The water adsorption behavior of several kinds of powder materials

The water adsorption property of materials is a great factor to the mechanical property and durability of civil engineering structure. Therefore, the adsorption behavior of six materials including haydite, mineral powder, coal ash, multi-wall carbon nanotubes, diatomite and bottom ash powder was investigated by dynamic vapor sorption (DVS) apparatus. The sorption isotherm curves and sorption kinetic were analyzed and the conclusion is as follows. The adsorption isotherm curves for all these materials except carbon nanotubes is Type II isotherm curves, whereas the curve for carbon nanotubes is Type I isotherm curve. The change of geometry and existence of metastability may lead to adsorption hysteresis. The order of water adsorption ability of the six materials is: bottom ash powder > diatomite > carbon nanotubes > coal ash > mineral powder > haydite. Water vapor sorption process of carbon nanotubes, diatomite and bottom ash powder can be described by an exponential kinetic model. In addition, the method of dynamic vapor sorption test can provide a reference for other civil engineering materials.