- [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
- [기술동향]Innovation Day at t...
- Innovation Day at the Seaport Space Extending the reach of WPI’s research and early-stage technologies Suzanne Scarlata, professor of chemistry and biochemistry, presented Universal Repair of Concrete Using Enzymes. “The problem we’re trying to solve is to rapidly repair concrete surfaces to give a product that is identical to the original structure,” she said. She described it as an infrastructure repair that’s easy, green, and a rapid, off-the-shelf method to repair cracks in something as small as a sidewalk or on airport runways. “There are so many infrastructure problems, especially in the developing world, that you want something easy and low-cost. “Nima Rahbar is in the Civil Engineering department, and is interested in material research. He came up to me after a talk and told me that people were using microbes for concrete repair, but there might be health hazards associated with it. I thought this was bizarre, and that there are better ways of doing it.” Amy Peterson, assistant professor in chemical engineering, presented two projects. The first, Self Healing Coatings, is aimed at providing a solution for the nation’s failing infrastructure. “America is currently facing an infrastructure crisis. The American Society of Civil Engineers has given America’s infrastructure a grade of D+ and estimates it will take close to $5 trillion to rehabilitate U.S. infrastructure,” Peterson explained. Reinforced concrete is the most widely used infrastructure material, but its durability suffers due to corrosion of the rebar, which causes expansion of the rebar, and spalling of the concrete off the rebar, she said. “In my PhD, I studied strategies for self-healing within fiber-reinforced composites, so I had a background in self-healing materials, and I was interested in coming up with a project to work on with my co-inventor, Aaron Sakulich, who works in concrete. We sat down over lunch one day and came up with this.” Her second project, Controlled Deformation Additive Manufacturing, offers the potential to manufacture items in shapes that had previously impossible to create, or could only be created with a lot of waste. “So it’s offering a lot of creativity for designers of new structures. However, there are significant problems related to the reliability of processes, as well as warping of structures due to residual stresses and limited strength of these structures, particularly in polymer additive manufacturing,” she said. “We’re aiming to overcome this by annealing out these residual stresses and building structures in such a way that when they are annealed they will have the desired final dimensions. “We are interested in processing-structure-property relationships in polymer additive manufacturing, and one of my students characterized a sample using a technique that heats a clamped specimen, and when it came out it was incredibly deformed, and we thought, 'that’s really strange … let’s explore that.'”