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| Magnesium sulphate test
BS EN 1367 Part 2 This test is to determine the resistance of the aggregate to repeated immersion in magnesium sulphate, followed by oven drying, and the growth of crystals that might result within the pores of the aggregate. This is a measure of the resistance of the aggregate to freezing and thawing, and is particularly relevant where the aggregate will be exposed to sea water or de-icing salts. Aggregates of the 10 mm to 14 mm size fraction are used. The test method involves five cycles of immersion in a saturated solution of magnesium sulphate at a constant temperature of 20ºC, followed by drying in an oven at 110ºC. |
After five cycles the sample is washed and the proportion of aggregates reduced to less than 10 mm in particle size is measured. The results are expressed as 'categories', such as MS 18 , MS 25 or MS 35 , where the number represents the percentage of the aggregate reduced to less than 10 mm in size. The lower the number the more resistant the aggregate will be to freezing and thawing. If the value is greater than 35 the actual number should be declared.
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