Abstract
A polycarboxylate superplasticizer (PC) of a new generation with multi-functions for multi-purposes has been developed. This PC shows a shrinkage reducing effect as well as a water reducing effect in a wide range of water-to-cement ratio. Superplasticizers have been thought to be adsorbed on solid phases and to show their particle dispersing effects by modifying the inter-particle potentials. On the other hand, shrinkage reducing agents of organic type have been thought to exit the interface between the aqueous phase and the pore phase and show their shrinkage reducing effects by reducing the surface tension. The mechanism of these confronting behaviors of the new PC is discussed through the analysis of the micro-texture of hardened cement and the aqueous phase of it. The surface tensions of the aqueous phase are modified by the addition of different type of admixtures and these changes result in the differences of drying shrinkage.
