Investigation of Standardized Tests to Measure the Bond Performance of Prestressing Strand

摘要

align="left">An experimental program was conducted to evaluate three different bond performance tests and their potential to predict the bond characteristics of seven-wire strands in pretensioned concrete applications. Simple pull-out tests, tensioned pull-out tests, and measured strand end slips were compared to companion transfer length measurements for 0.5 in. (12.7 mm) diamete~ Grade 270? lowrelaxation strands with varying surface conditions. Four strand surface conditions were tested: as-received, cleaned, silane treated, and weathered. Additionally, strands produced by three different manufacturers were tested in their as-received condition. Overan end slip measurements provided an excellent correlation with measured transfer lengths. When data from other research projects were included, a statistical correlation of 0.95 was demonstrated between measured transfer lengths and strand end slips. From these results, strand end slips are determined to be the best predictor of pretensioned bond. Therefore, strand end slip? easurements are recommended as a reliable standard measure to predict the bond performance of prestressing strands for pretensioned applications.