Compressive strength and hydration with age of cement pastes containing finely ground sand

Abstract

The aim of this work is to study the possibility of using finely ground sand as a part mass addition to Portland cement. Searching the effect of addition ground sand on development of compressive strength and hydration with age of cement pastes as a function of the percentage of ground sand ( physico-chemical and chemical effect) and the fineness ( physical effect). In order to understand better the pozzolanic effect of finely ground sand (quartz), we followed the mixtures hydration (90% OPC + 10% ground sand) by X-ray diffraction. The results proved the pozzolanic reactivity of ground sand: the main reaction is the fixation of the lime coming from the cement hydration in the presence of finely ground sand, to form calcium silicate hydrate C-S-H. Moreover, finely ground sand has an optimum effect on compressive strengths when the percentage is about 10% and a 20 µm fineness. Finely ground sand, despite its crystalline structure, presents a pozzolanic reactivity.

Key words: Portland cement, finely ground sand, pozzolanic effect, hydration.