Retrofitting of corrosion-damaged RC beams using novel bio-composite laminate system

Corrosion-damaged reinforced concrete (RC) beams were retrofitted using a bio-composite system consisting of a bidirectional bio-fibre mat (flax/hemp) and an ultra-high toughness cementitious composite (UHTCC) based on bio-fibre as the matrix. A total of 12 full-scale RC beams were fabricated and subjected to corrosion. Six beams were tested under a low shear span to effective depth ratio (a_v/d) and six were tested under a high a_v/d ratio. The damaged concrete beams were then retrofitted and the intensity of damage in terms of cover damage, cracking and mass loss was noted. The main parameters of the retrofitting schemes included the type of fibre mat (flax or hemp), a_v/d ratios of 5.0 and 3.9 and the type of discrete fibre (flax or hemp) in the UHTCC. The test results revealed that the restoration efficiency of the retrofitting scheme was 100% for all the beams tested under a_v/d = 3.9 and 90% for the beams tested under a_v/d = 5.0. A techno-economic sustainability study was performed through cradle-to-gate analysis, and the efficiency of the proposed retrofitting scheme in terms of cost, energy and carbon dioxide footprint was compared for practical implementations.