CONCRETE SOLUTION

I know that Pop Mech has an interest in the concrete and construction industry. I also feel that the current drive towards reducing our carbon footprint is universally important. I’m writing in to share my opinion on ways to reduce the carbon footprint in the construction industry.

I feel that the way that concrete structures are currently designed for durability (and even the way the design code is written) is opposed to achieving a reduction in the carbon footprint of a structure. The reason for this is that the current design methodology for durability in concrete calls for minimum cement contents (more cement), an increase in cover (more concrete) and the use of specific SCMs (supplementary cementitious materials, such as fly ash and slagment) and aggregates, which sometimes have to be transported over large distances (which result in increases in prices and the use of more fossil fuel). It’s true that concrete is a dominant factor in embodied carbon, but reinforcing

steel and structural steel has a minimum of 40 per cent higher carbon footprint than concrete. In addition, the conventional waterproofing measures are PVC- (plastic polymer), bitumen- (petroleum based hydrocarbon) and

EPDM- (synthetic rubber) based, which have a much higher carbon footprint than integral crystalline waterproofing systems. These conventional systems also come at a higher cost, carry a shorter warranty time and require a more frequent maintenance schedule.

It’s important to note that the embodied CFP (carbon footprint) of a building is the sum of: CFP of all construction materials; CFP of all construction operations; CFP of all maintenance operations; and CFP of demolishing operations and disposal of used materials.

Instead, by using a durable concrete mix with self-healing properties, the service life of a structure can be extended by 60 years and more. At the end of its service life, a building may either stay in service as is, or receive a new facade, monitoring and evaluation upgrades and be repurposed to serve a similar design life. As a result, the total embodied carbon footprint is either dramatically reduced or done away with entirely, effectively providing two structures with the CFP of a single structure. Moreover, the cement and concrete that is ‘saved’ becomes available for the construction of more infrastructure.

The International Concrete Repair Institute Committee 160 notes that the most effective sustainability strategy for concrete and masonry structures is to avoid the need for repairs. This puts the responsibility to co-operate on the whole value chain on a construction project with: 1) Designers – to design infrastructure with all the factors contributing to CFP in mind, and to design structures that are easier and faster to build, using the latest technology available and with full, lifetime cost of ownership in mind; 2) Project managers – to plan the project with efficiency in mind (having fewer individual operations and reducing the number of people on site will lower the chances of things going wrong and result in fewer repairs); 3) Concrete technologists – to design concrete mixes that are able to self-heal, that negate the need for maintenance and repairs, but with less cement; 4) Contractors – to ensure infrastructure is constructed right, the first time.

The skills, technology and knowledge is available, but it’s clear that the current philosophy of ‘this is how it is done, because this is the way it has been done for years’ will have to change.

Furthermore, I feel that the ‘refusal’ of structural concrete professionals to use the latest crystalline technology in concrete borders is irresponsible, and even gambling with clients’ and very often tax payers’ money. JOHAN VAN WYK

(PENETRON AFRICA)

These are excellent points, Johan. It’s imperative that every industry takes a very close look at its effect on our planet, and the construction industry specifically has scope to make easily achievable changes and significant improvements.

– Mark, Editor