Mortar is a workhorse material in masonry, and it is also one of the first places age, moisture, and movement show up. A new experimental study highlights a key takeaway for repair and retrofit work: when fiber reinforcement is bonded to cementitious materials, fiber direction can matter as much as fiber type.
In tests reported in Case Studies in Construction Materials, researchers strengthened small mortar prisms using three intraply hybrid composite fabrics, carbon glass, aramid carbon, and glass aramid. Each fabric was bonded with a two part epoxy, then installed in three orientations, horizontal, vertical, and diagonal at 45 degrees. Unstrengthened prisms had a baseline flexural strength of 6.66 MPa, and strengthened specimens ranged from 16.04 to 39.41 MPa.
The top bending result came from the carbon glass fabric installed diagonally, reaching 39.41 MPa, which is almost six times the baseline. The researchers tied that performance to crack behavior. Under bending, cracks form and turn. Diagonal reinforcement crossed those inclined crack paths at more points, which helped spread damage instead of concentrating it into one fracture line.
Compression performance told a different story. Only two configurations delivered clear gains over the 46.29 MPa baseline, carbon glass installed vertically at 53.70 MPa, and glass aramid installed horizontally at 53.51 MPa. Several layouts reduced compressive strength, and the study pointed to stress concentrations at sharp corners, end restraint from the test platens, and impregnation challenges in aramid yarns as contributing factors.
For mason contractors, the practical lesson is to avoid picking strengthening fabrics by datasheet tensile numbers alone. Layout and detailing drive performance. When FRP or textile reinforcement is part of a rehab scope, confirm the demand first, flexure versus confinement, align fibers with the principal tensile stress, and plan corner geometry and surface prep so the wrap and epoxy can stay engaged after cracking. The study also notes these were lab scale mortar specimens, so full scale assemblies, bond behavior, durability, and cyclic loading remain open checks for real projects.
Read the full, original article from Bioengineer.org here.