With the development of landscape architecture and the advancement of construction technology, new materials and processes such as quartz bricks are constantly being applied in floor and exterior wall decoration. Quartz bricks have superior physical properties such as high strength, high wear resistance, and low water absorption, and are widely used.
However, in some engineering projects, after the completion of quartz brick flooring for a period of time, there may be a phenomenon of alkali return, which seriously affects the visual effect and user experience of the entire garden landscape. So, what is alkali reflux? How was it generated? How should we prevent it? How to treat alkali reflux?
Paving auxiliary materials containing alkaline substances (such as cement, stones, soil, and grout), under long-term exposure to water and humidity, dissolve alkaline substances such as sodium hydroxide and calcium hydroxide in the cement into the water, and are carried along the joints of quartz bricks, driven by capillary action and transpiration of water, to the surface of the surface material, forming a white powdery substance. The alkaline substance that spreads to the surface of quartz bricks will undergo chemical reactions with substances such as carbon dioxide and sulfur dioxide in the air, forming various substances such as calcium carbonate, calcium sulfite, and calcium sulfate, which become white marble, misty or flowing. Baihua has a strong erosive effect.
So what can we do to prevent alkali relapse and maintain quartz bricks? Preventive measures for alkali return before paving:
1. When wet pasting and paving, active admixtures are added to cement mortar to eliminate calcium hydroxide such as fly ash and silica fume through secondary hydration reaction. This method can enhance the strength of cement mortar at a lower cost.
2. Use low alkali cement.
3. Attention should be paid when filling joints. Do not fill joints when the tiles are damp or the base is not completely dry. After the bonding mortar of quartz tiles is solidified, joint filling can be carried out. Generally, it takes more than 24 hours (when the thickness is large and the temperature is low, it should be appropriately extended), otherwise alkali may return.
Cleaning and treatment of alkali return after paving:
1. Use cleaning agents to clean.
Returning alkali and whitening are relatively easy to remove in the early stages, usually using water and cleaning agents to remove them, which can avoid the formation of stubborn stains on quartz bricks after drying. When cleaning, use a cleaning agent to thoroughly wet the contaminated area. For stubborn and heavy dirt, you can first use tools to remove it, and then continue to repeatedly use the cleaning agent to clean until it is completely removed.
2. After the gap returns to alkali, it should be pointed.
Clean the alkali return area thoroughly, scrape off the ash from the tile joints, ensure that the tile joints are in a dry state, and then re grout them using waterproof grout to prevent alkali return.
Returning alkali is a common problem in the application of outdoor paving materials such as stone and quartz bricks. Prevention first, combined with scientific management methods, effectively reduces the impact of alkali relapse.