Currently, in Texas, there is a need for different repairs on pavements and bridge decks; rapid repair materials designed for these repairs are available but the service life and durability of these products are often inadequate. Thus, the goal for the Texas Department of Transportation (TxDOT) is to implement repairs with an extended service life in a timely manner, in order to cause minimal disruption. Research performed under TxDOT Project 6723 (Development of Rapid, Cement-based Repair Materials for Transportation Structures) evaluated a wide range of rapid repair materials, including calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), fly ash alkali activated blends, and ordinary portland cement. Some of the properties which contribute to a long-term service life are: mechanical properties, early-age volume change, and the heat evolution; often, the early-age development of these repair materials can cause later durability issues. These properties were examined through a variety of experiments and test in the laboratory, as well as, in the field. / text

Composite materials have a wide range of applications in civil and structural engineering due to their advantages in mechanical properties and higher strengths over the base materials alone. Polymer-concrete composites are particularly attractive for use in industrial and infrastructure applications from combining the higher mechanical properties of the concrete in tension and the high tensile strength and ductile properties of the polymeric materials. However, these materials tend to be more expensive that typical concrete composites. This thesis explores the mechanical properties of two different polymer-concrete composites and their effectiveness in civil and structural applications: polymer concrete for rapid repair and 3D printed plastic-concrete composite members for energy absorption. The North Atlantic Treaty Organization (NATO) requires that emergency repair of military runways should be completed within 4 hours. In coordination with Luna Innovations Incorporated, a polymer concrete was developed by Luna for use as a rapid repair material for military runways to meet this requirement through its rapid heat curing. Its mechanical properties including its compressive and flexural strength, bond strength in various orientations, workability, modulus of elasticity, and coefficient of thermal expansion were tested and compared against another rapid repair material. The Tri-Service Pavements Working Group Manual recommendations for rigid repair materials were used as the requirements in determining whether the polymer concrete was an adequate rapid repair material. The polymer concrete formulation that was down-selected for further testing met these requirements for all tests except for the coefficient of thermal expansion. This was due to the resin itself having a high volumetric expansion when exposed to greater temperatures. As the polymer concrete is still under development, future tests are to be performed to determine the impact of the higher expansion on the surrounding runways. Additionally, inspired from naturally forming nacre found in some seashells, a 3D printed plastic-concrete beam structure was developed and tested in flexure to determine its energy absorption capabilities. The nacreous structure allows the material to experience a strain-hardening behavior, thus allowing for energy dissipation in the beam as it deflects from further applied load. It is theorized that the energy absorption capabilities would be suitable for withstanding the effects of dynamic loadings in structures, such as earthquake and blast loads. Multiple beam structures were developed and tested to determine the impact of percent-polymeric material and layout had on the energy dissipation. Overall, the specimens with more polymer in the cross-section demonstrated larger load vs. crack mouth displacement curves and fracture energy. These specimens demonstrated a higher toughness as well, making them more suitable for use in structural applications. As the project is still in development, future tests and analysis must be performed to determine their strength properties and feasibility as a structural material. The results of this thesis highlight the benefits of novel polymer composites in industrial and infrastructure applications, such as improved rapid setting characteristics and significantly enhanced mechanical and energy absorbing performance. Future work is needed to optimize these performance metrics, such as freeze thaw cycling, fatigue, and durability tests for the polymer concrete and analysis of moment capacity for the bioinspired nacreous composites. / Master of Science / Composite materials have a wide range of applications in civil and structural engineering due to their advantages in mechanical properties and higher strengths over the base materials alone. Polymer concrete composites are not as widely used due to their greater initial costs. However, they are very attractive in industrial and infrastructure applications because of the improved behavior in tension. This thesis explores the mechanical properties of two different polymer-concrete composites and their effectiveness in civil and structural applications: polymer concrete for rapid repair and 3D printed plastic-concrete composite members for energy absorption. The North Atlantic Treaty Organization (NATO) requires that emergency repair of military runways should be completed within 4 hours. In coordination with Luna Innovations Incorporated, a polymer concrete was developed by Luna for use as a rapid repair material for military runways to meet this requirement through its rapid heat curing. Its mechanical properties were tested and compared against another rapid repair material. The polymer concrete formulation that was down-selected for further testing met the requirements of the military for all tests performed except for the coefficient of thermal expansion. As the polymer concrete is still under development, future tests are to be performed to determine the impact of the higher expansion on the surrounding runways. Additionally, inspired from naturally forming nacre found in some seashells, a 3D printed plastic-concrete beam structure was developed and tested in bending to determine its energy absorption capabilities. The nacreous structure allows the material to experience a strain-hardening behavior, thus allowing for energy dissipation in the beam as it deflects from further applied load. It is theorized that the energy absorption capabilities would be suitable for withstanding the effects of earthquake and blast loads in structures. Multiple beam structures were developed and tested to determine the impact of percent-polymeric material and layout had on the energy dissipation. Overall, the specimens with more polymer in the cross-section demonstrated greater energy absorption capabilities. As the project is still in development, future tests and analysis must be performed to determine their strength properties and feasibility as a structural material. The results of this thesis highlight the benefits of novel polymer composites in industrial and infrastructure applications, such as improved rapid setting characteristics and significantly enhanced mechanical and energy absorbing performance. Future work is needed to optimize these performance metrics, such as freeze thaw cycling, fatigue, and durability tests for the polymer concrete and analysis of moment capacity for the bioinspired nacreous composites.

For repairing concrete transportation infrastructure, such as pavements and bridges, much importance is placed on early-age strength gain as this has a major impact on scheduling and opening to traffic. However, the long-term performance and durability of such repair materials are often not satisfactory, thus resulting in future repairs. This research project focuses on the evaluation of the durability of various rapid-setting cementitious materials. The binders studied in this project include calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), Type III portland cement, alkali-activated fly ash (AAFA) , and various prepackaged concrete materials. In addition, selected CAC and CSA mixtures were further modified with the use of a styrene-butadiene latex. The durability aspects studied include freezing-and-thawing damage and the implications of air entrainment in these systems, alkali-silica reaction, sulfate attack, and permeability of the concrete matrix and potential corrosion. / text