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Contractor (March 2016) Concrete Product and Technical Trends

01 Mar 2016

Rob Gaimster
Cement & Concrete Association of New Zealand (CCANZ)

The immediate future of the concrete and wider construction industry looks upbeat with levels of activity predicted to remain positive. Within this space there are various emerging markets for concrete.

These include architectural precast concrete, medium density / multi-storey residential construction (including basements), infrastructure (concrete pavements and intersections as well as pervious and permeable concrete), residential construction (concrete prefabrication, concrete masonry and insulated concrete formwork), not to mention seismic retrofits.

However, it is always beneficial to cast an eye slightly further afield to gauge ‘supplementary’ areas of concrete construction and associated undertakings. The following is a ‘snap shot’ of evolving concrete products and technical trends that may become influential in New Zealand over coming years.

3D CONCRETE PRINTING

Threatening to move beyond novelty value the ability to ‘3D print’ using concrete is generating a lot of headlines. Extruding concrete through a nozzle to build structural components layer-by-layer without the use of formwork or any subsequent vibration is touted as ideal for optimizing construction time, cost, design flexibility, error reduction, and environmental aspects.

CO2 CAPTURE IN CONCRETE

Carbon dioxide emissions are recognized as an issue relating to cement production and the use of concrete as a building material. One potential method to off-set this is to recycle captured carbon dioxide into concrete products. The method involves collecting carbon dioxide (CO2) and injecting it into fresh concrete (precast, masonry blocks or ready mix) where it becomes chemically sequestered within the concrete.

DEPOLLUTING CONCRETE

Depolluting concrete uses photocatalysts to accelerate the process whereby solar or ultraviolet energy breaks down pollutants. The principal catalytic component is titanium dioxide (TiO2), which takes the form of a white pigment within the specially blended Portland cement. The structure of TiO2 is altered to create tiny semiconductor particles capable of photocatalysis. These are activated by the energy in light to create a surface charge that reacts with the organic compounds.

IMBEDDED SENSORS (SMART BUILDINGS)

The global Internet of Things phenomenon is opening opportunities for sensor technology. Sensing capabilities are significant in all fields, particularly smart buildings.  The reasons for this uptake are several, from social to environmental to economical. Energy conservation, infrastructure monitoring, accident prevention, and disaster containment are just some of the fields that can benefit from interconnected sensing devices – all of which are related in some way to concrete structures.

LIGHTWEIGHT AGGREGATE

Lightweight concrete, whether placed in-situ or precast, offers reduced deadweight and longer spans, yielding reductions in material usage and larger developable space on the same footprint. New and innovative varieties made almost entirely from waste diverted from landfill are gaining a foot hold. Some new products incorporate mixed coloured cullet glass and industrial mineral wastes.

SELF-HEALING CONCRETE

Self-healing concrete ("bio-concrete") can prolong the service life of concrete structures, and therefore reduce associated maintenance or repair costs. It uses bacterial spores encapsulated within tiny clay pellets in the concrete mix, along with other chemicals and a nutrient agent. The bacteria are activated by moisture that penetrates the initial crack. Not only do the bacteria consume oxygen to lessen the likelihood of reinforcing steel corrosion, but they also produce carbon ions that react with the calcium in the concrete to create a type of limestone that seals the crack.

VALUE ADDED MIXES

There is a trend amongst some ready mixed concrete producers to look to white concretes as a means to secure market share. As customers call for decorative and specialty mixes, they are embracing integral colour and white cement as a way to boost returns. A growing number of producers see decorative concrete, white cement and other ‘value-added’ products as an important segment of their business.

ULTRA-HIGH-PERFORMANCE FIBRE-REINFORCED CONCRETE

Another ‘value added’ mix that is turning heads is Ultra-High-Performance Fibre-Reinforced Concrete (UHPFRC) - a concrete with a high degree of ductility combined with compressive strengths of 150MPa or higher, and Compact Reinforced Composite (CRC) - a special type of UHPFRC combining high-strength, steel-fibre reinforcement and closely spaced reinforcing bars. UHPFRC is gaining uptake for bridge applications, while architects are using CRC for slender balconies, staircases, beams and columns.

So while traditional uses for concrete will (literally) remain the foundation market over coming years emerging applications such as medium density residential construction and infrastructure will also gain a significant foothold.

Yet at the same time exciting niche concrete products and technologies are poised to grab headlines and ultimately market position.

Article appeared in Contractor magazine.