate were comp...
Article
In the present paper, alkali-activated metakaolin (AAMK) pastes modified with micro-size particles derivative from dehydroxylation of kaolinite (m-MK) at ratios fluctuated from 2% to 10% with an increment of 2%, by weight, were prepared. The workability and compressive strength, up to 450 days, were measured. After curing for 28 days, various paste...
Article
This work is the first attempt to investigate the possibility of using sugar beet waste named carbonation lime residue (CLR) as a cementitious material. For this purpose, cement was partially replaced with CLR at ratios of 5–25%, by weight. The effect of CLR on the consistency, setting time, bulk density, total porosity, water absorption and mechan...
Article
Recently, the introduction of steel fibers to geopolymers as a reinforcement has developed and increased owing to the rapid development of geopolymers. Despite geopolymers exhibit potential properties such as low energy consumption and carbon footprint, flame resistance, fire resistance, valuable compressive strength and good durability, they suffe...
Article
Full-text available
A first attempt was made to study the electrical properties of pastes and mortars prepared from the most common alkali-activated materials against those of Portland cement (PC). The properties included electrical conduction, dielectric constant, the real part of dielectric permittivity and loss tangent factor. The frequencies measured ranged from 1...
Article
Extensive amounts of ceramic and slag wastes are produced every year by ceramic and iron industries. Recycling of these wastes is one of the operational solutions to eliminate their disposal. It is appropriate to employ these wastes as a binder material in the field of construction to save the virgin natural raw materials and limit environmental po...
Article
To modify some properties of serpentine-based concretes, serpentine aggregate (S) was partially replaced with either hematite aggregate (H) or barite aggregate (B) at levels of 25% and 50%, by volume. To evaluate the impact of these aggregates, selected physical properties of the prepared serpentine-barite (AB25, 50) and serpentine-hematite (AH25,...
Article
Portland cement (PC) containing high-volume fly ash (HVFA) is usually used to obtain economical and more sustainable merits, but these merits suffer from dramatically low compressive strength especially at early ages. In this work, the possibility of using micro-size metakaolin (MSK) particles to improve the compressive strength of HVFA paste befor...
Article
Full-text available
The current article aims to elaborate an insulating material synthesized from metakaolin, limestone powder and phosphoric acid. For that purpose, metakaolin was activated with phosphoric acid to produce geopolymer paste. Afterward, metakaolin was partially replaced with limestone powder at ratios fluctuated from 1% to 5% with a step of 1%, by weigh...
Article
This study aims to improve the physico-mechanical properties of slaked lime – fly ash (FA) – ceramic waste powder (CWP) pastes through the incorporation of anhydrous gypsum (G) supported by thermal curing. Initially, the lime- FA paste was prepared with a ratio of (30/70 wt) as a reference binder. The FA was partially replaced with 5–25% of CWP mat...
Article
Full-text available
A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemically treated concrete waste (CTC) with slag. The treatment process was conducted by the addition of NaOH to concrete waste (CoW) at NaOH to CoW weight ratios of 0.2, 0.1, and 0.05 (namely, CTC-1. CTC-2, and CTC-3, respectively), followed by mixing with wa...
Article
Full-text available
Steel slag (SS) is an industrial product of steel making. It can be produced in either an electric arc furnace (EAF), of which steel is produced by melting scrap steel, or a basic oxygen furnace (BOF), of which iron is converted to steel. SS can be used in many fields such as soil improvement, agricultural fertilizer, asphalt concrete, road constru...
Article
This research is the first attempt to study the possibility of employing magnetic water (MW), Zamzam water (ZW) and seawater (SW) as mixing water for alkali-activated slag (AAS) pastes. The results of workability, pH value, compressive strength and microstructure of different specimens mixed with each type of water were compared with those mixed wi...
Article
Full-text available
The motivation behind this work is to evaluate the impact of nano-magnesium calcite (NMC) waste on the performance of cement mortar (CM) and its resistivity to sulfate attack. The addition of urea and urease enzyme to ground water resulted in the removal of Ca2+ and Mg2+ as NMC precipitate (byproductof treatment process). As a beneficial recycling...
Article
Full-text available
Geopolymer is an innovative material and a real alternative to traditional Portland cement for use in the construction industry. Incorporation of the use of geopolymers in civil engineering is one of the most-promising options for reducing environmental impact and the huge energy consumption of Portland cement manufacture. Since geopolymers were di...
Article
Full-text available
The motivation behind this work is to evaluate the impact of nano-magnesium calcite (NMC) waste on the performance of cement mortar (CM) and its resistivity to sulfate attack. The addition of urea and urease enzyme to ground water resulted in the removal of Ca2+ and Mg2+ as NMC precipitate (byproduct of treatment process). As a beneficial recycling...
