Case 1
Navigation
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
The cracking of tile works is a common failure associated with concrete backing wall. Cracks may be a result of:
- Normal service loads,
- Internal stresses
- Overloading of the structure
- Excessive shrinkage of concrete, which together with a drop in temperature gradient causes a decrease in volume. When this volume decrease is restricted by rigid joints, tensile forces are developed which leads to cracking of the tile multi-layer system. Due to the presence of such differential movements between the tiles and the backing wall, cracks resulted.
- Differential movement as a result of the differential settlement of the building foundation causing structural cracks along the tilework of reinforced concrete walls.
- Another possible factor is the laying of tiles on the substrate surface which has not been cured properly.
- Movement between the substructure (either contraction or expansion) and the mortar bed moving in the opposite direction.
One must always be on alert that facades are exposed to external environment under harsh combination effects of changes in (a) temperature, (b) moisture, (c) wind, (d) pollutants.
Falling of objects from facades of tall buildings cannot be compromised.
Consequence
Cracking on the façade is not merely an aesthetic problem but can also lead to other problems:
- Dirt may be collected on the cracklines. When rain, this dirt will be carried down to the surface of tiled façade and staining results.
- The cracklines may also permit ingress of water into the backing wall which may cause adhesion failure, corrosion of embedded steel and the formation efflorescence.
- Cracking of tiles may also be accompanied by delamination and vice versa. Any differential movement between the different layers in a tiling system will induce shear stress along the interfaces and tensile stress on the tiles. If the adhesion bond between the tiles and the substrate is weak, delamination of the tiles will from the substrate will occur. Otherwise, cracking on the tiles will take place. It is therefore common to see a combination of defects/ failures on a façade.