The effect of pre-curing at 50° C on autoclave expansion of high magnesia cements

The effect of pre-curing at 50°C for various periods of time on the expansion of specimens subsequently subjected to the ASTM autoclave test has been examined. High magnesia cements with and without the addition of fly ash were studied. The effect of pre-curing on autoclave expansion dependend principally on the lime/silica ratio of the cement but also varied with other factors such as whether the periclase present originated in the clinker or was deliberately added. It is concluded that changes in the curing schedule of the ASTM autoclave test of the type investigated here would not improved the reliability of the test. The work has however provided useful new insights into the mechanism of the stabilisation process.