Microsilica is a by-product of the production of silicon and ferrosilicon alloys for the IT industry and, as such, does not constitute a big detrimental effect on the environment. Also, the current generation of superplasticisers, based on polycarboxylate ethers (PCEs), and used to reduce the water content of the concrete are not energy intensive to produce. Therefore, I would suggest that it is possible to create this high-strength mix without using unduly environmentally harmful components.

On a side note, 16,000 years is not all that impressive – some of the earliest examples of its use have already been standing for over 5,000 years and there are many examples of Roman use of the material from later on, such as the Colosseum.

The majority of concrete is used in the production of floor slabs, walls and columns in building structures. The depth of a slab depends on several things but they are about as thin as they can get, in many structures acoustic performance limits the ‘thinness’ of slabs and some walls especially in composite construction. Thus stronger concrete is not required. There is also the issue with thinner beams, walls etc in bending, more steel will be required to resist the actions due to reduced lever arms of the thinner profiles thus saving on one material will increase the use of another material with just as high an environmental impact if not higher. Thus a reduction of environmental impact of 1/7 just seams impracticable. You can get better impact saving by using materials such as PFA or GGBFS which are bi products of existing processes and can reduce cement use by 40%.

The article does not say how the ultra high strength or higher density is achieved, I would expect it is with the addition of admixtures which can be hazardous to the environment and expensive. For gravity structures the increased density would be beneficial but will it be cost effective? And how much denser is it? If you would save a few cubic meters for every hundred poured for a large mark in price up in price it just won’t be worth it.

When talking about ‘green/sustainable’ solutions you really need to keep your feet on the ground and be careful of perceived headline benefits without looking at the whole life cycle.

Although I am sure it makes for interesting research and would be helpful in some situations for the vast majority of uses it just would not be practicable.