Low heat concrete with ground granulated blast furnace slag

The subject of the research is a concrete with partial replacement of cement with an increased amount of ground granulated blast furnace slag to reduce heat release of concrete for the structures of the Akkuyu Nuclear Power Plant (Iskenderun, Turkey). The concrete was tested for heat release, compressive strength and shrinkage. Several mixes with partial replacement of cement by the slag from «Iskenderun Demir ve Çelik A.Ş.» were used for testing. The heat release is reduced by up to 50 % and the loss of strength is not more than 36 %. This is the result of an increase in the slag content in the mixed binder (cement + slag) and a decrease in the cement content. The optimal slag content in the mixed binder is 25 %. There is an increase in concrete strength by 3-4 % and a decrease in heat release by 13 % compared to the cement binder. All tested concrete mixtures with the cement replacement by the slag have a decrease of the heat release, which is greater than a decrease in the concrete strength. The cement replacement by the slag leads to an increase in autogenous shrinkage. If the binder contains 50 % of the slag, the highest value of the autogenic shrinkage is observed. This value is approximately twice greater than the shrinkage of concrete with the cement binder. If the binder contains 75 % of the slag, the shrinkage is less. The replacement of the cement content by the slag is recommended to reduce the heat release of concrete, in order to increase its thermal crack resistance.