simultaneous effect of aggregate and cement matrix on the performance of high strength concrete

In the current experimental work, the simultaneous effect of fineness modulus, water-to-cementitious materials [w/(c+m)], and also micro silica content were investigated on workability, mechanical and physical properties of high strength concrete. for this purpose, 45 mix-designs were made by selecting five different ratios of micro-silica, three w/(c+m) ratios, and three distributions of particle size and then the slump, compressive strength, elastic modulus, and split tensile strength of each designed concrete mixture were determined. findings showed that increasing the micro-silica content up to 10 wt% improves the mechanical properties of concrete and then leads to a reduction in strength parameters, so that the effect of changes in the micro-silica content on mechanical parameters of concrete becomes more prominent with increasing and decreasing the fineness modulus of aggregate and w/(c+m) ratio, respectively. it was also observed that increasing the micro-silica content leads to reducing the slump and unit weight of concrete so that this reduction is more noticeable in the low fineness modulus of aggregate and water-cement ratio.