Flexural strength and durability of reinforced concrete beams strengthened with high performance textile reinforced mortar

  • Ameer Tuama Baiee

    Student thesis: Doctoral Thesis


    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.
    Date of Award2018
    Original languageEnglish
    Awarding Institution
    • University of Brighton
    SupervisorImran Rafiq (Supervisor)

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