Bond performance of prestressing strand in self-consolidating concrete

Abstract

An experimental investigation was conducted to study the bond of prestressing strand in self-consolidating concrete (SCC). The bond of 12.5-mm-diameter (0.5 in.), Grade 270 prestressing strand was evaluated using both the large block pullout test (LBPT) and the North American Strand Producers (NASP) test for both normal and high strength conventional concrete (CC) and SCC mixes. (The NASP test has now been formally adopted as ASTM A1081.) Results indicated that there was a strong correlation between the NASP and LBPT pullout loads in this study (R2 = 0.93). Furthermore, the NASP and LBPT pullout loads can be considered fairly accurate with respect to relative bond between strands, but in terms of absolute bond and rejecting or accepting strand based on set limits, the NASP test passed all three types while the LBPT only passed one out of the three. In addition, the statistical data analysis (both parametric and nonparametric) confirmed that SCC mixes had higher bond strength than the CC mixes.