Faculty Researcher Spotlight
Fred Aguayo, Department of Engineering Technology
Reducing the Carbon Footprint in Concrete Construction
"My research group is looking at how to move from conventional Portland cement to alternative or non-Portland cement binders with better environmental results and improved durability."
While at Texas State, my primary research interest has been in developing and evaluating new and sustainable cement-based materials used in concrete and on increasing their application in modern construction practice. Most concrete used today relies on environmentally unfriendly materials, so our research group focuses on finding ways to reduce the carbon footprint in concrete construction while still maintaining or improving long-term performance.
In the production of concrete, the primary ingredient, Portland cement powder, typically provides mechanical strength and binding properties. While most concrete producers worldwide use this type of cement in their mixtures, many new alternative binders now exist that can partially or even totally replace it. Many of these alternatives are formulated to have similar and, in some cases, improved performance to that of ordinary Portland cement. My research group is looking at how to move from conventional Portland cement to alternative or non-Portland cement binders with better environmental results and improved durability. We primarily focus on two ways of doing this:
- Use more environmentally-friendly binders: We are using binders that don’t require as much heat or energy to be produced and thus reduce the amount of harmful emissions into the atmosphere. The production of Portland cement requires a significant amount of heat and burns high amounts of calcium carbonate (CaCO3), which releases CO2 into the atmosphere. The release of this harmful greenhouse gas is often seen as the “ugly” side of the concrete industry. The reality is that when compared to many other building materials such as iron or steel, Portland cement production is better controlled, with significantly lower emissions. However, the cement industry has not done a great job over the last few decades in reducing these amounts or in achieving historically low levels.
Fortunately, there are now several other binder systems on the market that don’t require as much energy for production and that have similar and, in some cases, better qualities than Portland cement. Yet, their long-term history and research performance is limited, making their use in the field minimal compared to Portland cement. Research like ours is designed to reverse this trend by increasing our understanding of how these alternative binders perform.
- Use waste materials in concrete: In addition to better understanding the use of alternative binder systems, our group also focuses on how we can utilize waste material to increase our concrete’s performance. This ultimately has two positive effects: reduces the amount of waste being landfilled and thus recycles materials; and reduces the amount of cement used in concrete, ultimately reducing harmful emissions.
Most recently, our team was awarded a research project by the Texas Department of Transportation (TxDOT) designed to accelerate the construction time of Texas highways and bridges through the use of rapid setting hydraulic cements. We will investigate the feasibility and potential of using these materials in structural concrete.
For this project, we are looking at some interesting alternative binders. These are considered rapid-setting/hardening cements because they can become as strong as 28-day-old Portland cement concrete in a matter of just a few hours! Because of this unique characteristic, these binders are often used in repair applications that need to be completed as quickly as possible, such as highway pavement and lane/traffic closures. However, they have very little use in structural concrete such as columns, beams, piers, etc. due to their limited research in long-term performance. In fact, they are currently NOT allowed to be used in structural concrete at all in TxDOT specifications because of this.
But because of their fast-setting characteristics, these alternative binders have the potential for use in bridge and road construction, greatly reducing the length of these projects. This will ideally bring significant cost savings to a construction project, increase safety, and ease the burden millions of frustrated drivers feel when commuting through construction projects.