网格布-聚脲涂层耦合作用力学破坏机理研究OA北大核心CSTPCD

Polyurea is an excellent caulk-sealing and surface anti-seepage material.Composite coating composed of polyurea and mesh fabric can be found in some projects.However,this combination is only a simple imitation of the traditional polyurethane-mesh-fabric composite coating structure.Research on the coupling behavior and failure mechanism of this composite coating can rarely be found.Problems such as peeling,hydrolysis,and poor durability occurred.This study investigated the coupling effect between the mesh fabric and polyurea substrate,and explored the mechanical behavior and failure pattern of mesh fabric reinforced polyurea coating.The deformation behavior and load-carrying capacity of different material combinations were also analyzed.The main conclusions are as follows:Fabric fiber fracture leads to instantaneous stress pulse in the polyurea substrate,fiber fracture sur-face and stress-pulse-induced microcracks lead to the overall cross-section pull-off failure.The polyurea material exhibits a higher strength.Mesh fabric induced defects leads to an elongation decrease of more than 75％.The mesh fabric could undermine the strength and deformation capacity of the polyurea substrate,playing a negative role on the material performance.The polyurethane material generally exhibits a lower strength.The mesh fabric could increase the tensile strength by 14％.The mesh fabric could increase the strength of the polyurethane coating substrate,bringing a certain strengthening effect.However,the break elongation could also be decreased.As the elongation and strength of the mesh fabric dominates that of the composite coating,in practical engineering applica-tions,the mesh fabric should not be adopted when meeting the following conditions:(a)the coating elongation re-quirements are higher than that of the mesh fabric;(b)the substrate material strength is greater than the mesh fab-ric;(c)the substrate material strength is greater than the coating-substrate tangential bonding strength(e.g.3.2 MPa for concrete substrate).At present,the physical and mechanical properties in the existing polyurea related standards and specifications are proposed without adopting mesh fabric.The material properties proposed in the related standards and specifications can also meet the corresponding conditions for not using mesh fabric pro-posed in this study.Thus,mesh fabric should not be used with polyurea.