 | | Univ. of London Researchers Pave the Way to Salt-Resistant Concrete : 13/08/2019 | | International Society for Concrete Pavements (https://www.concretepavements.org/2019/08/13/univ-of-london-researchers-pave-the-way-to-salt-resistant-concrete/)
Every year, salt—also known as sodium chloride—gets spread in vast quantities on roads and pavements to stop them freezing. Water usually freezes at 0C (32F), but when salt is added, the freezing temperature drops below this level, and the salt prevents water particles from creating solid ice crystals. Most of this salt is ultimately washed away, but large quantities are absorbed as salty water, which causes the concrete to deteriorate and steel within to rust and corrode.
Now, researchers from Brunel University London have devised a new concrete mix that can be added to concrete to protect it from the harms of the salt sprinkled on streets and pavements during the winter in Europe and many other countries—that absorbs 64% less water and 90% less salt than normal concrete, while being up to 42% stronger. It’s hoped the new mix could lead to pavements that are best placed to withstand their annual dousing of salt.
Project Lead, Mazen Al-Kheetan, Ph.D. Student-Department of Civil and Environmental Engineering-Brunel University London said, “Incorporation of a sodium acetate compound into concrete, at the mixing stage, works on absorbing some of the water to form crystals that line the walls of the pores in the concrete. who is leading the project. These crystals increase the hydrophobicity of the concrete—the amount concrete repels the water—which ensures the reduction of water uptake through the pores. Also, when applying de-icing salt to pavements made from this concrete mix, the presence of the protective compound within the pores work on fending off both the water and the waterborne chlorides.”
Mr Al-Kheetan added that while ‘the long-term performance of this material is being evaluated’, the research team is confident that new mix can offer substantial economic advantages, as it’s cheap and easy to prepare, unlike currently available alternatives. They’re also confident that while the new mix offers better protection from salt damage, it doesn’t do so at the expense of performance in other areas.
“In our initial experimental work, we noticed that using the sodium acetate compound might reduce the compressive strength of concrete, despite its advantage in reducing the water absorption of concrete. Accordingly, we have worked on producing an optimum formulation of concrete with optimum compound dose to achieve maximum protection and preserved strength. Interestingly, we managed to produce concrete with the incorporated compound that has 64% less permeability than normal concrete and reduces chloride ingress by more than 90%. Meanwhile, when it came to the compressive strength of concrete, a maximum strength gain of 42% was achieved,” said Mr Al-Kheetan.
Speaking about the possibility of using this concrete mix in regions other than Europe, Dr. Moujib Rahman, co-author of the study, told Asharq Al-Awsat, ASHARQ AL-AWSAT Online News-CAIRO, “This concrete can be used in the making of bridges, pavements, highways, houses, ports, and infrastructures or any surface that usually sees heavy rainfalls or salt precipitations.
He added, “During our three-year study, we added different quantities of the sodium acetate compound to different concrete mixes, until we achieved the perfect mix providing these benefits. The new concrete mix still needs more long-term tests in cold and warm weathers, before it becomes available for the industrial use, noting that we still need two to three years of experiments before we can use the new mix on the roads.”
The initial surface absorption test, salt ponding, and compressive strength tests along with scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy analyses were conducted to evaluate the performance and investigate the interaction mechanism of each mixture. The results demonstarted that an optimum mix design could be produced by adding 4% ASAc into mixes with w/c ratio of 0.37 or 0.32. (From Abstract of research paper).
The RESEARCH PAPER titled “Integration of Anhydrous Sodium Acetate (ASAc) into Concrete Pavement for Protection against Harmful Impact of Deicing Salt” was recently published in the Journal of The Minerals (JOM), Metals & Materials Society: https://link.springer.com/article/10.1007/s11837-019-03624-3 | |
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