Experimental study of mechanical properties of conventional concrete and geopolymer concrete with and without white soil

Abstract Concrete is an important material in the construction of buildings, but the use of cement produces CO 2 gas emissions, so it is not considered environmentally friendly. One of the efforts to replace cement without reducing the quality of concrete involves utilising fly ash and a certain percentage of white soil as a substitute for fly ash. This study compares the compressive strength, elastic modulus, and Poisson’s ratio of conventional and geopolymer concrete with or without white soil substitution with 150 x 300 mm cylindrical specimens. The fly ash was F-grade from the Tanjung Jati B Jepara power plant, and the white soil was from Kupang, NTT. A conventional concrete mix composition used a ratio of cement to fine aggregate to coarse aggregate of 1: 1.831 : 2.434 with a cement water factor of 0.5. The geopolymer concrete maintains the same proportions, substituting cement with fly ash or white soil and incorporating an alkali activator composed of NaOH (12M) and Na 2 SiO 3 Be52 in a 1:2.5 ratio. The concrete treatment is dry curing (room temperature). The results showed that conventional concrete has a higher compressive strength and elastic modulus but a lower Poisson’s ratio compared to geopolymer concrete.