Investigation of Crack Control of Underground Concrete Structure with Expansive Additives

Abstract

Cracking of concrete structures during hydration often occurs during construction. This study investigated the expansive property of concrete with an unstrained expansive agent to reduce cracking. Laboratory tests, field measurement, and numerical simulations on deformation during hydration were investigated. The test results of the unstrained specimen indicated that the expansive ratio reached a peak in the first 14 h for the water–binder (w/b) ratios of 0.43 and 0.6. However, when w/b=0.3, the expansion ratio needed a long time to reach the peak (30 h). The expansion ratio remained unchanged after the peak. The amount of the expansive agent and the water–binder ratio show a significant correlation with the expansive capacity. The relative favorable content of the expansive agent and w/b ratio of concrete with the expansive agent were 10% and 0.43, respectively. A concrete floor with the expansive agent showed an overall compressed state, which indicates that concrete shrinkage was fully compensated by the addition of the expansive agent.