Influence of creep and shrinkage on cracking in high strength concrete

Abstract Efficient use of high strength concrete (HCS) depends on a thorough understanding of its long term behaviour. However, its good mechanical performance must not blind its durability properties which are affected by cracking, as recent studies have shown. This paper deals with surface microcracking developed both by creep and shrinkage on young age loaded HSC. The HSC cylinders were stored for 400 days in an air conditioned room (50% RH and 20°C). Creep load up to 32 MPa was applied 28 hours after batching. Moreover, the effect of the desiccation was studied in unloaded samples. Microcracking was observed by SEM with replica technique and analyzed with the stereological tools of total projections. The main conclusion is that the intensity of the compressive creep load disturbs the orientation and density of surface microcracking due to desiccation and that recovery after unloading induces surface microcracking, which is strongly oriented in a given direction.