How to address sanding on the base floor when applying self-leveling compound?
Release Time:
2016-07-08
Source:
How to address sanding on the base floor when applying self-leveling compound?
How to address sanding on the base floor prior to self-leveling installation?
Eighty percent of domestic subfloors exhibit sanding or dusting, which poses a significant challenge for PVC flooring contractors. Many construction sites present substantial difficulties, to the point where we are sometimes unable to even secure contracts. Below, I have compiled several methods to share with you.
Analysis of the Causes of Dusting Floors:
Causes of Sanding on the Floor
There are many reasons for sanding on concrete floors: insufficient cement grade, overly fine sand with excessive silt content, an excessively high water-to-cement ratio during batching, and untimely water curing, among others. The common causes of sanding include the following:
1. Excessive water addition during concrete and mortar mixing, or uneven mixing, can lead to segregation of the paste, resulting in sanding and peeling at the surface.
2. Insufficient number of surface calendering passes and inadequate compaction result in bleeding and sanding.
3. Improper control of the troweling timing, or troweling after final set, can damage the mortar surface layer and result in sanding.
4. The cement strength grade used is too low, resulting in failure to meet the required strength grade.
5. The gradation of the sand and gravel aggregate used is too fine, resulting in failure to achieve the required strength grade.
6. Improper curing: During the curing period, cement concrete may experience impaired normal hydration and hardening due to moisture loss or external factors.
Solution:
Once the floor surface has begun to chalk or flake, do not rush into applying a primer and self-leveling compound. First, address the underlying issue of loose, powdery concrete—this requires proper treatment, which entails additional costs. Therefore, it is essential to coordinate with the client and include the expense for this preparatory work in the PVC flooring contract. Begin by thoroughly removing all debris from the surface, such as putty, wall paint, and other residues. Next, apply a high-penetration cement hardener (e.g., cement-based or epoxy-based curing agents) to consolidate the concrete. These products are sprayed directly onto the concrete surface, where they penetrate deep into the material, activating the cement hydration process. Under the action of silicate compounds, free lime particles within the concrete transform into highly durable crystalline formations reminiscent of granite, resulting in a dust-free, dense, monolithic surface that significantly enhances the concrete’s strength, density, and wear resistance. This treatment can extend the service life of the concrete floor by more than ten years without disrupting its existing functionality.
If the base floor exhibits sanding or delamination that severely compromises its integrity, the base floor must be redone.
