EFFICIENCY OF USING A COMPLEX ADMIXTURE AS A MICROSILICA REPLACEMENT IN REACTIVE POWDER CONCRETE

Abstract

One of the most important ways to use resource-saving technologies in producing concrete and reinforced concrete products is to use active mineral admixtures. Microsilica is one of the most popular and effective admixtures of this type. However, the use of microsilica is not always economically reasonable due to its high cost. This paper presents the results of comparative studies of the effect of various active mineral admixtures on the properties of reactive powder concrete. Five different admixtures were investigated: ground quartz sand, blast furnace slag, fly ash, metakaolin and microsilica. The highest strength values were achieved for RPCs containing microsilica and fly ash together with metakaolin. The RPC compositions containing fly ash and metakaolin reached an average compressive strength of approximately 100 MPa and a flexural strength of over 16 MPa after 28 days. This is only on average 10-20% less than concrete containing microsilica. In particular, it shows the possibility of replacing the costly microsilica by the proposed composite mineral admixture consisting of fly ash and metakaolin. It has been shown that using such an admixture makes it possible to produce reactive powder concretes with strengths similar to those of concrete with silica fume. At the same time, the cost of such an admixture is significantly lower.