Role of fiber inclusion in adobe masonry construction

Abstract

Adobe masonry construction constitutes a notable portion of the buildings in both urban and rural areas in less developed countries. Seismic performance of adobe buildings is poor, and low-cost retrofitting measures are required to enhance the resilience of such buildings during an earthquake. In this study, mechanical properties of fiber reinforced and unreinforced adobe masonry were investigated. Sisal fibers with length of 25 mm were used as reinforcing elements for mortar and adobe bricks at a fiber content of 0.75%. A series of laboratory tests were performed on masonry triplets, couplets and prisms to determine shear strength, tensile resistance and compressive strength, respectively. Uniaxial compression and diagonal compression shear tests were performed on wallets and wall panels, respectively to determine compressive strength and shear strength of the adobe masonry. Finite element linear elastic analysis was conducted using ANSYS Finite-Element code to evaluate the stress state of loaded wall panels. The structural design of adobe masonry walls was carried out according to BS5628 and Eurocode 6 standards, by utilising material properties acquired from the experiments. The results showed that fiber inclusion in the mortar caused an increase in tensile strength of 31%, friction coefficient of 22%, and prism compressive strength of 25% compared with unreinforced mortar. The reinforced wallets exhibited a twofold increase in compressive strength while reinforced wall panels indicated threefold increase in shear strength. The stress state in the reinforced and unreinforced wall panels was not a pure shear state and was better described by RILEM recommendations. The allowable vertical load resistance was found to be 40 kN/m and 100 kN/m for unreinforced and reinforced walls, respectively. The allowable lateral shear resistance was found to be 25 kN/m and 80 kN/m for unreinforced and reinforced walls, respectively. Reinforced masonry elements exhibited considerable ductility and unreinforced masonry elements showed brittle behaviour.