Four of the latest innovations & trends in concrete as revealed at The Totally Concrete Expo.
It’s very easy to overlook concrete as just another building material necessary to achieve specific goals, but how often do we appreciate its ability to introduce us to a new world of flooring opportunity? In this article, we identify and explore some of the latest flooring innovations and trends in concrete as revealed at The Totally Concrete Expo held at the Gallagher Convention Centre in May 2016.
1. Self-Consolidating Concrete (SCC)
The construction industry has always longed for a high-performance concrete that can flow easily into tight and constricted spaces without requiring vibration. The need for this technology has grown as designers specify more heavily reinforced concrete membranes and more complex formwork.
Whereas conventional concrete is installed using vibrators to fill the forms, self-consolidating concrete (SCC) is a big step forward in full proofing that procedure. The key to creating SCC, also referred to as self-compacting concrete, is to produce a flowing mortar that retains a viscosity great enough to support coarse aggregates.
There are several key benefits of using SCCs. Firstly, as the self-consolidating property eliminates the need for vibration, it reduces labour requirements when installing SCC. In some instances, labour can be reduced by half of what is needed for conventional concrete applications. The energy consumption associated with vibration is also removed. In addition, the formwork is no longer subject to the stresses of vibration, which can reduce initial formwork costs, maintenance costs or both. In addition to the reduction in energy due to the elimination of vibration, the rapid discharge rate of SCC also allows for shorter dwell times of trucks at the job site.
Another benefit of the lack of vibration is noise reduction, which improves both the working environment and safety. This in turn increases employee productivity by reducing noise-induced and vibration-induced illnesses. Additionally, operations located within or near residential or commercial centres may experience less noise-based negative feedback from surrounding residents or businesses.
The aesthetic quality of SCC formed surfaces allows the bare concrete to serve as the finish surface, which is why additional material such as paint is not needed. This in turn reduces maintenance requirements and improves air quality.
2. White Cement
An emerging trend in decorative concrete is the usage of white cement, which is a key ingredient when aiming to achieve boundless possibilities in beautiful structures and landscapes.
White cement is typically specified to ensure clean, bright, consistent colours, including light pastels. White cement allows a wide range of colour options for producing structural and architectural concrete, as well as masonry and cementitious building projects. The final look and colour of concrete and masonry materials are affected by several factors:
• Colour of cement;
• Colour of supplementary and cementitious materials;
• Colour and dosage of pigment;
• Colour, gradation, and cleanliness of fine and coarse aggregates;
• Surface treatment of finished concrete;
• Water content; and
• Type and dosage of admixtures.
Decorative concrete floors made with white cement can be specified in place of other upscale finishes because they are durable and attractive. Polishing, in particular, has experienced rapid growth due to advancements in equipment along with more sophisticated installers.
White concrete floors, pavements and other surfaces are highly reflective. In interior spaces, this property reduces the need for artificial lighting. Lower levels of lighting in interiors can impact cooling requirements, and in turn reduce energy costs. Reflective surfaces also improve night-time safety and deliver greater illumination for retail, manufacturing and warehousing operations.
When it comes to specifying white cement, colour is an important quality control issue, where consistency in brightness and tone are principal concerns. The colour of white cement depends on both the raw materials and the manufacturing process. Metal oxides (iron, manganese and others) that are present in the finished material influence its whiteness and undertone, making it crucial to use carefully selected raw materials.
3. Translucent / Light-Transmitting Concrete
By switching the ingredients of traditional concrete with transparent ones, or embedding fibre optics, translucent concrete has become a reality. Three ingredients make up the dry mix; namely coarse aggregates consisting of larger pieces of material such as stones or gravel; fine aggregate made of smaller particles such as sand; and cement, a fine powder material that binds the mix together when water is added.
The simple formula for concrete, however, lends itself to endless modifications. By simply adjusting the ratio of ingredients, engineers can change the strength and texture of the material. Translucent concrete isn’t really “see-through” – the building material draws on optical fibres to transmit light through it while retaining the density that has literally made concrete the cornerstone of buildings around the world.
