Short- and long-term strain and strength properties of LWA concrete

Four LWA concrete types have been tested at short- and long-term loading in two recently performed investigations at SINTEF. In the short-term tests, the coarse aggregates were probably the reason to failure for the three relatively high strength concrete types, while the mortar certainly was the reason for the forth relatively low strength type. However, in the long-term tests, the failure was probably not caused by the coarse aggregates for any of the concrete types. The failure in the long-term tests is supposed to be caused by the development of cracks from local stress concentrations, which are increasing with time and finally makes the whole specimen unstable. From an overall evaluation, the long-term strength of these concretes was supposed to be 70-75 percent of the short-term strength. This is 5-10 percent lower than expected for concrete with natural aggregates.