Document Type : Research Paper
Authors
Civil Engineering Department, College of Engineering, The University of Al-Qadisiyah, Iraq.
Abstract
Reinforcement-concrete bond is a topic that has been extensively investigated with reference to normal concrete. Scanty attention, however, has been devoted so far to lightweight aggregate concrete, thus this study tries to cover this subject. The bond behaviour of steel bars in lightweight concrete containing expanded clay and steel fibres is investigated for different types of fibrous reinforcement. Sixteen beam samples were prepared with deformed steel bars having diameters of either 12 mm or 25 mm and contained three types of steel fibres with (l⁄d) ratio equal to 60 (straight microfibres, hooked fibres or hybrid fibres). Preliminarily, the physical and mechanical properties of the mixtures (either plain or fibre-reinforced) were investigated, and comparisons were made with the provisions of Model Code 10. The addition of fibres increases concrete density up to 8%, concrete compressive strength up to 28% and tensile strength in bending up to 163%, especially in the case of hybrid fibres. The tests on bond in the beam samples show that bond strength is obviously affected by both the bonded embedded length and bar diameter. The larger the bar diameter, the lower the bond strength is obtained. Suitable amendments are suggested for some expressions proposed in MC 10 (CEB-FIP,2010).
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