How to treat alkali return on walls/shop refurbishment

The peeling and alkali return of walls have troubled many families. Especially for newly renovated houses, looking at the beautiful wall paint peeling off in large areas, looking at the fashionable wallpaper bulging in large areas, and even moldy. Who should I contact to repair this problem? Some people look for those who apply latex paint, while others look for those who do waterproofing engineering, but it seems that these two professions are not very professional about this issue..... Isn't this making things difficult for people!

1、 Firstly, let's analyze the internal reasons for the alkali return of the wall

1. The cement mortar coating on the wall used unqualified cement. In order to save costs, the engineering party used cement produced by a small factory. However, the alkali content in the cement was not strictly controlled, resulting in the precipitation of ionized calcium and the phenomenon of alkali return when the cement encountered moisture in the air.

2. When painting the wall in winter, antifreeze with a high alkali content is added to the cement mortar, resulting in an increase in the total alkali content of the mortar layer. When the wall encounters water vapor, it leads to the precipitation of hydroxides.

3. The wall has been exposed to moisture for a long time, leading to the decomposition of unstable calcium silicate and the precipitation of components such as ionized calcium and ionized aluminum, resulting in the growth of white needle like substances.

2、 External factors of wall alkali return

1. The return of alkali at the entrance of the bathroom and below 50 centimeters is usually due to the lack of water blocking treatment on the door stone during waterproofing construction. When a large amount of water is used in the bathroom, the water in the bathroom will seep out from the lower part of the door stone, causing the wall at the entrance to be soaked by water vapor for a long time, and then the calcium hydroxide in the wall will precipitate.

2. The water blocking ability of the exterior wall is poor. During continuous rainy weather, rainwater infiltrates the wall, causing the wall to be soaked by rainwater and the release of hydrogen and oxygen substances in the mortar layer.

3. When the humidity in indoor air remains above 70% for a long time, the wall will absorb moisture, leading to the precipitation of unstable calcium hydroxide ions in calcium silicate.

3、 The treatment of wall alkali return is a comprehensive problem, and the first step is to observe why it returns alkali, so as to prescribe the right medicine.

1. Because the painting layer uses unqualified cement or contains additives with high alkali content.

In this situation, it is necessary to determine whether the cement of the wall is loose. If the wall is no longer strong, the mortar layer of the wall must be removed until it reaches the brick wall. Then, clean the brick wall with 10% -15% concentration oxalic acid, wait for it to dry, and use qualified repair mortar to repair the wall. The decorative layer can only be applied after 7 days of repair.

2. There is a phenomenon of alkali reflux at the entrance of the bathroom, which can basically determine whether the water vapor is seeping out from the door stone. This situation is usually caused by improper handling of the door stone during waterproofing construction. So first, we need to repair the entrance stone area to prevent moisture from seeping out from below. Then check if the area where the alkali returns is loose. If it is loose, the wall needs to be removed, cleaned with oxalic acid, and finally repaired with repair mortar. If it is not loose, use commercially available wall alkali Kexing for scraping treatment.

3. Due to water seepage from the exterior wall, the wall has returned to alkali. Therefore, it is necessary to carry out waterproofing treatment on the exterior wall and then follow the treatment method for alkali return at the bathroom entrance. After 7 days of processing, apply a decorative layer to the wall.