WORKABILITY, MECHANICAL AND DURABILITY INVESTIGATIONS ON SELF-COMPACTING CONCRETE WITH HIGH FLY ASH CONTENT AND RECYCLED FINE AGGREGATE

Abstract

Currently, in Vietnam, the natural sand resource is depleted; thus, it is unable to meet the growing demand for construction. In this context, recycled fine aggregate (RFA) from waste concrete emerges as an effective alternative for sand in the production of self-compacting concrete (SCC). In this paper, the author presents the experimental results on the properties of SCC with high fly ash content using RFA. The research utilizes RFA to replace natural sand at the rates of 0% and 100%, respectively while applying fly ash concurrently at a 50% volume ratio of cement. The evaluated properties of the SCC include its workability, compressive strength, flexural tensile strength, chloride ion permeability, and water absorption. The research results show that the use of RFA combined with high fly ash content can produce SCC that meets EFNARC requirements, with only a 1.48% reduction in compressive strength, 1.85% decrease in flexural tensile strength,  19.79% reduction in chloride ion permeability, and 5.12% increase in water absorption compared to the use of natural sand. These findings demonstrate the effectiveness of incorporating RFA and high fly ash to replace natural sand and cement in SCC production, opening up prospects in the construction industry with positive environmental impacts.