Textile concrete offers new potential

Textile Concrete is a relatively new concept, but is gradually gaining acceptance, not only here in South Africa, but also in other parts of the world – notably the USA and New Zealand. 

Development started with fluffy fibrous strands made by spinning a polypropylene staple fibre sheath onto a polypropylene stretched tape core. The fibres are bonded to the core so that under flex loading they cannot slide. The core can also be made of continuous multi-filaments and, in the case of ‘hi-tech’ strands, can be glass or carbon filaments, Kevlar (DuPont) or gel spun HDPE. 

The strands can be pre-stressed for use as is, cut in to fibres, woven or knitted into textiles – all for use in concrete, polymer concrete or gypsum plaster. 

The woven textile, which is locally developed and made on conventional looms, can be cut to shape, impregnated with a water-based matrix, cured at ambient temperatures to produce a hard strong and tough material which is difficult to corrode. 

The Textile is very receptive to cement slurry/mortar. It has an open weave through which the cement matrix can both flow and bond. The cement paste infiltrates the fibrous surface of the strands and, as hydration takes place, gel forms around the fine fibres creating a homogenous cement/fibre/textile composite. The cement mix can be applied by dipping, spraying or block brushing. 

It has the potential of taking cement as a matrix into a wide range of applications, the development of some having been already started. Examples of the possibilities are:

Textile concrete can replace glass-fibre resin for static applications, can be lighter, stronger and externally more durable than timber, and offers an alternative to aluminium for use at the coast, without the need for anodising or powder-coating. 

The textile was first used in the local market for the manufacturing of roofing for low-cost houses. This was followed by commercialisation and supply of mine-drainage channels for the gold mines. 

Visible examples of textile concrete work can be seen around Johannesburg - including décor mouldings on the casino at Gold reef City, fascia panels on the west office block in Nelson Mandela Square, Sandton and a floating model of Robben island at Wemmer Pan. 

Large complex shapes can be made without the need for a mould, as well as 3-dimensional hollow mouldings such as large vases or Amphorae.   

Amphora in textile concrete

Textile concrete is lightweight

Tilt-up construction - destined for growth

Tilt-up construction seems destined to attain new status in South Africa after recent decisions to use this special form of precast concrete construction. Recent projects utilising this unique method include:

But what is Tilt-up? 

By definition, tilt-up is a special form of precast concrete construction. The method is basically jobsite prefabrication, during which the walls of the structure are cast in a horizontal position, tilted to a vertical position and then set in place.

ECONOMY - In most cases, tilt-up results in the lowest first cost. Ready-mixed concrete, which is locally available, is used and no special labour skills are required. 

SPEED OF CONSTRUCTION - Panels are formed and cast on the construction site. With the use of high capacity mobile cranes, the panels can be quickly tilted, lifted, set in place and braced. In this way, large buildings can be constructed in a short period of time. 

MINIMUM MAINTENANCE - The concrete surfaces can be left unpainted. The wall panels resist daily contact damage and are easy to keep clean. 

ARCHITECTURAL APPEARANCE - Unlimited design freedom is made possible by surface colours and textures. Small changes in the shape of the panels can enhance the appearance of an entire building. 

'FLEXIBILITY' - Walls can be designed for easy removal and relocation for futre additions. 

FIRE SAFETY - Tilt-up concrete walls are fire resistant and allow closer spacing of buildings. This can result in a reduction in fire insurance premiums. 

OTHER SAFETY FEATURES - Vandalism and theft are discouraged because concrete is difficult to penetrate. Concrete walls are also effective radiation shields. 

SIMPLIFICATION OR ELIMINATION OF FORMWORK - The contractor can do away with the need of formwork or scaffolding. 

REDUCED HEATING AND COOLING COSTS - Heating and air-conditioning costs are lower than for metal buildings. 

For more information on Tilt-up construction contact the C&CI Information Centre, or TILT UP SYSTEMS on:  Tel: +44 31 767 3684  E-mail: tiltup@iafrica.com