Fresh concrete Limiting the temperature of the fresh concrete is a simple way of Maximum component temperature to be limited. In the case of massive components, a limitation to the following has proven to be effective in practice maximum 25°C proven. This has also found its way into specific sets of rules. A limit below this can also make technical sense. For example, the average annual ambient temperature or, in tunnel construction, the rock temperature is often used as a rule of thumb. Hardened concrete The maximum temperature in the component core of the cast concrete can be determined by calculation and, in addition to factors such as component thickness and cement type, is essentially dependent on the fresh concrete temperature. The maximum permissible concrete temperature indirectly determines the fresh concrete temperature. In order to avoid stress cracks, a maximum temperature difference of 20K between the core and the edge of the component is generally assumed. However, if expansions in the component are completely hindered, temperature differences of approx. 10K already lead to cracks in the concrete.