Masonry Walls Strengthened with Fiber Reinforced Concrete Subjected to Blast Load

The aim and objective of this research project was to develop and investigate a rapid method of strengthening the Unreinforced Masonry walls (URM) for out-of-plane action. A total of 12 URM walls, built inside a precast fiber reinforced concrete boundary frame, were strengthened with a cement based concrete mix with or without steel reinforcement. The concrete mixes included Fiber Reinforced Concrete (FRC) (two dosage of fibers (4.6 & 6.0 kg/m³)), Engineered Cementitious Composite (ECC), and plain concrete shotcrete (PLS). Two out of 12 walls were strengthened with steel mesh reinforced shotcrete (MRS) such that a steel mesh was attached to the surface of the walls prior to spraying with concrete. In addition, one wall was plastered only with conventional cement mortar (RF) to serve as a reference. The strengthening materials were applied to both sides of URM walls using shotcrete technology. The walls were exposed to the air pressure of an actual blast from 10 kg of TNT explosive at a 1 m stand of distance. It was found that strengthening the walls with the proposed method significantly improved the out-of-plane behaviour of the URM walls. The results showed that the walls strengthened with ECCS exhibited the least damage followed by FRS-6, FRS-4.6, MRS, and PLS. Whereas, the reference wall (RF) did not survive the blast induced pressure and fully shattered into small pieces.