Documento(s) 6 de 18

Introduction

Slag is a good example of one such industrial waste that is abundantin Brazil. A by-product of the country's steel industry, it is producedby purifying iron ore into pig iron, and sits in huge mounds outside ironfurnaces.  Brazil produces some three million tonnes of blast furnaceslag (BFS) per year, and its disposal is a problem. Once broken down, theslag is called granulated blast furnace slag (GBFS). 

With IDRC support, engineers of the Instituto de Pesquisas Tecnologicasdo Estado de São Paulo S.A. (IPT) at the University of SãoPaulo have designed and manufactured hollow wall panels and constructeda prototype house. The IPT-IDRC Composite Precast Panel System is a low-cost,environmentally sensitive technology. It uses GBFS-based cement re-inforcedwith coir fibres instead of traditional steel rebar. Taken from the outerhusk of the coconut, the stiff, coarse coir fibres are widely availablein Brazil and other Latin American countries. Since common Portland cementtends to destroy vegetable fibers, the IPT-IDRC composite is the firstto combine low alkaline water-resistant cement with coir fibers, resultingin a durable building material. 

Producing GBFS-based cement does not require burning, resulting in 70%less energy consumption compared to the amount necessary to produce Portlandcement. The cost of a wall panel plant is thereby reduced because no rotarykiln is needed, which means that smaller, more efficient plants can becomeeconomically viable. The cement itself is composed of GBFS (92%), hydratedlime (2 %), and gypsum (6%). The mix proportions are, by weight, 1:1.5:0.51(cement, sand, water), reinforced with a volume of 2% coir fibres, averaging30 mm long. Mixing is done in an ordinary concrete mixer. 

Designed to be easily produced on-site or in a small plant, the 40 cmwide and 250 cm high IPT-IDRC wall panels weigh less than 120 kg, and canbe assembled without any heavy or expensive equipment. Because steel rebaris not used as re-inforcement, there is no risk of corrosion in the panel.A complete performance evaluation was developed and performed, and thepanels comply with IPT standards, meaning that expected performance willbe equivalent to an ordinary hollow brick wall. 

To test the panels under real conditions, a 24 square metre prototypebuilding was constructed in 1989 on a São Paulo street. The externaland internal walls were finished with commercially available emulsion paint.After eight years, there is no visible degradation on the external walls.A detailed investigation of the degradation of the fibres and cement isbeing performed. First results confirm that no alkaline degradation norbio-deterioration occurs with the fibres. 

Impact

• Commercial potential - While the IPT-IDRC Composite Precast PanelSystem is not yet being produced commercially, partly owing to the downturnin the Brazilian construction industry since the mid-1980s, IPT researchersare confident that demand will be created for the panels. Their analysisis based on the combination of an economic improvement forecast for thenear future and economic reform. Recent economic reforms, including theprivatization of the Brazilian steel industry, may well advance the commercializationprocess for this technology, according to IPT's Dr. John. The reason isthat private steel companies are consideringselling granulated blast furnaceslag. This development will ensure an adequate slag supply at reasonablecost. As a result, a grinding mill would not be required in a wall panelplant, making it economically feasible to build a much smaller, less costlyplant, and, therefore, helping the technology to reach the market morequickly. 

A business plan has been developed using the model of a small productionplant based in São Paulo. A number of foreign companies have beenin contact with IPT concerning the technology, as have several Brazilianmunicipalities. 

Prerequisites

Potential users

Contact

Dr. Vahan Agopyan 
Escola Politecnica, Universidade de São Paulo 
CP GI548 
05508 -- São Paulo SP, BRAZIL 
Tel.: (55 11) 815-4322, ext. 3364/3452 
Fax: (55 11) 2114308 
E-mail: vagopyan@usp.br 
Web site: http://www.ipt.br/ 

Resources

Marchand, Denis. 22 January 1996. Rising from the ashes.  IDRCReports.

Documento(s) 6 de 18