* Norwegian Building Research Institute **AS Ing. Gunnar M. Backe, Norway


In order to reduce the risk of cracking in masonry, it is important to use relatively dry1 units in construction, but drying concrete too early, and so affecting curing, may reduce the final strength. The main purpose of this investigation is to study the effect of different curing conditions on the shrinkage and compressive strength of lightweight aggregate (LWA) concrete masonry units. Masonry units from the same production batch were exposed to five different curing conditions during the first month after production. The different curing conditions did not significantly influence the total drying shrinkage or the compressive strength. To reduce the risk of cracking of masonry made of LWA concrete blocks, it is recommended the blocks should be dried as early as possible after they have left the curing chamber.