Alkali-activated fly ashes: A cement for the future
TL;DR: In this paper, the mechanism of activation of fly ash with highly alkaline solutions is described, and the product of the reaction is an amorphous aluminosilicate gel having a structure similar to that of zeolitic precursors.
About: This article is published in Cement and Concrete Research.The article was published on 1999-08-01. It has received 1779 citations till now. The article focuses on the topics: Fly ash & Cement.
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TL;DR: In this paper, the potential position of and drivers for inorganic polymers (“geopolymers”) as an element of the push for a sustainable concrete industry are discussed.
1,444 citations
TL;DR: In this article, the authors present the results of comprehensive carbon footprint estimates for both geopolymer and OPC concrete, including energy expending activities associated with mining and transport of raw materials, manufacturing and concrete construction.
1,274 citations
TL;DR: Aluminosilicate-based alkaline cements have been classified into five categories as discussed by the authors, and the key advances made in the understanding of synthetic gels are discussed, which ultimately finds hybrid cements to be technologically viable materials for contemporary construction.
1,104 citations
TL;DR: In this paper, the authors present the work carried out on the chemical reaction, the source materials, and the factor affecting geopolymerization, and demonstrate that certain mix compositions and reaction conditions such as Al2O3/SiO2, alkali concentration, curing temperature with curing time, water/solid ratio and pH significantly influences the formation and properties of a geopolymers.
Abstract: Geopolymerization is a developing field of research for utilizing solid waste and by-products. It provides a mature and cost-effective solution to many problems where hazardous residue has to be treated and stored under critical environmental conditions. Geopolymer involves the silicates and aluminates of by-products to undergo process of geopolymerization. It is environmentally friendly and need moderate energy to produce. This review presents the work carried out on the chemical reaction, the source materials, and the factor affecting geopolymerization. Literature demonstrates that certain mix compositions and reaction conditions such as Al2O3/SiO2, alkali concentration, curing temperature with curing time, water/solid ratio and pH significantly influences the formation and properties of a geopolymer. It is utilized to manufacture precast structures and non-structural elements, concrete pavements, concrete products and immobilization of toxic metal bearing waste that are resistant to heat and aggressive environment. Geopolymers gain 70% of the final strength in first 3–4 h of curing.
1,078 citations
TL;DR: An overview of advances in geopolymers formed by the alkaline activation of aluminosilicates is presented along with opportunities for their use in building construction as mentioned in this paper, with respect to fresh and hardened states, interfacial transition zone between aggregate and geopolymer, bond with steel reinforcing bars and resistance to elevated temperature.
899 citations
References
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TL;DR: In this article, the results of a research project initiated to study the stability of these materials when exposed to aggressive solutions were presented, where prisms of mortar made of sand and alkali-activated metakaolin were immersed in deionized water, ASTM sea water, sodium sulfate solution (4.4% wt), and sulfuric acid solution (0.001 M).
510 citations
Patent•
29 Aug 1980
TL;DR: In this paper, the empiral formula of polysialates, a class of mineral polymers, has been proposed, which has a value up to about 7, where w is the degree of polycondensation.
Abstract: New mineral polymers called polysialates have the empiral formula M n [--(Si--O 2 --) z --Al--O 2 --] n ,wH 2 O where z is 1, 2 or 3, M is sodium, or sodium plus potassium, n is the degree of polycondensation, and w has a value up to about 7. The method for making these polymers includes heating an aqueous alkali silico-aluminate mixture having an oxide-mole ratio within certain specific ranges for a time sufficient to form the polymer.
220 citations
Patent•
01 Feb 1985
TL;DR: An early high strength mineral polymer composition is formed of a polysialatesiloxo material obtained by adding a reactant mixture consisting of alumino-silicate oxide (Si 2 O 5,Al 2 O 2 ) with the aluminum cation in a fourfold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxides, water, and a sodium/potassium polysilicate solution; and from 15 to 26 parts, by weight, based upon the reactive mixture of the poly sialatesILoxo polymer of ground blast furnace sl
Abstract: An early high-strength mineral polymer composition is formed of a polysialatesiloxo material obtained by adding a reactant mixture consisting of alumino-silicate oxide (Si 2 O 5 ,Al 2 O 2 ) with the aluminum cation in a four-fold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxide, water, and a sodium/potassium polysilicate solution; and from 15 to 26 parts, by weight, based upon the reactive mixture of the polysialatesiloxo polymer of ground blast furnace slag. Sufficient hardening for demolding is obtained in about 1 hour with this composition.
180 citations
Journal Article•
TL;DR: In this article, the physical, chemical and mineralogical nature of the reactants, their mixing ratio, order of addition of mix components, cure duration, microstructure and phase development, and compressive strength were investigated.
Abstract: Cementing materials based on metakaolin have been investigated. Parameters studied include the physical, chemical and mineralogical nature of the reactants, their mixing ratio, order of addition of mix components, cure duration, microstructure and phase development, and compressive strength. In general, elevated cure temperatures were required to develop the best strengths but binder phases with low crystallinity were generally preferable to the more crystalline binders obtained at >85°C. Additional characterization data for the products are presented and suggestions are made for the further development of silicate cements based on metakaolin
137 citations
TL;DR: In this paper, the authors consider that these processes occur through a heterogeneous reaction, and that they can be governed by three mechanisms: a) nucleation and growth of the hydrated phase; b) phase boundary interactions and c) any diffusion process though the layer of hydration products.
Abstract: The alkaline activation of blast furnace slag promotes the formation of new cement materials. These materials have many advantages over ordinary Portland cement, including high strength, low production cost and good durability. However, many aspects of the chemistry of alkaline activated slags are not yet very well understood. Some authors consider that these processes occur through a heterogeneous reaction, and that they can be governed by three mechanisms: a) nucleation and growth of the hydrated phase; b) phase boundary interactions and c) any diffusion process though the layer of hydration products.
92 citations