THE RELATIONSHIP AMONG CEMENT HYDRATION DEGREE, COMPRESSIVE STRENGTH AND AUTOGENOUS SHRINKAGE OF CONCRETE AT EARLY AGES

Autogenous shrinkage of concrete with different water_cement ratios was measured from 6 hours to 28 days with a new method. This measurement method adopts a type of micro_displacement sensor and the concrete is not to be touched during the test. Development of concrete compressive strength and cement hydration process were also studied under the sealed curing condition. The results show that autogenous shrinkage and early age autogenous shrinkage speed of concrete increase remarkably with the decreasing of water_cement ratio. For every concrete, the relation between autogenous shrinkage and compressive strength or cement hydration degree at early ages can be well figured by a linear equation. The lower the water_cement ratio is, the higher the autogenous shrinkage of concrete, but the lower the cement hydration ratio and chemical shrinkage of concrete is at the same ages. Therefore it is demonstrated that autogenous shrinkage and chemical shrinkage are two different physical quantities.