Effect of Silica in Cementitious Composites Using Thermodynamic Modeling

Abstract This article examines the effect of silica on pozzolanic performance of Portland cement blended with Ground Granulated Blast furnace Slag (GGBS), and Bagasse Ash (BA). Using the thermodynamic modeling and X-Ray powder Diffraction technique (XRD), the effect of different water to binder ratios in cementitious composites is analyzed through the hydration process of the proposed mixes. The hydration of the composites involves the formation of Portlandite, Calcium-Silicate Hydrate (C-S-H), tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), tetracalcium aluminoferrite (C4AF) and ettringite at 28 days. The results of thermodynamic modeling are compared with XRD technique, compressive strength and strength activity index test. Portland cement blended with GGBS attained better pozzolanic activity with 0.3 and 0.35 water to binder ratios than admixed BA. Also, the hydration products predicted from thermodynamic modeling and XRD peaks are highly resound in compressive strength and strength activity index tests.