Precooling Massive Concrete Mixes Using Cooled Aggregates or Chilled Water

Abstract

The exothermic hydration of cement generates heat, which increases the temperature in the core of the concrete members. This causes a temperature gradient, leading to thermal stresses, and sometimes cracks due to the expansion of the core and contraction of the surface, which reduces massive concrete durability. The goal of this study is to assess the impact of concrete precooling technologies on the quality of massive concrete constructions, such as dams constructed in desert climate. The impact on the strength of concrete and its hydration time under various operating circumstances have been investigated. In massive concrete structures, cooling can be accomplished by reducing the temperature of aggregates using ventilated cold air from an air conditioning system or by using chilled water. In order to determine the initial and the final settings of concrete, the Vicat test has been used. The use of chilled water in the preparation of mortar can increase the cement solidification time. According to experimental laboratory tests, concrete cubes prepared with chilled water have higher compressive strength than those prepared with cooled aggregates. The compressive strength of the concrete mixed with chilled water has increased by 35%, while a 10% increase in compressive strength in the concrete mix has been reached by using precooled aggregates. Results of compressive strength tests on mortar cubes prepared with chilled water have showed a 29% increase after 28 days of curing.