The behaviour of a cement flyash stabilised silt under cyclic loading was studied. Pore water pressure equilibrium during cyclic loading was ensured and the test results were interpreted in an effective stress space. The behaviour under 2-way cyclic loading was significantly different from that of 1-way loading.
The use of cementitious additive(s) in the stabilisation of sub-base or subgrade materials has been a recent development in road construction. Cement stabilisation of soft soil to considerable depth can also be achieved by the "Deep Mixing" Method. The use of a cement flyash mixture (abbreviated hereafter as CF) in lieu of cement alone may bring significant economical and environmental benefits, and has been reported by a number of researchers (Furguson 1993, Indraratna et al. 1995). It has not been uncommon that the strength of CF stabilised soils are characterised by unconfined compressive strength, despite recent research (Leroueil & Vaughan, 1990; Indraratna et al., 1995) demonstrated the applicability of effective stress principle to cemented soil subject to monotonic loading. Lo & Wardani (1998) studied the monotonic response of a CF stabilised silt and concluded that the mechanical behaviour can be consistently explained within a soil mechanics framework. However, there is still also a scarcity of information on the cyclic behaviour of lightly cemented soil, particularly test data that allows an effective stress interpretation. The primary purpose of this paper was to investigate deformation behaviour of a lightly CF stabilised silt under undrained cyclic loading. Both 1-way (compression) and 2-way cyclic loading were studied. The material tested was a sandy silt stabilised with a cement flyash slurry, the same material as discussed in an earlier paper by Lo & Wardani (1998). The grading curve of the parent soil is presented in Fig. 1.
