CD Designs Blog

    Self-healing concrete: sci-fi or possibility?

    Cracked concrete, a thing of the past?

    Cracked concrete, a thing of the past?

    Latest research suggests that cracked buildings and pavements could eventually become an eyesore of the past. A team of scientists at Northumbria University are working on a new ‘self-healing’ concrete which prevents ‘concrete cancer’. This phenomenon causes thousands of pounds of building damage every year, and shows itself in unsightly swelling and breakages, which damage the integrity of the structure over time and can become dangerous.

    So how does this new concrete work? Well, the team have used a ground-borne bacterium to manufacture calcite, which is a crystalline form of calcium carbonate. Calcite can be used to ‘block’ concrete pores, which keeps water and other problem substances out of the concrete’s structure. This prevents structural damage and visible signs of bulging and cracking.

    The team and industry observers are certainly hugely excited about the potential of the project, and the vision of creating buildings in the future that can look after themselves. Certainly, if the product developed to a commercial reality, the implications for future building work – both in homes, and for industry, would be immense. Could future pattern imprinted concrete driveways last even longer than 20 years? Could this new form of concrete become popular as a home construction material? We await further news with great interest!

    A Cracking Solution: Self-Healing Concrete, Coming All The Way from Rhode Island!

    Each year we see more and more advances in concrete science, from the plain cosmetic to the more utilitarian. But one advance that has really piqued or interest of late is a significant advance into self-healing concrete. Yes, it may sound like something straight out of the X-Men, but please — hear us out!

    Michelle Pelletier, a graduate student from the University of Rhode Island, has pioneered a method of creating concrete that self-heals, recovering some of its strength after being put under extreme stress. This works by embedding a micro-encapsulated sodium silicate healing agent directly into the concrete matrix. When the concrete is put under stress, the micro-capsules rupture and release the healing agent into any cracks that form, thereby prolonging the life of the material. The healing agent chemically reacts with the calcium hydroxide naturally present in the concrete mixture to form a gel-like material, which heals cracks and blocks pores in the concrete.

    Tests showed that Pelletier’s formula recovered about 26% of the concrete’s original strength, compared to about 10% for other similar proposals. This makes it more likely to be financially viable for commercial production: it could serve to significantly reduce repair costs and extend the life of concrete structures.

    And this is not all – the self-healing concrete has potential additional advantages, which are also being researched. For a start, it could reduce the level of Carbon Dioxide emissions that result from concrete production (the concrete industry is responsible for around 10% of all Carbon Dioxide emissions in the USA). Pelletier is also researching whether her new concrete design could reduce corrosion of the steel reinforcement bars you commonly find in concrete structures.

    Self Healing Concrete

    Avoiding Cracks with Self Healing Concrete

    Avoiding Cracks with Self Healing Concrete

    Another fascinating development in the quest to provide more eco-friendly concrete and other building materials – self-healing concrete is being hailed as the future answer to keeping pavements, structures – and perhaps one day our patios and pattern imprinted concrete driveways – in crack-free and in tip-top condition.

    Developed by Michelle Pelletier, a Masters student at America’s Rhode Island University, Pelletier has devised a concrete paint that helps it to ‘heal’ itself using bacteria containing a self-destruct code gene.

    At the same time, Newcastle university students have worked to create a new type of bacteria that acts as a glue on cracked concrete, effectively healing cracks and fissures, and reducing the need for rebuilds.

    The bacteria begins to germinate when it senses a change in the PH level of the concrete, automatically reproducing to fill the crack, until the bacteria begin to clump at the bottom of the fissure. At this point the cells change into three categories – calcium carbonate providers, filament acting cells that provide fibres to reinforce the concrete, and cells which produce a glue, to bind the materials together. Combined they harden within the crack to knit the structure back together.

    The bacteria’s self destruct gene prevents it from germinating in any place but a concrete structure, and the self-heal solution is being hailed as a way to reduce the need for replacing concrete buildings in the future, ultimately leading to significant benefits in carbon reduction.

    The students won prestigious science prizes for their work and now industry is looking at how their research can apply to everyday situations. Certainly it may be a while before those clever bacteria are burrowing their way into the designs of our pattern imprinted concrete driveways, to keep it in top-notch enduring condition, but it certainly marks an exciting development in the next wave of eco-friendly concrete materials.

    Image by Rik

    Expansion Joints

    When you’re dealing with concrete, it’s important to understand its characteristics. Whilst it is remarkably strong, it does need features like expansion joints to be properly positioned and correctly done, or it can suffer from some problems.

    As your pattern imprinted concrete driveway sets, it can expand and contract. Later on, atmospheric temperature changes (hot spells and cold snaps) can cause more expansion and contraction. Expansion joints, which are discreetly positioned in the overall driveway design, stop cracking and flaking problems. Concrete will always crack; it’s completely unavoidable. Expansion and crack control joints allow pattern imprinted concrete driveways to crack in a small, controlled way.

    When you’re adding features to your driveway design – essential things like manhole covers, or other features you’ve chosen – they’ll need expansion joints to be cut around them. Separate, non-concrete features won’t expand and contract like the concrete around them, and it’s around these areas that cracking is most likely to occur.

    A good contractor will know how important expansion and crack control joints are, and should be able to give you a comprehensive explanation of their function, and point out where they would be placed in your installation. Take a look at our case studies and you’ll see that these joints are very well hidden. But without them an entire pattern imprinted concrete driveway could be compromised.

    Complete Driveway Designs Ltd

    The Yard, Stubbins Lane, Ramsbottom, BL0 0PT
    T: 01706 827180

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