EFFECTS OF PARTIAL SUBSTITUTION OF LIME WITH GROUND GRANULATED BLAST-FURNACE SLAG (GGBS) ON THE STRENGTH PROPERTIES OF LIME-STABILIZED SULFATE-BEARING CLAY SOILS

Increasing global awareness of environmental pollution as well as incr easing waste material disposal legislation is providing impetus for ma terial upgrading by stabilisation of in situ soil as an alternative to its export to land-fill and replacement by imported granular fill. Th e use of ground granulated blast furnace slag (GGBS), an industrial by -product, is well established as a binder in many cement applications where it provides enhanced durability, including high resistance to ch loride penetration, resistance to sulphate attack and protection again st alkali silica reaction (ASR). This paper reports on efforts to exte nd the use of GGBS to highway and other foundation layers by determini ng the beneficial effect on strength of progressively substituting GGB S for lime in lime-stabilised clay soils, particularly in the presence of gypsum. This paper describes the results of laboratory tests on li me-stabilised kaolinite containing different levels of added gypsum an d on lime-stabilised gypsum (selenite) bearing Kimmeridge Clay to whic h, in both cases, the lime has progressively been substituted with GGB S. The tests determine the strength development of compacted cylinders , moist cued in a humid environment at 30 degrees C. The results illus trate that substitution of lime with GGBS in stabilising gypsum-contai ning clays produces significant improvements in strength development. The process has important practical applications, and the paper report s on-going pilot field trials aimed at realising these applications. ( C) 1998 Elsevier Science B.V. All rights reserved.