Rice husk and snail shell ash as partial replacement of ordinary Portland cement in concrete – A review

Abstract

This paper examines studies on the use of rice husk ash (RHA) and snail shell ash (SSA) as partial Ordinary Portland cement (OPC)  replacements in concrete and their effects on concrete properties. RHA contains over 80% amorphous silica, along with other oxides in  small quantities. Scanning electron microscopy (SEM) analysis showed that RHA has irregularly shaped particles with a porous, cellular  structure. Similarly, chemical analysis of SSA revealed it contains over 60% active calcium oxide with minor oxides, and SEM analysis  showed it has irregular semi-spherical particles with porous surfaces. The replacement of cement with RHA led to improved mechanical  and durability properties in concrete, although workability was reduced. RHA also demonstrated resistance to chloride penetration.  Combining RHA and SSA has the potential to produce stronger, more durable concrete, and could replace cement in high volumes in    concrete production.