水工混凝土涂聚氨酯涂层的抗冻性能研究

Study on Frost Resistance of Hydraulic Concrete Coated with Polyurethane

文章利用冻融循环试验、涂层耐低温性能试验和水汽渗透性试验,探讨了水工混凝土涂沥青改性聚氨酯涂层、聚氨酯涂层的抗冻性能。结果表明:聚氨酯涂层的防水性优于沥青改性聚氨酯涂层,其低温柔韧性也更好,对混凝土抗冻性和长效性改善效果更好;冻融循环达到1000次后混凝土相对动弹模量均≥98%,但沥青改性聚氨酯涂层已失去防护作用发生冻融破坏,而聚氨酯涂层仍然完好未产生冻融破坏;单一的利用动弹模量很难反映涂层改善混凝土抗冻性的效果,应结合受冻融循环作用后涂层下表面是否剥落或粉化、混凝土与涂层间的黏结情况以及涂层自身状态等综合评定。

In this paper,the freeze-thaw cycle test,low temperature resistance test and water vapor permeability test were used to study the antifreezing performance of polyurethane coating modified by asphalt on hydraulic concrete.The results show that polyurethane coating has better water resistance than asphalt modified polyurethane coating,and its low temperature flexibility is also better,and the improvement effect on frost resistance and longterm performance of concrete is better.The relative dynamic modulus of concrete is not less than 98%after 1000 freeze-thaw cycles,but the asphalt modified polyurethane coating has lost its protective effect and freeze-thaw damage occurs,while the polyurethane coating is still intact and does not produce freeze-thaw damage.The single use of dynamic modulus can hardly reflect the effect of coating on improving the frost resistance of concrete.It should be comprehensively evaluated by considering whether the lower surface of the coating is peeled or chalky after the freeze-thaw cycle,the bond between the concrete and the coating,and the state of the coating itself.