Shrinkage of Concrete Containing Greywacke Sandstone Aggregate

Greywacke sandstone is a widespread aggregate resource and is increasingly being used in concrete construction around the world. The geological properties of this sedimentary rock are fairly diverse such that greywacke aggregate may produce a range of hardened concrete properties. Therefore, it is important that the aggregate can be easily characterized to obtain predictable concrete properties. Fifteen different sources of crushed, semi-crushed, and rounded greywacke were tested from around New Zealand, and aggregate and hardened concrete properties are reported in this paper. Findings indicate that some greywacke aggregate may not be dimensionally stable under changing moisture conditions and may increase the drying shrinkage potential of concrete. Results from this survey established clear trends that can be related to the underlying geology of the aggregates. A number of simple characterization techniques can be used to predict the influence these aggregates have on the hardened properties of concrete, particularly drying shrinkage. [PUBLICATION ABSTRACT]