Strengthening of RC beams using steel fiber reinforced high strength lightweight self-compacting concrete (SHLSCC) and their strength predictions

Highlights: • In this research, strengthening of SHLSCC-RCC beams is performed. • Using strengthening layers' significant improvements in beam stiffness and peak load were observed. • Stress distribution models for SHLSCC with and without longitudinal steel are developed. • Predicted beam bending moment capacities match well with the tested ones. • A useful application of the outcomes is obtained to in-situ structure repair and strengthening. Repair and strengthening of reinforced concrete (RC) members in existing structures are very important to extend their service life. Strain hardening cementitious composite developed by addition of steel fibers to concrete may be utilized for strengthening of existing structures. In this study, steel fiber reinforced high strength lightweight self-compacting concrete (SHLSCC) developed by the authors is applied for the strengthening of RC beams to improve their bending moment capacities. There are significant improvements in stiffness of strengthened beams as well as 14–58% improvements in peak load when strengthened with 40 mm, 50 mm and 60 mm layers of SHLSCC. Application of SHLSCC in lower half (Tension zone) of the beam increased its peak load by 33.1%. Further, developed stress distribution models are effectively applied for the prediction of enhanced moment capacities of the strengthened beams. Comparison of experimental results with those calculated from the models showed maximum variation of 4%. The outcomes of this study will be very helpful in applying the modelled observations to in-situ structures allowing timely completion of repair and strengthening strategies.