Development of Alkali Activated Concrete using flyash for reducing carbon footprint

Abstract

The consumption of cement is increasing day by day due to the remarkable development in the infrastructure. One tonne of cement produced emits approximately one tonne of carbon dioxide into the atmosphere. To reduce the use of cement, new-generation concretes such as Alkali Activated Concrete, also known as geopolymer concrete (GPC), have been developed. Geopolymer is a novel material with the potential to replace conventional Portland cement. It is an inorganic material with an amorphous to semi-crystalline polymeric structure that is manufactured by alkali activation of amorphous aluminosilicates at ambient or slightly higher temperatures. In this study, geopolymer concrete was made with low-calcium fly ash. The geopolymer was created by combining sodium silicate and sodium hydroxide solutions with fly-ash. Other materials used for GPC include locally obtainable coarse aggregate and fine sand that is surface dried. Mettur Thermal Power Plant's low-calcium, Class F fly ash was used to make geopolymer concrete. Alkaline solution to fly ash ratio was varied from 0.3 to 0.45. The sodium hydroxide solution concentration was kept constant at 12M (Molars). After being cast in moulds; the specimens were placed in a 60°C oven for 24 hours before being allowed to air dry at room temperature. The compressive strength of geopolymer concrete was tested at 7 and 28 days of age. The test results show that compressive strength increases with an increase in alkali ratio and alkali-to-fly-ash ratio. The slump value for GPC is very less compared with conventional concrete.