Limestone Powder- A New Type of Mineral Admixture for Dam Concrete

Influences of limestone powder on the hydration progress of cement and the properties of dam concrete were studied in this paper. The results show that, as mineral admixture, limestone powder accelerates the cement early hydration and takes part in this hydration which produces the calcium monocarboaluminate hydrate, but, limestone powder doesnt have the pozzolanic activity. Limestone powder has an adverse impact on the pore system of hardened pastes, especially these pores size range from 3 nm to 107 nm. Fortunately, the pore system will be optimized by using some fly ash instead of part of limestone powder. Limestone powder, no matter used alone or blended with fly ash or ground blast furnace slag to form a double-doped material, can be used as mineral admixture for the dam concrete including conventional and roller-compacted concrete. Compared with fly ash, it increases concrete water content and improves the 7 days strength, but almost has no function on the 90 days strength.