TEMPERATURE DEPENDENCE OF THE DISPERSING PERFORMANCE OF POLY-BETA-NAPHTHALENE SULFONATE SUPERPLASTICIZER

摘要

Incompatibility of the dispersing performance of superplasticizer is one of the serious problems for control of the workability of concrete. Although polycarboxylate superplasticizer (PC) has become popular in Japan because of its superior fluidity retaining ability, poly-beta-naphthalene sulfonate superplasticizer (BNS) has been the most popular one all over the world. One of the incompatibility problems is the different temperature dependence of the dispersing performance of PC and NS. Because NS is known to show poor performance at low temperature, the mechanism is investigated in this study. A fluidity test of limestone powder paste revealed the inherent superior performance of BNS at lower temperature that is harmonious with the theoretical estimation of electrostatic force. However, the paste of normal Portland cement with BNS showed reverse tendency. This behavior is thought to be attributed in the different adsorption characteristic of BNS on cement particles affected by the difference of cement hydration under different temperature conditions.