Crack-Arresting Effect Of Polymer Cement Base Coat

The key material Polystyrene board external thermal insulation system is the adhesiveand the surface mortar. Therefore, it is important for the wall energy conservation and thematerial for energy conservation to improve the crack-arresting property and to control theproducing of crack. And at the same time, it can provide the gist in theory for the select ofchemical additive.The crack-arresting and shrinkage property of cement-based composites in which fibrealcohols and polymer emulsion was added were studied. It was found that these chemicaladditives were favorable for the improvement of the cracking-arresting and shrinkageproperty. But the degree of the improvement is related to the kind and amount of theadditive. The more additive is added, the better is the cracking-arresting property. In theseadditives, the wood fibre of 1mm long polyvinyl alcohol and PAE emulsion is the best.On the basis of the former experiment of crack-arresting, we choose PAE and differentproportion of cement and sand and different granularity of sand and other three additive.Of course, water absorption and bond strength is considered, the orthogonal experiment isdone. The best directions of cement-based coat is found: p/c 0.09; c/s: 2.0; granularity ofsand: 0.154~0.180; the amount of polyvinyl alcohol:0.06%; wood fibre of 1mm:0.5%;water-keeping agent:0.15%.On the aspect of mechanics, during the evaporation of water, an uneven force isproduced because of the shrinkage, so the crack on the surface of cement-based coat isformed. Therefore, in order to analyze the mechanism, the shrinkage property of cement-based coat is researched.At the same time, the mechanism on the aspect of mocrocosmic is studied by theresearch of setting time and of the microstructure. It is found that fibre alcohols andpolymer emulsion can prolong the setting time. So the structure is compact, the cracking-arresting property is improved.