Cracking of concrete slabs poses serious problems with respect to the durability and serviceability of structures. Restraint in concrete leads to the development of tensile stresses and possible cracking. To manage cracking, designers have traditionally specified a 56 day shrinkage strain.
This experimentally based thesis aims to build upon work being done by researcher in the field on the effects of early age shrinkage on industrial concrete pavements. Recent research has focused on quantifying the effects of environment and restraint on early age shrinkage (within the first 12 hours) and the effects on long term shrinkage. Three commercial concrete mixes with specified shrinkage strains of 400, 650 and 800 microstrain were batched and instrumented with strain gauges. The aim was to investigate the relationship between early age shrinkage, which is not measured in the standard drying shrinkage test, standard 56-day drying shrinkage strain values and actual strains in slabs.
The results were compared with various prediction models from relevant codes. As concrete codes are being updated to autogenous shrinkage, it is important to determine the accuracy of the models. The models do not take into account early age effects taking into account drying and autogenous shrinkage after one day.