Construction World August 2019

CEMENT & CONCRETE TECHNOLOGY

Fibertex solutions for concrete surface enhancement encompass Formtex Controlled Permeability Formwork (CPF) liners, suitable for concrete used in bridges and tunnels, marine structures, water treatment plants, drinking water tanks, as well as dams and sluices.

CURING BLANKET DEVELOPED Fibertex SA – specialists in the manufacture and supply of a wide range of geosynthetic products – has developed a new curing blanket, designed to optimise the curing of concrete and to protect the new structure.

T he Fibertex curing blanket, which is used to cover concrete surfaces when the material has set, has been designed to reduce the loss of internal and surface moisture and to control the temperature, for optimum hydration of the cementitious materials and to prevent discolouration. “It is important that when concrete has been poured, it is protected against drying and from temperature variations, to prevent shrinkage and to ensure better abrasion and scaling resistance - thus greater durability of the structure,” explains Clive Hitchcock, CEO, Fibertex SA. “The Fibertex curing blanket is manufactured from a high-quality absorbant synthetic fabric, coated with a thin impermeable polyethylene film. The fabric absorbs and distributes water evenly, resulting in optimum and uniform curing conditions for concrete, with minimal colour variations. “The impermeable film of the blanket prevents loss of moisture needed for concrete curing, without drying or shrinkage. The white pigmented blanket reflects sunlight and reduces temperature variations in the day and night, even in hot temperature conditions.” The Fibertex curing blanket is available in single-use and multiple-use quality options. Care must be taken not to damage the sensitive concrete surface during

application and for this reason, the blanket is packaged in a convenient roll for easy installation. The fabric must be placed with the fabric side facing the concrete. Panels should overlap by 10 cm and must extend beyond the edges of the slab and be at least twice the thickeness of the slab to prevent drying of concrete edges. The use of a roller is recommended to ensure full contact between the concrete and curing blanket. Fibertex specialists recommend placing rows of sand, or pieces of lumber along all edges and joints to protect the curing blanket from displacement. Concrete should be kept covered for the first seven days, depending on the concrete structure and weather conditions. Fibertex solutions for concrete surface enhancement also encompass Controlled Permeability Formwork (CPF) liners, suitable for concrete used in bridges and tunnels, marine structures, water treatment plants, drinking water tanks, as well as dams and sluices. The main functions of this geosynthetic material – Formtex - are to improve the durability of a concrete structure, extend its service life and reduce maintenance costs. 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 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 fresh water supply structures. CPF liners also minimise the penetration of graffiti media. 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. Fibertex products are manufactured to consistent quality standards at all eight production facilities globally and are supported by a technical advisory and back-up service. 

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CONSTRUCTION WORLD AUGUST 2019