Experimental Study on Friction Coefficient and Stress Loss of Retard-bonded PC Steel Strand

摘要

In order to verify the influence of curing degree of retarded binder on the friction coefficient of retarded-bonded PC steel strand, 3 PC beams with 3300mm in length and 300×400 cross-section is manufactured and 3 retard-bonded PC steel strands in straight-through arrangement at each PC beam is set. According to different retarder curing degree, tensile test of retard-bonded PC steel strands is carried out in batches with each batch of 3 PC steel strands. During the curing process of the retarder, long-term measurement of pre-stress loss of the PC steel strands has been carried out too. The experimental results showed that: 1) Under the same retarder curing degree, friction coefficient of PC steel strand would gradually decrease with the increases of tensile force. 2) As stress of PC steel strands reached control stress, the friction coefficient would gradually increase with the increase of retarder hardness. And when shore scleroscope hardness of retarder reached the value of 83.1, friction coefficient κ of the PC steel strands increased to 0.5384. 3) The stress loss of PC steel strands was large upon completion of tensioning. The stress loss would decline gradually with the curing time increasing, and would tend to stable after 109 days.