Freeze-thaw and deicing salt resistance of concrete testing by the CDF method CDF resistance limit and evaluation of precision

Abstract

RILEM TC 117-FDC decided unanimously that the precision of any freeze-thaw and deicing test procedure must be assessed in accordance with ISO 5725. In addition, a resistance limit for concrete should be approved with respect to practical performance. In this article it is shown that these requirements are fulfilled by the CDF test (capillary suction of deicing chemicals and freeze-thaw test). To verify this, different compositions covering the design rules as defined by standards and given by long-term experience have been measured. The repeatability covering the scatter of the materials and the test procedures was calculated using a large data base of 400 tests. To determine the reproducibility, which includes repeatability and between laboratory scatter, 26 comparison tests between two universities, one internal and two European round robin tests were evaluated additionally. The mean scaling after 28 cycles (14 days) at 1500 g m−2 proved to be a reliable CDF resistance limit. At this level a coefficient of variation for repeatability has been established at 11% and for reproducibility at 18%. An acceptance criterion may be proposed for further discussion at 1800 g m−2 as the upper 5% fractile. This minimizes the risk for both customer and supplier.