EN 15304:2010 – Determination of the freeze-thaw resistance of autoclaved aerated concrete
4 Principle Cubic test specimens (two equal groups consisting of main test specimens and reference test specimens) are cut from products sampled from normal production, saturated in water for (48 ± 1) h, removed and then placed in polythene bags or similar protecting against drying for (24 ± 1) h to equilibrate.
The main test specimens are subjected to repeated freezing at (–15 ± 2) °C for at least 8 h followed by thawing in an environment of > 95 % relative humidity and (20 ± 2) °C for at least 8 h. The reference test specimens are stored in a climatic chamber at (20 ± 5) °C in conditions that prevent drying of the AAC during storage. After the specified number of freeze-thaw cycles (not less than 15), the mass loss of the main test specimens is determined.
The dry density and moisture content is also determined on the reference test specimens. If the loss in compressive strength is also required to be determined, then Annex A should be followed.
NOTE Depending on the conditions at the place of use, the number of freeze-thaw cycles and requirements for limit values of loss in mass and compressive strength can be specified by national provisions.
5 Apparatus
5.1 Saw with rotating carborundum or diamond blade or similar equipment for cutting test specimens. 5.2 Balance, capable of determining the mass of the test specimens to an accuracy of 0,1 %.
5.3 Callipers, capable of reading the dimensions of the test specimens to an accuracy of 0,1 mm. 5.4 Container, to store the test specimens under water at (20 ± 2) °C. 5.5 Feeler gauge, capable of measuring 0,1 mm, (if required) 0,5 mm and 1 mm. 5.6 Room or cabinet for thawing of the main test specimens able to maintain a relative humidity > 95 % at (20 ± 2) °C.
5.7 Storage room for reference test specimens able to maintain a relative humidity > 95 % at (20 ± 5) °C. 5.8 Freezing chamber with internal air circulation capable of maintaining a uniformly distributed temperature of (–15 ± 2) °C. 5.9 Ventilated drying oven, capable of maintaining a temperature of (105 ± 5) °C. 5.10 Straight edge, at least 200 mm long, and a square.
5.11 Compression testing machine, preferably hydraulically operated, which meets the requirements of EN 12390-4.
NOTE The room according to 5.6 needs not necessarily be humidity-controlled. Alternatively it is possible to substitute moisture losses by 2 h prior to the end of the thawing period placing the main test specimens in underwater storage for 1 h at (20 ± 5) °C and subsequently leaving the test specimens to equilibrate in air for 1 h at (20 ± 5) °C before freezing. This procedure is especially appropriate in combination with automatic systems. It should be ensured that the starting moisture content is not exceeded.
EN 15304:2010 – Determination of the freeze-thaw resistance of autoclaved aerated concrete