SHRINKAGE MICROCRACKING IN CEMENT-BASED MATERIALS WITH LOW WATER-CEMENT RATIO

摘要

This paper deals with shrinkage microcracking due to internal restraints in high-strength cement-based materials. The two types of internal restraints that have been studied are restraint of the aggregate particles and self-restraining due to differential shrinkage in a drying specimen. For a number of reasons it is very difficult to detect autogenous shrinkage microcracks in the bulk of concrete using destructive microscopy techniques. However, in this paper a destructive microscopy method is described, which allows to detect autogenous microcracks, provided that the aggregate content is chosen in such way that the autogenous microcracks form a completely interconnected network. The mixtures studied are far from being concrete, but nevertheless their autogenous shrinkage microcracks patterns can be used to validate numerical models that predict shrinkage and cracking of cement-based materials. The drying shrinkage microcracking behaviour of these cement-based materials with 'manipulated' aggregate content has also been studied.