- [기술동향]'Self-healing' roads? ...
- 'Self-healing' roads? Here's how some engineers are working to curb potholes Alvaro Garcia, University of Nottingham; Juliana Byzyka, Brunel University London, and Mujib Rahman, Brunel University London Potholes are a perennial problem. They are dangerous to road users, and the damage they cause to vehicles can be hugely expensive. The cost of repairing them is also vast. But still they appear, and reappear, in countless places. So why do these pesky crevices pose such a difficult challenge? And is there any light at the end of this pothole-filled tunnel? Potholes often begin as imperceptible microscopic cracks in the road surface. Bad weather, poor drainage and heavy traffic can all cause that surface to loosen and wear away. In 2017, more than 2m potholes were repaired on UK roads, at a cost of some £120m. Image: iStock A perennial problem At the moment, where and when these microscopic cracks will appear is hard to determine. But in the future it is likely that high precision measuring techniques will be able to predict the time and location that potholes will appear. To repair the road before potholes grow, machines will be installed into autonomous vehicles, cleaning out the damaged areas and filling them in again. Self-healing roads In the meantime, the development of new types of road material, such as “self-healing” asphalt, something we are investigating at the Nottingham Transportation Engineering Centre, could reduce the necessary frequency of repairs – and hopefully help turn potholes into a distant memory. Asphalt roads are composed of mineral aggregates that give structural stability, and bitumen, a viscous liquid that binds the other materials together. When cracks appear in the road, bitumen drains into the cracks and fills them. The problem is that bitumen is a very viscous liquid at normal temperatures, and the healing of the cracks can take weeks. With regular traffic, the rate of crack growth may occur at a faster rate than they are filled – allowing potholes to form. To accelerate the “healing” of the road, we are exploring the addition of tiny capsules containing asphalt rejuvenators such as sunflower oil, or tall oil, a byproduct of paper production. (The inspiration for the capsules came from watching an episode of the Spanish version of the TV series MasterChef, in which a contestant used a technique to form spheres that resemble caviar when submerged in a liquid.)The idea is that when roads start to crack, the capsules break open and release the oil within, softening the surrounding asphalt. This helps the asphalt stick back together more swiftly, effectively filling in cracks and preventing small defects from deteriorating. With this idea, we expect to delay the first potholes by at least five years, reducing the need for maintenance and all the troubles that come from it, such as slow traffic and travel delays. Warming things up According to the Local Government Association, road repair bills in England and Wales could soon reach £14 billion, dwarfing the £4.4 billion highways budget of councils. Another solution being investigated at Brunel University – which could save a fortune – is the use of infrared heat to make repairs cheaper and longer-lasting. Wet weather, combined with cycles of freezing and thawing, dramatically accelerates pothole development – and many repairs fail prematurely. This is because the traditional way to repair potholes with heat is to inject them with boiling hot asphalt. But if the road is cold, the temperature of the repair material falls significantly, creating weaker bonds with the surrounding material. Some new “repaired” patches can start to show deterioration within a few months. To increase the performance of asphalt patch repair, the Pavement and Ground Engineering Research Group at Brunel has developed the Controlled Pothole Repair System (CPRS). This new method uses a portable infrared heating machine to preheat the road surface (and the area below) before making the repair. The CPRS allows much more precise temperature control, providing much greater bonding strength for the replacement materials. The machine is also designed to be easily transported to repair sites, and is compact enough to be operated within a single lane of the road, so that extensive road closures are avoided. The aim is to deliver repairs that last a lot longer than their current life expectancy. This will create better quality road surfaces that would make for fewer accidents and smaller maintenance budgets. We hope that with further research, CPRS can improve asphalt patch repair to last for as long as five years – as opposed to the average of two years that most authorities currently expect with conventional methods. We estimate this could cut costs by 25% to 50%. Rolled out nationwide, it would mean a network of better quality roads, lower maintenance and compensation costs – and fewer accidents. Alvaro Garcia, Lecturer in Engineering, University of Nottingham; Juliana Byzyka, PhD Candidate, Brunel University London, and Mujib Rahman, Senior Lecturer in Civil Engineering, Brunel University London This article is republished from The Conversation under a Creative Commons license. Read the original article. Source: https://www.wheels24.co.za/News/Gear_and_Tech/self-healing-roads-heres-how-some-engineers-are-working-to-curb-potholes-20180913
- [기술동향]Self-healing concrete
- Self-healing concrete By Arthur HarrissonThe formation of cracks in concrete is a common occurrence and in many cases is not regarded as a major issue. However, in some circumstances they may pose a threat to a concrete structure if its purpose is to prevent the movement of water or if there is a risk of the ingress of deleterious materials. Research is underway in a number of locations to investigate ways of encouraging healing of the cracks without major intervention. A characteristic of Portland cement is its high content of calcium oxide (CaO). In nearly every case this CaO originated as calcium carbonate (CaCO3) in limestone. The process of producing clinker involves heating the limestone in the presence of other materials containing silica (SiO2), iron oxide (Fe2O3) and alumina (Al2O3) so that the CaCO3 loses the CO2 part of its constitution and the remaining CaO combines with the other oxides to form the compounds we know in clinker as alite (tricalcium silicate), belite (dicalcium silicate), aluminate (tricalcium aluminate) and ferrite (tetracalcium alumino-ferrite) phases. The exact stoichiometry of these phases varies, sometimes quite appreciably, from the chemical analyses implied by the names in brackets. Source: https://www.cemnet.com/Articles/story/164873/self-healing-concrete.html
- [기술동향]Self-healing cement at...
