Strength, durability and micro-structural assessment of slag-agro blended based alkali activated engineered geopolymer composites

Abstract

Alkali Activated Engineered Geopolymer Composites (AA-EGC) usually comprises of fly ash and silica sand as per the literatures available. It is necessary for the researchers to study the effect of other precursors based on local availability. This research paper focuses on the investigation towards the maximum utilization of high-volume industrial slag wastes along with an Agro waste to develop eco-friendly AA-EGC. Here, ground granulated blast furnace slag, rice husk ash, copper slag, Manufactured-Sand (M-sand) and polyvinyl alcohol fibers formed the primary composite ingredients. The optimization of copper slag content w.r.t M-sand was investigated, while considering the best of other mix-factors, based on literatures. Sodium based alkali activators along with polycarboxylic acid ether based super-plasticizer were used as liquid ingredients to activate the geo-polymerization reaction and to improve the workability respectively. Several experimental tests were conducted such as flow table test on fresh composite properties; compression, tensile, rapid chloride permeability test and sorptivity tests on hardened composite properties to evaluate the strength and durability performances. Scanning Electron Microscope (SEM) analysis with Energy Dispersive X-Ray (EDAX) were performed to evaluate the micro-structural properties along with Non-Destructive Test (NDT) to ensure the composite quality. The experiments revealed that the volume of copper slag as fine aggregate could be limited to 60% with respect to M-sand to avoid segregation and bleeding. Maximum of 31.1 MPa compressive strength was achieved with 40% copper slag under ambient curing conditions at the age of 28 days. Increase in copper slag content helped the composite in arresting the chloride ion penetration and absorption of capillary surface water. According to NDT, as the copper slag content increases, the pores were arrested making it denser. The quality of the composite in terms of dense packing, presence of unreacted binders, absence of air pores and unexpected reactions were ascertained with micro-structural investigations.