Abstract
Different techniques have been implemented for repair or strengthening RC structures. Drawbacksand 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 Award | 2018 |
|---|---|
| Original language | English |
| Awarding Institution |
|
| Supervisor | Imran Rafiq (Supervisor) |