The main purpose of this study is to provide fundamental data in reducing thermal cracks of mass concrete by using Urea. Substitution methods of Urea mixed concrete was different from existing substitution method of concrete. Therefore existing research for Urea mixed concrete had no definite criterion in performance evaluation. In this research, setting-up new criteria, Urea/Water ratio, when evaluating experiment results. As result of experiment, Cement Paste flow was increased largely when mixed in addition method. But there were almost no differences in degree of temperature reduction and time-delay.

The possibility to determine the setting time of cement paste using the electrical impedance response of early-age hydrating cement paste is investigated. Electrical impedance responses of cement paste are continuously measured immediately after mixing and during hydration process. Measured responses are then analyzed and compared with temperature responses of hydrating cement paste.

This study investigates the effect of emulsified refined cooking oil (ERCO) on the fundamental properties of cement paste, and their results are compared with that of shrinkage reducing admixture (SR). Results showed that ERCO decreased early strength, but retained the strength at the later age of 28 days, slightly higher than pure OPC