Final answer:
The temperature of concrete should be maintained at at least 50°F for optimal curing in cold weather. The calculation of thermal stress is crucial for engineers to prevent damage due to temperature changes.
Step-by-step explanation:
The temperature of concrete should be maintained at least 50°F for 5 days in cold weather to ensure proper strength development and curing. In the context of calculating thermal stress, which involves understanding thermal expansion or contraction of materials, the temperature change can significantly affect concrete. If concrete blocks are placed without any space between them, as they warm from 5°C during construction to 38°C on a hot day, they will try to expand. The inability to expand can create internal stresses. The stress induced depends on the thermal expansion coefficient of the material and the change in temperature.
For the given scenario where the compressive Young's modulus of concrete is Y = 20 × 109 N/m², the stress induced in the concrete blocks due to a temperature increase can be calculated using the formula for thermal stress. This concept is extremely important for engineers and construction professionals who need to consider these effects during the design and building phases to prevent structural damage.