Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

Concrete has the potential to become a solution for thermal energy storage (TES) integrated in concentrating solar power (CSP) systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20) is tested at high temperatures up to 600 ◦C. Specimens are thermally cycled at temperatures in the range of 400–300 ◦C, 500–300 ◦C, and 600–300 ◦C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 ◦C (room temperature), 500–25 ◦C, and 600–25 ◦C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 ◦C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 ◦C and 300 ◦C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.