Bond Strength of Self-Consolidating Concrete for Prestressed Concrete Applications.

摘要

Self-consolidating concrete (SCC) has recently gained significant popularity in the precast industry in the United States. Due to its high flowability, SCC has been used for many precast concrete structures, especially those require narrow forms and heavy reinforcement. However, there have been concerns regarding the bond strength, transfer length, and development length of SCC with prestressing strands and steel reinforcement. Further, there are no design guidelines for bond strength, transfer length or development length when using SCC. In this study, a literature survey on the bond strength of SCC was conducted. Moustafa pullout tests were performed to determine bond strength of 0.6-in. pretensioning strands with SCC. The transfer lengths of three pretensioned concrete bridge girders were measured using Demec points. Pull-out tests were also performed on 41 specimens using No. 4, No. 6, No. 8 bars and 0.6-in, strands. All the tests were performed using specimens cast with both SCC and conventional concrete. Limited test data have shown that the bond strength of SCC with deformed reinforcing bars was adequate. However, the use of viscosity-modifying admixtures in SCC may adversely affect the early compressive strength and the bond strength of SCC with pre-tensioning strands. Further investigations into the SCC bond strength issues such as the development length are warranted.