Influence of Curing Methods on the Formation of Microcracks in High-Strength Concrete

摘要

The microstructure of concrete, especially of High Performance Concrete/ High Strength Concrete (HPC/HSC), usually shows many microcracks. The aim of this research project is to investigate the reasons for microcracking in HSC, especially the influence of different curing methods. Different specimens were stored at 20 ℃/65 % r.h., underwater, in a 40 ℃ furnace and under 40 ℃ hot wind. Additionally, the HSC was made with and without silica fume to determine the effect on the structure and on the formation of microcracks. Compressive strength of the investigated concretes ranged from 80 - 100 MPa. The main result is, that the wet curing led to a higher number of microcracks in HSC, than the curing at 20 ℃/65 % r.h. and also a higher numberthan the curing method in the furnace or under a hot wind. Additionally, the effects of microcracking on servicability and durability were investigated. The results showed that the numberof microcracks did not influence mechanical properties like compressive strength and splitting tensile strength nor water permeability. Specimens with high number of microcracks showed in these tests also higher values of Young's modulus.