Acoustic emission monitoring for assessment of prestressed concrete beams Mohamed K. ElBatanouny a,⇑ , Paul H. Ziehl a , Aaron Larosche a , Jesé Mangual a , Fabio Matta a , Antonio Nanni b a Department of Civil and Environmental Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208, USA b Department of Civil, Arch. & Environ. Engineering, University of Miami, 1251 Memorial Drive, McArthur Engineering Building, Coral Gables, FL 33146, USA highlights  Prestressed concrete beams were tested using CLT method proposed by ACI Committee 437.  Acoustic emission (AE) technique was used for damage assessment during CLT.  AE assessed damage in the specimens favorably and also detected existing damage.  Crack maps plotted by AE were in a good agreement with visually observed cracks. article info Article history: Received 5 August 2013 Received in revised form 28 January 2014 Accepted 28 January 2014 Available online 3 March 2014 Keywords: Acoustic emission Non-destructive testing Prestressed concrete Corrosion Cyclic load test (CLT) abstract Acoustic emission (AE) was used to monitor eight prestressed concrete (PC) T-shaped beams that were tested per the ACI 437 cyclic load test (CLT) method. Limited research has examined the validity of this test method for PC structures. The study aims to explore the use of AE for damage evaluation as a sup- plement to conventional measurements used to assess the condition of a structure based on the CLT acceptance criteria. The beams had different initial conditions: five specimens were pre-cracked and cor- roded to different corrosion levels while the remaining unconditioned beams served as control speci- mens. AE enabled to monitor the accumulation of damage during the load tests and damage quantification charts based on AE data are presented. These charts allowed determining load test failure with better sensitivity than the existing ACI 437 evaluation criteria. The charts enabled the assessment of damage regardless of the specimens’ initial condition. In addition, it is shown that accurate damage source location and crack mapping can be achieved by using suitably filtered AE data. Published by Elsevier Ltd. 1. Introduction There is a growing need for an effective non-destructive evalu- ation (NDE) method to assess the condition of in-service struc- tures. Currently, condition assessment of constructed facilities is performed through load tests [1–5]. The monotonic (24-h) load test method set forth in the current ACI building code [6] has been widely used. Recently, ACI Committee 437 [7,8] has proposed a load test method based on the application of a series of load cycles that is referred to as the cyclic load test (CLT). The CLT method as- sesses the condition of structures based primarily on the relation between load and deflection. However, these measurements are of- ten difficult to obtain in the field and may yield misleading results in some cases. Limited research was conducted to examine the validity of this method on prestressed concrete (PC) structures as compared to reinforced concrete (RC) structures [9,10]. This study investigates the use of acoustic emission (AE) to as- sess the integrity of PC beams during load testing as a substitute for conventional deformation measurements. AE was chosen over other NDE methods due to its high sensitivity to damage (and cracking in particular) and ease of application. AE allows detecting stress waves emitted from a sudden release of energy, such as crack initiation and growth [11,12]. AE also enables the mapping of areas of concern, primarily cracking in the case of RC and PC structures, provided that suitable data filtering and reduction techniques are utilized. The method lends itself to field implemen- tation as AE sensors are easy to attach and wireless nodes are http://dx.doi.org/10.1016/j.conbuildmat.2014.01.100 0950-0618/Published by Elsevier Ltd. ⇑ Corresponding author. Tel.: +1 803 348 5182. E-mail addresses: elbatano@email.sc.edu (M.K. ElBatanouny), ziehl@cec.sc.edu (P.H. Ziehl), a.larosche@gmail.com (A. Larosche), jesemangual@yahoo.com (J. Mangual), fmatta@sc.edu (F. Matta), nanni@miami.edu (A. Nanni). Construction and Building Materials 58 (2014) 46–53 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat