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Title: Flexural strength and durability of reinforced concrete beams strengthened with high performance textile reinforced mortar
Author: Baiee, Ameer Tuama
ISNI:       0000 0004 7961 5613
Awarding Body: University of Brighton
Current Institution: University of Brighton
Date of Award: 2018
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Different techniques have been implemented for repair or strengthening RC structures. Drawbacks and limitations in the form of cost, safety, durability and performance of these techniques made Textile Reinforced Mortar (TRM) a promising strengthening material. In spite of the merits of this material, it has limited applications due to the lack of information and the premature failure (debonding) of the TRM strengthening layer. In addition, as the corrosion of steel reinforcement has significant influences in reduction the performance of RC beams, that impact with higher extent applies to the strengthening RC beams, which has not been fully addressed for TRM. Thus, this study explores the behaviour of RC beams strengthened with TRM with and without the presence of corrosion under flexural loading. In particular, attention has been focused on improving the bond strength of the interface between the substrate RC beams and the TRM strengthening layer to prevent the premature failure. Novel chemical and physical improvements are examined on the existing TRM strengthening technique to improve the interface bond strength. The chemical improvement is included using high strength mortar (HSM) instead of regular strength mortar as a matrix of the TRM, which provides higher adhesion with the substrate. The physical improvement included an application of high strength cementitious connectors at the interface to resist the shear and tensile stresses. These improvements would improve the efficient use of textile fibres and allow achieving high enhancement of the strengthened members. For thickness of concrete cover of 20mm, the experimental results demonstrated the efficiency of the proposed improvements; however, the effectiveness of the cementitious connectors was found profoundly influenced by the strength of substrate concrete. Besides, the experimental data also were assisted in validating the numerical interface bond model used in the finite element models for the beams and good agreement was evident between numerical and experimental load-deflection curves. Moreover, case studies with different properties of substrate RC beams and strengthening layer was carried out and it was found that about 100% increasing in ultimate capacity can be achieved for high strength substrate concrete beams (C60). The effect of steel reinforcement corrosion on the flexural behaviour of RC beams was investigated in two phases. During the first phase, control RC beams were corroded using impressed current (to simulate aging and deterioration of beams) and then repaired by the application of TRM composites. The objective in this phase was to investigate the effectiveness of repair of the corrosion-damaged beams. It was found that the degree of corrosion less than 4% exhibited a non-considerable effect on the repair process. During the second phase, the strengthened RC beams were later subjected to the impressed current based accelerated corrosion. The objective for this phase was to investigate the durability and longevity of the TRM based strengthening technique. The results demonstrated that the degree of corrosion higher than 10% can lead to losing the effectiveness of strengthening due to cover separation and that should be considered in the design of RC beams by means of remove the cover before strengthening.
Supervisor: Rafiq, Muhammad Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available