Effect of polyolefin macro fibers and handmade GFRP anchorage system on improving the bonding behavior of GFRP bars embedded in self-compacting lightweight concrete Alireza Doostmohamadi, Mohammad Karamloo ⇑ , Oveys Afzali-Naniz Department of Civil Engineering, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran highlights  Effect of polyolefin macro fibers on bond behavior of GFRP bars has been assessed.  Efficacy of different anchorage systems on bond behavior of GFRP bar was evaluated.  Fracking mode of specimens were changed were the fibers were added to the mix.  Different codes showed far too conservative results than experiments. article info Article history: Received 9 September 2019 Received in revised form 6 February 2020 Accepted 16 April 2020 Keywords: Bonding behavior Self-compacting lightweight concrete Macro polyolefin-based fibers GFRP Anchorage system abstract In the present paper, effect of polyolefin based macro fibers as well as handmade GFRP anchorage system on the improvement of the bond between GFRP bars and self-compacting lightweight concrete, SCLC, has been assessed. To do so, 60 direct pull out tests have been carried out, in which parameters were the com- pressive strength of concrete (21 MPa, 30 MPa, 36 MPa, and 40 MPa), length, and diameter of anchorage system. Besides, two fiber volume fractions of 0.3% and 0.5% by concrete volume and four types of hand- made anchorage systems have been considered. All tests were carried out in displacement control con- dition by means of a closed loop servo-electro controlled universal testing machine and the loading rate was set to 1.2 mm/min. The slip of bar at free ends, was measured by means of linear variable dif- ferential transformers. Test results indicated that the fibers eliminated the concrete splitting. Moreover, not only the fiber contents enhanced the maximum developed stress of the GFRP bars, but also the com- bination of 0.5% fiber volume fraction and DA2 anchorage system showed the best performance among all specimens. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction During the recent two decades, fiber reinforced polymer (FRP) bars have played a leading role in the construction industry due to high corrosion resistance, high tensile strength, and lightweight. However, the lack of ductility and low modulus of elasticity were found to be the drawbacks of these bars [1]. Indeed, exposure to very harsh environment and elevated temperature was also con- sidered by some researchers [2–5]. As a result of these studies, it is reported that very harsh environment, such as alkaline solutions with PH higher than 12 or acidic solution with PH = 3.5 could lead to a decrease of flexural and compressive strength of GFRP pultruded profiles [3]. Besides, the study of Guo et al. [2] suggests the need to accurately predict the long performance of GFRP in a place where they are exposed to high alkalinity solutions. Jarrah and his co-workers [6] considered the effect of elevated tempera- tures on the tensile performance of GFRP and CFRP sheets and their results showed that the tensile strength of GFRP sheets showed a significant reduction of about 87% after exposure to 600 °C. Indeed, the design of a GFRP reinforced concrete could be a different mat- ter in which the bond between the bars and concrete would be of greatest importance due to the fact that the very harsh environ- ment or exposure to elevated temperatures could be somehow rare in building industry. In this regard, since bonding between the con- crete and FRP bars, embedded in concrete, affects the ultimate limit states as well as serviceability of the concrete, several inves- tigations have been reported in the literature regarding the param- eters affecting the bond between GFRP bars and concrete. For https://doi.org/10.1016/j.conbuildmat.2020.119230 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: m.karamloo@sru.ac.ir (M. Karamloo), Oveys.afzali@sru.ac.ir (O. Afzali-Naniz). Construction and Building Materials 253 (2020) 119230 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat