混凝土梁耐久性防护涂层基本性能试验

Basic Performance Test of Durable Protective Coatings for Concrete Beams

为研究桥梁混凝土梁耐久性的涂层防护效果,通过室内土工试验,筛选出改性聚氨酯涂层PS1、PS3和改性环氧树脂涂层E3这3种成膜型涂层,针对上述涂层开展了一系列混凝土耐久性的防护涂层基本性能试验。测试分析了涂层的附着力、裂缝追随、耐酸、耐碱、耐盐雾、耐候性等效果。结果表明,E3、PS3涂层的附着力分别为4.71 MPa、3.62 MPa,均符合成膜型涂层的附着力要求,E3涂层与混凝土基材的粘结强度高于PS3涂层粘结强度;PS3在张拉过程中表现出粘结成膜的现象,且部分涂层会粘附在裂缝内部,因而能更好的跟随裂缝扩展,进而起到一定的封闭裂缝的效果;PS1、PS3和E3均表现出较好的耐碱性及耐盐雾性能;PS1、E3耐酸性优于PS3、PS1及E3在试验前后表面均无起泡,而PS3表面出现少量直径在0.5 mm之内的气泡;PS1、PS3老化1000 h后涂层基本稳定,E3耐候性最差,在老化试验进行500 h就已完全失光,失光率高达82%。上述3种涂层对混凝土有一定的防护效果,可以提高混凝土的耐久性,延长混凝土结构的使用寿命。

To study the protective effect of coatings on the durability of bridge concrete beams,three types of film-forming coatings,namely modified polyurethane coatings(e.g.,PS1 and PS3)and modified epoxy resin coatings(e.g.,E3),were selected through indoor geotechnical tests.A series of basic performance tests of protective coatings for concrete durability were conducted on these coatings.The adhesion,crack tracking,acid and alkali resistance,salt spray resistance and weather resistance of the coating were tested and analyzed.The results showed that the adhesion of E3 and PS3 coatings were 4.71 MPa and 3.62 MPa respectively,which met the adhesion requirements of synthetic film coatings.The bonding strength between E3 coating and concrete substrate was higher than that of PS3 coating;PS3 exhibited a phenomenon of adhesive film formation during the tensioning process,and some of the coatings adhered to the interior of the cracks,thus facilitat⁃ed itself to follow the crack propagation and achieving a certain effect of sealing the cracks;PS1,PS3 and E3 exhibited good alkali resistance and salt spray resistance;PS1 and E3 had better acid resistance than PS3.There were no bubbles on the surface of PS1 and E3 before and after the experiment,while a small amount of bubbles with a diameter of less than 0.5mm appeared on the surface of PS3;After aging test for 1,000 hours,the coating of PS1 and PS3 were basically sta⁃ble while E3 had the worst weather resistance,specifically after 500 hours of aging test,it had completely lost light with a loss rate up to 82%.The above three coatings had a certain protective effect on concrete,which could improve the durability of concrete and extend the service life of concrete structures.