Effects of ground blast-furnace-slag with highly hydraulic activity on the cement properties

A series of experiments have been carried out to investigate the effects of ground blast-furnace-slag(GBS) on cement properties.Results obtained indicated that the slag powder exerts distinctive influence on sample strength,especially in maintaining early strength as the slag's chemical module exceeded 1.8.When a portion of ground clinker powder was replaced by GBS with Blaine fineness of 550—650 m~2·kg~(-1),the 3-day flexural strength of Portland blast-furnace-slag cement(PSC) approximately equaled that of Portland cement.However,the 7day flexural strength of the PSC was slightly greater than the Portland cement and increased with the increasing slag proportion.For compressive strength of the PSC,the GBS's effects presented some different features.The PSC's 3-day compressive strength was slightly lower than that of Portland cement,while the 7-day compressive strength approached that of Portland cement.The effects of GBS addition on late period strength present some distinction between flexural and compressive strength.Remarkable augmentations in the 28-day flexural strength were observed in the samples containing GBS.whereas the compressive index of the same samples were lower than or approximately equal to the Portland cement.Altering GBS addition and fineness result in no appreciable response in 28-day compressive index.The initial and final setting time of the PSC is slightly longer than Portland cement in the case of slag content within 50%.Generally,it is shown that water demand for cement paste with normal consistence may increase with GBS addition.