Effects of partial substitution of lime with ground granulated blast furnace slag (GGBS) on the strength properties of lime-stabilised sulphate-bearing clay soils

Suppression of swelling associated with ettringite formation in lime stabilized sulphate bearing clay soils by partial substitution of lime with ground granulated blastfurnace slag (GGBS)

The use of ground granulated blast furnace slag (ggbs) is well established in many cement applications where it provides enhanced durability, including high resistance to chloride penetration, resistance to sulphate attack and protection against alkali silica reaction (ASR). The use of ggbs in soil stabilization is, however, still a novel process in the UK although it has been used in South Africa. This paper reports on efforts to extend the use of ggbs to highway and other foundation layers by determining the beneficial effect which it has on the reduction of expansion due to the presence of sulphates. The paper describes the results of laboratory tests on lime-stabilized kaolinite containing different levels of added sulphate to which different amounts of ggbs have been added. The tests determine the strength development of compacted cylinders, moist cured in a humid environment at 30°C, and the linear expansion of these moist cured cylinders on soaking in water. The results illustrate that small additions of ggbs to sulphate containing clays which are stabilized with lime reduce substantially their expansion when exposed to water and have no significant deleterious effect on strength development.

Effects of ground granulated blast furnace slag (ggbs) on the strength and swelling properties of lime-stabilized kaolinite in the presence of sulphates

Effects of monovalent and divalent metal sulphates on consistency and compaction of lime-stabilised kaolinite

Mechanisms by which ground granulated blastfurnace slag prevents sulphate attack of lime-stabilised kaolinite

This paper describes the problems encountered with the use of lime stabilisation in the M40 Motorway Banbury IV contract in England, and alerts highway engineers to a mechanism of lime stabilisation which has not been generally appreciated. The problems on Banbury IV appeared to occur only where the road ran over lower lias rock; they emerged at the end of the winter after the lime-stabilised element of the capping layer was constructed during Spring and Summer 1989. It was found that the carriageway had lifted by up to 150mm; the lime-stabilised layer had softened, was moister than expected, and its thickness had increased from 250mm to 400mm. The unexpected heave of the lime-stabilised material, found here and during very recent American research, emphasises the need for detailed chemical and laboratory studies of both soil and ground water in any project considering the use of lime stabilisation; conventional test methods are sometimes insufficient. The results show that the heave is caused by ettringite/thaumasite formation. In order for this to occur, the following conditions are necessary: a) high pH conditions; b) a sufficient clay mineral content giving an adequate supply of alumina, silica and carbonates; c) the presence of sulphates; d) the correct temperature conditions; and e) availability of sufficient water. These conditions were present on Banbury IV. The Department of Transport is now considering the implications for specifying lime stabilisation. (TRRL)

J Temporal

Papers

M40 motorway banbury iv contract - lime stabilisation