A linear test method for determining early-age shrinkage of concrete

For certain applications, the early-age dimensional stability of concrete can significantly affect aesthetics and long-term durability performance. The combined effects of plastic settlement, plastic shrinkage and autogenous shrinkage in fresh and hardening concrete will depend on mix proportions, constituent materials and environmental conditions as well as levels of crack inducing restraint. A new linear test method has been developed for measuring early-age shrinkage in concrete to allow investigation of the effects of new constituents on early volume stability. Single operator repeatability under laboratory conditions was investigated and the sensitivity of the test to varying temperature (20 degrees C +/- 2 degrees C and 40 degrees C +/- 2 degrees C), relative humidity (10% +/- 2%, 50% +/- 5%, 95% +/- 5%) and wind velocity (7.5 km/h) was also determined. The test method was deemed suitable for use as a tool to measure the influence of new types of cements and aggregates on the early-age volume stability of concrete.