Effectiveness and durability evaluation of rendering mortars made with metallic soaps and powdered silicone

Metallic soaps and powdered silicones are used to control water absorption in rendering mortars. This paper looks at the effectiveness of several types of waterproofing after 7, 14 and 28 days of curing. The efficiency is analyzed by capillary water absorption experiments, while durability is evaluated after exposing the samples to different environments, including water and hydrochloric acid solutions. Finally, to simulate the effect of acid rain a combination of sulphuric–nitric acid was used. After ten cycles of exposure it was confirmed that powdered silicone showed the best resistance to acid attack. Additionally, the sulphuric–nitric solutions attacked the external layers of the samples by forming gypsum. The effects on the samples were followed and quantified throughout the cycles.