The fibre strands, which attract and transmit both natural and artificial light, comprise about 5% of a translucent concrete block’s surface volume. The fibres run parallel to each other, transmitting light between two surfaces of the concrete element in which they are embedded. The fibres are mixed with traditional concrete components and are evenly distributed throughout the surface. Through the resulting translucent panels, a viewer can clearly see the outline of an object on the opposite side of the concrete. In fact, optical fibres transmit light so effectively that there is virtually no loss of light conducted through the fibres – it’s even possible to see colours through the concrete. Despite this clarity, however, a translucent concrete retains its stout, crack-resistant, load-bearing quality. After setting the concrete is cut to plates or stones with standard machinery for cutting stone materials.
The opportunities for translucent concrete are endless, and has been used to create stairs, decorative tiles, partition walls and even lamps. They have the ability to transform the interior of concrete buildings, making them appear fresh, open and spacious.
4. Ultra-High Performance Concrete (UHPC)
As a material on the leading edge of concrete innovation, UHPC provides a new technology to expand a precaster’s business with new products and solutions. The material’s combination of superior properties facilitates the ability to design thin, complex shapes, curvatures and highly customized textures – applications which are difficult or impossible to achieve with traditional reinforced concrete elements.
UHPC is a range of formulations which may be used for many different architectural and structural applications. Reinforced with high-carbon metallic fibres, structural UHPC products can achieve compressive strengths up to 200MPa and flexural strengths up to 20 MPa. For architectural UHPC applications, Polyvinyl Alcohol (PVA) fibres are used.
Due to the material’s superior compressive and flexural properties, the need for passive reinforcing can be eliminated or greatly reduced. It is also highly mouldable and replicates form materials with extreme precision. The material replicates textures, form and shape with high precision and can be produced in a range of long-lasting colours. It works well for new, innovative concrete applications and supports new trends in architecture to achieve purity of line, delicacy, enhancement of texture and mineral bias. The advantages of UHPC are numerous and typically include reduced global costs such as formwork, labour, maintenance and speed of construction. Applications include decks, stairs, large-format floor tiles and bridge beams.
5. Self-healing Concrete
As far as innovation goes, this is truly an exciting development in the world of concrete and opens up a world of possibilities with regard to creative applications. The inspiration for self-healing concrete comes from nature, and more specifically, limestone producing bacteria.
When embedded in concrete, these bacteria should be able to repair cracks in it. However, to be able to survive in concrete, they have to come from good stock: the pH-value of concrete is around 13, which is an extremely alkaline environment. Moreover, the bacteria have to be able to survive the concrete mixer and then they have to wait for years before being able to carry out their restoration work.
Bacteria of the bacillus species have exactly the right characteristics. In concrete, they will only come to life if water and oxygen are ‘added’ i.e. if a crack appears in the concrete. They are then able to multiply and produce limestone, thereby closing the crack in a few weeks.
A healing agent for concrete has been developed that is made up of two components; bacillus spores and calcium lactate nutrients. These are set separately into expanded clay pellets, or alternatively in compressed powder granules, a few millimetres in size. The pellets are then added to the wet concrete mix. When cracks begin to form in the concrete, water will enter and open up the pellets.
The bacteria will germinate and start to feed on the lactate, combining the calcium with produced carbonate ions to form calcite or limestone. It will be intriguing to monitor developments as far as outdoor testing is concerned, and undoubtedly, there are individuals or companies who will find innovative ways of applying this technology going forward.
As we write this, there are several new trends, technologies and innovations which are being explored and perhaps already underway. It is important to be aware of these trends, as they can very likely inspire new ideas that can be successfully implemented within the flooring industry. Considering that concrete is the most used construction material after water, it becomes clear just how important its role is, and will continue to be, in the construction industry.
Acknowledgement and thanks go to the following for the material contained in this article: Concrete Society of Southern Africa; http://www.cement.org/cement-concrete-basics; http://home.howstuffworks.com; http://illumin.usc.edu; http://precast.org; http://www.tudelft.nl/