Use of waste steel fibers from CNC scraps in shear-deficient reinforced concrete beams

İlker Kalkan, Yasin Onuralp Ozkilic, Ceyhun Aksoylu, Md Azree Othuman Mydin, Carlos Humberto Martins, Ibrahim Y. Hakeem, Ercan Isik and Musa Hakan Arslan

Abstract

The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to sheardominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5- 23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.

Key Words

deformation ductility index; diagonal tension; energy absorption capacity; recycled scraps; shear-deficient beam; shear-dominated failure; waste materials

Address

İlker Kalkan: Department of Civil Engineering, Kirikkale University, 71450, Kirikkale, Turkey Yasin Onuralp Ozkilic: 1)Department of Civil Engineering, Necmettin Erbakan University, 42100, Konya, Turkey 2)Department of Civil Engineering, Lebanese American University, Byblos, Lebanon Ceyhun Aksoylu: Department of Civil Engineering, Konya Technical University, 42100, Konya, Turkey Md Azree Othuman Mydin: School of Housing, Building and Planning, Universiti Sains Malaysia, 11800, Penang, Malaysia Carlos Humberto Martins: Department of Civil Engineering, State University of Maringa, Brazil Ibrahim Y. Hakeem: 1)Civil Engineering Department, College of Engineering, Najran University, King Abdulaziz Road, Najran, Saudi Arabia 2)Science and Engineering Research Center, Najran University, Najran, Saudi Arabia Ercan Isik: Department of Civil Engineering, Bitlis Eren University, Bitlis 13100, Turkey Musa Hakan Arslan: Department of Civil Engineering, Konya Technical University, 42100, Konya, Turkey

← Back to Volume 49, No. 2