Effect of Cement and Exposed Environment Differences on DEF Expansion: Joint Investigation Using Constituents from Japan and France

Many structures damaged by Delayed ettringite formation (DEF) have been reported in France while Japan has not yet reported structures clearly affected by DEF even if they were exposed to high temperature over 70 ℃. In this paper, the difference of cement characteristic and environment between Japan and France were focused on. Cubic concrete specimens with French and Japanese cements, French aggregate and high temperature curing at early age were exposed at four places in Japan. The expansion strain was continuously measured with observation of expansion cracking. As a result, the effect of exposed environment on DEF expansion rate in Japan was varied according to cement types while the ultimate expansion was likely to be not affected by the environment but by cement type. The laboratory DEF expansion tests using the same concrete mix proportion and heating process as those in field experiment also suggest that the temperature dependency of expansion rate is different in each cement type.