- Self-healing cement at Pacific Northwest National Laboratory Posted by Brittany McIntosh, Reporter RICHLAND, WA - The scientist at Pacific Northwest National Laboratory have created and worked on a type of concrete that can self heal on its own. "The idea here is to introduce some small amount of polymer that have the ability to seal the crack, but at the same time have a strong interaction with the cement," Carlos Fernandez said. "So it basically combines it well and keeps the fractures closed." The main idea is that the solution is made with Polymer a plastic material that mixes together with concrete and pours just like the type of concrete you see on construction sites. But this time when a crack forms in the concrete this solution will gravitate the crack and self heal by filling up the gap. Most concrete last up to five years before it starts to crack, but with Fernandez's new creation he is expecting his concrete to last up to 30 years. "Self healing events take place over and over again throughout the lifetime of cement, something that the current cement does not have" Fernandez said. This project originally was thought of for underground tunnels and for engineering, but Fernandez believes that in a few years this type of concrete will be in stores ready for people to purchase and make some of their own. Source: http://www.nbcrightnow.com/story/39043885/self-healing-cement-at-pacific-northwest-national-laboratory
- [기술동향]The most important tr...
- The most important trends for self-healing materials Several trends are emerging in the self-healing materials market. None of these are completely new, but they are important developments that market researchers from N-tech believe will shape the self-healing market going forward and are indicative of where future opportunities will be found. The three trends that N-Tech is seeing as most notable in the smart materials space are the growing role of biomaterials and biomimetics in the design and creation of self-healing materials, improving performance from commercial products and the emergence of self-healing concrete as a real product. These are not entirely independent developments. Self-healing roads could significantly reduce maintenance costs for public municipalizes. (Source: Paweł Michałowski - Stock.Adobe.com) Self-healing trend 1: Biomaterials and biomimetics growing in importanceN-tech believes that reversible polymers will continue to have the largest share of the self-healing market with 37 % of the market by 2022. Also, reversible polymers will probably grow in terms of types and self-healing mechanisms. For example, a team at Harvard has recently patented a new kind of self-healing rubber. Rather than cracking when a lot of force is applied, this material will return to its original form when the stress is released. N-tech also sees an important meta-trend towards the use of biomaterials and biomimetics that will not only shape polymer-based self-healing materials, but will impact self-healing materials across the entire spectrum of materials and self-healing mechanism. Self-healing trend 2: Performance is more in sync with applications needsAnother meta-trend worth noting is that the performance of self-healing materials is getting better. More specifically, self-healing materials are increasingly in sync with real world applications needs, although as n-tech sees things they still have way to go in this regard: The automotive sector already uses self-healing aftermarket coatings but has begun to sample much higher performing self-healing materials that can comply with the industry’s demanding coatings requirements. The rapidly growing use of relatively fragile composites in the automotive sector is a strong driver for the development of self-healing composites. And we are seeing a transition from user applied low-performance self-healing coatings to professionally applied higher-performing self-healing coatings, such as FeynLab Heal Plus. Self-healing trend 3: The rise of self-healing concreteN-tech believes that self-healing concrete may turn out to be – in a sense – the killer app for self-healing technology. First, it is relatively easy to build a case for self-healing concrete, when one considers the vast amounts of money that is spent of repairing concrete. Self-healing concrete would also prevent sending engineers into precarious situations on bridges, roads and skyscrapers to search for cracks. And if next-generation self-healing concrete turn out to be a success it should do much to enhance recognition of self-healing technology as a whole and give it a much-needed boost. Although self-healing concrete is only at an early stage of development, it is well suited to current self-healing technology, because fixing the smallest cracks is what is needed here. Typically, the construction industry believes that the smallest cracks can lead to the biggest problems in the long run – and it is typical for small cracks to form in concrete after just three years. Further informationThis article is based on a more detailed report of Lawrence Gasman of N-tech Research in European Coatings Journal 7+8/2018. The article is also available digital in European Coatings 360° for subscribers of the digital service. A trial subscription is free of charge. Source: http://www.european-coatings.com/Markets-companies/The-most-important-trends-for-self-healing-materials