Assessment of mechanical and microstructural properties of geopolymers produced from metakaolin, silica fume, and red mud (original) (raw)
Related papers
Analytical Review of Geopolymer Mortar
Mortar is one of the most widely used construction material; it is usually associated with Portland cement as the main binder. Portland cement production is under critical review due to high amount of carbon dioxide gas released to the atm. The use of Portland cement is still unavoidable in the future; efforts are made to reduce use of Portland cement in concrete. These efforts include utilization of supplementary materials such as fly-ash, silica flumes, granulated blast furnace slag, rice husk ash and metakaolin as alternative binders to Portland cement. In this respect, Geopolymer Technology show considerable promise for application in the concrete industry as an alternative binder to Portland cement. GEOPOLYMER MORTAR is new that doesn’t require use of Portland cement as a binder. Instead, the sources of materials such as fly-ash that are rich in silicon, aluminum, are activated by liquids to produce the binder. Hence mortar with no Portland cement. This paper covers constituents of Geopolymer mortar, casting procedure, curing methods, advantages, limitation and Economical benefits of Geopolymer mortar.
Effect of Concentration of Alkaline Solutions on the Development of Geopolymer Mortar
International Journal of Engineering Technology, Management and Applied Sciences, 2017
Concrete/mortar is the oldest and most popular today's man-made construction material. However, high-energy requirement, and pollution involved in the production of cement and concrete hampers the image of cement concrete/mortar as a sustainable material. Similarly due to increasing demand of electricity, coal based power plants are also increasing which produce large amount of fly ash and creates disposal problem. Experimental investigation has been carried out to study the combined effect of sodium silicate and sodium hydroxide solutions on workability in terms of flow and the compressive strength of fly ash-based geopolymer mortar. Mortar cubes of size 70.7mmX70.7mmX70.7mm were made with various activated liquid to fly ash ratio, namely, 0.25, 0.30, 0.35, 0.40, 0.45 and 0.50 using 2.91, 5.61, 8.10, 11.01, 13.11, and 15.08M concentrated NaOH solution. All the specimens were cured in oven at 24 hour duration at the temperature of 40, 60, 90, and 120 0 C. Effect of various parameters such as solution-to-fly ash ratio, concentration of NaOH in terms of molarity, temperature and its duration on workability in terms of flow, compressive strength, and alkalinity in terms of pH are studied. Test results show that compressive strength of geopolymer mortar increases with increase in concentrations of alkaline activators. Similarly same trend have been shown when alkaline activators-to-fly ash ratio increases. It is also observed that the geopolymer mortar achieved higher strength within a period of 24 hours at certain elevated temperature than 28 days cured cement mortar.
Ain Shams Engineering Journal, 2016
We report the effect of metakaolin (MK) substituted granulated blast furnace slag (GBFS) on the early strength of geopolymer mortars (GPMs) for potential repair applications. Such GPMs were prepared by activating MK (0-15%) replaced GBFS. Solution concentrations ratio of SiO 2 :Na 2 O were varied in the range of 1.08-1.26 to achieve appropriate geopolymerization. Various proportion of Na 2 O:dry binder (7, 8, 9, 11 and 13%) were used. The mass ratios of sodium silicate to sodium hydroxide (NS:NH) and the binder to fine aggregate (B:A) were fixed to 3.0 and 0.90, respectively. The mechanical properties of the synthesized GPMs were determined at ambient temperature after 24 h of casting and curing. It is demonstrated that 5% of MK replaced GBFS with 1.16 of SiO 2 :Na 2 O and 0.40 of S:B achieved an early compressive strength as much as 47.84 MPa at 24 h. The bond strength results exhibited the prospect of such GPMs as suitable alternative repair material. Production and hosting by Elsevier B.V.
Investigations on the properties of geopolymer mortar and concrete with mineral admixtures: A review
Construction and Building Materials, 2019
h i g h l i g h t s A comprehensive review of geopolymer mortar and concrete with mineral admixtures. A total of 126 research papers spanning a period of 22 years are reviewed. Mineral admixtures effects on fresh, mechanical and durability properties. Use of OPC, GGBFS, Nano-silica, Metakaolin, and Alccofine in Geopolymer products. Microstructure analysis of geopolymer mortars and concrete is reviewed. Research gap has been identified and elaborated.
Civil Engineering Journal
Great efforts are being made to minimize the negative impact of the Portland cement industry on the environment by using industrial by-products during the manufacture of clinker or by the partial replacement of cement during the preparation of concrete. However, the carbon footprint remains relatively high in addition to the large consumption of natural resources such as sand and other aggregates. A solution to these problems is to completely replace Portland cement with a new generation of mineral binders, commonly known as geopolymers, which have properties similar to those of Portland cement. These binders can be obtained by the alkali-activation of siliceous or aluminosilicate materials. This study aims to develop pozzolanic type binders at room temperature (20°C) from the alkali-activation of aluminosilicate materials based on metakaolin and blast furnace slag at different percentages. Different activators were employed, including solid (NaOH) and liquid (Na2SiO3.nH2O). The opt...
