Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Inorganic Chemistry

Cement-less bricks were prepared using different industrial and agricultural wastes. Firstly, the cement-less pastes were prepared from mixing of ground granulated blast-furnace slag (GGBFS) with hydrated lime (HL) and cement kiln dust (CKD). HL and CKD were used as activators for GGBFS hydration. Different HL (10, 20, and 30 wt., %) and CKD (30 and 50 wt.,%) contents were added as substituent for GGBFS. The physico-chemical and mechanical properties such as chemically combined water, free lime, water absorption and compressive strength were carried out for hardened cement-less pastes. Different instrumental techniques such as X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), infrared (IR) spectroscopic analysis and scanning electron microscopy (SEM) were used for hydration products characterization. The results showed that GGBFS individually replaced by 20 wt., % HL and 50 wt., % CKD gave the highest mechanical properties. Whereas, the mixes containing 10 and 30 wt., % HL as well as 30 wt., % CKD showed the lowest compressive strength. The free lime content increased with the increase of HL and CKD content. 20% HL and 50% CKD have a positive impact on the reduction of water absorption of the hardened pastes. In order to study the effect of silicate sources in free lime consumption, 5, 7.5 and 10 wt., % rice husk ash (RHA) were added to mixes containing 30 and 50% HL and CKD, respectively. The results also showed that, the free lime content decreased with RHA content as proved by XRD and TG/DTG analyses. The cement-less bricks were made by mixing of optimum blends with air cooled slag (ACS) as fine and coarse aggregate

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