Concrete can develop tensile stress when it is restrained from shrinking freely. Standard tests, like the restrained ring test (ASTM C1581-09) can be used to quantify how likely a mixture may be to crack under constant temperature conditions. The standardized restrained ring test is a passive test where the residual stress that develops due to restraint can be quantified using strains measured on the inner steel ring. The residual stress can be compared with the tensile strength to determine how close a mixture may be to cracking. A test method that has been recently developed (i.e. the dual ring testing device) has been used to describe the early age behavior of mixtures that expand or mixtures that undergo a temperature change. This paper describes a testing approach to use the dual ring test to quantify the reserve stress capacity (i.e. the stress that can be applied before the concrete fails) by allowing stress to develop under a constant temperature before reducing the temperature rapidly to induce cracking. To demonstrate this approach, a plain mortar and three internally cured mortar mixtures were tested and their results will be discussed.
Citation: Aci Materials Journal Journal
Pub Type: Journals
Autogenous shrinkage, concrete, early age, internal curing, lightweight aggregate, residual stress, restrained shrinkage ring test, thermal cracking.