CSIR investigates use of natural fibre composites in construction

The building and construction sector is a significant consumer of raw and natural materials, while also contributing to the emission of global warming gases. In line with strategies proposed in Agenda 21 - a United Nations programme in support of sustainable development - the Council for Scientific and Industrial Research (CSIR) is investigating the application of natural fibre composites (NFCs) in construction, with the aim of producing construction materials that are less harmful, recyclable and made mainly from renewable materials.

Explaining the impact of building and construction activities on global resources, senior CSIR researcher Llewellyn van Wyk cites some thought-provoking statistics. "Construction and post-construction activities consume 50% of all material resources globally and 70% of global timber products. In addition, 45% of all energy generated is used to heat, ventilate and light buildings and 40% of water is used for sanitation and other uses in buildings. The current population increase of 73 million per year will also place higher demands on the consumption of raw and natural materials."

A pilot study conducted earlier by the CSIR investigated the use of industrial waste, agricultural crops and recycled materials in construction. The study found that alternative applications of industrial waste were increasingly being used in response to pressures such as increasingly stringent environmental laws, the need to minimise waste, and investor demands for improved economic and environmental performance. The pilot study found that the use of agricultural crops, most notably the use of plant fibres such as flax, hemp and sisal, offered significant promise in construction applications.

Subsequent research was aimed at establishing whether a natural fibre composite could match the mechanical properties of known conventional construction materials. "The argument made in support of this goal relates to the ability to develop technologies which would directly improve the sustainability of building and construction activities of the construction industry in South Africa," says Van Wyk. "In addition, the use of a natural fibre could support new agricultural markets and further develop the emerging farming sector."

The CSIR's experimental work focused on identifying and researching combinations of fibres and compatibilisers and determining the resultant impacts. The research results of this experimental work confirmed that NFCs fall within the targeted mechanical properties range for tensile strength, flexural strength, and impact for load-bearing elements. Further work is proposed with regard to the compressive strength and fire retardation.

Research was also undertaken to determine the other properties of conventional construction products in order to generate a matrix of matches between the technical specifications of conventional products and the properties of NFCs. In support of the sustainable development argument, preparatory work was done in the emerging field of life cycle analysis to enable NFCs to be assessed in subsequent work.

"Our research has provided sufficient evidence to warrant further prototyping development of the material," says Van Wyk. "It has also generated a useful generic approach to the exploration of other emerging materials such as lightweight steel, structural glass, fibre reinforced concrete, and ultra-thin concrete panels."

One of the unexpected outcomes of the project was research into the emerging field of off-site construction. The use of 'plastic' materials allows the production processes used in the automotive and aeronautical industries to be applied in the construction sector as well. This has led to the launch of an Advanced Construction Technology Platform (ACTP) within the CSIR. This project seeks to establish a science and technology base to explore advanced materials and construction methods, the development of theories, principles and indicators, and the preparation of design manuals for five technology pillars (conventional, fringe, hybrid, bio and nanotechnologies).

Van Wyk points out that the project is characterised by research partnerships and a strong commitment to human capital development and transformation. The multi-disciplinary research team includes the Bay Zoltan Institute of Polymer Science in Hungary, the Institute of Natural Fibres in Poland and the MG University in Kerala, India. An international specialist in fibre-reinforced composites was recruited to work on the project, while two black post-graduate students are finalising their respective Masters and PhD theses as part of the project. In addition, two black students employed by the CSIR are completing their undergraduate diploma studies in polymer technology at the Tshwane University of Technology. - CSIR


June 2007