The upshot for U.S. homeowners is that moisture damage due to failed sealants is responsible for much of the $65 billion to $80 billion they collectively shell out for house repairs annually.
Researchers at the National Institute of Standards and Technology (NIST) are assembling a toolkit of measurement devices and scientific data that will help manufacturers of sealants systematically improve the protective performance of their products.
Their latest contribution, described in the current issue of the Review of Scientific Instruments,* is an outdoor testing system that tracks real weather conditions—by the minute—and measures the squeezing and stretching that occur in sealants as the building moves with temperature changes.
The NIST-developed testing devices could supplant current methods, which essentially entail exposing sealants to the elements for extended periods with no movement and then visually inspecting the materials for cracks and other signs of degradation. Using materials that can be purchased at the local hardware store—such as wood, PVC pipe and toilet flanges—and combining them with arrays of load and environmental sensors, NIST research chemist Christopher White and his colleagues built a state-of-the-art testing system representative of real-world conditions.
In construction, sealants are used to close gaps between building materials—usually unlike materials, such as steel and glass or wood and concrete. Different materials expand and contract differently in response to changes in temperature, relative humidity and other conditions. Because of these differences between adjacent materials, sealants are regularly stretched, compressed and, in effect, pulled in different directions.
All that motion, White says, can cause the material equivalent of fatigue, tearing and adhesion loss, allowing the water to breach the sealant defense.
"When you apply a sealant to a building joint—such as between window glass and steel in the building frame—you are trying to seal displacements that occur because the materials expand and contract at different rates," White says.
"These new and very inexpensive testing devices," he explains, "induce movements that are very similar to what a sealant would see in the actual application, in a building."
Designs of the experimental testing devices have been shared with a consortium of U.S. sealant manufacturers who have already adopted this new technology. Additionally, these designs are incorporated in a new ASTM draft standard soon to be put to vote.
* C. C. White, K. T. Tan, E. P. O'Brien, D. L. Hunston, J. W. Chin and R. S. Williams. Design, fabrication, and implementation of thermally driven outdoor testing devices for building joint sealants. Rev. Sci. Instrum. 82, 025112 (2011); doi:10.1063/1.3543817
Mark Bello | EurekAlert!
Concrete from wood
05.07.2017 | Schweizerischer Nationalfonds SNF
Modular storage tank for tight spaces
16.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
22.08.2017 | Health and Medicine
22.08.2017 | Materials Sciences
22.08.2017 | Life Sciences