Improving early compressive strength of precast concrete by increasing active silicon content

In order to make the precast concrete reach the design strength quickly, by increasing the active silicon content of the precast concrete, the influence mechanism of the active silicon on the early compressive strength of the precast concrete was studied. The early hydration process, early pore structure, and chemical composition of precast concrete mixed with different types and dosages of water-soluble active silicon materials (WASM) were characterized through heat of hydration test, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The increase of active silicon content in precast concrete can greatly improve the early compressive strength of precast concrete (PC) under steam curing conditions. The increase of active silicon content in PC can greatly improve the early hydration process of cement and accelerate the rate of early cement hydration heat release. The addition of active silicon in the early stage of cement hydration can promote the rapid conversion of Ca(OH)(2) generated in the gelling system to high-strength CSH gel. A large amount of high-strength CSH gel is formed in the early stage of cement hydration, which can promote the formation of a dense internal structure of PC as soon as possible, thereby promoting the rapid improvement of the early compressive strength of PC.