Zuhair K. Al-Jaberi1, and John J. Myers2
1) Graduate Research Student, Missouri University of Science and Technology
1304 Pine Street, 201 Pine Building, Rolla, MO 65409, USA
e-mail: zkayc7@mst.edu
2)  Professor of Civil, Arch. and Envir. Engr and Associate Dean, Missouri University of Science and
305 McNutt Hall, 1400 N. Bishop Ave., Rolla, MO 65409, USA
e-mail: jmyers@mst.edu

Keywords: Reinforced Masonry, Strengthening, FRP, Environmental, FRCM.

Abstract. In recent years, composites materials have been proved as an effective strengthening technique for civil engineering applications. The effectiveness of a strengthening system depends on the long-term bond behavior between fibers and the masonry substrate. There is a lack of long-term data on the performance of strengthened masonry walls under combined environmental exposure. This research focused on the effect of combined environmental cycles on flexural behavior of reinforced masonry walls strengthened with an externally bonded fiber reinforced polymer (EB FRP) or fiber reinforced cementitious matrix (FRCM). The walls performance was investigated by exposing the specimens to 350 different environmental cycles were induced through a computer-controlled environmental chamber. These cycles are proposed to simulate 20 years of the typical in-situ weather conditions of the Central US. Nine reinforced masonry walls were built for this study. An identical reinforced masonry wall in its unstrengthened form was used as a control specimen. Two sets of four specimens each were strengthened using EB FRP with different types of fabric (glass fabric and carbon laminate) and FRCM system. The first set was tested after at least 28 days as a curing period under laboratory conditions, while the other set was tested after 72 days of exposure to combined environmental conditions. The walls were tested under four-point bending and subjected to cyclic loading with loading rate 1.27 mm/min. In terms of flexural capacity, the specimens strengthened with carbon laminate or FRCM were affected by weathering condition more than the specimens strengthened with glass fabric. Different modes of failure occurred in this study, including crushing failure through the concrete block, as well as debonding of strengthening system from the masonry substrate.