Experimental investigation of interface behaviour of RC beams strengthened with concrete layers

Flexural strengthening of concrete elements by adding new concrete layers is a commonstrengthening technique. In design, in order to simplify the calculations, the strengthened element isusually assumed monolithic but, in many cases, this assumption is not conservative as interface slip is acritical parameter that affects the level of damage to a strengthened element. In the present study, anexperimental investigation of RC beams strengthened with concrete layers is presented. From bendingtests, the interface slip value is evaluated. It is found that interface preparation and the type ofstrengthening (tensile or compressive) considerably influence effectiveness. Through a comparisonbetween strengthened and respective monolithic and initial specimens, the efficiency of thestrengthening technique is evaluated. In addition, a comparison with respective experimental resultsfrom the literature is presented.