Researchers at Washington State University have developed permeable sealants through nanomaterials engineering that better protect concrete from moisture and salt corrosion. Moisture and salt are the primary threat factors that cause concrete infrastructure to collapse in the northern states.
Comparing the results of the laboratory study with the sealants on the market, the new sealant improved by 75% in terms of waterproof and moisture resistance, and 44% in reducing salt corrosion. This work could provide new ways for the United States to address aging bridges and sidewalks.
Professor Shi Xianming of the Department of Civil and Environmental Engineering, who led the work, said: "We focus on moisture resistance, which is one of the main factors affecting the integrity and durability of concrete. If concrete is kept dry, most durability problems will be solved. ”
Professor Shi and his graduate students recently published their work in the Journal of Civil Engineering Materials and filed for a provisional patent.
Screenshot of the paper
Many of the nation's critical infrastructure, such as the U.S. highway system, was built in the 1950s and 1970s and is now nearing the end of its design lifespan. Since the late 1990s, the American Society of Civil Engineers has provided a U.S. Infrastructure Report every four years, and the results have been poor or even failed. In the United States, about 8 percent of every roughly 600,000 bridges are considered structurally flawed, and one in every 5 miles of highway pavement is in poor condition. In cold climates, the problem has become exacerbated by repeated freezing and melting, as well as concrete degradation caused by increased use of de-icing salts in recent decades.
"Although concrete looks like hard rock, it looks like a sponge under a microscope." Professor Shi said, "It is a highly porous, heterogeneous composite material. ”
Comparison of concrete samples coated with nano-modified sealants (left) and untreated concrete samples (right| references[2]
Professor Shi mentioned that local sealants have become a tool for protecting concrete, and many state transportation departments use them to protect bridge decks, especially those that are very badly corroded by salt. Sealants on the market can provide some degree of protection, but moisture always gets into the concrete.
In their study, the researchers added two nanomaterials, graphene oxide and montmorillonite nano-clay, to the commercial silicate sealant. Nanomaterials make the microstructure of concrete dense, making it difficult for liquid water to penetrate. They also form a barrier against water vapor and other gases from entering the concrete. Nanomaterials also protect concrete from physical and chemical attack by de-icing salts. Designed for versatility, permeable sealants can also be used as a curing aid for uncoagulated concrete.
Professor Shi added that the sealant developed by Washington State University is water-based rather than using organic solvents, which means it is more environmentally friendly and safer for workers.
"The conventional wisdom is that using water instead of organic solutions means reducing the performance of the sealant." "And we've shown that using nanomaterials can mitigate the problem of performance degradation," he said. ”
Researchers have conducted a preliminary market analysis with industry stakeholders and are investigating ways to further optimize sealants. They have already begun working on the nanomaterial-based sealant, trying to reveal the extent to which the sealant can help protect concrete from microbial damage or wear. They plan to conduct pilot-scale demonstrations over the next two years, with concrete infrastructure trials on the Campus of Washington State University or in Pullman.
This work was supported by the WSU-led National Center for Transportation Infrastructure Durability and Life-Extension and the WSU Office of Commercialization, led by the University of Washington.
bibliography
[1]https://www.eurekalert.org/news-releases/943613
[2]https://news.wsu.edu/press-release/2022/02/16/nano-engineered-sealer-leads-to-more-durable-concrete/
[3] https://ascelibrary.org/doi/10.1061/%28ASCE%29MT.1943-5533.0004148
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Research team
Corresponding author Xianming Shi: Professor in the Department of Civil and Environmental Engineering at Washington State University, committed to reducing infrastructure and environmental degradation and achieving sustainable road maintenance and operations through interdisciplinary research.
Lead author Zhipeng Li: Graduate Research Assistant, Department of Civil and Environmental Engineering, Washington State University.
Published the Journal of Materials in Civil Engineering
Published January 18, 2022
论文标题Effects of Nanomaterials on Engineering Performance of a Potassium Methyl Siliconate–Based Sealer for Cementitious Composite
(DOI:https://doi.org/10.1061/(ASCE)MT.1943-5533.0004148)
The areas of the article are cement, nanomechanics, traffic engineering
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