Geopolymerization Behaviour of Red and White Clays (original) (raw)
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Development of construction materials from the geopolymerization of red clay and coal fly ash
BIBECHANA
Red clay contains solid aluminosilicate has been shown to be reactive in the presence of an alkaline activator. The addition of coal fly ash and lime has shown improvements in their mechanical and physical properties of the geopolymer products. FTIR analysis and SEM images of the product have shown the formation of aluminosilicate gel in the geopolymeric product. The maximum compressive strength of the geopolymer products GP-RFL was achieved to be 15.92 N/mm2 having water absorption of 10.47 % and bulk density 2.81 g/cm3. These results indicated that geopolymer mortars made from red clay, coal fly ash and lime could be used as an alternative construction material./p> BIBECHANA 19 (2022) 119-126
(Micro)-structural comparison between geopolymers, alkali-activated slag cement and Portland cement
Journal of The European Ceramic Society, 2006
Concurrently to research conducted on ordinary Portland cement (PC), new types of binders were developed during the last decades. These are formed by alkali-activation of metakaolin or ground-granulated blast furnace slag (GGBFS) and are named, respectively, geopolymers (GP) or alkali-activated slag (AAS). Four different cementitious materials were synthesised: PC, AAS, GP, and a mix GP-AAS and fully compared about their compositions and (micro)-structures. X-ray diffraction has revealed the presence of semi-crystalline C S H gel binding phase in PC while AAS, GP and GP-AAS are nearly amorphous. Progressive structural changes have been observed between the different samples by means of infrared spectroscopy, 29 Si and 27 Al magic-angle-spinning nuclear magnetic resonance spectroscopy: there is a polymerisation extent of the (alumino)-silicate framework from PC [SiQ 1 and SiQ 2 units] to AAS [SiQ 2 and SiQ 2 (1Al) units] and finally to GP [SiQ 4 (2Al) and SiQ 4 (3Al) units]. Scanning electron microscopy has shown that GP is a homogeneous matrix while the other materials are composites containing GGBFS grains surrounded by a binding matrix. Energy dispersive X-ray EDX analyses (line scans) have shown the absence of formation of any specific phase at the matrix-grains interfaces.
Processing and applications of geopolymers as sustainable alternative to traditional cement
2014
The development of sustainable construction and building materials with reduced environmental footprint, in both manufacturing and operational phases of material life cycle, is attracting increasing interest. In this frame, new geopolymer-based materials seem very attractive, due to their good mechanical properties, chemical and fire resistance. In addition, as compared to the ordinary Portland cement, they are characterized by higher environmental sustainability, in terms of reduced production energy requirements and lower CO2 emissions. In this paper we have prepared different geopolymer materials starting from a calcined clay. Pastes and mortars showed a good mechanical strength. Starting from these samples, materials characterized by different macroscopic features were developed, including a lightened concrete, a multilayer sample and macroporous materials at increasing pores amount and size, with the aim of investigating the applicability of geopolymers towards different buildi...
PROPERTIES OF GEOPOLYMER CEMENTS
Geopolymer cement, high-alkali (K-Ca)-Poly(sialate-siloxo) cement, results from an inorganic polycondensation reaction, a so-called geopolymerisation yielding three dimensional zeolitic frameworks. High-tech Geopolymer K-Poly(sialate-siloxo) binders, whether used pure, with fillers or reinforced, are already finding applications in all fields of industry. These applications are to be found in the automobile and aeronautic industries, non-ferrous foundries and metallurgy, civil engineering, plastics industries, etc. Geopolymer cement hardens rapidly at room temperature and provides compressive strengths in the range of 20 MPa, after only 4 hours at 20°C, when tested in accordance with the standards applied to hydraulic binder mortars. The final 28-day compression strength is in the range of 70-100 MPa.The behaviour of geopolymeric cements is similar to that of zeolites and feldspathoids; they immobilize hazardous materials within the geopolymeric matrix, and act as a binder to convert semi-solid wastes into adhesive solids. Their unique properties which include high early strength, low shrinkage, freeze-thaw resistance, sulphate resistance and corrosion resistance, make them ideal for long term containment in surface disposal facilities. These high-alkali cements do not generate any Alkali-Aggregate-Reaction. Preliminary study involving 27 Al and 29 Si MASNMR spectroscopy and the proposed structural model, reveal that geopolymeric cements are the synthetic analogues of natural tecto-alumino-silicates.
