Mix Design of Fly Ash Based Geopolymer Concrete

Abstract: New type of redox heterogeneous catalysts based on geopolymer aluminosilicate materials was developed and their catalytic properties have been demonstrated on industrially important reactions. Geopolymers can be regarded as amorphous analogues of zeolitic materials (three dimensional network of SiO 4 and AlO 4 tetrahedra with negative charge of the network balanced by extra-framework cations, variability in chemical composition, ion exchange properties, presence of rings forming cationic sites for bare cations), but possessing some advantages as network formation at ambient or low temperatures, mesoporosity and low cost preparation. It is shown that the geopolymer network enables incorporation of transition metal ions as active centres for catalytic reactions. The catalytic activity of geopolymer-based catalysts with Fe, Co and Cu metal ions in extra-network sites and Pt species is demonstrated on the selective catalytic reduction of nitrogen oxides by ammonia and the total oxidation of volatile hydrocarbons. These findings open a potential for synthesis of new types of robust catalysts for heterogeneously catalysed reactions.

Abstract: This experimental study is intended to identify the mix ratios for different grades of Geopolymer Concrete by trial and error method. A new Design procedure was formulated for Geopolymer Concrete which was relevant to Indian standard (IS 10262-2009). The applicability of existing Mix Design was examined with the Geopolymer Concrete. Two kinds of systems were considered in this study using 100% replacement of cement by ASTM class F flyash and 100% replacement of sand by M-sand. It was analyzed from the test result that the Indian standard mix design itself can be used for the Geopolymer Concrete with some modification.

Abstract: Geopolymer concretes (GPCs) can be produced by chemical activation of industrial by-products and processed natural minerals that contain aluminosilicate. There have been a few demonstrative constructions built using of GPCs as a greener alternative choice to Portland cement concrete (PCC); unfortunately, there is no standard or specification of guidelines for the design of GPC mixtures. This is partially because of so many variables affecting GPC manufacture, such as the property of raw materials, type and dosage of activator and curing scheme. Despite the fact of convention of building industry, the lack of proper mixture design method limits the wide acceptance of GPC in industry. In this paper, a review on currently reported mixture design methods of GPC prepared with slag and fly ash is presented. The various methods are classified into three categories: target strength method, performance-based method, and statistical factorial model method. The difference in the procedures, advantages and disadvantages among those methods are discussed. It is recommended that a proper design method should be chosen according to actual production situation and performance requirement of GPC.

Abstract: Nowadays, an exigency has gone through the roof for cementitious material. Unfortunately, the present process of production of Ordinary Portland Cement (OPC) is found associated with pessimistic impacts on environments because of an emission of immense magnitude of CO2 – a primary Green House Gas (GHG). This has, on the whole, pushed around concrete scientists and construction industries to hunt for innovative, sustainable, durable, user plus eco-benign and of course, cost-efficient substitutes for current binders and construction materials. Quite recently, Geopolymer binders produced by a synthesis of Silica and Alumina rich pozzolanic precursor – like Fly Ash, with alkali solution as an activator through the process of Geopolymerization have become known as luminously promising option to conventional cement. This study includes not only development of rubberized Geopolymer concrete but also investigates on its strength and durability criteria. What’s more to add, at this time, natural sand is over exploited for construction and industry creating a scarcity for it, which in turn, resulted into a swift escalation of its cost. In the current study, the waste rubber tire fibres are employed as a partial substitute of fine aggregates. The study reveals that the application of waste rubber tire fibre as a replacement of Sand is not merely cost-effective but also user- and eco-benevolent appropriate corridor for developing rubberized Geopolymer concrete sans compromising its sustainability. This paper is a scientific approach for complying the performance evaluation of strength studies such as Compressive Strength, Flexural Strength, Split Tensile Strength, Modulus of elasticity; Pull off strength and durability parameter like abrasion resistance of fly ash based rubberized geopolymer concrete and compared the results with OPC rubberized concrete. The outcomes of comparison have unearthed that Rubberized Geopolymer Concrete (RGPC) enjoys superiority in context of all the above parameters to its counterpart Rubberized OPC-Concrete.

Abstract: Due to the environmental impacts resulting from the production of Ordinary Portland cement (OPC), the drive to develop alternative binders that can totally replace OPC is gaining huge consideration in the construction field. In the current study, attempt was made to determine the strength characteristics of glass fibre-reinforced fly ash based geopolymer concrete. Sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) were used as alkaline solutions (for activation of geopolymer reaction) at 12, 16, 20 M. Glass fibres were added to the geopolymer concrete in varying proportions of 0.1–0.5% (in steps of 0.1%) by weight of concrete. A constant weight ratio of alkaline solution to fly ash content of 0.43 was adopted for all mixes. British standard concrete test specimens were cast for measuring compressive strength, split-tensile strength, and flexural strength. Concrete specimens were cured by heating in oven at 90 °C for 24 h and natural environment, respectively. From the results, thermally cured concrete samples had better mechanical properties than the ambient (natural) cured samples. Thermally cured concrete specimen, containing 0.3% glass fibre and 16 M NaoH, achieved a maximum compressive strength of 24.8 MPa after 28 d, while naturally cured samples achieved a strength of 22.2 MPa. There was substantial increase in tensile strength of geopolymer concrete due to the addition of glass fibres. Split tensile strength increased by 5–10% in glass fibre-reinforced geopolymer concrete, containing 0.1–0.5% glass fibre and 16 M NaoH when compared to the unreinforced geopolymer concrete (1.15 MPa).

