Few people realise that concrete is the most used man-made material in the world, with three tons used annually for each man, woman and child. Twice as much concrete is used around the world than the total of all other building materials, including wood, steel, plastic and aluminium. Sustainability has a important role in all of this.
Apart from being versatile, durable and capable of providing sustainable infrastructure development and cost-effective products, it is recyclable without placing a burden on the environment. Concrete in its various forms offers design flexibility, structural integrity, cost effectiveness and low maintenance.
There are, of course, aspects of concrete manufacture that are not as green we would wish them to be…yet. According to the Cement Sustainability Initiative, Geneva, the production of concrete, notably it’s most important ingredient, cement, poses several sustainability issues that need to be managed:
“Cement production emits CO2 and other air emissions, and the quarrying of raw materials produces local impacts such as noise and dust. Also, water use needs to be carefully looked at in locations where water is scarce. The industry is well aware of these impacts and addresses them both collectively, via the CSI or regional and national trade organizations, and individually as producers within their sphere of influence.”
Says Bryan Perrie, Managing Director at The Cement and Concrete Institute, South Africa: “The local industry is very sensitive to energy consumption and environmental damage. Sustainability is a key driver. The cement industry has been and is continuously working on reducing energy consumption. The producers are using more and more extenders (which are secondary products with low embodied energy from other industries) in cement production. Rehabilitation of quarries is also being dealt with. The South African cement and concrete industry, compares very well with overseas countries.
One also has to take into account that some applications of concrete are greener than others, such as the different methods used to retain eroded earth or cut and fill slopes caused by excavation activity. The locally developed Terraforce concrete retaining wall and erosion control systems are considered sustainable products and have been since their development 35 years ago – long before it became fashionable to “ride the green wave”.
It is a hollow core and closed faced system allowing for maximum water absorption and plant growth, once installed. It is also an easy to use, cost-effective mortar less system that requires less material and equipment staging areas and fewer requirements of large pieces of equipment for manufacture and installation than cast in-situ solid concrete solutions.
Says Johan van Wyk, CEO of Klapmuts Concrete, a concrete retaining block (CRB) manufacturer based in the Western Cape: “A well designed Terraforce wall, properly vegetated with water-wise plants, is as green as it gets. The walls can be constructed with curves and angles to fit into any slope profiles, thus keeping in line with the existing environment. The blocks can also be manufactured in colours to match the environment.”
In addition, most licensed Terraforce producers locally and abroad use concrete building rubble and industry by-product in the manufacture of the blocks. Says van Wyk: “We recycle all reject blocks as well as blocks that get damaged during the “split” operation of the rock face blocks. We accept “clean” building rubble (no timber, plastic, metal, etc.) from builders as well as all the rejects from another building block manufacturer in our area. To ensure that the rubble can be used in our products without it compromising quality it is graded by a SANAS accredited laboratory.”
The bottom line is that durability is the key to sustainability. If the useful life of a structure can be extended by using concrete, that’s a huge gain for sustainability. Developments in concrete technology will continue to improve the industry’s ability to respond.