Search

Degradation of reinforced concrete could occur in various forms including spalling of concrete cover as a result of reinforcement corrosion. The degradation would shorthen the service life of the reinforced concrete structure. Patch repair method may be employed to recover this type of degradation using a suitable patch repair material. The authors have developed a patch repair material made from unsaturated polyester resin (UPR)-mortar. In this paper, the mechanical properties of this material which includes compressive strength, elastic modulus, flexural strength and bond strength are highlighted. Comparisons are also made with the normal mortar to emphasize the superior properties of UPR-mortar. Based on these properties, the potential application of UPR-mortar for repairing damaged reinforced concrete slab is examined through finite element simulation. It is pointed out that the tensile stress intensity in the UPR-layer is reduced with a consequence of reducing a risk of cracking in the repair zone. In addition, the patching of damaged zone with UPR-mortar could minimize the deflection.

Degradation of reinforced concrete (RC) element could lead to a reduction of its strength and serviceability. The degradation may be identified in the form of spalling of concrete cover. For the case of RC beam, spalling of concrete cover could occur at the web of the shear span due to corrosion of the web reinfocements. The shear strength of the damaged-RC beam possibly will become less conservative compared to the corresponding flexural strength with a risk of brittle failure. Patch repair could be a choice to recover the size and strength of the damaged-RC beam. This research investigates the shear failure of patched RC beam without web reinforcements with a particular interest to compare the shear failure behaviour of patched RC beam and normal RC beam. The patch repair material used in this research was unsaturated polyester resin (UPR) mortar. The results indicate that the initial diagonal cracks leading to shear failure of patched RC beam occur at a lower level of loading. However, the patched RC beam could carry a greater load before the diagonal crack propagates in length and width causing the beam to fail in shear.

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

This research is aimed to investigate the flexural behaviour of patched reinforced concrete beam with patching material made from unsaturated polyester resin mortar. The variable studied is the dimension of patching zone as compared to the control beam (without patching). Based on the load-deflection observation of the beam under a four-point bending loading, it is confirmed that the flexural behaviour of the patched reinforced concrete beam is similar to that of control beam at a loading up to about peak load. After this load the patched reinforced concrete beam tends to behave more ductile. The patched reinforced concrete beam show less cracking density compared to control concrete.

Under the influence of aggressive environment, structural concrete could exhibit degradation in various forms. One of the symptoms of the degradation could be shown in the form of local delamination of concrete cover. Patching method could be a preference choice to repair this type of degradation to regain its structural performance and durability. This paper presents the structural behaviour of patched-reinforced concrete beam under flexural loading with particular interest on the use of unsaturated polyester resin (UPR) mortar as patch repair material. The repair area is replicated in the tensile zone of the beam. The behaviour investigated in this study is the cracking evolution of the patched – reinforced concrete beam and its effect on the deflection. It is shown that the higher strength of the UPR-mortar leads to a reduction in the intensity of cracks compared to that of un-repaired (normal) reinforced concrete beam. The lesser cracks intensity is beneficial to restore the flexural stiffness of the beam.