Case 2

Tile – Cracks

Introduction

Type of Building: Residential

The crazing of glazed homogeneous tile in a bathroom is shown in the picture above. It was found that cracks were randomly oriented and widespread. Some of the cracks are random within individual tiles while others were propagated to the adjacent tiles. The widths of most cracks were wide near the center of the bedding layer and spread narrowly towards the tile or render layer. This indicated that cracks had initiated from the bedding layer.

Some slag particles were detected in the bedding layer, which is compromised with Portland cement with no aggregates. Variations in the capillary porosity were observed. Higher capillary porosity was identified in several places that indicated having a higher water/cement ratio. It appeared that the mixing of bedding adhesive has not been carried out properly.

A higher amount of calcium hydroxide was found around cracks at the bedding tile interface where there is higher capillary porosity. This indicates that water might have collected in these pores. Carbonation was also observed along the bedding-tile interface along the cracks closer to the bedding-tile interface while isolated carbonation was found in a few locations.

In the rendering, a low degree of hydration was found. In addition, variations in the porosity were also observed. The water/cement ratio ranged from 0.55 to 0.70, resulting in the non-homogeneity of cement paste.

All the tiles were found to achieve the standards of crazing resistance, modulus rupture expansion, and moisture expansion of tile according to SS 483 specifications.