Article
Full-text available
Carbonation in concrete is the formation of calcium carbonate (CaCO 3 ) in the binder by a chemical reaction. It results when ions of carbonate from dissolved carbon dioxide (CO 2 ) react with calcium ions (Ca ⁺ ) in the binder and precipitate calcium carbonate. The major effect of carbonation is the destruction of the passive layer forming on stee...
Article
Disposal of slag resulting from pig iron process is one of the main eco-friendly confrontations. This confrontation is still increasing with the increase slag content and diminishing the landfill space latitude. Accordingly, studies have been achieved to reuse granulated ground blast-furnace slag (denoted as slag) by way of high-volume (HVS) as a c...
Article
Recently, the inclusion of different types of fibres into geopolymers, as reinforcement, has amplified due to the rapid increase in geopolymers developments. In spite of geopolymers have prospective properties such as low carbon footprint, low consumption of energy, good compressive strength, resistance to fire, resistance to flame, resistance to c...
Article
Full-text available
Currently, the introducing of basalt and natural fibers into different geopolymer swift growth of geopolymers. Despite of geopolymers have good properties such as fire resistance, flame resistance, higher compressive strength and higher durability, they suffer from low tensile strength and flexural strength. Different types of fibers were used to i...
Article
The purpose of this work is to investigate the resistance of alkali-activated metakaolin (AAMK) paste specimens blended with different amounts of quartz powder (QP) against different environmental conditions. Metakaolin (MK) was partially substituted with QP at levels of 10, 20, 30, and 40%, by weight. After initial curing, specimens were exposed t...
Article
In the current investigation, the opportunity of employing nano-SiO2 (NS) to modify fire resistance of metakaolin-based geopolymer pastes has been explored. Metakaolin (MK) was partially substituted with NS at ratios of 0.5%, 1%, 2%, 3% and 4%, by mass. After curing for 28 days, the specimens were subjected to high temperatures altered from 400 to...
Article
Full-text available
In the current work, the properties of cement pastes doped with high amounts of ground granulated blast-furnace slag (HVS) were investigated. Portland cement (PC) was substituted with ground granulated blast-furnace slag (donated as slag) at very high amounts of 85%, 90%, 95% and 100%, by weight. PC paste without any content of slag was used as a r...
Article
In the recent years, grinding technology has been brought a new product with prospective properties. If quartz sand is ground, a new product is obtained with superior properties than its original. The literature contains some studies focused on employing quartz powder (QP) in traditional cementitious materials and geopolymers as additives to obtain...
Article
LECA is the abbreviation of lightweight expanded clay aggregate. LECA is produced from special plastic clay with no or very little content of lime. The clay is dried, heated and burned in rotary kilns at 1100–1300 °C. LECA is porous ceramic product with a uniform pore structure with almost potato shape or round shape due to the kiln circular moveme...
Article
Portland cement (PC) blended with ground granulated blast-furnace slag (denoted as slag) is frequently used to produce more sustainable matrix as well as economical and technical benefits. In this research work, the opportunity of employing \(\hbox {nano-SiO}_{2}\) (NS) to improve compressive strength of high-volume slag (HVS) paste prior and after...
Article
Applications of carbon nanotubes (CNTs) in traditional cementitious materials, have been accentuated more attentions in the recent years. Some properties of these materials were improved by applying suitable concentration of CNTs. This article presents a review of the earlier studies carried out on adding CNTs into traditional cementitious material...
Article
Phosphogypsum (PG) is a by-product from the industry of phosphate fertilizer. Approximately 4-6 tonnes of PG are generated per tonne of phosphoric acid production. The continuous growth in the world population increases food production demand which requires an increase in phosphate fertilizer production resulting in an increase in PG content. Appro...
Article
To achieve the highest thermal insulation and the lowest carbon dioxide emissions, different geopolymer mortar types with low thermal conductivity, reasonable compressive strength and high fire resistance were investigated and compared with traditional cement mortar (TCM). Two different types of aluminosilicate materials, namely metakaolin (MK) and...
Article
Full-text available
The use of energy in the building sector accounts a significant part of the world’s total energy and greenhouse gas emissions. In order to meet the demands of improved energy efficiency, thermal insulation of buildings plays an important role. To attain the highest possible thermal insulation, new insulation plaster types with low thermal conductiv...
Article
Full-text available
Ground granulated blast-furnace slag (designated as GGBS) has been utilized as building material due to the environmental, economic and technical benefits. In this study, the possibility of improving compressive strength of high-volume GGBS (HVS) paste before and after being exposed to elevated temperatures using metakaolin (MK) in micro-size (mMK)...
Article
Vermiculite is a mica-like mineral with a shiny flakes which is one member of the phyllosilicate group. It can be expanded up to 30 times its original volume when heated at 650–950 °C. The expanded vermiculite (EV) exhibits prospective properties such as low thermal conductivity, low bulk density, endurance, chemical inertness and relatively high m...

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Please let me know at any temperature degree the sample for TGA test should be dried

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