Behaviour assessment of ready-to-use mortar with waterproofing treatment with crystallizing admixtures

Abstract The presence of water in coating rendering mortar is the main cause of the onset and dissemination of pathological problems, compromising durability and the surface protection of walls under harsh weather. On the other hand, waterproofing treatments as crystallising admixtures are designed to create a barrier against water penetration. This research study assessed 36 hours’ and 72 hours’ ready-to-use mortars, with and without the application of crystallising admixtures (liquid and powder), in order to evaluate their behaviour in the presence of humidity in the liquid and vapour states. The mechanical strength and permeability were evaluated in hardened mortars. The conclusion was that the 36 h mortars had the best results. The treatment with crystallising admixtures reduced water absorption and increased mechanical strength. The liquid crystallising admixture proved to be more appropriate, since the powder crystallising admixture decreased vapour permeability, which causes damage to the coating.

摘要 抹灰砂浆中的水分是引发并扩散各类病害的主要诱因，在恶劣气象条件下会损害墙体的耐久性与表面防护性能。而采用结晶型外加剂（crystallising admixtures）的防水处理工艺，旨在构建阻隔水分渗透的防护屏障。本研究针对36小时型与72小时型即开即用砂浆，分别设置施加液态、粉末状结晶型外加剂与不施加外加剂的实验组与对照组，以评估其在液态与气态湿度环境下的性能表现。本次测试以硬化砂浆的力学强度与渗透性能作为核心评估指标。研究结论显示，36小时型砂浆的综合表现最优；施加结晶型外加剂可降低砂浆的吸水率并提升其力学强度。其中液态结晶型外加剂的适配性更佳，因粉末状结晶型外加剂会降低气态透湿性，进而对抹灰涂层造成损伤。