CEE Seminar - Concrete and the Environment

It is widely known today that portland cement concrete is the most commonly used manufactured material. It is also well-known that portland cement production contributes approximately 8 to 10 percent of global anthropogenic CO2 emissions. However, what is often overlooked in such statements is the fact that portland cement concrete-based materials constitute about 50% of what humanity produces and 30% of what humanity uses, including fossil fuels. Additionally, we often fail to acknowledge that the composition of the Earth's crust does not allow us to produce any other economically viable alternative material on such a large scale. Let me be clear: I do not suggest that we should not strive to reduce the carbon footprint of concrete; however, we need to be realistic and seek solutions that are both feasible and economically viable. In this talk, I will elaborate on my thoughts regarding potential solutions and the challenges involved.
Given the large-scale use of portland cement concrete, it is no surprise that it has significant environmental emissions and implications, but the interaction of concrete with the environment goes beyond just CO2 release. Concrete forms a substantial part of our infrastructure, and in this talk, I will discuss two topics related to how concrete interacts with our environment beyond CO2 emissions. First, I will explain how concrete can become a source of PFAS (per- and polyfluoroalkyl substances) release due to exposure to Aqueous Film-Forming Foam (AFFF); PFAS can infiltrate concrete, leading to its release from concrete over time. I will highlight some of our findings on the mechanisms of PFAS transport in concrete under unsaturated conditions. Secondly, I will discuss the transport of Tetrachloroethylene (PCE) and benzene in concrete, a problem that arises when a concrete pipe carries water through soils contaminated with chlorinated solvents or hydrocarbon fuels. I will describe the transport mechanisms involved and how we have measured them. In each of these areas, I will share my thoughts on future research directions and the fundamental questions that remain for the next generation of scientists and engineers to address.