Visions of the future of concrete

Consider also that there are many materials that have fallen out of use in modern engineering. I haven't seen so many masonry arch bridges built recently to carry motorways, neither have I come across large orders for wrought ironwork in any of my recent projects. So, surely it is perfectly reasonable

Of course, the reality is that materials typically only cease to be used when overtaken by something more financially advantageous or structurally efficient (for example, steel replacing iron, or, as in the case of asbestos, perhaps where deficiencies are found to outweigh the benefits to society).

While a material continues to serve a useful purpose and demonstrates such versatility of application, there is no obvious driver for change. In this context it is inconceivable that a material that was discovered by accident and has been refined and improved over the last 2000 years does not have a future, especially given the ever-rising global population and accelerating consumer and construction demand.

So, what is the future of concrete? How will concrete's constituent parts evolve over time and to what new applications will it be turned? Engineers, both in isolation and in collaboration with architects, have long sought to stretch and challenge the technologies available to them, while at the same time using materials ever more sparingly and efficiently.

Technology

Modern structural analysis and the evolution of increasingly powerful computers enables the engineer to deliver the continually challenging concepts proffered by the architect, constrained only by the physical limitations of the materials with which they are working. The Penguin Pool at London Zoo (see Figure 1) offered a glimpse of pro-computer age refined structural engineering in reinforced concrete. Some 16 years later, in 1951, the completion of the elegant shell roofs of the Brynmawr Rubber Company's factory employed such refinement on a truly industrial scale (see Figure 2).

Looking into the future, I anticipate the continuous evolution of the structural form to deliver ever more graceful structures. A brief study of the natural world quickly demonstrates that many of the most efficient structural engineering concepts are merely borrowed from nature (see Figure 3). Human nature will, of course, play its part as well, with our near ceaseless quest for structures that are 'bigger, better, faster, more'. If nothing else, higher strength concretes will be expected to deliver more slender sections and to support, both physically and metaphorically, our quest for the skies in which concrete will undoubtedly play its pail (see Figure 4).

The Penguin Pool and Brynmawr factory depict structures in which concrete performs only a single function. However, concrete will inevitably cease to be an isolated building material. In the drive for greater efficiency and integration, it will no longer be acceptable for concrete to function simply as a wall or floor slab, in the same way that it will no longer be acceptable for a root rafter to simply hold up a roof. Materials will evolve to act compositely in far more than just a structural sense. We are already seeing the thermal mass properties of concrete being used as an intrinsic part of the climate control within modern buildings, procured by enlightened clients. As enlightenment spreads, so too will the drive to use materials more intelligently - a holistic approach to development.

Recycling and reuse

Of course, the quest for more sustainable development is also driving us firmly towards recycling and reuse. Perhaps in the future, precast concrete components will he dismantled regularly and reused. But how long will it he before we see concrete comprising 100% recycled materials in common use, and why aren't we seeing this today?

Apart from the direction that societal and environmental drivers might lead us in the future, clients and specifiers should by now he leaping at the opportunity to reduce the carbon footprint of their structures. Why aren't they queuing up to leap? Are we afraid of second-hand goods? (See Figure 5). How far can we reduce the embodied energy in concrete? Is a zero embodied energy concrete feasible? Perhaps not; physics has long dictated, you cannot get something for nothing, but we will certainly learn to use materials and 'energy' sources more intelligently and coherently than we do today. Also, we should not overlook the steps that have already been taken in cement manufacture with secondary fuels and the use of ground-granulated blastfurnace slag and pulverised-tuel ash as cement replacements.

From the macro scale to micro and beyond

Long ago, concrete ceased to be simply a collection of sand, cement, aggregate and water in roughly appropriate proportions. Its properties are already analysed and indeed manipulated at the molecular level (see Figure 6) and this 'material technology' will continue to evolve to deliver compounds that offer not merely higher strengths but concretes that are more ductile, more resilient to a diverse range of aggressive environments, lighter, denser, more readily handled and compacted. Perhaps also, this will include concretes that are more thermally efficient and offer better electrical conductive properties - each tailored and specific to the particular structure or application in which it is being used. Plus, is it too fanciful to imagine a concrete that, when subject to a trigger, can even break itself down and decompose into its constituent parts at the end of a structure's life? The holy grail of materials recycling perhaps?

Concluding remarks

Concrete is certainly not what it was, nor will it be the same in the future. It will continue to evolve with ever more subsets, constituents and physical properties for specific applications. Think! What do you want your concrete to do for you tomorrow?

"Concrete is certainly not what it was, nor will it be the same in the future. It will continue to evolve with ever more subsets, constituents and physical properties for specific applications."