STP1095

    The Nature of the Immediate Reaction of Lime in Treating Soils for Road Construction

    Published: Jan 1990


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    Abstract

    It is now well-known that the geotechnical characteristics of wet cohesive soils are improved rapidly by adding lime (immediate effects) and that, subsequently, the mechanical characteristics of the compacted mixture generally develop in course of time (long-term effects). Whereas the pozzolanic nature of the slow reactions which result in long-term stabilization has been recognized, that of the immediate reactions still remains a point of controversy. By replacing lime with an equivalent amount of various mineral substances that may react in a similar manner, an attempt was made to obtain the same immediate effects as those produced by incorporating lime into wet, silty soil. The tested substances are: the hydroxides of strontium, barium, and sodium; the sulphates of calcium and aluminum; and calcium chloride.

    The results show that the whole of immediate effects are obtained only when alkaline-earth ions (calcium, strontium, or barium) and hydroxyl ions are present at the same time. The hypothesis of the clay particles being linked as a result of physico-chemical adsorption of calcium hydroxide [Ca(OH)2] molecules or CaOH+ ions accounts well for the experimental observations.

    Keywords:

    soil treatment, improvement, cohesive soils, lime, additive, immediate effects, granulation, crump stability, plasticity limit, clay minerals, strength, curing


    Author Information:

    Verhasselt, AF
    Belgian Road Research Centre, Brussels,


    Paper ID: STP23543S

    Committee/Subcommittee: D18.15

    DOI: 10.1520/STP23543S


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