Aggregate Distribution Investigation in Box Beams Fabricated with Self Consolidating Concrete

摘要

In 2004, the Texas Department of Transportation initiated Project 0-5197 to investigate the feasibility of increasing the allowable compressive stress limit at prestress transfer. Initially, the live load performance of 36 specimens was evaluated by Birrcher and Bayrak (TxDOT Report 5197-1, 2007). Report 5197-4 presents the subsequent research conducted based on recommendations of Birrcher and Bayrak (2007). In this portion of TxDOT Project 0-5197, 45 Type-C beams and 10 4B28 box beams were tested to experimentally determine their cracking load. The Type-C beams were produced in four different fabrication plants using conventionally consolidated concrete. The 10 4B28 box beams were produced in two fabrication plants using concrete mixture designs of both self consolidating concrete as well as conventional concrete (Schnittker and Bayrak, CTR, 2008). After testing the 10 box beams procured in TxDOT Project 0-5197, Schnittker and Bayrak (2008) reported increased amounts of top flange cracking at release, substantially lower modulus of elasticity (along with increased deflections under live loading), slightly higher cambers near 28-days, and lower than expected flexural cracking loads under live loads. The present investigation is carried out in an effort to explain the poor performance of the beams fabricated with SCC as reported in research report 0-5197-4.