Humidity control materials prepared from diatomite and volcanic ash

The preparation of humidity control materials has been studied by sintering a mixture of diatomite and volcanic ash with and without the addition of sodium perborate. The final products were analyzed to identify moisture adsorption–desorption performances, porous and mechanical properties. In addition, effects of sintering temperature and various mixed portions on the final products were also investigated. The sintered products have mesoporous structure with the pore diameter tends to be in the range of 2–50 nm, and the porous properties reach from 14.1 ± 1 to 65 ± 3 m2/g in BET surface area and from 65.23 ± 3 to 70.84 ± 5% in porosity. In addition, moisture adsorption–desorption ability of the humidity control materials increases as diatomite content increases. The results indicate that the adsorbed moisture amount of the best products manufactured from the mixture of 90% diatomite, 8% volcanic ash and 2% sodium perborateat sintering temperature of 1000° C and 1100° C reach 65 ± 4 and 55 ± 2 g/m2, respectively. The best products show excellent performance as a humidity control building material with fine mechanical properties and can be used for various construction applications at low cost.