POSSIBILITIES TO CONTROL CONCRETE SHRINKAGE BY MEANS OF CHEMICAL ADMIXTURES

The main object of the present paper is to describe the possibilities to control shrinkage of concrete by means of chemical admixtures. In a n introductory part, also a general overview on the state of knowledge in the field of concrete shrinkage is given. The actual experience in dicates that the control of concrete shrinkage with the traditional pl asticisers and superplasticisers is quite limited, despite the water r eduction obtained at same concrete consistency. A decrease in concrete shrinkage in the order of 30% is, however, possible by the addition o f special shrinkage-reducing admixtures. The use of sulfoaluminate-bas ed expansive admixture allows in principle to compensate completely th e shrinkage of concrete. An effective means to improve the shrinkage c ompensating effect is the combination of the expansive admixture with a shrinkage-reducing admixture.