Investigations of Concrete Masonry. Uniform Concrete Masonry Testing Procedure.

Fourteen groups of concrete masonry units were tested for drying shrinkage by CRD-C 73. During the drying period, samples were tested for moisture condition by the relative humidity method CRD-C 76. The tests were performed at six Corps of Engineers laboratories. The relation between shrinkage, expressed as length change, percent, and equilibrium relative humidity was studied. No single pattern was apparent. Units at modified British equilibrium which would be expected to be in equilibrium with 21 relative humidity were found by test to be in equilibrium with relative humidities from 0.0 to 33.5. Further study is recommended. Author