Geosynthetics comprise of an extensive range of products available in the market and these can be categorized as Geotextiles, Geogrids, Geonets, Geomembranes, Geosynthetic Clay Liners Geotextile Encased Columns and Geocomposites
Geosynthetics are manufactured from different polymers like: polyolefin (Polypropylene and Polyethylene, with a very high chemical resistance) or polyester (PVA, glass, aramide). Usually in the overall project, geosynthetics are categorized through their role or function in the design or project such as any other engineering materials. There are 7 functions recognized for geosynthetics and they include the following: filtration, separation, reinforcement, drainage, barrier; surface erosion control, and protection.
At the beginning, geosynthetics were not used in critical applications; they were mainly used as ‘buffer’ for safety, usually to cater for incorrect installation or poor quality workmanships. Almost 100 years later, geosynthetics are now widely used in many civil and mining sectors as a key-role player in the overall project, which can be the reinforcement of roads, lining of a heap leach pads, or just a simple erosion control on the shoreline (embankment on soft soils, bridge abutments, noise barriers, flyovers, reinforced load transfer platforms LTP on piles). Significant cost savings and improvement of the whole structure can be achieved thanks to the use of Geosynthetics.
Geosynthetics in the African Market
The geosynthetics market in Africa is growing steadily. While a large portion of the market is limited to mining and allied sectors, geosynthetics has been adopted by various applications in the infrastructure, environmental (landfill) and hydraulic (shore protection, scour protection in harbours, dykes,) sector. Early adoption of geosynthetics in this market was in mining but has proven its benefits in various construction applications which include: rail construction, paved and unpaved roadways, reinforced soil walls (asphalt reinforcement) among others.
Geosynthetics has emerged as a recognized technology in Africa because it is slowly reducing and replacing the burden on natural resources. As Africa’s infrastructure develops and urbanizes, the load on natural resources will increase. Geosynthetics can be used in a wide variety of infrastructure challenges, right from mining applications to ground stabilization in pavements, container yards, and many more.
For instance, geotextiles can be placed as a separator creating a stable platform for the contractor to work. Geogrids can improve the quality of the pavement layers in order to avoid the use of crushed stone, while geocomposite for drainage can intercept seeping water and geomembranes helps in avoiding any land fill leachate getting into the ground.
According to Mr. Victor Ibrahim of ACE Geosynthetics a manufacturer of geosynthetics in Taiwan, the geosynthetics market in Africa is growing. South Africa is still the leading user of geosynthetics, with most of the applications focused in the mining sectors. Non-woven geotextiles, woven geotextiles, Geosynthetic clay liners and geomembranes are the most widely used and requested geosynthetic materials in Africa.
“We do expect to see an increased growth in geosynthetics usage in line with massive amount of infrastructure projects on-going in other parts of Africa, especially in East Africa. With these infrastructure projects, we expect to see further usage of geosynthetic materials such as geotextiles and geogrids for soil/slope stabilization, reinforcement of roads, highways, railways and pavement application,” Mr. Victor Ibrahim.
Francesco Fontana managing Director of Manifattura Fontana a company specialized in the production of added-value needle punched nonwoven geotextile comments that “Enviromental aspects in Africa need to be evaluated even more than in other parts of the world because of of its precious natural peculiarity Geosynthetics allow us to save a big amount of CO2 emissions compared to traditional technologies with sand, gravel and concrete. This is a huge advantage for the environment.”
Globally, there is a huge emphasis on sustainability and the impact of urbanization on the environment. In the geosynthetics market, the research and development funding and innovation is driven towards more products and technologies that minimize the impact on the environment and allow re-use of different types of material; this is according to Richika Bhawnani of Strata a leading provider of soil reinforcement technology and many geotechnical solutions in India (Geosyntetics reduce the carbon footprint).
Geotextile mattress for slope protection”For example, various geosynthetics enable re-use of waste materials and site-won materials (such as ash, slag, poor quality soil etc.). Essentially, it allows for use of locally (possibly marginal) soils and material. This minimizes the effort, costs, and environmental impact produced by importing material from elsewhere,” he adds.
Furthermore, according to Michelle Neermal of Maccaferri a designer and developer of complex solutions in the civil engineering, geotechnical and environmental construction markets, the variability of geosynthetics materials is huge, making very difficult for non-expert in the field to make the right choice in design and implementation. “Manufacturers are more and more coming closer to engineers and project manager to assist them with design recommendations, guidelines and even trial testing in order to support the right choice for the project,” she says.
