The Influence of Physical Properties of Aggregate on Shrinkage in High Strength Slag Cement Concrete

In order to investigate the influence of aggregate on autogenous shrinkage and drying shrinkage in high-fluidity, high-strength concrete containing ground granulated blast-furnace slag (GGBFS), a study was made of the water-binder ratio (W/B), quality of coarse aggregate and replacement ratio of GGBFS (replacement ratio of slag) at different levels. In this test, W/B was 23, 28, 33 and 43%, replacement ratio of slag was 0, 50 and 75%, five types of coarse aggregates were used. The authors investigated the relationships between W/B and autogenous shrinkage or drying shrinkage, physical properties of aggregate and concrete shrinkage, and replacement ratio of slag and concrete shrinkage. Particularly in this study, the authors paid attention to aggregate crushing value of physical properties of aggregate. The aggregate crushing value was measured by method which was defined in British Standard. The following findings were obtained. (a) The smaller the W/B, the greater the percentage of autogenous shrinkage in drying shrinkage. (b) The aggregate crushing value is a critical factor in concrete shrinkage. (c) An increase in replacement ratio of slag leads to an increase in the percentage of autogenous shrinkage in drying shrinkage. (d) The practical significance of these data is that we should consider the aggregate crushing value in evaluating autogenous shrinkage of high-strength, high-fluidity concrete.