Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering
Zachary Shepard - Assumption College
Co-Author(s): Surabhi Godble, Northeastern University, Boston Ivan Ding, Xuejian Lyu, Aaron Sakulich, and Amy Peterson, Worcester Polytechnic Institute, Worcester, MA
Roads and bridges in the United States are in a state of disrepair due to the corrosion of concrete-reinforcing rebar. When rebar corrodes, it expands in volume, which leads to cracking of the concrete and degradation of roadways. The goal of this project was to develop an epoxy and microcapsule-based self-healing coating that would utilize tung oil to prevent corrosion. Microcapsules synthesized for this project were poly(urea-formaldehyde) shells with a tung oil core. SEM images demonstrated the effect of reaction conditions (pH, reaction time, amount of shell material, and amount of surfactant) on the formation of microcapsules. Steel rebar was coated in epoxy containing suspended microcapsules, both optimized through the modification of reaction conditions and a baseline capsule (Brown et al, 2003). The experiment involved rebar samples that were uncoated, coated with unmodified epoxy, coated with epoxy and 1% wt. optimized microcapsules, coated with epoxy and 10% wt. optimized microcapsules and coated with epoxy and 10% wt. baseline microcapsules. Half of the unmodified, 1% wt., and 10% wt. coated samples (optimized and baseline microcapsules) for accelerated corrosion testing were impact damaged in order to assess the self-healing capabilities of the coating. Impact damaging ruptured the microcapsules in the epoxy coating and released the encapsulated tung oil. Accelerated corrosion testing (still ongoing) was used to determine the effect of the coating on the corrosion process. Pullout testing determined the effect of the coating on the bond between the rebar and concrete and showed that the bond interface between the rebar and the concrete was not affected by the coating. Based on the current test results, a microcapsule-based self-healing coating is a viable method for corrosion prevention. Some of the questions addressed in the project remain unanswered. Accelerated corrosion testing is still ongoing and will test the effect of the coating on corrosion prevention. Future research questions involve multiple dip coating of rebar in unmodified epoxy to determine the effect of coating thickness.
Funder Acknowledgement(s): National Science Foundation Award #1359064 (Title - REU Site: Interdisciplinary Research On Sustainable Infrastructure Materials, PI - A. Sakulich).
Faculty Advisor: Aaron Sakulich, firstname.lastname@example.org
Role: I played a role in all of the research mentioned in the submitted abstract. I cut, cleaned, and coated rebar with experimental coatings. The rebar was encased in concrete, which I mixed and cured. I made 70 rebar and concrete samples for pullout and accelerated corrosion testing and 15 concrete compression cylinders. I ran the pullout testing and attempted to start accelerated corrosion testing, but I could not rebuild the set up (I spent two weeks trying). I synthesized about 40 batches of microcapsules and assisted in the imaging of some of them.