The treatment of materials for road pavement layers with quicklime or hydrated lime has generally been successfully used for many years. A review of thirty-seven specifications throughout the world indicates that there are considerable variations in the construction processes and testing standards. The need to review and attempt to rationalise these procedures is particularly urgent as some notable failures have been recorded and there is evidence to suggest that more failures have occurred. The international review is reported in this paper in relation to the research findings on soil improvement at the University of Birmingham, UK, over the last ten years and whilst the criteria used are based on those used in British practice the significance of the findings are of wider interest. The research shows that construction 'mellowing' periods, the period between mixing and compacting, are considerably longer than those used in standard laboratory testing. The results indicate that this variation in time can significantly affect the performance of the lime-treated material. The paper contains recommendations for a laboratory design procedure to replicate expected site conditions and construction. (a).
Abstract