Influence of Mineral Admixtures on the Autogenous Shrinkage and Porosity of High-Strength Concrete

摘要

This paper illustrates the effect of silica fume, ultra fine fly ash and ground granulated blast furnace slag on the compressive strength, shrinkage and the development of pore structure of high performance concrete. Shrinkage measurements were carried out using a modified version of ASTM C-341, as proposed by Tazawa and Mizawaya. The experimental data obtained demonstrates how the material composition, the water to binder ratio, and the distribution of pore volume influence strength, autogenous, drying and total shrinkage. High strength mixtures containing ultra fine fly ash, silica fume and ordinary Portland cement exhibited an increased drying shrinkage rate, when compared with the slag mixture. By using a 10% replacement of UFFA, a large improvement with respect to autogenous shrinkage, relative to a 10% silica fume replacement in high strength concrete occurs, without any noticeable effect on compressive strength. The pore structure of the matrix paste at early ages of hydration appears to have a strong effect on autogenous shrinkage.