Research Focus

My research focuses on the prediction of long-term durability and characterization of early-age volume change of cement-based materials. My approach results in translational research that combines fundamental scientific understanding with the development and improvement of test methods and specifications that enhance concrete performance.

Contributions making the greatest impact from my research have come in the area of assessing and developing test methods for alkali-silica reaction (ASR), developing mitigation techniques to reduce this deleterious reaction and assessing field structures undergoing ASR. This work has directly influenced the development of national specifications and guidance documents that inform state and federal agencies of the best practices for testing potentially reactive aggregate sources, and determining mitigation strategies. As recognition of my expertise I was asked to provide an international keynote lecture at the EPFL AAR series to a group of government and industry professionals in Switzerland who are managing infrastructure affected by ASR. My research activities and service to the profession are inextricably linked. I have taken on a leadership role as Subcommittee Chair of ASTMs C09.50 “Risk Management of AAR” where I am championing a new standard specification for diagnosing and mitigating ASR (C2.1.45). My expertise in ASR has led to a prestigious role as a consultant on a multi-million dollar master planning study of a 1930s era historic bathhouse in Pelham Bay Park, NY, owned by the New York Dept. of Parks and Recreation.

Investigating shrinkage at both early and later ages in cement-based materials has also been a research focus with sustained funding from the Oregon DOT (ODOT) and PacTrans – a University Transportation Center. These projects have lead to 1) fundamental understanding about the high levels of inherent shrinkage in high performance concrete mixtures in Oregon 2) solutions to reduce the drying shrinkage of these mixtures 3)models to a predict both long-term drying shrinkage from short-term measurements and inherent cracking risk of a mixture based on standard test methods and 4) improvements to standard testing methods which will allow future researchers to perform more thorough experiments and data analysis. Currently, we are working closely with ODOT to establish performance-based drying shrinkage limits using a “cracking potential index-CPI” rather than a singular limit value. The universal approach of the CPI can easily be adopted by other Departments of Transportation and agencies who manage concrete infrastructure. Ultimately, this research will result in significantly reduced cracking in HPC bridge decks and thus reduced maintenance expenditures and increased service life.

My experimental work investigating calcium aluminate cement lead to a significant discovery about the nature of the inherent volume change associated with metastable and stable hydrates in these systems. This volume change was unexpected and vastly different from the well-studied portland cement on which many assumptions about other cementitious materials are often based. This fundamental work has lead to continued industry-sponsored research for a PhD student at OSU to explain the mechanisms behind volume change in blended CAC systems. My investigations into CAC are leading to the development of a new standard test method to assess the impact of hydrate formation on long-term performance of this material.

Concrete, the most widely used building material in the world, is a sustainable material when properly designed and constructed. While new materials may show promise, they are often made from natural resources that are simply not found in quantities abundant enough to compete with or even replace the most used construction material in the world, concrete. It is for this reason that concrete is the most advantageous for further development as an advanced material, and enhancements to concrete to generate special properties or to achieve superior performance may be a central path forward to ensure both long-term durability and sustainability.