FREEZE-THAW AND DEICING SALT RESISTANCE OF CONCRETE TESTING BY THE CDF METHOD CDF RESISTANCE LIMIT AND EVALUATION OF PRECISION

RILEM TC I17-FDC decided unanimously that the precision of any freeze- thaw and deicing test procedure must be assessed in accordance with IS O 5725. In addition, a resistance limit for concrete should be approve d with respect to practical performance. In this article it is shown t hat these requirements are fulfilled by the CDF test (capillary suctio n of deicing chemicals and freeze-thaw test). To verify this, differen t compositions covering the design rules as defined by standards and g iven by long-term experience have been measured. The repeatability cov ering the scatter of the materials and the test procedures was calcula ted using a large data base of 400 tests. To determine the reproducibi lity, which includes repeatability and between laboratory scatter, 26 comparison tests between two universities, one internal and two Europe an round robin tests were evaluated additionally. The mean scaling aft er 28 cycles (14 days) at 1500 g m(-2) proved to be a reliable CDF res istance limit. At this level a coefficient of variation for repeatabil ity has been established at 11% and for reproducibility at 18%. An acc eptance 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.