CD Designs Blog
Concrete is a great building material in so many ways. It is very strong under compression, fireproof, vermin proof, and fairly inexpensive. But it is not without problems. One major bugbear many harbour about concrete is its environmental impact: it involves a lot of gravel excavation and material transit, it is not very recyclable, and its production involves a lot of Carbon Dioxide emissions.
For those worried about the environmental impact of their concrete, there is a new, eco-friendly alternative available called GigaCrete. This uses a proprietary non-toxic binder instead of Portland cement, consisting of various commonly found elements. The great thing about GigaCrete is that 80% of an average mixture is comprised of fillers, and the fillers used are all recycled materials. These include sludge from paper production; waste fibres from agriculture, waste bottom ash from coal fired power stations, waste paper, and recycled cardboard, plastics and polystyrene.
Mixing these materials with the GigaCrete binder results in a fireproof material that is much lighter than concrete, and has strength close to, or even exceeding that of concrete in some tests. Production of GigaCrete binder produces less Carbon Dioxide and uses less water than Portland cement. So what are we waiting for? GigaCrete could well replace concrete for a lot of purposes. The main question really will concern whether it works as well with cosmetic processes such as pattern imprinting and polishing. And this remains to be seen.
4th October 2011
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.
2nd October 2011
In case you’ve been wondering about the origins of the pattern imprinted concrete you know and love, and where things might be going into the future, we thought we’d start this text with a little history lesson.
Concrete has been used to build things for 2000 years or more – there is evidence that concrete was used in the Egyptian pyramids, and the Romans built their structures out of a mixture of quicklime, pozzolana and an aggregate of pumice. The secret of concrete was lost for several centuries after the fall of the Roman empire, but we can see it used in classic structures such as the Canal du Midi in Southern France, built in 1670, and with work of British engineer John Smitten, who pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. He was active in the latter half of the 18th century (1750s onwards).
Concrete as we know it today, using Portland cement, was first seen in around 1840.
Concrete is a central feature of transport systems and urban architectures the world over. Its incredible popularity is due to the ready availability of its ingredients pretty much anywhere, and its incredible strength and durability. But can we improve on this tried and tested formula? For one thing, environmental concerns become more pressing every day in society. Concrete is already a fairly eco-friendly material, as it can be constructed from local materials, including waste materials from other industrial processes, it can absorb CO2, and its production requires far less land and processing compared to say, harvesting lumber.
Nevertheless, concrete production does take its toll, as we use so much of it. Each tonne of concrete produced results in a tonne of CO2 being released into the atmosphere, and we make around 30 billion tonnes each year – this totals between 5 and 10% of all CO2 produced. Scientists at MIT in the US have been working hard to further improve concrete’s efficiency by studying it at a molecular level, allowing them to try millions of different combinations in their search for the perfect mixture.
The mixture they have found is stronger and more durable, predicted to last around 20,000 years as opposed to 100 for traditional concrete. This will save us so much money in the long run, and have a hugely positive effect on the environment.
16th August 2011
Concrete has surprised many by being heralded as a green building material, thanks to new production techniques, composite materials, and the application of specialised coatings and designs, designed to reduce pollution, ‘self-clean’, and perform other cooling or filtering functions.
Certainly concrete has come a long way from being used in industrial council buildings or swirly pattern imprinted concrete driveways across the majority of British homes.
Traditionally concrete has been made from sand, cement, gravel and water mixes. The use of cement – a potentially hazardous and environmentally unfriendly product has courted controversy for many years, thanks to its fuel intensive production requirements, increasing levels of demand, and tax on quarries from stone and sand mining.
However, technology is moving at a pace to provide eco alternatives, and new concrete formulations are being developed all the time that provide the usual benefits of cost, flexibility and durability – without damaging the environment.
Cement substitutes are being used – minerals and recyclable materials which reduce carbon emissions and cut landfill disposals at the same time.
Fly ash is an example of these materials – once dumped into landfill in huge amounts, now recycled into a strong and durable cement compound suitable for intensive industrial use, and domestic use. AshCrete is another substitute made from 97% recycled materials, including fly ash and borate – and it’s known to be twice as strong as traditional concrete mixes.
The newest compound mix is carbon concrete, made with a thermoplastic from oil refinery by products. It cannot be used for tall buildings, but can be used for paving – whether that’s for town roads, or pattern imprinted concrete driveways outside homes.
Additionally, scientists are working on ways to recycle and reduce cement materials, and make use of recycled additions. Developments such as foamCrete – a lightweight concrete requiring little production energy, and GrassCrete – referring to a cellular laying pattern that allows grass to grow between blocks, improving drainage and reducing total concrete use.
Green builders are already supplying viable alternatives to traditional concrete, so it’s worth speaking with your local concrete expert to find out more, give us a call for example.
25th June 2011
There has never been a time when ecological issues have been more widely discussed. As awareness of global warming and our own personal carbon footprints has become widespread, we’ve all had to start thinking more about the impact that we as individuals, and as species, are having on our planet. As the pressure on all industries to act in a greener way has increased, there have been a number of breakthroughs in the development of ecologically friendly materials. One of these is a potentially revolutionary new type of cement.
A UK-based organisation called Novacem, connected to Imperial College London, have developed a cement with a difference. By replacing the limestone used in traditional cement production with magnesium silicates, they’ve developed a cement which requires much lower heating temperatures in the production process (650C compared to 1,500C), which saves energy. The new cement also gives off less carbon dioxide as it’s heated, reducing polluting emissions.
Even more impressive than that, once the cement has been combined with aggregates and water to make concrete, has been laid, and is beginning to set, it absorbs carbon dioxide in the air around it as part of its hardening process. It’s even possible for it to continue to do so after it has set. Novacem claim that their cement will absorb 0.6 tonnes of carbon dioxide for every tonne of cement.
The Carbon Trust has recognised the dramatic implications of this new cement; Novacem were finalists in the “Buildings” category of the Trust’s 2009 Innovation Awards. Of course, there will be a while to wait before this eco-friendly cement becomes a widely used industrial product. Novacem still have a patent pending on their cement, and there will be a few years of testing before it can be used for large scale construction projects. Still, it’s heartening to know that scientists and engineers are working towards (and succeeding in) coming up with solutions to the incredibly important issue of ecologically responsible construction.
6th January 2010