Water absorption of ambient-cured geopolymer concrete

Abstract

This study aims to determine the effect of the activator-binder ratio on the water absorption of ambient-cured geopolymer concrete. Class F fly ash from Mpanau power plant was used as precursor. This raw material was activated by a mixture of sodium silicate and sodium hydroxide solution, with an activator-binder ratio of 0,45; 0,50; 0,55; 0,60. Five percent replacement of fly ash by slaked lime was added to achieve ambient curing. The test specimen for the absorption test is made in the form of a cylinder with a size of 100 mm dia x 100 mm height. The absorption test used ASTM C642-06, and the test was conducted at the age of 28 days. The test results show that the geopolymer concrete with the largest activator/binder ratio has the lowest absorption, and volume permeable of voids. In this research, it was found that for the geopolymer concrete, activator-binder ratio of 0.60 has the lowest absorption and volume of permeable voids but gave the highest compressive strength. In addition, the test results show that normal concrete has the highest absorption and volume permeable of voids compared to the geopolymer concrete