The revision and combination of the standards NT BUILD 485 and EN 1367-1 has led to the following fundamental alterations:
- The samples are tested in either pure de-ionised water or 1% solution of NaCl in de-ionised water. The same requirements in the product standards do not apply.
- The thawing out sequence is controlled either by air circulation or water circulation in the cabinet to obtain the correct temperature of the reference sample.
The frost resistance of the aggregate is determined by subjecting it to the cyclic action of freezing and thawing. The freeze-thaw resistance of aggregate, as measured by the proportion of undersize passing the ½ size sieve as sieved from the test portion, is considered separately for each portion and then expressed as a mean % by mass.
This European Standard specifies a test method to assess the frost resistance of aggregates when it is subjected to the cyclic action of freezing and thawing. In areas where frequent freeze-thaw cycling occurs and seawater sprays or de-icers are abundant it is more apropriate to use a 1% solution of NaCl in de-ionised water instead of pure deionised water.
The test is applicable to aggregates having a particle size between 4 mm and 63 mm.