Franco Zunino pursues a two-fold strategy for the new green concrete: first, reducing the clinker content, i.e. the amount of clinker per unit of cement; second, lowering the ratio of cement in the concrete. This dual strategy offers flexibility in tailoring low-carbon concrete compositions to individual markets. “The ideal would be to implement both at the same time; but the individual components are independent of each other. In some markets, it may be difficult to implement both aspects of the dual strategy, as production capacity and infrastructure need to be put in place. However, it is possible to implement at least one of them and still save reduce CO2 emissions,” Franco Zunino explains.
Calculations by Zunino and his team have shown that the CO2 emissions of Ultra Green Concrete can be reduced from 300 kg per cubic metre to about 80–100 kg per cubic metre. Depending on the application, up to two-thirds of CO2 emissions could be consequently saved without compromising material performance. Although the researcher emphasises that there is no such thing as inherently climate-neutral or carbon-negative concrete, he believes there are no excuses for the industrialised world not to adopt this new and more sustainable building material right away.
More cost-effective than traditional concrete
One reason for the reluctance might be that the concrete industry is not particularly innovative. Concrete has proven to be highly successful due to being cost-effective, safe and user-friendly. According to Zunino, “green concrete” could be even cheaper than conventional concrete. The proportion of expensive components is lower, while the quality and thus price of the concrete remain the same. This creates financial incentives for using more environmentally friendly material.
Safety aspects are also important, of course. Franco Zunino comments: “Anyone who builds a house wants to use a material that insures it will stand for a hundred years. But we have to ask ourselves whether this really makes sense in view of the enormous CO2 emissions involved. Could we instead use a material that meets the structure’s required life cycle but emits significantly less CO2? In a climate-crisis scenario, one tonne of CO2 saved today is more valuable than the same tonne saved in 50 years.”