Study On The Effect Of Carbonate Powder On Properties Of Mortar

Supplementary cementitious materials, including fly ash, ground granulated blast furnace slag and silica fume, have been widely used in portland cement concrete. The resources shortage of fly ash and Silica is also gradually revealed, and the resources can not meet the market demand. In addition, it is necessary to find new types of high quality supplementary cementitious materials. There are many kinds of carbonate powder that is abundant and distributed uniformly in China. Therefore,In this study, limestone powder, dolomite powder, this two carbonate powder, andfly ash, slag are selected as primary SCM to prepare cement-limestone, cement-limestone-fly ash, cement-limestone-slag, cement- dolomite, cement- dolomite-fly ash, cementdolomite-slag cementitious system mortar. Workability, mechanical properties and drying shrinkage performance of mortar was mainly investigated.The results show that: The limestone powder can improve the workability of the mortar with or without any other supplementary cementitious materials(fly ash, slag), but the best result for workability came from proportion containing both limestone powder and fly ash, the optimized proportion was 15% limestone powder with addition of 10% fly ash. With the increase of the limestone, the strength of the mortar gradually decreased; The double addition of limestone and fly ash had a little effect on the improvement of mortar's strength; The double addition of Limestone powder and slag made a better improvement on the mortar's flexural strength, against little impact on the improvement of compressive strength. The sample containing 10% limestone powder and 10% slag had a better show.The dolomite powder can improve the workability of the mortar with or without any other supplementary cementitious materials(fly ash, slag), but the best result for workability came from proportion containing both dolomite powder and fly ash. The single addition of dolomite powder improved the mortar's late strength when the content is no more than 10%; The double addition of dolomite powder and fly ash was disadvantageous to the development of the mortar's strength; The late strength of the mortar increased when mixing with dolomite powder and slag. The sample containing 10% dolomite powder and 10% slag had a better show.The fineness of limestone powder and dolomite powder have a certain effect on the drying shrinkage of mortar, and the drying shrinkage is improved when adding single mineral of them; The improvement of dry shrinkage was not obvious when mixing with fly ash or flag.Some tentative research experiment is also made to test whether dolomite powder can restrain the alkali carbonate reaction. Adding proper amount of dolomite powder can restrain the alkali carbonate reaction.