Experimental investigation on physical and mechanical properties of alkali activated concrete using industrial and agro waste

Abstract

Increasing infrastructure demands the need for using huge quantities of concrete. Concrete manufacture requires large amounts of cement whose production of one-ton results nearly one ton of CO2 emission into the atmosphere attributing to global warming. As a step towards sustainability, the use of supplementary cementitious materials (SCMs) for cement has been adopted globally. Alkali Activated Concrete (AAC) and Geo polymer Concrete (GPC) are great alternatives for regular conventional concrete because they make use of industrial and agro wastes as binders without cement. AAC is composed of two components-paste and aggregates. The paste is essentially a mixture of rich Calcium silicate or Alumino silicate materials as solid precursor and alkaline activator. Activators like alkali silicates, alkali hydroxides, alkali sulphates, alkali carbonates can be used to increase the value of pH of the mixture and quicken the splitting of the solid precursor. The present study proposed the novel mix proportioning of alkali activated concrete with possible industrial and agro wastes as precursors and homogeneous mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) as alkaline solution activator followed by experimental investigations. Series of experimental investigations are conducted to evaluate the fresh and hardened properties of AAC with constant NaOH molarity of 10 M and alkaline solution to binder ratio of 0.5. Several combinations involving fly ash, fly ash and slag, slag, fly ash and rice husk ash, slag and rice husk ash, etc will be adopted for the experimental investigations. Fresh concrete properties like workability and mechanical properties like compressive strength will be evaluated based on the work carried out using different combinations. Curing of AAC specimens is carried out in ambient temperature and the expected outcome will be a benchmark in making small scale concrete products like balusters, concrete benches at parks, paver blocks, and any other non-load bearing components using AAC mixes.