Construction World May 2018

DAMS & RESERVOIRS

SURFACE ENHANCEMENTS for aggressive environments

Water tank.

Fibertex Controlled Permeability Formwork (CPF) liners, are designed and manufactured for concrete surface enhancement in diverse applications, including highly aggressive environments.

tance of concrete structures of sewage plants and settlement tanks are important factors for consideration. The concrete face, which is in constant contact with wastewa- ter, needs to withstand the penetration of aggressive substances and high-pressure cleaning procedures. “In drinking water tanks, mechanical resistance of the concrete is also imper- ative, as the concrete face is subjected to high-pressure cleaning and, because micro-organisms flourish in voids and feed on oils, it is critical that the concrete surface is smooth, uncontaminated and free from blowholes. “A recent application for Formtex was at a large container terminal – a heavily rein- forced structure exposed to high chloride, CO 2 and moisture levels, as well as elevated temperatures. "This dense, yet workable concrete CPF liner, provided a fast and safe workflow. Other benefits are extended service life of

T ypical applications of Fibertex Formtex® CPF liners are in drinking water tanks, sewage and water treatment plants, settle- ment tanks, container terminals, bridges and tunnels, marine structures, as well as dams and sluices. Formtex is a two layer CPF liner, consist- ing 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 con- crete 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. “The main functions of these robust geo- synthetic materials are to improve the dura- bility of a concrete structure, to extend its service life and reduce maintenance costs,” explains Clive Hitchcock, CEO, Fibertex SA. “Formtex CPF liners, which are suitable for all shapes of concrete elements, ensure high quality, durability and low maintenance of concrete elements. “The chemical and mechanical resis-

LIGHT STEEL FRAME BUILDING

Sustainability is the name of the game John Barnard, Southern African Light Steel Frame Building Associa- tion (SASFA) director, says it is encouraging that an increasing num- ber of construction professionals are recognising the environmental benefits and long-term cost savings of LSFB. He says that sustain- ability with regard to buildings is essentially based on three criteria: social acceptability, affordability and energy efficiency and that LSFB rates highly on all of the sustainability considerations:

• LSF buildings appear no different to ‘conventionally’ built structures, except that the quality of finishes is typically better with the former. It has found rapidly growing acceptance for ‘affordable’ as well as up-market buildings in South Africa. • It is a cost-effective building method, with financial savings emanating mainly from significant time savings to complete building projects, less rework, reduced logistical costs –which are of growing importance due to the escalation of fuel prices and general construction inflation – and a drastic reduction of wastage and rubble on building sites, when compared with the brick-and- mortar alternative. • LSF building is significantly more energy efficient than heavy construction methods – both with regard to ‘embodied energy’ of the materials and components, as well as ‘operational energy’ relating to heating and cooling of the building over its design life. All three of Barnard’s criteria are met on the Kaap Agri project. In fact, as far as energy efficiency is concerned, the R-value (the mea- sure of thermal insulation) of the Kaap Agri external walls is greater than 3 m².K/W which is more than four times better than what would have been achieved using a double brick wall. Barnard says that the Kaap Agri project is indicative of an area of construction where LSF is increasingly playing an important role. “It is not only perfect for extensions of existing buildings, but, also, LSF building is becoming increasingly relevant in a construction environ- ment that is striving to reduce impact on the environment.” So successful was the solution brought by Rancor to Kaap Agri, Rancor was asked asked to assist with a solution to the Kaap Agri Simonduim project, about halfway through the Paarl Head Office construction period. Both projects were finished on time and within budget. 

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CONSTRUCTION WORLD MAY 2018 CONSTRUCTION WORLD MAY 2018