Weryfikacja wytycznych normowych dotyczących oznaczania zawartości części organicznych w gruntach organicznych metodą strat masy przy prażeniu

The key feature of organic soils is the acquaintance of organic matter content, which determines the possibility of their classification and possible usefulness for building purposes. Information included in Eurocode 7 (PN-EN 1997-1:2008; PN-EN 1997-2:2009), new classification standards (14688-1, 2:2006) and specifications (PKN-CENISO/TS 17892:2009) are general and do not specify which method should be applied to determine organic matter content. Therefore, the loss on ignition method according to the Polish standard (PN-B-04481:1988) is often used in Poland, although the standard guidelines are not precise enough, because the temperature range suggested for soil roasting is wide, from 600°C to 800°C, and the time recommended for sample roasting is 4 hours and additionally from 3 to 4 hours. The ambiguity of standard conditions for tests was the basis for undertaking research in order to verify the influence of leading parameters, i.e.: temperature and time, on the results of roasting. The tests were conducted on organic soil samples. A number of tests were conducted for temperatures, from 550°C to 850°C and for different time periods from 3 to 9 hours. In total, 756 samples were tested in 63 testing series. The test results revealed that the only main parameter to decide about the outcome of a roasting test is temperature. This, in turn, has a practical meaning, as it enables the test procedure to be facilitated and the roasting process to be shortened.