Can Pumice Support Structural Foundations?

Abstract

The current practice with regard to pumice soils is to remove them when encountered during excavation for the foundations of multi-storey buildings. Consequently, foundations become unusually deep where pumice deposits are located near ground level and extend to a significant depth. The decision to avoid pumice as a foundation-supporting soil is logical, although not supported by literature. The question of whether pumice can support structural foundations was triggered by observation of the current practice with regard to this unique geological material. The question was approached through a literature review that aimed to find out what is known so far about pumice, point out what should be known, and suggest what to do with regard to pumice as a foundational supporting material. It was revealed that pumice is abundant in many parts of the world and has peculiar characteristics in comparison to most geotechnical materials. Many studies are concerned with pumice as a building material applied in concrete manufacturing and block making, but not as a foundation supporting strata. Pumice materials are characterised by high porosity, low specific gravity, low strength, and high crushability. A limited number of studies have indicated that pumicious materials require special treatment in laboratory testing, insitu testing, and the interpretation of results. Insitu and laboratory tests on pumice materials were conducted in this study for the purpose of enriching the discussion. Further research is recommended in areas of characterisation, insitu testing, correlations between test results, and improvement of pumice materials for consideration as foundation-bearing strata