Bond performance of prestressing strand in self-consolidating concrete 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 highlights  There was a strong correlation between the NASP and LBPT pullout loads in mortar.  The NASP and LBPT tests can be considered fairly accurate for bond of strands.  The statistical data analysis confirmed that SCC had higher bond strength compared to CC. article info Article history: Received 30 July 2019 Received in revised form 20 September 2019 Accepted 30 September 2019 Keywords: Conventional concrete Self-consolidating concrete Experimental study Bond strength Large block pullout test Moustafa pullout test abstract An experimental investigation was conducted to study the bond of prestressing strand in self- consolidating concrete (SCC). The bond of 12.5-mm-diameter (0.5 in.), Grade 270 prestressing strand was evaluated using both the large block pullout test (LBPT) and the North American Strand Producers (NASP) test for both normal and high strength conventional concrete (CC) and SCC mixes. (The NASP test has now been formally adopted as ASTM A1081.) Results indicated that there was a strong correlation between the NASP and LBPT pullout loads in this study (R 2 = 0.93). Furthermore, the NASP and LBPT pull- out loads can be considered fairly accurate with respect to relative bond between strands, but in terms of absolute bond and rejecting or accepting strand based on set limits, the NASP test passed all three types while the LBPT only passed one out of the three. In addition, the statistical data analysis (both parametric and nonparametric) confirmed that SCC mixes had higher bond strength than the CC mixes. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction The flowable nature of self-consolidating concrete (SCC) elimi- nates the needs for mechanical vibration and finishing, which are typically required during placement of conventional concrete (CC), saving 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 compara- ble structural quality compared to CC, make SCC especially of inter- est to precasters. Although the economic and performance benefits make SCC desirable for use in construction, the addition of admix- tures and adjustments to mix proportions that give SCC its unique qualities can alter structural properties when compared to CC, especially in terms of bond performance of prestressing strand. 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 Departments of Transportation, to investigate the effects of SCC on prestressing strand and determine if SCC is acceptable for precast plants to use in construction of prestressed members, such as infrastructure elements [1]. While the bond of prestressing strand in SCC has been a current research subject, the bond quality of prestressing strand in general has also been a topic of interest in recent years. Only in the past few decades have concerns regarding excessive end slips of strands and measured transfer lengths significantly longer than those pre- dicted by the AASHTO LRFD-10 [2] and ACI 318-14 [3] equations begun to surface [4]. 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. Today’s strands are typically https://doi.org/10.1016/j.conbuildmat.2019.117125 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: Arezoumandi@txstate.edu (M. Arezoumandi), klooney@ wallacesc.com (K.B. Looney), volz@ou.edu (J.S. Volz). Construction and Building Materials 232 (2020) 117125 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat