Building Materials, Third Edition

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The clay ridge and ceiling tiles (Fig. 2.17) are grouped as class AA and also A and should fulfil
the following requirements.
Class AA Class A

1. Maximum water absorption (%) 18 20


2. Minimum breaking strength (kN) 0.015 (average) 0.011 (average)
   0.0125 (individual) 0.0095 (individual)

The length of the ridge tile measured from face to face excluding the portion containing the
catch should be 375, 400 and 435 mm with a tolerance of 15 mm. When a ridge tiles is placed
on a horizontal plane (Fig. 2.17 (a)), the triangle formed in elevation by producing the inner
faces of the tile should have a base of 265 mm and height of 100 mm with a tolerance of ± 5 mm.
The tiles shold be not less than 100 mm thick throughout.
The ceiling tiles may be of single lug or double lug type as shown in Fig. 2.17(b).

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The flooring tiles are of three classes–class 1, class 2 and class 3. These are available in following
sizes.

150 × 150 × 15mm, 150 × 150 × 20mm, 200 × 200 × 20mm
200 × 200 × 25mm, 250 × 250 × 30mm

The average dimensions should not vary by more than ± 5 mm and that for a given area and
space the dimensions of individual tile should not vary by more than ± 2 %. For thickness these
limits are ± 2 mm and ± 1 mm respectively.
The characteristics of these tiles are given in Table 2.6.

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A good roofing tile should have the following properties:

1. uniform texture.


2. accurate size and shape.


3. free from defects like flaws, cracks and nonuniform burning.