Using SP and SF to Lower Cement Content

Abstract

In the present research, using different percents of superplasticizer (SP) and silica fume (SF) to improve the characteristics of concrete is performed. SP and SF are added to two types of normal concrete, the first is of mixing ratio (1:2:4) and the second is of mixing ratio (1:1.5:3).The results show that adding SF lead to increase compressive strength for first mix by about 45.3% and 47.7% while adding SP lead to increase the compressive strength by about 43% and 41% compared to reference mix at 7 and 28 day respectively. The corresponding values for second mix are 46.7%, 49%, 44% and 43% respectively.The maximum compressive strength when SP and SF used together can be attained when the percents of SF and SP are 5% and 3% respectively. The increase in compressive strength is about 49.3% and 48.4% for first mix, while the corresponding values for second mix are 52.4% and 51.2% as they compared to reference mix at 7 and 28 day respectively.For Tensile strength, adding SP lead to increase it by about 29.2% and 31.6% for first and second mix respectively, while the corresponding values when adding SF are 38.1% and 40.3%. The effect of using SP and SF together on increase tensile strength is more than the effect of using each one separately. The maximum tensile strength can be attained when the percent of SF and SP are 5% and 3% respectively as they increase the tensile strength by about 38.9% and 40.7% for first and second mix.The effect of using admixtures on cement content can be noted clearly as the maximum reduction percents are about 8.7% and 9.35% for first and second mix respectively when the percent of SP is 3%. The corresponding values are 9.4% and 11.26% when the percent of SF is 5%. Using SP and SF together at percent 3% and 5% respectively lead to reduce cement content by about 10.15% and 13.54% for first and second mix respectively.