What are the causes of tile hollowing and detachment?
Release Time:
2015-08-10
Source:
What are the causes of tile hollowing and detachment?
Common instances of tile delamination are primarily caused by mismatches between traditional tiling techniques and new building materials, resulting in tiles becoming loose or falling off. Additionally, mismatches can occur when new decorative finishes are used with conventional adhesives. For example, thick-bed mortar application combined with high-density porcelain or vitrified tiles often leads to tile delamination and detachment.
When tiles are installed using the thick-bed mortar method with seamless grouting or with grouting applied too early, the excess water in the bonding mortar—far exceeding the stoichiometric water requirement for cement hydration—has no means of evaporating. As a result, the waterproofing layer remains continuously saturated, leading to a substantial reduction in the tensile strength of the waterproofing material. Prolonged water saturation further compromises the bond strength. Under these conditions, the combined weight of the 20–30 mm-thick cement mortar bed and the porcelain tiles can exceed 20 kg per square meter, far surpassing the load-bearing capacity of the saturated waterproofing layer. Consequently, interlayer delamination of the waterproofing system is virtually inevitable on vertical surfaces.
Precautions:
① Ensure the waterproofing layer meets the specified thickness, and allow sufficient curing time before tiling.
② When laying tiles, leave expansion joints between the tiles and perform grouting 24 hours later (adjustments may be made depending on climatic conditions);
③ Select tile adhesive as the bonding material and apply it using the thin-set method.
Tile adhesive is an improved formulation based on cement mortar. Tile Adhesive Materials It features: ① thin-application installation, resulting in light self-weight, reduced material consumption, and cost savings; ② excellent bonding performance and outstanding durability; ③ no need to soak bricks or wet walls during application, which enhances efficiency and ensures convenient, rapid installation; ④ superior impermeability and aging resistance; ⑤ the addition of redispersible latex powder enables it to absorb stresses between the substrate and the tiles, thereby preventing hollowing or detachment of the tiles; ⑥ slip resistance and adjustability; ⑦ non-toxicity, odorlessness, and environmental friendliness. Due to the inherent superior adhesion of tile adhesive, it is typically applied using the thin-set method (1.5–3 mm), which not only ensures reliable bonding but also reduces costs. By contrast, if the thick-set method (10–30 mm) is used, the baseline deformation of the tile adhesive—caused by cement hydration and changes in the external environment—will be amplified, leading to greater overall deformation of the adhesive. Although tile adhesive exhibits good compatibility with cement-based waterproofing materials, ensuring effective bonding between them, the significant difference in thermal expansion coefficients between tiles and tile adhesive can result in substantial differential deformation, ultimately causing hollowing or detachment at the interface.
Precautions: Perform installation using the correct thin-set method.
In addition, there is a mismatch between new-type finishing materials and traditional adhesive materials.
The thick-bed mortar application method combined with high-density porcelain tiles and vitrified tiles can lead to tile hollowing and detachment.
Bonding principle of cement mortar: Cement mortar infiltrates the voids on the back of the tile, where it sets and hardens, creating a mechanical interlock akin to a key fitting into a lock and thereby bonding the tile to the substrate. The bond strength depends on the porosity of the substrate and the water absorption rate of the tile.
Principle of tile adhesive bonding: Tile adhesive not only relies on the traditional mechanical interlocking mechanism of cement mortar, but also, when the tile surface is free of voids and has low water absorption, it can achieve adhesion through intermolecular forces generated by the polymer film at the interface between the tile and the adhesive.
Therefore, when the facing tiles are new high-density porcelain tiles or vitrified tiles, using traditional cement mortar as the bonding material makes it difficult for the mortar to penetrate the porcelain layer and achieve mechanical interlocking, resulting in tile detachment from the mortar bed. This problem is particularly pronounced when tiles are installed with a seamless joint.
Precautions:
When the facing tiles are new high-density porcelain tiles or vitrified tiles, tile adhesive shall be used as the bonding material, and the corresponding standardized construction procedures shall be followed.
In summary, to fundamentally prevent hollow sounds and tile detachment, we must first dispel conventional assumptions and develop a correct understanding of new materials and innovative construction techniques. Second, it is essential to select products from reputable brands and ensure that installation is carried out by qualified professionals in strict accordance with applicable construction codes and product instructions. In particular, designers must comprehensively consider factors such as mortar types, adhesive materials, tiles, and local climatic conditions to develop well-justified material selections and construction plans; otherwise, unforeseen consequences are almost inevitable.
Principle of cement-sand mortar bonding: The cement-sand mortar penetrates the voids on the back of the tile, where it sets and hardens, creating a mechanical interlocking effect akin to a key fitting into a lock and thereby bonding the tile to the substrate. The bond strength depends on the porosity of the substrate and the water absorption rate of the tile.
Principle of tile adhesive bonding: Tile adhesive not only relies on the traditional mechanical interlocking mechanism of cement mortar, but also, when the tile surface is free of voids and has low water absorption, it can achieve adhesion through intermolecular forces generated by the polymer film at the interface between the tile and the adhesive.
