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各类病害问题并使其扩散的主要诱因，在恶劣天气环境下会损害墙体的耐久性与表面防护性能。另一方面，采用结晶型外加剂（crystallising admixtures）作为防水处理手段，旨在构建阻挡水分渗透的屏障。本研究针对添加与未添加结晶型外加剂（分为液态与粉体两种形态）的36小时型及72小时型即用砂浆开展测试，以评估其在液态和气态湿度环境下的性能表现。研究对硬化砂浆的力学强度与渗透性能进行了评估。研究结论显示，36小时型砂浆的综合表现最优。添加结晶型外加剂可降低砂浆吸水率，同时提升其力学强度。其中液态结晶型外加剂被证实更为适配，因为粉体结晶型外加剂会降低气态渗透性能，进而对涂层造成损害。