EFFECT OF NANO-SILICA, SILICA FUME, CEMENT CONTENT AND CURING CONDITIONS ON THE CONCRETE COMPRESSIVE STRENGTH AT 7 AND 28 DAYS

Recently there is a strong trend in engineering researches in the field of engineering materials for the production of high and ultra- high strength concrete. Using different additives which are added to the concrete mix reduced the water cement ratio and caused an increase in the concrete strength. As well as the use of ultra-fine materials such as Nano-silica increase the strength of concrete dramatically. In spite of the success of this research to get to compressive strength up to 150 MPa or more, however, many problems have found in the mechanical behavior of these concretes, which turned into a decrease in the fracture toughness significantly. An experimental program was designed to investigate the effect of cement content, silica fume and Nano silica percent, and curing on the compressive strength of concrete at different curing ages. The results of the present work clearly showed an increase in the value of 28-day concrete compressive strength with existence of silica and Nano silica. Steam curing, also, led to an improvement in compressive strength as compared to water curing.