An intelligent humidity regulation material hydrothermally synthesized from ceramic waste

Huge amounts of ceramic waste are being produced during manufacturing ceramic products in China and even all around the world, which are very difficult to recycle due to its stability by high temperature sintering. With simulating the diagenesis of accumulative rocks underground and cycling their elements of Si, Al and Ca, the ceramic waste has been hydrothermally synthesized into calcium aluminum silicate hydrate (C-A-S-H) gel and further into Al-tobermorite, which are the most important strength-producing constituents of cement/concrete. The formations of C-A-S-H gel and Al-tobermorite are beneficial to both enhance strength and promote porosity of the specimens, favorable to produce a tough porous building material (flexural strength≥20 MPa) for regulating humidity indoors. Introduction of diatomite into ceramic waste samples effectively improved the humidity self-regulating performance (from 50 to 150 g/m2). The increment in moisture self-adsorption/desorption is attributed to the improvement of porosity offered by the both residual diatomite and formed tobermorite in the matrix. Moreover, calcium chloride was also introduced to further promote the humidity regulation performance, and the moisture self-adsorption could increase sixfold (~300 g/m2) than that without calcium chloride addition (~50 g/m2). Different from the diatomite addition, the calcium chloride addition could make more moisture adsorbed by mesopores and provide pores with higher moisture adsorption/desorption ability. •A novel intelligent humidity regulation material was synthesized from ceramic waste.•The Al-tobermorite formation could enhance strength and porosity of the specimens.•Diatomite could improve the moisture adsorption due to its excellent porosity.•CaCl2 could promote more moisture adsorbed by more mesopores.