Principles underlying the steam curing of concrete at atmospheric pressure

Abstract

Summary: This paper summarizes the conclulions drawn from experimental work carried out at the Cement and Concrete Association Research Station and elsewhere concerning the principles underlying steam curing at atmospheric pressure. It is shown that if the temperature gradient of the concrete after the time of mixing does not exceed a certain value, the concrete gains strength during and after treatment in relation to its “maturity” (reckoned in temperature-time) approximately in accordance with the same law as holds for normally cured concrete. Concrete which is raised in temperature more rapidly is shown not to obey this law, and to be adversely affected in strength at a later age. The use of the too rapid early temperature rises often employed in practice introduces various opposing variables which suggest optimum temperatures, delayed treatments and other arrangements of the curing cycle; such expediencies are unnecessary, however, if a slow initial temperature gradient is used. The paper contains tables of results supporting these conclusions, and an appendix in which a possible cause of the phenomena is suggested.