Mechanical and durability characteristics of GGBS-Dolomite geopolymer concrete using recycled coarse aggregates

Abstract

Increased construction rate in recent times has led to many problems in the sector such as increased use of cement, exploitation of natural resources, and increased amount of demolition waste. To overcome these problems, using geopolymer binders in place of cement and replacing natural aggregates with recycled aggregates can be a good solution. In order to determine the impacts of adding recycled concrete particles to geopolymer concrete, this study examines the hardened and durability qualities ofthe material. In this study, Geopolymer concrete was made with GGBS and Dolomite as precursor material, and alkali solution made with sodium silicate to sodium hydroxide ratio of 2.5 and alkali to source material ratio of 0.6. In the geopolymer concrete, recycled coarse aggregates were used to replace traditional coarse aggregates by 50%. Results showed that compared to regular geopolymer concrete (NGPC), recycled aggregate geopolymer concrete (RAGPC) tends to have reduced compressive strength, split-tensile strength, and flexural strength by 14%, 13%, and 16%, respectively. For assessing the durability characteristics, tests on water absorption, acid attack, and sulphate attack were conducted. The water absorption of RAGPC was 1.14% more than NGPC. The acid resistance and sulphate resistance of RAGPC were found similar to NGPC after exposure to H2SO4 and MgSO4 solution for 90 days. The results indicate that RAGPC has similar durability characteristics to GPC. Since recycled coarse aggregates don't considerably diminish strength and have comparable durability qualities, the study indicates that it can be used to economically substitute natural coarse aggregates in geopolymer concrete.