STUDIES ON PORTLAND BLAST-FURNACE SLAG CEMENT WITH LIMESTONE AS A RETARDER

Portland blast-furnace slag cement pastes with 5% limestone as a retar der have been investigated. The hydration kinetics measured from the f ree lime and combined water contents as well as mechanical properties have been determined. The results revealed that the limestone can be u sed instead of gypsum as a retarder. The limestone increased the pH va lue of the hardened cement paste. The increase of slag content decreas es the water of consistency and increases the setting time. In additio n, the increase of slag content tends to decrease the combined water a s well as free lime contents. The slag content has slight effect on th e mechanical properties.