Reactivity of Cementitious Additions on Properties of Micro

Abstract

Reactive powder concrete (RPC) is a new generation of concrete material which is actually a micro mortar with a maximum aggregate size not exceeding 0.630mm. It should be noted that when incorporating cementituous additions, this type of concrete shows a better homogeneity, an increased compactness of the cement matrix and an improved microstructure leading to high initial as well as final physic- mechanical performance in fresh and hardened state. The objective of this paper is to study the effect of the addition of dune sand and slag, finely ground on mineralogical, rheological andmay thus be a simplified approach of that of the mixtures SD-RPC or S-RPC, in which the main reaction is the fixa mechanical properties of RPC. The compactness of the cement matrix, principal source of strength gain, is closely linked to the consumption of portlandite occurring during hydration of cement silicates to produce new calcium silicate hydrates (C-S-H) more compact and insoluble in water. This so-called pozzolanic reactivity depends on the nature and structure of the used cimentituous additions. In order to better evaluate the gain in strength of the RPC containing finely ground dune sand (SD) and slag (S), the microstructural aspect has been examined by X-ray diffraction. The study of mixtures SD-lime and S-lime tion of lime, resulting from cement hydration to produce additional C-S-H.In this work, the results obtained from tests carried out on RPC show that both compressive and tensile strengths increase when incorporating mineral additions in cement, thus improving the compactness of mixtures by their filler and pozzolanic effects.