For decades we have seen cement mixers stationed at construction sites around the world. The processes of mixing the powder to create concrete has been crucial in engineering projects of all shapes and sizes. While many may simply accept this as the standard way to produce concrete, there is an alternative which has some significant environmental benefits compared to the traditional method.
The harmful environmental nature of cement may not be known to all but the figures in a 2018 Chatham House report detail just that. As the world most widely used construction material, it is a major source of carbon dioxide. Cement contributes around 8 per cent of the world’s CO2 emissions.
However, as mentioned, there is an alternative which if it is used more widely, can hopefully start to reduce the CO2 levels created by traditional cement.
The product is called Concrete Canvas, and it was developed by two British university students in 2004. Initially, the fabric was developed to create semi-permanent inflatable disaster relief shelters.
While the company still produces them today, Peter Brewin and Will Crawford (the founders) realised that the fabric had far greater market potential, notably in civil engineering.
There are three key features to Concrete Canvas which make it a more environmentally friendly option than traditional poured or sprayed concrete.
No On-Site Mixing Required
Concrete Canvas is part of a class of materials called Geosynthetic Cementitious Composite Mats (GCCMs), and it’s often referred to as ‘concrete on a roll’. This is because unlike traditional concrete solutions, it arrives on-site on a roll ready to install. Poured or sprayed concrete needs to be mixed on-site, and this means having a mixing machine running for long periods.
Not only is this damaging for the environment because of the cement needed but also the actual mixing machine is contributing harmful emissions such as CO2 while it is running.
The amount of traditional poured concrete needed to cover the same area as a single pallet of 8mm thick Concrete Canvas would require two 17 ton mixing trucks. Material savings on a typical construction project can be up to 95% when using Concrete Canvas compared to traditional methods.
One of the main issues with poured or sprayed concrete is waste. It’s very easy for liquid concrete to splash away from the target area, this then immediately becomes waste as it can’t be reused.
Furthermore, it’s difficult to install concrete in areas which are environmentally sensitive because of the damage it can cause to wildlife. With GCCMs, these issues do not exist as the material is cut to the exact size needed. Once in place, the fabric is then hydrated to start the hardening process.
Because there is no waste and no need for mixing equipment, this form of concrete installation can take place in environmentally sensitive areas and also hard to access areas without damaging the natural environment in the way traditional concrete would.
Unlike traditional concrete or even specialist underwater concrete, Concrete Canvas has a very low washout rate as the concrete powder is contained in a 3-dimensional fibre matrix. This allows the mass loss to be significantly reduced.
While specialist underwater concrete typically loses between 10-15%, Concrete Canvas loses only 3%. Also, as the alkaline reserve in Concrete Canvas is limited, the fabric is not classed as an irritant and is, therefore, less damaging to the environment.
As an indication of its lower environmental impact, Concrete Canvas has been used by the UK’s Environment Agency on multiple projects and classed as an eco-friendly concrete alternative. The wide range of uses for Concrete Canvas make it useful in a variety of sectors for applications were erosion control is required, including channel lining and concrete resurfacing.
With the ever-increasing need to reduce our carbon footprint it’s highly likely that, along with Concrete Canvas, other low-carbon and more eco-friendly building materials will need to be developed and used.