Gabriel Arce

Bacterial concrete is a promising self-healing alternative due to its ability to seal cracks. However, to ensure effective self-healing, bacteria must be protected from the harsh conditions... Practical ApplicationsThere is a type of concrete capable of healing its own cracks through bacterial activity. However, bacteria struggle to survive in the harsh environment of concrete. Many rese...

Supplementary cementitious materials (SCMs) are key for the durability of transportation infrastructure. Fly ash (FA), the most used SCM in the U.S.A., is becoming scarce, creating issues for state departments of transportation. To address the FA shortage, reclaimed FA products are becoming available; however, this is only a temporary solution. A promising long-term solution is the use of calcined clay (CC) either in the form of limestone calcined clay cement (LC3) or LC3-like systems, known as LC2, where Portland limestone cement (PLC) is simply blended with CC. This study examines the particle size, chemical composition, reactivity, strength activity, and effects on workability of two CCs (CC-1 and CC-2) from U.S. sources, and compares these to reclaimed FA and slag cement (SC). CC-1 was chosen for further studies in mortars because of its commercial availability in powder form. Mortar specimens with six binder systems (LC3, LC2-30% CC, LC2-50% CC, PLC, PLC-30% FA, and PLC-50% SC) and two water-to-binder ratios (0.4 and 0.45) were produced and systematically compared. Early- and long-term strength development, heat of hydration, bound water, calcium hydroxide content, and environmental impacts were evaluated. Results suggest that LC2 and LC3 systems are promising alternatives to alleviate the FA shortage, particularly because of their comparable or superior performance in key parameters such as strength development and environmental impact compared to the PLC system.

Alkali–silica reaction (ASR) can create significant cracking, compromising the durability and structural integrity of concrete elements. Currently, there is no known way to halt or reverse ASR damage, and the expansion will continue until it impairs ride quality or structural capacity, requiring the replacement of the affected elements. For certain existing structures or structural elements, the progression of an alkali–silica reaction may slow down depending on the type, dimensions of the affected element, service conditions, and environmental factors. Early intervention with repairs, however, may delay the need for replacement and extend the service life of the structure. Repair methods, such as crack filling, sealing, and breathable coatings, help reduce moisture intake and slow expansion. These repairs can also be combined with strengthening techniques to counteract the expansive forces caused by ASRs. The primary goal of these repairs is to extend the life of the structure until replacement or abandonment is necessary. There is a lack of information regarding the long-term performance of repairs and the most widely accepted repair methods. However, the literature and knowledge from the field shows that the time gained through these repairs varies significantly depending on location and exposure conditions, indicating that replacement remains the only reliable solution. Still, given that repairs can cost only 10–20% of full replacement, they remain a viable option for agencies managing limited budgets for immediate replacement.