Surface opening cracks are common defects in large civil structures like bridges. They allow penetration of water or other agents that result in loss of durability earlier than expected. Their repair can be conducted by the injection of epoxy material that seals the crack sides keeping out any aggressive substances in addition to the recovery of strength. In order to evaluate crack parameters before impregnation as well as to determine the final repair effectiveness, a combination of Rayleigh and longitudinal waves is applied. Rayleigh waves demonstrate the filling condition of the material into the shallow layer near the surface while tomography using longitudinal waves through the thickness yields information about the area inside the structure. Wave propagation dispersion features are exploited by the proposed tomography at different frequencies, demonstrating that higher frequencies lead to more accurate characterization.

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Repair evaluation of concrete cracks using surface and through-transmission wave measurements

Damaged RC beams repaired by bonding of CFRP laminates

Combined use of thermography and ultrasound for the characterization of subsurface cracks in concrete

Characterization of mechanical performance of concrete beams with external reinforcement by acoustic emission and digital image correlation

Flexural behavior of beam to column joints with or without an overlying concrete slab

Repair and structural performance of initially cracked reinforced concrete slabs

Interlocking masonry wall as a structural load-bearing element is still unexplored simply because its basic behaviour and complete response to failure is not known. In addition, there is no design code available to provide necessary guidance for a safe design of interlocking walls. This paper provides an attempt to ascertain the structural response of interlocking masonry walls compared to conventional bonded walls. Individual block units, prisms and full-scale wall specimens were tested under the action of concentric and eccentric compressive loads. The effect of different patterns of reinforced concrete stiffeners has also been investigated. The test results were discussed in terms of wall efficiency, strength capacity, deflection, strain distribution, cracking patterns and failure modes. The results indicate a promising future use of the interlocking masonry system in construction.

M. Razali A. Kadir

Papers

Repair and structural performance of initially cracked reinforced concrete slabs

Structural Behaviour of Mortar-Less Interlocking Masonry System under Eccentric Compressive Loads: