Experimental study of FRP-strengthened concrete beams with corroded reinforcement
Journal article, 2021

Corrosion of steel reinforcement is the major cause of deterioration in reinforced concrete structures. Strengthening of concrete structures has been widely studied. However, most research was conducted on sound structures without considering the effects of corrosion. This paper presents an experimental study of the feasibility of using externally bonded FRP laminates combined with U-jackets, applied directly without repairing the deteriorated concrete cover, to strengthen beams with corroded reinforcement. Ten beams were tested in four-point bending. Two beams were not deteriorated and non-strengthened; these served as references. The other eight were pre-loaded to induce flexural cracks and then exposed to accelerated corrosion. Two of the deteriorated beams were not strengthened, three were strengthened with glass-FRP (GFRP) laminates and three with carbon-FRP (CFRP) plates on the beam soffits. On the six strengthened beams, CFRP U-jackets were installed along the span. Local corrosion levels were evaluated with a 3D-scanning technique. Pitting corrosion significantly reduced the load-carrying and deformation capacity of the deteriorated beams. Despite average corrosion levels of 20%, local corrosion levels up to 57% and corrosion-induced cracks up to 1.9 mm wide, the FRP-strengthening method (applied directly to the beams without repairing the deteriorated concrete cover) was effective in upgrading the load-carrying capacity and flexural stiffness. The applied U-jackets effectively suppressed the delamination of the concrete cover and led to the rupture of GFRP laminates and a utilisation ratio of CFRP plates up to 64%. However, improvement in the deformation capacity was not noticeable; this requires further research.

FRP composites

Pitting corrosion

Flexural strengthening

Reinforced concrete

3D scanning

Local corrosion level

Corrosion-induced cracks


Jincheng Yang

Chalmers, Architecture and Civil Engineering, Structural Engineering

Reza Haghani Dogaheh

Chalmers, Architecture and Civil Engineering, Structural Engineering

Thomas Blanksvärd

Luleå University of Technology


Karin Lundgren

Chalmers, Architecture and Civil Engineering, Structural Engineering

Construction and Building Materials

0950-0618 (ISSN)

Vol. 301 2021 124076

Repair and strengthening of concrete structures with corroded reinforcement

Swedish Transport Administration (TRV2019/64827), 2019-08-01 -- 2022-09-30.

Areas of Advance

Building Futures (2010-2018)

Subject Categories

Infrastructure Engineering

Building Technologies



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9/3/2021 1