How to deal with delamination of mortar flooring?
Release Time:
2020-08-31
Source:
How to deal with delamination of mortar flooring?
I. Cause Analysis:
The substrate surface is not thoroughly cleaned, with loose dust, laitance, or other contaminants remaining. In particular, whitewash adhering to the substrate significantly impairs the bond between the substrate and the finish coat. If the substrate is excessively dry and insufficiently wetted during plastering, the mortar will lose water too rapidly, resulting in low strength and poor adhesion to the substrate. Moreover, dust on an overly dry substrate surface is difficult to remove, which can act as a barrier and reduce the bond between the mortar and the finish coat.
The substrate is excessively smooth; standing water on the substrate increases the water-cement ratio of the cement mortar, thereby reducing its strength and bond with the substrate. To enhance the bond between the cement mortar and the substrate, a bonding layer of neat cement slurry should be applied. However, if the slurry is brushed too early, it will dry and harden by the time the finishing layer is laid, which not only fails to improve bond strength but also creates an isolating barrier.
II. Preventive Measures:
Strictly prepare the substrate: when applying cement mortar, ensure the substrate is thoroughly wetted—water it the day before construction; for substrates that are excessively smooth, roughen the surface by chiseling or scoring. Alternatively, apply a concrete interface treatment agent before applying the cement mortar. During construction, ensure there is no standing water on the substrate surface; after brushing on a layer of neat cement slurry, promptly proceed with laying the mortar.
III. Post-Event Handling:
After construction, if a small patch of clear water oozes out on the surface in a localized area and the amount is relatively small, and if this is detected early, sprinkle a moderate amount of dry cement and yellow sand in a 1:2 ratio and then smooth it out. If detection is delayed, once the moisture has evaporated, apply a moderate layer of dry cement; after it has absorbed the moisture, first rough-trowel with a wooden trowel and then finish with a steel trowel. If large areas exhibit significant water seepage, remove the cement mortar, mix in an appropriate amount of dry 1:2 cement and yellow sand, blend thoroughly, and reapply. For extensive hollows, cracks, or delamination in cement-sand flooring, removal and reapplication may be the only viable option.
IV. Sand and Dust Removal Treatment Agent:
There is a floor treatment agent specifically designed to address sanding and dusting on concrete, cement, and wear-resistant flooring surfaces. It is suitable for renovating old floors, refurbishing old wall surfaces, and restoring diamond-grit wear-resistant floors, as well as for treating sanding and dusting on all types of industrial warehouses, logistics centers, factory buildings, parking lots, and other facilities where the substrate is concrete or cement mortar. This includes addressing issues such as damaged cement floors, frost-induced cracking and spalling, insufficient cement grade or strength, sanding and dusting on diamond-grit wear-resistant floors, color mottling and fading on such floors, cracks in cement floors, sanding and dusting on fine-aggregate concrete, cracking and spalling on factory floors, cement spalling, bubbling after troweling on cement floors, hollowing (bubbling) in the surface layer of cement mortar floors, peeling and efflorescence on cement floors, dusty and weak cement floors, poor overall floor strength, extensive crazing after leveling cement floors, uneven floor surfaces with countless cracks, whitening and loosening of cement color, surface delamination of cement concrete, dusting or pitting on the floor, flaking of the hardened cement crust exposing loose cement and sand, cracking at slab joints, hollowing and damage to cement floors, and repair and remediation of burn damage and freeze-thaw deterioration.
Detailed construction steps:
1. First, thoroughly clean the floor to remove all dust and debris, ensuring that no dust accumulates. If water-based cleaning is required, the work must be carried out on a subsequent day, and it must be ensured that the floor is free of standing water or excessive moisture.
2. Dilute the floor penetrating agent in a 1:1 ratio, stir thoroughly to ensure uniformity, and apply as follows: use a roller brush to apply directly to the cement floor, repeating the application twice with a 3-hour interval between coats. Note that in areas with severe sanding, additional coats are required; the number of additional coats and the amount applied should be determined based on site conditions. For areas where there is significant material detachment or rapid penetration, promptly reapply the product to ensure adequate penetration and impregnation. Generally, areas with higher surface density absorb less, while those with lower surface density absorb more; these differences must be addressed accordingly during application. The key points are: first coat—roller application; second coat—roller application.
3. Curing: The floor permeation agent may be used only 24 hours after application.
4. Repair of damaged floor surfaces: For areas where the floor has been previously repaired due to earlier damage but has subsequently experienced delamination and required removal, resulting in unevenness, or for other causes of surface irregularities that necessitate repair, such repairs shall be carried out only after the aforementioned construction procedures have been completed.
