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close this bookQuality Control Guidelines - Fibre or Micro Concrete Tiles (SKAT, 1991, 79 p.)
close this folder2. Raw materials
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View the documentCement / Visual test
View the documentCement / Quality test
View the documentSand & aggregate clay & silt content test
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View the documentSand & aggregate grading test
View the documentFibres chemical purity

Fibres chemical purity

Laboratory test

Why this test

Polluted fibre reduces the strength of the tile and lengthens the setting time of the mortar.

How

Put about 20 g of fibres into about 0.1 Iitre of water (an ordinary water glass) and store them in the water for 2 hours. Keep also a glass of clean water beside the fibre water glass.

Remove the fibres and discard. Mix exactly 50 g of cement with 15 g of the fibre water in a container and keep the container close to the fibre water glass. Prepare at the same time a mix of SO g cement and 15 g of clean water and place the container close to the clean water glass.

During setting time cover the containers with a plastic sheet.

Check the stiffening time of the two cement pastes every 30 minutes by pressing the sharp end of a pencil or a nail into the surface. Note the time when the paste is so hard that the pencil or the nail only with difficulty can be pressed deep (3 mm) into the paste.


Clean waler / 20 g fibres in 0.1 l water for 2 hours


Mix 50 g cement with 15 g water


Check stiffening every 30 minutes

Who

Laboratory staff

When

When a bad fibre quality is suspected.

Result

Record keeping: yes
The stiffening time of the fibre water paste should not be considerably longer than that of the clean water paste.

Consequence

If test fails
If the stiffening time of the fibre water paste is more than double that of the clean water paste or if the stiffening time of the fibre water paste is more than 50°/0 longer than earlier tests have shown the fibres should be washed in water before being used.