Wax on, melt offSeptember 13, 2017
Drexel University researchers have made a discovery that could create roads that deice themselves during winter storms. Their secret? -- Adding a little paraffin wax to the road's concrete mix.
In a paper recently published in journal Cement and Concrete Composites researchers, led by Yaghoob Farnam, PhD, an assistant professor in Drexel's College of Engineering, explain how substances like paraffin oil -- known as "phase change materials" in chemistry -- can be used in concrete to store energy and release it as heat when a road needs a melt-off.
Keeping roads open to travel is a persistent challenge during winter months, but efforts to make them safely passable -- including the constant use of snow plows, deicing chemicals and road salt -- tend to deteriorate the surface. The chemicals and road salts currently used to melt snow and ice can also have a deleterious environmental impact when surface runoff carries them into nearby ecosystems -- which is pretty likely considering the state of Pennsylvania alone dumps more than 900,000 tons of it on roads each winter. So researchers have been searching for a better winter option than salting and plowing for some time.
Farnam's group in collaboration with researchers from Purdue University and Oregon State University, is among the first to demonstrate that using phase change materials as an environmentally friendly alternative can be just as effective as the standard salting and scraping methods.
"Phase change materials can be incorporated into concrete using porous lightweight aggregate or embedded pipes and when PCM transforms from liquid to solid during cooling events, it can release thermal heat that can be used to melt ice and snow," Farnam said. "By inhibiting the formation of ice and snow on the pavement or bridge surface, the use of PCM may reduce or eliminate the need for deicing chemicals/salts, snowplowing or both -- thus saving money and positively influencing the environmental impact of such operations."
Paraffin oil, a common ingredient in candles, wax polishes, cosmetics and water-proofing compounds, was their material of choice for this endeavor because it is organic, widely available, chemically stable and relatively inexpensive. Like all phase change materials, it releases thermal energy when it changes its physical state, which means as temperatures drop and the oil begins to solidify it releases energy through latent heat of fusion. This means paraffin oil can be tailored to embed deicing capabilities in a road surface so that it becomes thermally active during snow events or when deicing is needed.
To test its snow and ice-melting ability, the team created a set of concrete slabs -- one with paraffin-filled pipes inside, one containing porous lightweight aggregate that had been infused with paraffin, and a third reference slab without paraffin. Each was sealed in an insulated container and then covered with about five inches of lab-made "snow."
With temperatures inside the boxes held between 35-44 degrees Fahrenheit, both of the paraffin-treated slabs were able to completely melt the snow within the first 25 hours of testing, while the snow on the reference sample remained frozen. The slab with the paraffin-filled tubes melted the snow slightly faster than the one composed of paraffin-treated aggregate. Farnam suggests that this is because the paraffin inside the tubes is able to solidify more quickly -- thus releasing its energy -- because of the regular diameter of the pipes. While the diameter of the pores of the aggregate vary in size.
But in the group's second experiment, in which the ambient air temperature in the box was lowered to freezing before the snow was added, the paraffin-treated aggregate was more effective than the embedded pipes. This is because the capillary pore pressure delayed the freezing of the paraffin, thus allowing it to release its heat energy over a longer period of time.
"The gradual heat release due to the different pore sizes in porous light-weight aggregate is more beneficial in melting snow when concrete is exposed to variety of temperature changes when snow melting or deicing is needed," Farnam said. "We believe that using porous lightweight aggregate can be potential way of incorporating phase change materials in concrete as it is easy to be implemented in practice and can cover environmental conditions of various locations in the US dealing with snow, especially melting snow or deicing in roads and bridges in the Northeast."
One of the first uses of this infrastructure technology could be at airports, where keeping runways clear of snow and ice is vital and a perpetual challenge in the winter. The Federal Aviation Administration supported this research as part of its Heated Airport Pavements Project in its Partnership to Enhance General Aviation Safety, Accessibility and Sustainability program.
"Additional research is needed to further understand other factors influencing concrete constructability, including concrete fresh and hardened performance when the concrete contains phase change materials, and the phase change material's thermal performance in different locations in the U.S.," Farnam said. "Eventually this could be used to reduce the amount of deicing chemicals we use or can be used as a new deicing method to improve the safety of roads and bridges. But before it can be incorporated, we will need to better understand how it affects durability of concrete pavement, skid resistance and long-term stability."
Related Concrete Articles:
UBC engineers have developed a more resilient type of concrete using recycled tires that could be used for concrete structures like buildings, roads, dams and bridges while reducing landfill waste.
Engineers have known for some time that calcium chloride salt, commonly used as deicer, reacts with the calcium hydroxide in concrete to form a chemical byproduct that causes roadways to crumble.
It has been possible to demonstrate scientifically that tobermorite can be produced at 400 C when above 200 C it had been thought to be impossible.
Professor of the Institute of Civil Engineering of Peter the Great Saint-Petersburg Polytechnic University (SPbPU) Andrey Ponomarev and a graduate student Alexander Rassokhin developed a new construction technology.
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed.
Engineering research at the University of Nottingham, UK, and Ningbo, China, has found laser scanning is a new and viable structural safety technique to detect the damaging effects of fire on concrete.
Rice University materials scientists develop techniques to control the microscopic shape of cement particles for the bottom-up manufacture of stronger, more durable and more environmentally friendly concrete.
TU Dresden's professors Manfred Curbach, Chokri Cherif, and Peter Offermann are the winners of the 'Deutscher Zukunftspreis 2016' (German Future Award).
