Intelligent closed-loop control of concrete moisture levels

The concrete moisture content must be maintained after curing. The cement particles in concrete cannot fully hydrate and transform to a stable crystalline form if the concrete is not well hydrated. In addition, moisture loss may result in shrinkage, deformation and cracks, which will affect the structure durability. Concrete specifications and experience have shown that the concrete surface humidity should be no less than 95% during curing. Humidity diffusion theory was used to develop a mathematical model for the concrete moisture conservation with the third type of boundary condition at the surface. Information technology and mechanical control theory were then used to develop an intelligent control method for the concrete moisture conservation. An intelligent control system was then developed to automatically collect the temperature, humidity and wind speed near the concrete surface and to then calculate the concrete surface humidity. The intelligent control system provides real-time feedback warnings and intelligently controls a spray tube which reduces labor costs and ensures the concrete quality. The intelligent control equipment can be flexibly adapted to various large, complex engineering projects. © 2021, Tsinghua University Press. All right reserved.