Studies on Development of Strength and Durability of Class C Fly ash Geopolymer Lightweight Concrete

Abstract

The study presents development of Geo-Polymer Lightweight Concrete (GPLWC) using newlineindustrial by-products such as Class-C flyash and GGBFS as binder materials and processed newlineslag sand and sintered flyash aggregates as replacement to fine and coarse aggregates newlinerespectively. ACI absolute volume method of mix proportioning was used to arrive at newlinevolumetric proportioning of composites. The liquid - binder ratio of 0.4 was used to develop newlinecement concrete (CC). Activator solution having SiO2/ Na2O ratio of 0.6 was used for the newlinedevelopment of GPLWCs. newlineThe ambient temperature air cured GPLWC developed had mass density in the range of about newline1800Kg/m3 to 1900Kg/m3. The workability of concrete was measured with help of Slump Cone newlineTest, Compaction Factor Test and Flow Test using inverted slump cone. The workability test newlineresults indicate that the composite under study can be compared with self-compacting and selflevelling newlineconcrete. Higher the GGBFS content better was the strength, workability and density. newlineThe compressive and flexural strengths of developed GPLWCs were studied. The strength newlineresults indicate that, the developed GPLWCs were superior to CC and also could be used for newlinestructural purposes. The SEM and XRD microstructural analyses of the GPLWC samples newlineclearly indicate the development of amorphous gel aiding strength development newlineThe durability of the developed GPLWC was studied by exposing individually to 10% Sulfuric newlineacid, 5% Sodium Sulphate solution and 5% Magnesium Sulphate solutions for up to 90 days newlineperiod. The GPLWC specimen were immersed in acid and Sulphate solutions after air curing newlinefor 90 days. The effect of high temperatures on strength properties were also studied. The newlinedurability test results indicate the GPLWCs developed with only FAC and GGBFS as binder newlinematerials have limitations, when subjected to acid, sulphates and elevated temperatures. The newlineSEM and XRD microstructural analyses clearly indicate the formation of deleterious newlinecompounds like ettringite and gypsum, which contribute to strength deterioration. newlineUtilization of industrial by-products reduces the energy intensive manufacturing process of newlineconventional building materials, leading to carbon neutrality. Hence Geopolymer Concretes newlinecan be considered as sustainable concrete. newline