Development and Application of Self-Healing Engineered Cementitious Composites (ECC) for Durable and Sustainable Infrastructure.

Abstract

While concrete is the most widely used construction material in the world, its inherent brittle behavior makes it prone to cracking, which negatively impacts the structural resiliency, durability, and sustainability of concrete infrastructure. As the demand for concrete continues to increase, the development of a concrete material that can regain any loss of performance due to cracking is highly desirable.

The development of a concrete that is capable of self-healing could solve many of the challenges associated with cracking seen in current concrete infrastructure. Although many approaches have been used to induce self-healing in concrete, the self-healing of Engineered Cementitious Composites (ECC) has proven to be one of the most promising approaches, as it has shown the ability to achieve recovery of transport and mechanical properties.

This research focused on the further characterization of the self-healing phenomena in ECC and developing a scientific understanding of the observed behavior. In addition to characterizing the self-healing behavior of ECC under the random and sometimes extreme conditions of the natural environment, the effects of age and exposure temperature on the self-healing phenomena were also determined. The experimental observations indicated a strong correlation between the recovery of mechanical properties and cracking characteristics of ECC, and this led to the development of an analytical scale-linking model to predict the level of material stiffness recovery due to self-healing as a function of imposed tensile strain.

Lastly, this work investigated the potential application of self-healing ECC in the railroad industry. There are many technical challenges associated with the prestressed concrete railroad ties in use today, and the development of an ECC railroad tie could mitigate many of these challenges. While the self-healing functionality of ECC would allow ECC ties to regain transport and mechanical properties should damage occur, the ductile nature of ECC could eliminate the need for prestressing steel. These benefits of ECC could increase the durability and sustainability of railroad infrastructure by increasing the service life of ties, decreasing the need for track maintenance, simplifying the tie manufacturing process, and reducing the use of raw materials in comparison to current prestressed concrete ties.