外墙涂料透水性试验影响因素的讨论

Discussion on the Factors Influencing the Water Permeability of Exterior Wall Coatings

对于GB/T 9755—2014《合成树脂乳液外墙涂料》中附录B规定的一种测量合成树脂乳液外墙涂料透水性的试验方法,结合实际实验情况,提出了一些可能影响结果的实验细节,并对其进行实验设计与验证,探讨了不透水漏斗不同的密封方式(包括上端口)、密封材料、试样放置平台以及实验用底材—无石棉纤维水泥平板的含水率对实验结果的影响。结果表明,不同密封材料对实验结果影响不大;不透水漏斗的不同封胶方式对实验结果影响较大,可能由于透水面积影响受到直接影响;不透水漏斗上端口的过度密封使透水性结果变小,且使漏斗内部产生较多气泡;将试样放置在平坦平台上时,实验结果可能比放置在镂空托盘或架子上的小;完全湿润的无石棉纤维水泥平板放置在标准试样环境下时,其含水率在前4 h变化较大,之后24~96 h,含水率变化较小;在标准环境下养护24 h后,延长底材的放置时间对实验结果影响较小,但仍旧可以看出透水性随含水率降低而增大的趋势。

Appendix B in GB/T 9755—2014 Synthetic Resin Emulsion Coatings for Exterior Wall provides an experimental method of measuring the water permeability of exterior wall synthetic resin emulsion coatings.In this paper,some experiment details which might influence the result are proposed according to the actual experiment,experiment design and verification are conducted for them and the influence of the impervious hopper(including the upper port)sealing method,sealing material,sample placement platform and water content of the substrate–asbestos-free cement panel on the experiment result is discussed.The results show:different sealing materials have little influence on the experiment result;different impervious hopper sealing methods have great influence on the result,probably because of the direct influence of the permeated area;if the upper port of the impervious hooper is sealed too tightly,the water permeability result is lower and a lot of bubbles appear in the hopper;the samples put on a flat table probably give lower results than those on a hollow tray or shelf;if water-saturated asbestos-free cement panels are put in the standard testing environment,their water content decreases dramatically in the first 4 h and slightly goes lower in next 24~96 h;after maintenance in the standard environment for 24 h,extension of the substrate placement time has little influence on the experiment result,but the trend of water permeability increasing as the water content decreases can still be noted.