Papers by Author: Jeffery S. Volz

Abstract: Self-consolidating concrete (SCC) has the potential to significantly reduce costs associated with concrete construction. SCC is a highly flowable, nonsegregating concrete that has a variety of advantages over conventional concrete (CC). However, SCC is not without its problems, which can include increased creep and shrinkage, as well as decreased bond and shear strength. The goal of this research project was to evaluate the creep, shrinkage, and shear behavior of a chemically-based SCC mix. One of the benefits of a chemically-based approach is the potential to eliminate the negative side effects of many SCC mixes. The investigation included development of the mix design, construction and testing of creep and shrinkage specimens, and construction and testing of full-scale beam specimens to evaluate the shear behavior. The results indicate that a chemically-based SCC performs as well or better than conventional portland-cement concrete.

Abstract: With worldwide production of fly ash approaching 800 million tonnes annually, increasing the amount of fly ash used in concrete will remove more material from the solid waste stream and reduce the amount ending up in landfills. However, most specifications limit the amount of cement replacement with fly ash to less than 25 or 30%. Concrete with fly ash replacement levels of at least 50% – referred to as high-volume fly ash (HVFA) concrete – offers a potential green solution. The following study investigated the structural performance of HVFA concrete compared to conventional portland-cement concrete. Specifically, the research examined both the bond strength of reinforcing steel in HVFA concrete as well as the shear behavior of HVFA reinforced concrete. The results indicate that HVFA concrete performs as well or better than conventional portland-cement concrete.

Abstract: In this study, the corrosion process of enamel-coated deformed rebar completely immersed in 3.5 wt.% NaCl solution was evaluated over a period of 84 days by EIS testing. Three types of enamel coating were investigated: pure enamel, 50/50 enamel coating, and double enamel. Surface condition of the enamel coatings that were intentionally damaged prior to corrosion tests was visually examined at different immersion times. After 84 days of testing, the damaged coating areas were characterized by SEM, and the corrosion products on and adjacent to the damaged areas were collected and analyzed by XRD. Corrosion initiated at the damaged locations with no undercutting of the coating observed. The 50/50 enamel coating had the least corrosion resistance, due to its interconnected pore structure, and prior damage drastically reduced the corrosion resistance of pure and double enamel coated rebar.