My research interests lie in the toughness enhancement of brittle matrix composites, which is incredibly important to the practical viability of the built environment. Thus far, my research activities have spanned two broad categories: a) Understanding th fracture mechanics of brittle-matrix composites and, b) Rehabilitation of existing infrastructure. In the first category, my research has been on the fracture mechanics of fiber reinforced gypsum and concrete, where in I focused on both the test method and the material characterization. I configured an instrumented drop-weight impact machine to study Mode I crack propagation in FRC, and examined the influence of fibres (material, geometry) in crack growth under impact. My research on size effects under impact is among the first on plain concrete and the first known work on FRC. Until three years ago, while at USG (industry), I focused on the mechanisms of failure in gypsum wall-boards, and my proposals have lead to a reduction in board weight. I have been involved with the use of innovative materials in repair (parkade, Vancouver) and structural health monitoring (Brookside Cemetery, Winnipeg). The repair of the parking level in Vancouver is the first documented application of hybrid fibre reinforced concrete.
A related and continuing interest is in shotcrete technology, where in I have explored the use of industrial waste and by-products towards a) limiting land-fill problems, b) easing shotcrete production and c) improving shotcrete structural properties. This interest spans both civil and mining engineering applications. In 2007, data from my study on the boiled absorption and permeable voids in shotcrete was used to define the ACI guideline on this topic within the ACI Committee 506 (Shotcrete).
Current research is along two broad initiatives: a) development of tough lightweight and controlled low strength building materials; b) relating durability to fracture toughness in cement-based materials. Within the first scheme, I am developing fibre reinforced hydraulic lime mortars to enhance durability and toughness in heritage stone masonry structures. Here, I am part of a 3-phase program (with the Universities of Manitoba and Calgary) commissioned by Public Works Canada, on the study of repointing mortars for the seismic rehabilitation of Heritage Masonry Structures with particular emphasis on the rehabilitation of the Parliament of Canada. For the first time, hydraulic lime mortars were characterized at high loading rates, described in detail in journal publications (under review) and one MSc thesis by my student, Ms. Rachel Chan. Also, lightweight composites are being studied for toughness enhancement at high strain rates to be applied in shock absorption and protective construction. This has led to fundamental studies on shear enhancement in RC members, specimen size effects and density effect on the strain rate sensitivity of concrete. Within the second scheme, I am investigating the permeability of high performance concrete under mechanical stress. This effort has the support of CTEP (consortium of members in Alberta with interest in Transportation Engineering). It is expected that this project will lead to a more realistic standardized test method for concrete durability.