Author : Syed Asad Ali Gillani
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (123 download)
Book Synopsis Degradation of the Residual Strength of Concrete by : Syed Asad Ali Gillani
Download or read book Degradation of the Residual Strength of Concrete written by Syed Asad Ali Gillani and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is devoted to the study of the debonding of thin bonded cement-based overlays from the concrete substrate under mechanical loading. As repair materials, fiber-reinforced and rubbberized cement-based mortars are used. Under these conditions, assessment of durability of the repairs necessarily involves the study of the degradation of the bridging strength under fatigue loading. In this context, tensile fatigue tests controlled by crack mouth opening displacement (CMOD) are conducted on composite specimens in order to establish the degradation law of fiber-reinforced and/or rubberized mortar. The bridging strength decreases with the number of fatigue cycles for the same maximum crack width, whatever the nature of the composite. The maximum cyclic bridging strength degradation occurs in plain mortar. The cyclic bridging strength degradation for large pre-cracked widths is limited for mortar reinforced with metallic fibers. In case of rubberized mortar, cyclic bridging strength degradation is limited at less pre-cracked width values. A combine use of rubber aggregates and fibers in mortar appeared to be a suitable solution to limit the cyclic bridging strength degradation for a wide range of pre-cracked widths. It confers to the composite an interest for durable application such as cement-based thin bonded overlays. Taking into account the main cause of distress in thin bonded cement-based applications i.e. cracking and interface debonding, different surface preparation techniques were evaluated in this research. Among them, the sandblasting one is usually implemented in actual conditions. In order to investigate the structural performance, composite beams consisting of a thin repair layer on top of sandblasted substrates are subjected to three point bending tests (monotonic and fatigue). For monitoring the evolution of cracking in the repair layer and of debonding at interface, digital 3D image correlation technique is used. It emerges as a conclusion that the rubber aggregates incorporation in repair material is helpful to control micro-cracking, which results in the delay of the debonding initiation. Moreover, a fiber-reinforcement of repair material is also helpful to limit the interface debonding propagation by restraining opening of the crack. So, the dual-use of rubber aggregates and fibers in the repair material of thin bonded cement-based overlays can be a suitable solution to delay the debonding initiation and also to limit the interface debonding propagation. This shows that the synergetic effect provided by the combine use of rubber aggregates and fibers remains valid under fatigue loading also. The used rubber aggregates are obtained by grinding end-of-life tyres. In such conditions, the approach brings an added value, the recycling of this industrial by-product being also a contribution to the maintenance of a clean environment. Incidentally, this approach also helps towards the development of a circular economy.
