ESEM DRYING TESTS: MICROCRACKING INITIATION IN THIN CEMENT PASTE DUE TO EARLY AGE DRYING

摘要

Scattered and discontinues microcracking as a subsequent side-effect of deformations due to early age drying, occurs in thin (approximately 1 mm thick) cement paste samples, when stepwise dried in ESEM. Microcracking of cement paste and restrains appear to be practically unavoidable. They are related to a phenomenon of interfaces ('matrix' and 'inclusion'), which exists at every scale. The combined effects of sample age, curing conditions and w/c ratio, influence development of microstructure at an early age as well as appearance of microcracks and their width (0.1-2.5 μm). However, rapid change of environmental conditions in cycles of drying-wetting induces full fracture of thin cement paste samples, regardless of the mentioned effects.