International Journal For Science Technology And Engineering, 2021
Consumption of cement as a major construction material is a global phenomenon. Cement manufacturing unit have been observed as one of the most imperative users of carbon based fuels that considerably contribute to greenhouse gas emissions. Hence there is a need to produce an essentially cement free binding material called Geopolymer. In the present research, an experimental study on setting characteristics of geopolymer paste, optimization of geopolymer mortar and microstructural analysis to correlate the compressive strength of geopolymer mortar wasstudied. The test results showed that initial and final setting time of Set1 and Set2 ranges from 15-320minutes and 40-640minutes respectively which was more than that of setting time of standard cement paste 65and 270minutes.This shows that increase in molarity makes the paste to set at a faster rate, whereas in increase of sodium silicate delays the setting time. The 28days compressive strength of Set1 and Set2 geopolymer specimens at ambient conditions was in the range 5.49-23MPa and 28days with one day oven curing was in the range 9.42-30MPa.Comparing the results of Set1 and Set2, 14M with activator ratio 1:2.5 gave the highest strength of 23MPa and 30MPa at ambient and oven curing conditions respectively. Geopolymer mortar at ambient conditions gave 10% less and oven cured samples gave 10% more strength than standard cement mortar. But there is still room for increase in strength as observed from microstructural analysis. From microstructural analysis, it was observed that the rate of reaction of geopolymer mortarincreases with the increase of NaOH concentration resulting in higher compressive strength and rate of reaction decreases with the increase of sodium silicatewhich results in lower compressive strength. The bonding at the age of 28 days (oven cured for 24 hours) samples was more when it was compared with 28 days ambient cured sample which indicates that the greater compressive strength. Also the bonding was more for the optimum activator ratio of 1:2.5 compared to all other activator ratios. Therefore the optimum dosage of alkali solution is 14M NaOH with activator ratio of 1:2.5. According to many literature papers the compressive strength gained in geopolymer mortar up to 28 daysis only around 75%-80%, after 28 days there is possibility for improvement in the strength around 10%-15 %.
IJERT-Influence of Curing and Water to the Mechanical Properties of Geopolymer Mortar
International Journal of Engineering Research and Technology (IJERT), 2016
https://www.ijert.org/influence-of-curing-and-water-to-the-mechanical-properties-of-geopolymer-mortar https://www.ijert.org/research/influence-of-curing-and-water-to-the-mechanical-properties-of-geopolymer-mortar-IJERTV5IS020082.pdf This paper presents experimental research investigating the effects of curing times, curing temperatures and water to the mechanical properties of geopolymer mortar incorporating different fly ash content. Geopolymer cements were synthesized from calcined kaolin and shale clay residues with Si/Al ratio of 2.0 with sodium and potassium silicates (Na2SiO3/K2SiO3) modulus ranging from 1.50 ÷ 1.95. Specimens were cured in two different environmental conditions: furnace and ambient. Tests were performed to establish the water to fly ash mass ratio increased the mechanical properties of geopolymer mortar decreased. Microstructural observations of fly ashes and pure geopolymer cement have been carried out by means of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX).
Impact of By-Products on Characteristics of Geopolymer Mortar Mixtures
2019
Јеlena Bijeljić 1 Nenad Ristić 2 Zoran Grdić 3 Gordana Topličić Ćurčić 4 Dušan Grdić 5 UDK: 666.972.124 DOI: 10.14415/konferencijaGFS2019.045 Summary: This paper researched physical-mechanical characteristics of geopolymer mortar mixtures based on fly ash, with addition of waste aluminosilicate materials such as red mud, biomass ash, silica dust and waste ceramic tiles. Four mixtures are made with the same 90:10 ratio of mass of fly ash and other binders, while on one mixture is made with fly ash only. The quantities of other materials required for making of geopolymer mortars such as the quantity and type of aggregate, aluminosilicate activators and water are constant. All mixtures are cured in the same laboratory conditions, at the temperature of 95°C for 24 hours, and afterwards the specimens are cured at the temperature of 22°C until the testing. The goal of this research is determining how the same water/binder and binder/agreggate ratio affects the physicalmechanical character...
Sustainability
Recent trends in reducing the ecological footprint of the construction industry have increased the attention surrounding the use of alternative binding systems. Among the most promising are geopolymer binders, which were found to have the capability to substantially reduce the environmental impact of Portland cement use. However, even the use of this alternative binding system is known to be heavily dependent on the use of industrial byproducts, such as precursors and an alkaline source, produced through an energy intensive process. To address this and provide a greener route for this binding system, this study adopts the use of natural kaolin and raw ceramic powder as the main precursors. The activation process is performed by using solid potassium hydroxide in conjunction with sodium and magnesium sulfate, which are naturally available, to produce geopolymers. To assess the resulting geopolymer samples, 28 mixes are produced and a series of physico-mechanical and microstructural a...
Mineral geopolymer binders can be an attractive and more sustainable alternative to traditional Portland cement materials for special applications. In geopolymer technology the precursor is a source of silicon and aluminium oxides, the second component is an alkaline solution. In the synthesis of geopolymer binders the most commonly used alkaline solution is a mixture of sodium or potassium water glass with sodium or potassium hydroxide or silicate solution with a low molar ratio, which is more convenient and much safer in use. In this paper, we present the influence of sodium or potassium silicate solution on the physical and mechanical properties of fly ash and ground granulated blast furnace slag-based geopolymer mortars. Mercury intrusion porosimetry and microstructural observation allowed for comparing the structure of materials with a different type of alkaline solution. The evolution of compressive and flexural tensile strength with time determined for composites using 10%, 30% and 50% slag contents (referring to fly ash mass) was analysed. The tests were performed after 3, 7, 14 and 28 days. It was observed that, as the amount of slag used increases in the precursor, the strength of the material grows. Mortars with the sodium alkaline solution were characterised by a higher strength at a young age. However, the values of strength 28 days were higher for geopolymers with potassium alkaline solution reaching 75 MPa in compression. Geopolymer mortar microstructure observation indicates a high matrix heterogeneity with numerous microcracks. Matrix defects may be caused by the rapid kinetics of the material binding reaction or shrinkage associated with the drying of the material.