Geosynthetics offer durability for concrete structures

Geosynthetic products manufacturer and supplier Fibertex South Africa’s geosynthetic solutions encompass controlled permeability formwork (CPF) liners, which are designed for concrete surface enhancement in harbour infrastructure projects.

“The main functions of Formtex CPF liners at harbours and ports are to improve the durability of a concrete structure and extend its service life, and reduce maintenance costs,” says Fibertex South Africa technical sales engineer Brian Potgieter.

“Typical applications for this material in harbour infrastructure include wharfs, bridges, tunnels, precast concrete units and marine structures. Apart from harbour projects, these liners are also used in water treatment plants, drinking water tanks, as well as dams and sluices.”

Potgieter also says degradation of concrete structures is normally accelerated by the effects of salt water, high temperature and increased carbon dioxide (CO2) levels in the air.

“Traditional formwork is impermeable to air and water, which leads to water and air migrating to the interface between the formwork and concrete. The result is an increased water and cement ratio in the cover region, where air bubbles also become entrapped and lead to the development of pinholes. “The use of an innovative material like Formtex CPF liner could potentially double the lifetime of a concrete marine structure, by improving the quality of the concrete.”

Formtex is a two-layer CPF liner, consisting of a drainage layer that allows water and air to escape and a filter layer with a pore size designed to retain cement particles. When surplus water and air is drained from the surface of the freshly poured concrete during compaction, the water/cement (w/c) ratio in the concrete cover is reduced.

This results in a denser and stronger concrete, with a blemish-free surface.

Formtex CPF liners, which are suitable for the rounded shape of concrete elements, are suitable for use in the casting of bridge pillars and bridge spans. This is to ensure high quality, durability and low maintenance of the concrete elements that need to withstand highly aggressive environments.

Formtex also reduces the formation of blowholes and other blemishes on the concrete surface that normally require extensive deburring after the formwork is removed. The smooth, dense and strong concrete cover is dust-free and because there are no release agents, it is an ideal prepared base for further surface treatment or coatings.

Formtex CPF liners, which reduce micro bacterial growth, are a highly efficient alternative to slip agents for freshwater supply structures. CPF liners also minimise the penetration of graffiti media, making it easy to remove from a surface.

Formtex is designed for tensioned, glued or self-adhesive mounting to vertical or inclined surfaces. Once Formtex is attached, concrete casting is performed as usual. These liners can easily be removed from the concrete during formwork striking.

The Fibertex geosynthetics range encompasses nonwoven and woven geotextiles, gabions and mattresses, drainage pipes and fittings and erosion control and cellular confinement solutions. The company also supplies soil reinforcing products, including geogrids and geocells, as well as geosynthetic clay liners as part of composite lining systems in modern landfills.

Fibertex products are manufactured to consistent quality standards at all production facilities globally and are supported by a technical advisory and back-up service.

Fibertex is the largest manufacturer of ultraviolet stabilised virgin polypropylene nonwoven geotextiles produced in Africa, with certification for durability of over 100 years, in accordance with the latest European standards.