Influence of sun flower stalk ash (SFSA) on the behavior of Portland cement pastes

Abstract

In the current study, several measurements are carried out to characterize the influence of sun flower stalk ash (SFSA) on the physical, chemical and mechanical properties of Portland cement pastes as heat of hydration, chemically combined water and free lime contents, bulk density, apparent porosity and compressive strength. It is concluded that the gradual incorporation of SFSA with the cement, increases the surface area or fineness of the whole cement batches. The SFSA can improve and enhance all specific properties of the OPC pastes, particularly the compressive strength. The free lime content often decreased with the SFSA content, i.e. as the SFSA addition increased, the free lime content decreased. The cement pastes containing 24 ​wt % SFSA was the optimum batch because it achieved the best results, while that containing 30 ​wt % SFSA exhibited the lowest values at all hydration times. So, the higher amounts of SFSA must be avoided. The XRD patterns, DTA thermograms and FT-IR spectra showed that the intensity of free lime peaks is obviously decreased with SFSA content. Also, the amount of CSH improved and increased with the increase of SFSA content.