The autogenous deformation of the hydrating cement pastes was monitored using a custom-built dilatometer immersed in a constant temperature (± 0.1 ºC) oil bath [15,16]. The cement paste was cast into corrugated polyethylene tubes (length of approximately 300 mm and an inner diameter of about 22 mm) that were sealed and placed in the dilatometer. There, linear displacement transducers were used to record the subsequent shrinkage/expansion of the tube during hydration of the enclosed cement paste. Typically, autogenous deformation was measured simultaneously on two nominally identical specimens and the average result was reported. The results reported in all plots are always relative to a deformation of zero at the time of set for the cement paste being evaluated. The setting time can be accurately determined by the abrupt change in slope in the original deformation vs. time curves, as the cement paste begins to offer a finite resistance to the autogenous deformation. After setting was achieved, the maximum standard deviation in relative deformation between readings made on companion specimens was 48.13 microstrains, with average standard deviations being in the range of 6.4 microstrains to 30 microstrains. The dilatometer has been used successfully in the past to study the large influence of silica fume on the autogeneous deformation of hydrating cement paste .