Research On The Performance And Evaluation Methodology Of Hygroscopic Materials

The humidity environment condition is the important influence factor of indoor air comfort degree, studies show that body will feel most comfortable between 40-60% relative humidity. Using the sell-adsorption ability of porous materials improve the indoor humidity environment is the newest passive moisture control idea. The adsorption ability of porous materials is closely related to the interior microcosmic performance. This paper observed the microstructure and tested the pore size distribution of wood fibre, sepiolite, glass bead, expanded perlite and 5A zeolite molecular sieve as thermal insulation aggregate, used nitrogen adsorption and moisture adsorption methods, we can known that the initial micropore adsorption ability is direct proportion to the specific surface area of materials, the adsorption ability of the same type is relative to the mesoporous diameter distribution and the pore volume distribution.From the analysis of pore structure to these thermal insulation aggregates, this paper proposed "V" pore pattern to simplify the interior micropore and mesoporous of materials, to supplement the neglect of micropore adsorption in Kelvin capillary condensation theory. Assume that the micropore volume with mesoporous volume present linear distribution and form the adsorptive angle θ within the some effective adsorption pore diameter, and the size of angle influence on the quantity and length of micropore, we can own the revised effective adsorption pore diameter. Adding the adsorptive angle of the effective pore diameter increases the interior theory adsorptive volume of materials.Optimizing the combination and matching of these thermal insulation aggregates, we can get one kind of green passive moisture control plaster mortar, WSE (Wood fibre、 Sepiolite、 Expanded perlite)-based mortar (B type mortar) for short. This paper tested the microcosmic performance, adsorption ability, thermal performance and the mechanical property of B type mortar. The experimental results show that the interior pore diameter distribution of B type mortar is reasonable and the adsorption ability is bigger than A type mortar. The heat conductivity coefficient of B type mortar is less than 1.2 W/(m·K), so that mortars have the heat preservation ability, and the results of the tested mechanical property satisfied the demand of mortar for coating to work on the indoor wall.In the three B type mortar, B-1 is the based mortar, the mixing of B-2 and B-3 is polypropylene fiber and 5A zeolite molecular sieve. The mechanical strength of B-2 is bigger than B-1 for the adding of polypropylene fiber (the compressive strength increased 6%, tensile bonding strength increased 70%), and the interior specific surface area reduced. The adsorption ability of B-3 is improved for the addition of 5A zeolite molecular sieve. So the B type mortar can be extended to the WSE-based passive moisture control mortar. The performance of mortar is changed with the adding mixture to the B-1-based mortar as needed, but the adsorption ability just around the adsorption ability of B-1 localized change.The hygroscopic materials moderate the changed indoor temperature and humidity from the self-sensitiveness and strain capacity, such as the response of hygroscopic material to the cohension of water vapour on the object surface, which was commonly known as "damp condensation phenomenon". This paper proposed Ultimate Moisture Buffering Value (UMB V), put two types of ultimate temperature and relative humidity states in the test of moisture buffering value. The test method of UMBV can better reflect the true coping capacity of materials to the indoor overtop and too low relative humidity than the test method of moisture buffering value. The assessment of hygroscopic materials examine the situation of mold growth, is the truthful response of hygroscopic materials to the indoor climate.