Cement manufacturing is among the most carbon-intensive industrial processes, but an international team of researchers has found that over time, the widely used building material reabsorbs much of the CO2 emitted when it was made.
University of Nebraska engineers Christopher Tuan and Lim Nguyen have developed a cost-effective concrete that shields against intense pulses of electromagnetic energy.
Related Concrete Reading:
Concrete (Mini Format)
by William Hall (Author), Leonard Koren (Contributor)
A visual exploration of the world's most extraordinary and inspiring concrete architecture - in a stylish and compact format.
"Yes, concrete can be cold and imposing - but as the structures in the book attest, it can also be colourful, playful, and delicate." —Wall Street Journal
In this new, reimagined, and easy-to-use stylish size, Concrete takes a fresh look at the world's most versatile and abundant building material. Collating fascinating and beautiful concrete buildings by some of the most celebrated architects of the last century, it features familiar... View Details
Foundations & Concrete Work: Revised and Updated (For Pros By Pros)
by Editors of Fine Homebuilding (Author)
Building a good foundation is critical to any home. Is it glamorous work? No, but it’s vital as it provides a solid structure upon which all other work rests. Written by seasoned builders from across the country, this revised edition of Foundations & Concrete Work features 15 new articles from Fine Homebuilding magazine, the most respected residential construction magazine in the country.
With more than 300 on-the-job photos and drawings, this resource distills decades of hands-on, builder-tested methods and techniques and places them right into... View Details
Reinforced Concrete: Mechanics and Design (7th Edition)
by James K. Wight (Author)
For courses in architecture and civil engineering.
Reinforced Concrete: Mechanics and Design uses the theory of reinforced concrete design to teach readers the basic scientific and artistic principles of civil engineering. The text takes a topic often introduced at the advanced level and makes it accessible to all audiences by building a foundation with core engineering concepts. The Seventh Edition is up-to-date with the latest Building Code for Structural Concrete, giving... View Details
Concrete Manual: Based on the 2015 IBC and ACI 318-14
by P.E Gerald B. Neville (Author)
The Concrete Manual, now updated to the 2015 IBC and ACI 318-14, provides the guidance and information that inspectors and other construction professionals need to become more proficient in concrete field practices and inspection. The Concrete Manual will: • Introduce concrete and explain what it is and why it behaves as it does • Explain conventional concrete construction procedures • Cover special concrete technologies such as Autoclaved, self-consolidating and pervious • Discuss control and inspection procedures • Explore statistical quality control methods and their application... View Details
Design of Reinforced Concrete
by Jack C. McCormac (Author), Russell H. Brown (Author)
Design of Reinforced Concrete, 10th Edition by Jack McCormac and Russell Brown, introduces the fundamentals of reinforced concrete design in a clear and comprehensive manner and grounded in the basic principles of mechanics of solids. Students build on their understanding of basic mechanics to learn new concepts such as compressive stress and strain in concrete, while applying current ACI Code. View Details
The Rose That Grew From Concrete
by Tupac Shakur (Author)
Tupac Shakur's most intimate and honest thoughts were uncovered only after his death with the instant classic The Rose That Grew from Concrete.
His talent was unbounded -- a raw force that commanded attention and respect.
His death was tragic -- a violent homage to the power of his voice.
His legacy is indomitable -- as vibrant and alive today as it has ever been.
For the first time in paperback, this collection of deeply personal poetry is a mirror into the legendary artist's enigmatic world and its many contradictions.
Written in his own hand... View Details
Concrete Planet: The Strange and Fascinating Story of the World's Most Common Man-Made Material
by Robert Courland (Author), Dennis Smith (Foreword)
Concrete: We use it for our buildings, bridges, dams, and roads. We walk on it, drive on it, and many of us live and work within its walls. But very few of us know what it is. We take for granted this ubiquitous substance, which both literally and figuratively comprises much of modern civilization’s constructed environment; yet the story of its creation and development features a cast of fascinating characters and remarkable historical episodes. This book delves into this history, opening readers’ eyes at every turn.
In a lively narrative peppered with intriguing details, author... View Details
Guide to Concrete: Masonry & Stucco Projects (Quikrete)
by Phil Schmidt (Author)
Concrete information for long-lasting concrete projects
This book is an all-new hardworking visual guide to the most popular home concrete and masonry projects, endorsed by the biggest manufacturer of concrete products in North America. Readers can save hundreds or even thousands of dollars with this book, since concrete materials are one of the least expensive and long lasting of all building materials.Quikrete Guide to Concrete includes the most common home repairs, but goes a step further by offering some of the most exciting new techniques... View Details
Working with Concrete (For Pros By Pros)
by Rick Arnold (Author)
Whether you're pouring a concrete walkway or staking out the excavation for a basement foundation, doing the job right demands a thorough knowledge of concrete construction techniques. In Working with Concrete, veteran builder Rick Arnold explains everything from mix characteristics and formwork options to waterproofing details and repair procedures. You'll benefit from Arnold's years as a general contractor, framer, and foundation contractor as he offers time- and money-saving advice that comes from understanding the subject from all angles. Get the rock-solid results youre after... View Details
Design and Control of Concrete Mixtures, 16th Edition
by S. H. Kosmatka (Author), M. L. Wilson (Author)
16th Edition! Published in 2016! Do not spend money on an outdated edition! Shrink wrapped and brand new. View Details