The durability of concrete beams (150 × 250 × 1,600 mm3) strengthened using creative profiles with near-surface mounted (NSM) CFRP ropes under severe sulfate cyclic conditions was experimentally investigated.
Parabolic and straight profiles of NSM-CFRP ropes were implemented without and with internal vertical and lateral dowelings using the CFRP ropes. Another group of concrete beams was repaired using similar schemes after being exposed to sulfate damage. The mechanical response of virgin (control), and sulfate damaged beams as well as of those retrofitted before and after exposure to sulfates, was evaluated under a four-point loading setup.
Mechanical evaluation of concrete indicated an increase in concrete’s brittleness and a decrease in its compressive strength by 21%. The beams strengthened using proposed configurations before being exposed to severe sulfate attack showed reductions in load capacity, displacement ductility and toughness of up to 24, 22 and 53%, respectively, yet an increase in stiffness of up to 16% compared to counterpart virgin-strengthened beams. The implantation of vertical and lateral dowels helped maintain the load capacity and improve the stiffness and displacement ductility for former beams by as much as 35 and 16%, respectively. In contrast, beams exposed to the same stage of sulfate treatment and then repaired with a parabolic profile (with and without vertical dowels) attained or surpassed the mechanical performance of relevantly strengthened and then sulfate-treated ones. The adopted retrofitting configurations did not alter the ductile flexural failure mode observed for virgin and sulfate-damaged beams.
Concrete beams were strengthened and then subjected to sulfate attack in the absence of actual loading, which is not the case in the field.
Encouraging the use of the proposed repair configuration with CFRP ropes for concrete elements subjected to severe sulfate attack.
The repair proposed may help maintain the integrity of marine structures for a long time to save on municipal spending on repair issues.
Limited work (if none) on the evaluation of repair durability of concrete flexural elements under sulfate severe condition was reported.