Effect of Alkaline Activators, Binders and Fibers on Strength Development of Geopolymer Mortar
International Journal of Recent Technology and Engineering (IJRTE), 2019
Nowadays Environmental pollution is the major problem faced by the world. The emission of pollutants by construction industry during production of Portland cement are the main causes for environmental pollution. With the increase in use of industrial by products in our construction industry the pollution effect on environment can be reduced. Geopolymer is the one which uses by products and are environmentally friendly. In the present study to produced geopolymer the Portland cement is replaced with fly ash and fine aggregate is replaced with quarry dust and for binding materials alkaline are used. In this study for polymerization the alkaline solutions used are sodium hydroxide (NaOH) and Sodium silicate (Na2Sio3) solution. To prepare different mixes different molarities of sodium hydroxide solution i.e. 6M and 8M and comprehensive strength is calculated for each mix. The size of cube specimen considered are 150 mm x 150mm x 150mm.The comprehensive strength of geopolymer concrete sp...
2018
1.( Introduction In the past three decades, urbanization has proceeded faster in developing countries. Ordinary Portland Cement (OPC) based materials such as concrete are nowadays the most widely used construction materials. Unfortunately, the cement industry accounts for around 4% of the total global greenhouse gas emissions and up to 8% of the total global anthropogenic CO2 emissions [1]. It has become a major environmental issue. Geopolymer cement is considered to be the most effective ways of reducing the environmental impact of the cement industry. These eco-materials can be synthesized by the alkaline activation of aluminosilicates at room temperature and providing a low cost, fast setting, low permeability, resistance to fire and acid attack [2], ability to radically decrease the heavy metal ions mobility [3], great resistance to freeze thaw cycles, and good compressive strength resistance [4]. The properties of geopolymer materials are mainly affected by the aluminosilicate ...
Application of Clay - Based Geopolymer in Brick Production: A Review
Advanced Materials Research, 2012
This paper reviews and summarizes the current knowledge and application of clay as a geopolymer material in production of geopolymer brick. As we understand, the nature of source materials give a significant impact to the strength of geopolymer. For example, geopolymer made from calcined source material such as calcined kaolin, fly ash, ground granulated blastfurnace slag (GGBS) and others produce a higher compressive strength compared to geopolymer made from non-calcined source material such as kaolin. This paper is reviewing on the suitability of clay application as a geopolymer material in geopolymer brick production. The chemical composition of clay-based material show high content of SiO 2 and Al 2 O 3 compound which is similar to the fly ash. Clay-based Geopolymer showed a good potential in a brick production.
Results in Physics, 2016
This paper is based on the characterization of synthesized geopolymer binders based on either powder or solution silicate, and the amount of water contained in synthesized binders is determined to evaluate their possibility to coat a brick. The structural evolution of the formed geopolymers was investigated using FTIR spectroscopy. The mechanical properties were evaluated using compression tests. The structural evolution ensured that the solutions prepared from silicate powder or liquid had different degrees of polymerization, which modified the polycondensation reaction of the mixture. Nevertheless, the use of aluminosilicate solutions based on powder or liquid display similar behavior in a polycondensation reaction. The obtained materials show good mechanical properties, and it is possible to deposit this binder on the brick depending on the water content.
Alkali-silica reaction resistance versus susceptibility of geopolymer binders
MATEC Web of Conferences
Alkali–silica reaction (ASR) is a deterioration chemical process that causes expansion along with cracking of cement paste and aggregate particles, resulting in concrete degradation. Numerous factors influence ASR including aggregate reactivity, cement alkali content and moisture availability. Due to the high alkali content of the activator, the risk of ASR could be anticipated to be greater in geopolymer concrete than in Portland cement concrete. This article reviewed the susceptibility or resistance of geopolymer binders to ASR deterioration, based on published data in the literature. Generally, the vulnerability of geopolymer binders to ASR expansion is influenced by two factors comprising, the chemical composition of the aluminosilicate precursor and the alkaline activator solution characteristics. It is evident that low-calcium geopolymer binder systems exhibit very much lower ASR expansion than high-calcium geopolymer binders. Moreover, ASR expansion increases with increase in...