Cement-Based Matrix-Grid System for Masonry Rehabilitation

Abstract

The research presented in this paper focuses on a cement-based matrix-grid (CMG) system developed for masonry rehabilitation. The objectives of the research and development program were to determine the mechanical properties of the CMG system and to assess its effectiveness for improving unreinforced masonry (URM) wall seismic performance from a load bearing capacity and deflection limits point of view. CMG system is a composite consisting of a sequence of layers of cement-based matrix and alkali resistant (AR) glass coated reinforcing grid. The experimental program included materials and structural tests. Tensile and flexural tests were carried out on unaged and aged composite to assess its long term durability up to the equivalent of approximately 129 years service life. Selected tensile test results are presented in this paper, whereas full details of materials tests are presented in a separate paper. Structural tests included in-plane shear concrete masonry unit (CMU) walls. Three composite configurations were explored and the results were compared with those obtained using various fiber reinforced polymer (FRP) systems overlay configurations also tested in in-plane shear. Retention of tensile properties over time was approximately 75-80% after the equivalent of approximately 50 years service life. Structural test results demonstrated the ability of the cement-based system to strengthen the walls, and showed superior performance of field CMG system compared to FRP alternatives. X-cracking failures were observed, there was no delamination of the system from the CMU walls, and the system held the masonry pier together at failure. Due to its advantages and unique properties this system is a potential alternative to traditional and new FRP masonry rehabilitation and strengthening techniques.