Figure 6: Early curing shrinkage for material C. Figure 7: Early curing expansion for material F. N.B. the ordinate scales on these graphs are not the same.

Tests for this property are not standardized but a suitable method under ambient conditions was devised and undertaken on prismatic samples 40mm square×160mm long cast in an identical manner to compression modulus samples. At the age of approximately 17 hours each sample was carefully removed from its mould and on opposite cast faces 140mm long acoustic vibrating wire strain gauges were attached. Samples were then transported to an out-building to cure under polyethylene covers for the first month. The temperature and humidity of air in the out-building varied between 12°C and 22°C, and 50% and 90%, respectively. Results indicated that shrinkage of the materials is not significantly affected by these temperature or humidity variations. The results can therefore be considered to represent the behaviour of the materials at a mean temperature of 16°C and a mean relative humidity of 68%.