The Study of Incorporation of Fly Ash and Lightweight Expanded Clay Aggregate (LECA) in Mortar

Abstract

The utilization of supplementary cementitious material as a cement replacement has become essential for providing sustainability to concrete. Fly ash is a by-product of coal combustion in thermal power plants and contributes significant waste generation annually. Moreover, improper disposal of fly ash in landfills has resulted in environmental concerns. Due to this obstacle, fly ash is used as a recycling material for substantial modification. This study is aimed to use fly ash as a cement replacement with percentages of 0%, 5%, 10%, 15%, and 20% of fly ash by weight of cement. In the study, LECA was also introduced as a partial replacement of sand for determining the final density of lightweight mortar. The percentages of LECA used were 0%, 5%, 10%, 15%, 20%, 25% and 30% of LECA in sand. The chemical composition for both cement and fly ash using XRF testing. Four types of trial mixes were used in the study. The mortar strength was investigated at room temperature and after exposure to water curing at 7, 14, and 28 days. The results indicated that cement replacement with 5% fly ash showed an optimum strength compared to the control sample. The incorporation of 10% LECA as a replacement of sand increased the compressive strength value compared to the control sample. Both optimum results gained from those trials were used to confirm the best combination mixes for achieving mortar strength. The final trial mix showed that the final compressive strength results in brick, achieving the strength according to MS 76: 1972. It can be concluded that the application of both fly ash and LECA can be used as a partial replacement for cement and sand. These combination percentages have resulted in good strength and reduced final product density.