Laboratory and in situ evaluation of stabilisation of limestone aggregates using lime

摘要

A study was conducted in France, in the Region of Seine et Marne, to evaluate the potential for improvement of soft limestone granular materials, widely available in this region, by lime treatment. Three experimental sections of low traffic pavements were built, with 3 different limestone base course materials. Each section was divided in two parts, one treated by addition of 1% of quicklime and one untreated. These sections were followed up by deflection measurements and FWD tests. Laboratory tensile strength and modulus measurements were performed on the same materials, after different curing times. For all three limestones, the study indicated that the addition of 1 % of quicklime leads to a very significant increase in performance, due to several mechanisms, including: lime hydration, leading to moisture reduction and precipitation of calcite; carbonate cementation due to reaction of lime with carbon dioxide to form calcium carbonate that coats the aggregates. Values of elastic modulus and tensile strength of the materials increased considerably with time, leading to elastic moduli ranging from 4000 to 8000 MPa after 1 year. These improvements were verified on site, by FWD tests and deflection measurements: after 2 years, the modulus increased to 3000 to 5500 MPa for the lime-treated layers, compared with 600 to 700 MPa for the non-treated layers.