Mitigating autogenous shrinkage of hardening concrete

The probability of early age cracking in hardening concrete can be affected by using additives that reduce the total shrinkage of a mixture with emphasis on the reduction of autogenous shrinkage. In order to become more insight in the effectiveness of shrinkage reducing additives, an experimental programme is currently running at TU Delft. Experiments are performed for water/cement ratios varying from 0.3 to 0.5, for Portland cement as well as Blast Furnace Slag cement. All mixtures are tested isothermally at 20°C. The early-age shrinkage deformations are measured over a testing period of 90 days. The development of compressive strength, tensile splitting strength and elastic modulus will be determined from respectively cubes and prisms that harden under similar conditions. Results obtained from this experimental programme provide the effectiveness of shrinkage reducing additives and their influence on development of the mechanical properties. The autogenous shrinkage, being a single contribution of total shrinkage, will be addressed explicitly.