Volcanics for construction (VOLCON)

Steve Mathers, British Geological Survey, Project R7117

Throughout history volcanoes have exerted a strong influence on man and, with the development of sophisticated communications, the awesome explosive power of volcanic eruptions is now regularly reported from sites all around the world. Volcanic eruptions cause considerable loss of life either directly through the physical act of eruption or indirectly through floods produced by tsunami or famine generated by subsequent crop failure. The names of many famous volcanoes such as Krakatoa, Vesuvius and St Helens are synonymous with death and destruction. Yet, despite the considerable dangers there is another side to the story. Aesthetically many volcanoes such as the relatively dormant Fuji, Rainier and Kilimanjaro are recognised as objects of great beauty with rich spiritual and mythological histories. More tangible benefits from volcanic activity include geothermal energy, fertile soils and, perhaps most significantly, the varied rocks produced by eruptions - many of which are significant raw materials in construction.

Project participants meet during the Project Forum at Keyworth May 1999.

Photo: Steve Mathers

The utilisation of volcanic rocks in construction is the focus of a three-year KaR project which began in September 1998. This article profiles the project and reports on its progress to date. The project aims to improve the understanding of the properties of volcanic raw materials and to develop applications for them. The principal materials are lavas, pumice/scoria, perlite, zeolite-rich rocks, ashes and tuffs. These are used as sources of aggregate, lightweight aggregate, pozzolana for cement and concrete, and expanded perlite which is used as loose-fill granules and in plasterboard. Volcanic deposits are plentiful in many developing countries but are often under utilised. Project components include:

· the design and testing of exploration methods to identify prospective raw materials

· capacity building through joint field and laboratory studies with counterpart staff

· the provision of advice and technical information to public bodies and the private sector

· the publication of technical fact sheets and a comprehensive manual describing the exploration, evaluation and usage of volcanic raw materials

· dissemination of the project findings through three regional workshops.

Mount St Helens, Washington, USA erupted violently in 1980. Despite the awesome destructive power at many volcanoes the deposits produced often make useful construction raw materials.

Photo: Steve Mathers

The philosophy of the approach is to try wherever possible to evaluate the potential of volcanic raw materials in situ rather than through systematic sampling and laboratory testing. In simple terms, we are trying to take the laboratory to the rocks rather than the converse. The advantage of this is the considerable savings in shipment costs and the ability to focus detailed laboratory work only on the most promising raw materials. With this in mind we are evaluating several chemical tests which permit the field identification of zeolite minerals and are using the portable infrared minerals analyzer (PIMA) to directly identify zeolite-bearing rocks and hydrated volcanic glasses which are prospective perlites.

Besides the more routine laboratory techniques (including density, porosity, grain size, resistance to wear and the use of X-ray diffraction, X-ray fluorescence, differential thermal analysis, microprobe and petrographic examination, and image analysis), more specialised end-user experiments have been also undertaken. These include the construction of an inclined furnace enabling the laboratory testing of hydrated volcanic glasses as prospective perlites (in consultation with the local engineering consultants Mike Allen Associates), and in-depth studies of the pozzolanic properties of the volcanic ash recently erupted on Montserrat being carried out by our partners at the Buildings Research Establishment, Garston, UK.

Field exploration has been undertaken in Kenya, Tanzania, Costa Rica and Ecuador. Counterpart staff have received extensive advice on the identification and field testing of the volcanic raw materials and, at the same time, prospective deposits of pumice, scoria, pozzolanic ash, perlite and zeolites have been located and the main prospects sampled and evaluated.

In May 1999 the project partners from all the participating countries attended a forum at BGS Keyworth in order to:

· review project progress and strategy

· make presentations about the own countries raw materials and needs

· visit UK industrial minerals operations

· be provided with extensive teaching materials to ensure dissemination of the project work in their own countries

· become familiar with laboratory testing procedures

· enable everyone to meet all their fellow collaborators and exchange views.

The main project publications will include scientific papers, technical reviews and fact sheets, and a comprehensive manual. Two major technical reviews have been produced to date: one on alkali-silica reactivity by Ted Sibbick of the Buildings Research Establishment and another on volcanics in infrastructure construction by Martin Woodbridge from the Transport Research Laboratory based at Crowthorne, UK. A series of seven technical fact sheets on varied volcanic raw material commodities are in press and will be distributed widely in the next few months. The manual will be the major publication which will detail all the techniques used for exploration, evaluation and usage of volcanic raw materials: it is scheduled for publication in March 2001. Three regional workshops will be held to disseminate the results of the project.

The VOLCON project is led by a team at the British Geological Survey comprising Steve Mathers, David Harrison, Peter Dunkley. Simon Inglethorpe, Ellie Evans and Claire Cotton. Other UK-based collaborators include Ted Sibbick of the Buildings Research Establishment (BRE); Martin Woodbridge from the Transport Research Laboratory (TRL) and Mike Allen of Mike Allen Associates.

The other key participants are John Kagasi (Department of Mines and Geology, Nairobi, Kenya). Zacharia Bongole (Ministry of Energy and Minerals, Dodoma, Tanzania), Fernando Alvarado (ICE, San Jose, Costa Rica), Mario Maya (INGE-OMINAS, Bogota, Colombia), Jose G and formerly Bolivar Flores (DINAGE - formerly CODIGEM, Quito, Ecuador)

More information can be obtained by contacting the project manager Steve Mathers at the British Geological Survey, Keyworth, Nottingham. E-mail: sjma@bgs.ac.uk.