Nano-engineered sealer leads to more durable concrete

Date:
February 16, 2022
Source:
Washington State University
Summary:
A nanomaterials-engineered penetrating sealer is able to better
protect concrete from moisture and salt -- the two most damaging
factors in crumbling concrete infrastructure in northern states. The
novel sealer showed a 75% improvement in repelling water and a 44%
improvement in reducing salt damage in laboratory studies compared
to a commercial sealer.



FULL STORY ==========================================================================
A nanomaterials-engineered penetrating sealer developed by Washington
State University researchers is able to better protect concrete from
moisture and salt -- the two most damaging factors in crumbling concrete infrastructure in northern states.


==========================================================================
The novel sealer showed a 75% improvement in repelling water and a 44% improvement in reducing salt damage in laboratory studies compared to a commercial sealer. The work could provide an additional way to address
the challenge of aging bridges and pavements in the U.S.

"We focused on one of the main culprits that compromises the integrity
and durability of concrete, which is moisture," said Xianming Shi,
professor in the Department of Civil and Environmental Engineering
who led the work. "If you can keep concrete dry, the vast majority of durability problems would go away." Shi and graduate student Zhipeng
Li recently published their work in theJournal of Materials in Civil Engineering and have applied for a provisional patent.

Much of the nation's critical infrastructure, such as the U.S. highway
system, was built from the 1950s to the 1970s and is now reaching the
end of the lifetime for which it was designed. Every four years since
the late 1990s, the American Society of Civil Engineers has provided a
report card of U.S.

infrastructure that shows consistently poor or failing grades. About 8%
of approximately 600,000 bridges in the U.S. are considered structurally deficient, and one out of every five miles of highway pavement is in
poor condition. The problem is exacerbated in cold climates by multiple
freeze and thaw cycles and by the increased use of deicer salts in recent decades, which can degrade the concrete.

"Concrete, even though it seems like solid rock, is basically a sponge
when you look at it under a microscope," Shi said. "It's a highly porous, non-homogenous composite material." Topical sealers have emerged as one
tool to protect concrete, and many state departments of transportation
use them to protect bridge decks in particular, which seem to suffer the
worst from salt damage. The sealers on the market provide some level of protection, but moisture is often able to make its way into the concrete,
Shi said.

In their study, the researchers added two nanomaterials, graphene
oxide and montmorillonite nanoclay, to a commercial siliconate-based
sealer. The nanomaterials densified the microstructure of the concrete,
making it more difficult for liquid water to penetrate. They also formed
a barrier against the intrusion of water vapor and other gasses that tend
to make their way into the concrete. The nanomaterial also protected the concrete from the physical and chemical attacks of deicing salts. The penetrating sealer is designed to be multi-functional, as it can also
serve as a curing aid for fresh concrete.

The WSU sealer is water-based instead of using any organic solvent, which
means it's more environmentally friendly and safer for workers, Shi added.

"Traditionally, when you switch from an organic solvent to water, you
sacrifice the sealer's performance," he said. "We demonstrated that
the use of nanomaterials mitigates that reduction in performance."
The researchers have done preliminary market analysis with industry stakeholders and are studying ways to further optimize the sealers. They
are investigating how the nanomaterials-based sealers might help protect concrete from microbial damage or abrasion, the daily wear and tear
that damages the material in high-traffic areas. They plan to conduct pilot-scale demonstrations in the next two years, deploying an experiment
of concrete infrastructure on the WSU campus or in the city of Pullman.

The work was supported by the WSU-led National Center for Transportation Infrastructure Durability and Life-Extension and the WSU Office of Commercialization.

========================================================================== Story Source: Materials provided by Washington_State_University. Original written by Tina Hilding. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zhipeng Li, Xianming Shi. Effects of Nanomaterials on Engineering
Performance of a Potassium Methyl Siliconate-Based Sealer for
Cementitious Composite. Journal of Materials in Civil Engineering,
2022; 34 (4) DOI: 10.1061/(ASCE)MT.1943-5533.0004148 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220216083006.htm

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