Adding Finely Crushed Dune Sand to Cement on the Evolution of Hydration of Pasta Portland Cement

Influence of adding finely crushed dune sand Sd to cement , on the physical-mechanical performances results primarily from two effects : a physical-chemical and a chemical effect. On one hand it modifies the hydration process of cement as well as the structuring of hydrated products, on the other hand, it reacts on the cementing medium and develops new hydrated products. These effects act simultaneously and in a complementary way on the final performan ce of cementing materials . In order to better understand the gain in strength of the premixed cement OPC of the finely crushed dune sand, the microstructural aspect has been examined. Mixtures of Sd lime pastes present a hydraulic setting which is due to the formation of a CSH phase. The latter is semi-crystallized. The study of mixtures Sd-lime paste is thus a simplified approach of that of the mixtures Sd-OPC in which the main reaction is the fixation, by the Sd, of lime coming from the hydration ofC3S in the form ofCSH.