Effect of shrinkage reducing admixtures on the shrinkage and cracking of concrete

Cracking of concrete surfaces has become an increasing problem, due partly to the development of concretes containing more water than previously (workability demands of pumping concrete and the use of crushed aggregates). This leads to substantial water evaporation, causing shrinkage. Shrinkage problems can also be considered a result of improper curing. In recent years much attention has been paid to researching the shrinkage behaviour of concrete in the plastic and hardening stages. This topic has been studied, for example, by Japanese (Tazawa, E. & Miyazawa) and Scandinavian researchers (Radocea, A., Kronlöf, A., Leivo, M. & Sipari, R). Some years ago at VTT in Finland, a research programme was launched to clarify the basic phenomena of plastic shrinkage. The test series presented here is a continuation of this research programme.