The African continent is also experiencing climatic conditions such as high temperatures and long- term exposures to sunlight. This according to Pavel Razbegaev, Head of International Projects Department at PRESTORUS, a multi business engineering company, has resulted to the need for African market and manufacturers take into account such conditions when it comes to design and product choice being placed placed on the table.
“We recommend reinforced and weld free geocells which are favorable with climate change such as our GEOCORD and GEOSTEP products. These geocells are used in design, construction, reconstruction and repair of infrastructure facilities under 1-5 climatic conditions and at temperatures from -65 up to +70°C. GEOCORD can be used with great success to fix the ballast layer in railway clothes and GEOSTEP can be used for reinforcement of slopes,” said Pavel Razbegaev.
When it comes to geomembranes, Peter Hardie, Technical & International Sales Manager AKS Lining Systems (Pty) Ltd notes that they are mostly used for very high risk containment applications (either protecting the environment or protecting a client’s asset).
“HDPE Geomembrane liners for instance offer many advantages over conventional clay lining systems, not only from a chemical resistance and life expectancy aspect, but also from greatly reduced construction time and additionally carrying capacity in most containment applications,” said Peter Hardie.
Peter further explains that “It is vitally important to check and confirm that the liner being purchased conforms to the Internationally accepted GRI-GM13 (or our own SANS 1526) specifications. These specification ensure the liners will last in our African sun in terms of UV resistance and offer the maximum life expectancy.”
Dam liners are essential for preventing water loss from reservoirs and ponds; however it is essential that high quality dam liners are purchased if a long term waterproof solution is required. Predominantly manufactured from (high density) Polyethylene and Polypropylene, these geo membranes are used extensively for the containment of liquids, solids and gases in a variety of applications, including Attenuation Tanks, Flood Alleviation, Dam Liners, Gas Barriers, Landfill baseliners & Capping and process water ponds.
These liners will normally be provided in rolls which have to be welded together. This requires an experienced welding technician using the correct welding machinery; so as to ensure a proper bond is attained at the seam. Low quality brands offer poor adhesion properties, resulting in leaks from the seams over time. Replacing or repairing leaking linings can be very expensive, in addition to being time consuming and inconvenient. A little extra investment in a high quality liner should keep repair costs to a minimal level. (Proper installation of the liner as well as careful procedures for the installation of cover layers is crucial).
According to Philippe Grimmelprez of Mattex Geosynthetics, which is a major manufacturer of woven geotextiles in Dubai – UAE and Non-woven Geotextiles in Al Jubail-Saudi Arabia, can quality Geotextiles offer many advantages for contractors, consultants and governments. In principle are geotextiles, woven or non-woven, used in almost every civil engineering project. Often are the geotextiles used also in combination with other Geosynthetics like Geogrids, Geomembranes, Geocells and Gabions.
The selection of the right polymer for the application concerned is the starting point for the selection of the best suitable geosynthetic. Commonly are polypropylene and polyester non-wovens and wovens used and its usage depends on the application and requirement. For the most critical applications and soils is polypropylene the preferred polymer thanks to its resistance against chemicals (polluted soils and environments with a high PH – e.g. concrete) that often can be found on sites. The excellent mechanical and hydraulic characteristics that can be achieved with polypropylene fibres also contributes to this significant preference. Today – with the current modern technology of Mattex Geosynthetics – can much higher strengths per unit mass be reached than ever before. This high performance geotextiles results in a significant advantage in the product, installation and transport cost.
“Mattex Geosynthetics is able to reach strengths that are up to 30% higher than geotextiles with similar weight a couple of years ago. This also leads to significant cost savings as the product is cheaper, more economical to transport and easier to install than heavier products. Contractors, designers, consultants and governments are more aware of the advantages and cost savings that Geosynthetics can bring to a project. Aside the significant cost savings that can be achieved with quality Geosynthetics is this also an environmentally friendly construction method,” he adds.
Challenges in the Market
The biggest challenge faced in this market is awareness. Like many new technologies, enablement and adoption becomes a challenge. Especially in developing countries where exposure to these products are minimal, it is important to study and understand the use of geosynthetics.
According to AKS lining systems Laboratory Manager, a supplier of geomembranes in Africa, challenges in the market include: Inexperienced customers who purchase the cheapest lining option and do not consider the quality of the lining required for their specific application, transport of containers of lining from Port to remote sites; meeting deadlines and time-frames for inaccessible, remote locations and also Problems with Customs clearances relating to consumables and returnable tools
As one of the experts in this industry, Strata takes several steps to ensure prospective and existing clients are technically sound with the material. This includes installation guidelines, product guidelines, exhaustive test reports, informative case studies, technical in-person workshops, and several informational videos.