Innovative Flexural Repair Technique of Pre-Damaged T-Beams Using Eco-Friendly Steel-Fibre-Reinforced Geopolymer Concrete

Abstract

This paper presents an innovative flexural repair technique for pre-damaged reinforced concrete T-beams using eco-friendly steel-fibre-reinforced geopolymer concrete (SFRGPC). The study considers various parameters such as repair layer depth, location and configuration, and the use of additional reinforcement in one beam. The beams were preloaded to 50% of their ultimate flexural capacity. Extensive measurements were taken, including crack initiation and propagation, crack width, initial stiffness, load deflection, peak loads, ductility index, and strain values. The structural performance of the repaired T-beams under flexural loading was predicted using an analytical model. The repaired beams showed an increase in carrying capacity, stiffness, and ductility, but the failure mode was identical to the control samples. The study shows that SFRGPC shows great promise as a technique for not only repairing pre-damaged reinforced concrete beams but also for their strengthening. The best results were obtained with three-sided jackets with fibrous geopolymer concrete only, resulting in a load-carrying capacity increase of 25.8% compared to reference T-beams. The bonding between SFRGPC and existing concrete was effective, with no slippage or disintegration at the interface. The repaired beams’ structural behaviour and performance under flexural loads were successfully predicted using the analytical model, with a precision of about 98%.

Upper and Lower Bounds to Pull-Out Loading of Inclined Hooked End Steel Fibres Embedded in Concrete

“…Though the averaging has removed vibrational scatter in the loading an irregularity remains in each plot which can defy an accurate prediction. Despite this, most reports on pull-out testing continue to identify a sequence of failure events within the plot of pull-out load versus fibre slip [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The first event is the region along a rising curve within which fibre debonding has occurred.…”

“…short strand steel fibres, are available in different size, shape and alloy type. Of these, hooked end steel fibres have recently received greatest interest among engineers and researchers [4] because of their resistance to being pulled out under tensile loading.…”