Setting, Hardening and Mechanical Properties of Some Cement / Agrowaste Composites - Part I

Abstract

The main objective of this study is to reutilize the barely and rice husks (BH & RH) after its conversion to ashes by firing at 600C (BHA & RHA) as replacing materials of Ordinary Portland cement (OPC) to prevent or at least to reduce the problems of air pollution and energy consumption. The results showed that the water of consistency and setting times of fresh cement pastes increased gradually by the addition of either BHA or RHA. Generally, all the studied properties are improved and enhanced with curing time up to 90 days. The combined water content, bulk density, flexural and compressive strengths decreased with curing time up to 3 days, whereas the apparent porosity increased. During the later ages from 3 up to 28 days and then decreased onward, these properties increased, while the apparent porosity decreased. These characters improved and increased only with 16 wt.% BHA or RHA content and then decreased. The free lime content of the OPC pastes increased as the curing time proceeded up to 90 days, while those containing either BHA or RHA increased only up to 3 days and then decreased up to 90 days and then reincreased onward. It was concluded that the higher contents of BHA and RHA (20 wt.%) must be avoided due to its outstanding cementing properties. The FT-IR spectra and SEM images appeared a slight improve in the crystals and microstructures of the newly formed phases.