Study on use of fly ash cenospheres for patial replacement of fine aggregate in structural lightweight concrete production

Abstract

This paper presents the experimetal results on use of hollow microspheres from fly ash, also known ascenospheres (FAC) to partially or fully replace fine aggregates in concrete to make structural lightweight concrete with density in the range of 1300 to 1800 kg/m³, compressive strength over 40 MPa. Sand was usedtopartially replace cenospheres at sand/FAC ratios of 0, 20, 40, 60, 80 and 100% by volume. Experimentalresults show that when replacing sand by FAC, the density of concrete decreases respectively, from 2180 kg/m³ of the 100% sand mix to 1312 kg/m³ of themix fully replacing sand by FAC. However, the basic mechanicalproperties of concrete using FAC such as compressive strength, flexural strength, elastic modulus were reduced, and water absorption was increased, despite the specific strength (ratio of compressive strength and density) increased significantly.