Synthesis reaction and compressive strength behavior of loess-fly ash based geopolymers for the development of sustainable green materials

Abstract

This study investigated the potential use of natural loess to activate a geopolymerization reaction, and also to identify the efficient fly ash ratios that is to be combined with loess for the development of a new geopolymer material. A combination of two chemical solutions, sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as well as a plasticizer were used to investigate the synthesis reaction and the compressive performance on loess-fly ash based geopolymer pastes. A consecutive addition ratio of 10% of L/FA is added within the range of 10–100% was adopted and the specimen’s mass loss measurement, relative density variation and compressive strength comparison were performed at different time frames. The test results showed that the presence of high porosity in the geopolymer specimen makes it a light weight material with limited compressive strength and density directly proportional to its strength factor. It was found that the geopolymer pastes derived from 90% loess and 10% fly ash ratios represent the most significant ratio with compressive strength value of up to 14.54MPa at 7days curing period. It was also found that when appropriate proportions of loess and fly ash were used, the interaction between the two materials provided the desired short-term and long-term geopolymer properties. This indicated that a very high quantity of loess at a given lowest fly ash proportion gave high strength and provided a greener alternative to Portland cement with maximum economic solution.