Study On The Preparation And Properties Of Desulphurization Gypsum Light-weight Insulation Materials

Nowadays, the dramatically increasing annual production of the desulphurization gypsum causes some problems such as low efficiency and the mass stack, which easily leads to pollution and land-wastage. Meanwhile, with the shortage of energy sources and the increase of the housing area, our country has improved the standard for energy efficiency of construction, which results in the increasing demand for new wall insulation materials. What's more, most of the current organic insulation materials have a poor effect of heat insulation and are inflammable, which makes them unable to meet the building fire-resistance requirements. And to inorganic heat preservation materials, there are such problems as high density, low strength and poor heat insulation effect. To solve these problems mentioned above, in this paper, the desulfurization gypsum, cement and fly ash were chosen as the gelled material while polystyrene particles were chosen as light aggregate; the ultra-high molecular weight polyethylene fiber and the redisperse latex powders were added as the reinforced material to prepare the excellent gypsum light-weight insulation materials with the method of chemical foaming. The main research contents and results are as follows:Since the setting time of pure desulfurization gypsum was short which limited the operation time, the effects of the content of retarder on setting time and mechanical strength of samples were studied through experiment, which shows that the best content of retarder was 0.1%. The mechanical properties and waterproof properties of pure desulfurization gypsum were poor; desulfurization gypsum could be partly replaced by silica raw materials, such as cement and fly ash, to make the ternary gel composite, which could improve the mechanical strength and water resistance; it shows that the ideal contents of cement and fly ash were both 16%. The fly ash has low hydration activity, so chemical activator were used to promote the hydration activity. It shows the best ratio of complex activator were 3% CaO, 2% CaCl2 and 2% Na2SO4; the 7d and 28 d flexural and compressive strength of samples which under the ratio were, in order, 5.96 MPa, 22.26 MPa and 6.35 MPa, 6.35 MPa.The effects of preparation method of gypsum light-weight insulation materials, content of foaming agent and foam stabilizer, and mass ratio of ternary gel composite and polystyrene grain on the performance of samples were studied. It shows the ideal preparation method was preparing foamed slurry firstly and then mixing the polystyrene particles with foamed slurry. The basic ratio of samples was determined after single factor tests, which shows that the best content of foaming agent and foam stabilizer were both 4% and the ideal mass ratio of ternary gel composite and polystyrene grain was 17.24; the density, thermal conductivity, flexural and compressive strength of samples under the ratio were, in order, 239kg/m3, 0.057 W?(m?K)-1, 0.13 MPa and 0.21 MPa.The mechanical properties of gypsum light-weight insulation materials were poor, so some measurements, such as adding ultra-high molecular weight polyethylene fiber and the redisperse latex powder, as making shell for polystyrene particles and so on, were taken to improve the mechanical strength of the samples for tests. It shows the optimal content of ultra-high molecular weight polyethylene fiber was 0.6%. Strong oxidant was used to modify the surface of fiber to improve the mechanical strength of samples further. The effects of the content of redisperse latex powder on the mechanical properties and waterproof properties of samples were studied, which shows that the optimal content of redisperse latex powder was 3%. Binder and cement were used to make shell for polystyrene particles to enhance the unified Interface between polystyrene particles and ternary gel composite; the results of the relative tests shows the proper admixture quantity of cement was double quality of polystyrene particle. The effect of the combination of three enhancement methods was studied through orthogonal experiment, which shows that the ideal composition was A2B1C1, that is the optimal content of fibers was 0.6%, the optimal content of emulsion powder was 2.5% and the proper admixture quantity of cement was 1.5 times as much as that of polystyrene particles.In the study of exploring the water-resistance ability of gypsum light-weight insulation materials, the optimal content of complex water-proofing agent was determined to be 4%, but water-resistance ability of these samples could not meet the requirement of standard. On the basic of mixing water-proofing agent, methyl sodium silicate solution was sprayed on the surface of samples to improve the water-resistance ability further. It shows the best volume ratio of methyl sodium silicate solution and water was 1:8; the 2h, 24 h specific absorption of volume and softening coefficient of samples were 8.27%, 9.94% and 0.60 respectively.