What is the general rebound strength of c35 and c40 concrete at 7 days, 14 days and 28 days?

As for the early strength of C35 and C40 concrete, it usually reaches more than 70% in 7 days, which is the initial strength performance of concrete just after pouring. By 28 days, its strength will increase significantly, generally reaching more than 100%. Standards for high-quality projects usually require that the 28-day strength of concrete must be at least 115%, which means that the overall performance of the concrete is excellent. If the number of concrete groups in a project is less than 10, the strength of each group should exceed 115% to ensure the quality of the project.

The rebound strength test is carried out on the concrete surface through a rebound rod (dowel rod), measuring the distance of the rebound of the weight, and using the rebound value as an indicator to evaluate the hardness and strength of the concrete. This method is based on the correlation that exists between the surface hardness and strength of concrete. In the project, when the rebound value of the concrete standard sample reaches more than 70%, the formwork is allowed to be removed to ensure structural stability.

The rebound method is a commonly used method to test the compressive strength of ordinary concrete. It uses a rebound meter to hammer the concrete surface and reads the rebound value to infer the hardness of the concrete and then estimate its hardness. Compressive strength. This method is simple and intuitive and suitable for on-site construction quality control.