Limestone is an extremely valuable raw material and is one of the most versatile of all industrial rocks and minerals. Its main use, however, is in the construction industry, as an essential raw material for cement manufacture, as crushed rock aggregate and also as a source of building and ornamental stone. Limestone is therefore widely extracted, often by poorly-regulated open-pit quarrying in many developing countries. There is an increasing awareness of the environmental impact of limestone quarrying and of the need for geological resource studies to guide strategic mineral planning and development plans. In many developing countries there is often no factual basis to assess either potential total or workable stone resources, nor their quality, to inform the planning process.
The work summarised in this report was carried out under the Department for International Development Technology Development and Research Programme as part of the British Government's programme of aid to the developing countries. The project was formulated to develop and apply cost effective field and laboratory procedures for rapid assessment of limestone resources in developing countries based on appropriate technologies. The project was undertaken in collaboration with the Department of Mineral Resources, Thailand who carned out project field mapping, and assisted in field trials and in the generation of resource assessment data.
An area near Surat Thani in southern Thailand was selected for project fieldwork and this area was geologically surveyed at the 1:50 000 scale applying rapid mapping techniques to identify mappable limestone units (formations) and geological structure. Each formation was sampled for laboratory studies of physical, mechanical and chemical properties.
Dining the limestone mapping and sampling, field trials were carried out on a range of techniques for determination of dolomite and also for rock strength testing. Density determination, using a sodium polytungstate (heavy liquid) method developed during the project, proved to be a rapid, reliable method for determining dolomite content and was routinely used in the field to rapidly map the main zones of dolomitisation. A portable spectrometer (PIMA) was also investigated for dolomite discrimination and proved to be a potentially useful tool for field reconnaissance. In order to assist field assessments of the aggregate properties of limestones two techniques, the Schmidt hammer and the Point Load Tester, were investigated and the Schmidt hammer was routinely used during fieldwork to estimate rapidly rock strengths.
A further objective of the project was to investigate rapid techniques for laboratory analysis of limestones and dolomites. To achieve this aim the range of available techniques were reviewed and laboratory trials were carried out using several methods for determination of carbonate content. Laboratory techniques for testing aggregate properties, brightness and lime burning were also investigated with the emphasis on the development of simple, rapid procedures.
The field and laboratory data generated during the project have been used to assess the limestone resources of the project's study area in Surat Thani, Thailand and to generate a limestone resource map which categorises the limestone quality in terms of physical and chemical properties.
It is anticipated that the resource assessment methodologies so developed will be applicable to other regions and countries. Overall, the results presented in the report are aimed to be of benefit not only to geologists, but also to planners, environmentalists and engineers.
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