Abstract: Spectacular technological progress has been made in the last few years through thedevelopment of new materials such as «geopolymers», and new techniques, such as «sol-gel». New state-of-the-art materials designed with the help of geopolymerization reactions are opening up new applications and procedures and transforming ideas that have been taken for granted in inorganic chemistry. High temperature techniques arc no longer necessary to obtain materials which are ceramic-like in their structures and properties

Abstract: Inorganic polymers based on alumina and silica polysialate units were synthesised from dehydroxylated aluminosilicate clay (metakaolinite) condensed with sodium silicate in a highly alkaline environment. Reaction of the aluminosilicate with alkali polysilicates yields polymeric Si–O–Al three-dimensional structures with charge-balancing positive ions such as hydrated Na+ in the framework cavities. A statistical study of the effect on the polymerisation process of the molar ratio of the component oxides and the water content of the mixture showed the latter to be a critical parameter. The polymerisation mechanism and structures of the products were investigated using NMR, XRD and FTIR spectroscopy. 29Si liquid-state NMR shows that some compositions do not cure properly because of incomplete reaction of the sodium silicate with the metakaolinite. FTIR confirms that during drying of the incompletely cured samples, Na migrates to the surface where it undergoes atmospheric carbonation. The cured polymers were found to be essentially X-ray amorphous, with bulk densities of 1.3–1.9. During polymerisation the coordination of Al in the metakaolinite reactant (IV, V and VI) changes almost completely to IV in all the polymer compositions. The environment of the Na is unchanged irrespective of the polymer composition. The solid-state 29Si NMR spectra indicate a range of Si–O–Al environments. Typical mechanical properties of the best polymers were: Mohs hardness >7, Vickers hardness about 54, and compressive strength (after drying for 1 h at 65°C) 48.1 MPa.

Abstract: To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. This paper presents the development of fly ash-based geopolymer concrete. In geopolymer concrete, a by-product material rich in silicon and aluminum, such as low-calcium (ASTM C 618 Class F) fly ash, is chemically activated by a high-alkaline solution to form a paste that binds the loose coarse and fine aggregates, and other unreacted materials in the mixture. The test results presented in this paper show the effects of various parameters on the properties of geopolymer concrete. The application of geopolymer concrete and future research needs are also identified.

Abstract: Environmental issues will play a leading role in the sustainable development of the cement and concrete industry in the 21st century. The World Earth Summits in Rio de Janeiro, Brazil in 1992, and Kyoto, Japan in 1997, have made it abundantly clear that unchecked increased emission of greenhouse gases to the atmosphere is no longer environmentally and socially acceptable for overall sustainable development. The primary greenhouse gas emissions discussed in the sessions of the above conferences are carbon dioxide emissions. Other greenhouse gases such as nitrous oxide and methane, are of serious concern, but the amount involved is relatively small compared with that of carbon dioxide. Consequently, developed countries are considering regulations and mandatory quotas on the emission of these gases, and the main thrust is to stabilize these emissions to the 1990 level by the year 2010. Since the manufacture of portland cement contributes significantly to carbon dioxide emissions, this article discusses the increase use of large volumes of fly ash and other supplementary cementing materials in the construction industry and its role in reducing these emissions.

Abstract: Environmental issues will play a leading role in the sustainable development of the cement and concrete industry in the 21st century. The World Earth Summits in Rio de Janeiro, Brazil in 1992, and Kyoto, Japan in 1997, have made it abundantly clear that unchecked increased emission of greenhouse gases to the atmosphere is no longer environmentally and socially acceptable for overall sustainable development. The primary greenhouse gas emissions discussed in the sessions of the above conferences are carbon dioxide emissions. Other greenhouse gases such as nitrous oxide and methane, are of serious concern, but the amount involved is relatively small compared with that of carbon dioxide. Consequently, developed countries are considering regulations and mandatory quotas on the emission of these gases, and the main thrust is to stabilize these emissions to the 1990 level by the year 2010. Since the manufacture of portland cement contributes significantly to carbon dioxide emissions, this article discusses the increase use of large volumes of fly ash and other supplementary cementing materials in the construction industry and its role in reducing these emissions.