Cover Image
close this bookQuality Control Guidelines - Fibre or Micro Concrete Tiles (SKAT, 1991, 79 p.)
View the document(introduction...)
View the document1. Introduction
close this folder2. Raw materials
View the document(introduction...)
View the documentCement / Visual test
View the documentCement / Quality test
View the documentSand & aggregate clay & silt content test
View the documentSand & aggregate moisture content test
View the documentSand & aggregate grading test
View the documentFibres chemical purity
close this folder3. Production process
View the document(introduction...)
View the documentMortar preparation workability test
View the documentMortar preparation mortar strength test
View the documentDemoulding / Size and shape
close this folder4. End control
View the document(introduction...)
View the documentPore and crack test
View the documentRing test
View the documentBending test
View the documentNib tensile test
View the documentWater tightness test
View the documentWeight test
View the document5. Further readings
View the documentAnnex 1 - Summary of tests
View the documentAnnex 2 - Preparing sample sand
View the documentAnnexes related

Demoulding / Size and shape

Field test

Why this test

Only the correct size and shape of all tiles ensures a proper fixing on the roof. Poorly fitting tiles easily crack under load and wind driven water may enter the roof.

Tiles that are not square will not fit properly and the overlap will not be sufficient.

Tiles that are too thin will leak and are not strong enough.

How

Check every tile that it has the right dimensions, shape and profile during the demoulding operation. For tiles the special quality control jig developed by JPM Parry can be used.

Hold the mould on edge and place the tile against the quality control jig. Roll the mould with the tile over on the jig’s pivots until upside down. Lift the mould off. Remove the plastic interface sheet by pulling straight across from the side edge.

Run around tile edge with a knife to remove any excess flash. Check carefully that the tile fits the jig and does not wobble.

The edge of the bar should be seen, but should not have a gap showing beneath it.

If the jig is not available the test can also be done on a mould.

Always use an especially assigned mould only used for this purpose. If a plastic mould is used then it must be adequately supported to prevent flexing.

Squareness:

Test on a standard mould that the edges of the tile are parallel with the mould.

Thickness at the edges:

Check if the thickness of the upper part of the tile (a) differs from the thickness of the lower part of the tile (b). For a 6 mm thick tile it should range between 5.5 and 6.5 mm. Check on both ends of the tile.

Thickness in the middle:

Occasionally, check also the thickness of the tile in its center, by breaking the tile.


Figure


Figure

Who

Worker

When

During demoulding

Result

Record keeping: yes
The product should be within the following tolerances:

Tolerance on length

+/-

10 mm

Tolerance on width

+/-

5 mm

Tolerance on profile

+/-

3 mm

Tolerance on thickness

+/-

0,5 mm

Tolerance on squareness

+/-

3 mm

Consequence
If test fails
Discard tiles that fail the test. If the thickness varies too much the mix has to be examined and/or the worker should improve his performance.