Journal of Building Engineering 29 (2020) 101218 Available online 28 January 2020 2352-7102/© 2020 Elsevier Ltd. All rights reserved. Development length of prestressing strand in self-consolidating concrete vs. conventional concrete: Experimental study Mahdi Arezoumandi a, * , Krista B. Looney b , Jeffery S. Volz c a Ingram School of Engineering, Texas State University, San Marcos, TX, USA b Wallace Engineering Structural Consultants, Inc., 410 North Walnut Ave., Suite 200, Oklahoma City, OK, 73104, USA c School of Civil Engineering and Environmental Science, University of Oklahoma, 423 Carson Engineering Center, 202 W. Boyd St., Norman, OK, 73019-1024, USA A R T I C L E INFO Keywords: Conventional concrete Self-consolidating concrete Experimental study Development length ABSTRACT An experimental investigation was conducted to compare the development lengths of prestressing strand in self- consolidating concrete (SCC) and conventional concrete (CC). Development lengths and bond performance of 12.5 mm diameter, Grade 270 prestressing strand were evaluated using rectangular beams and the North American Strand Producers (NASP) test for both normal and high strength CC and SCC mixes. (The NASP test has now been formally adopted as ASTM A1081.) Results indicate that the current AASHTO and ACI equations for development length are conservative for both SCC and CC mixes. All development length test beams failed in fexure due to concrete crushing and exceeded the calculated nominal moment by 10–15%. Furthermore, all the SCC and CC beams showed negligible strand end slip during testing. Overall, SCC and CC appeared to exhibit comparable development lengths. 1. Introduction Self-consolidating concrete (SCC) is a relatively new mix of concrete which is characterized by its high degree of workability. SCC is very fowable and doesn’t require any vibration while placing in the form- work. SCC also fnishes very smoothly, leaving a glassy fnish after curing. SCC originated in Japan in the 1980’s due to Japan’s decreasing labor force [1]. SCC saves costs in the form of labor, time, and equipment as well as increasing production rates at precast plants. The cost saving attributes, combined with the improved appearance and comparable structural quality relative to conventional concrete (CC), make SCC especially of interest to precasters. Because SCC mixes typically have decreased amounts of coarse aggregate and high amounts of admixtures, industry members have expressed concerns that the bond of prestressing strand in SCC may be compromised. In response to these concerns, some research programs have recently been implemented, especially by state De- partments of Transportation, to investigate the effects of SCC on pre- stressing strand and determine if SCC is acceptable for precast plants to use in construction of prestressed members, such as infrastructure ele- ments [2]. Research has since indicated that bond quality is an inherent property of the strand and can vary from source to source. These recent issues with bond quality are most likely due to the current production process of prestressing strand compared to the original production processes [3]. Larson, Peterman, and Esmaeily [4] undertook a project funded by the Kansas Department of Transportation (KDOT) to investigate the bond performance of prestressing strand in SCC. Several types of beams were then constructed with 12.7 mm diameter, Grade 270 prestressing strand to evaluate development length through four-point load testing. The same SCC mix, which contained no viscosity modifying admixture (VMA) or supplemental cementitious materials, was used for all speci- mens. Six single strand beams (SSB) with 203 mm � 305 mm cross-sections were cast with one strand located 50.8 mm from the bottom, and six top strand beams (TSB) with 203 mm � 610 mm cross-sections were cast with one strand located at 559 mm from the bottom in order to study the top strand effect. The depth of the TSB’s was decreased to 305 mm at the maximum moment range so the SSB and TSB results could be compared. Finally, four T-beams (TB) were cast with strands at a depth of 483 mm. All development length tests failed in fexure due to strand rupture. The actual maximum moments surpassed the calculated nominal moment capacities by 10–20% for the beams tested at 100% of the calculated development length and 25–30% for the beams tested at 80% of the calculated development length. Overall, they * Corresponding author. E-mail addresses: Arezoumandi@txstate.edu (M. Arezoumandi), klooney@wallacesc.com (K.B. Looney), volz@ou.edu (J.S. Volz). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: http://www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2020.101218 Received 17 October 2018; Received in revised form 23 January 2020; Accepted 25 January 2020