Abstract: In order to observe microstructure cementation bond, determine the element composition and its spatial distribution microstructure, a series of SEM-EDS tests for Zhanjiang clay using the method of ‘whole area to micro zone, consolidation point’ are carried out. Moreover, the relationship between microstructure, chemical composition and mechanical behavior is discussed. The results show that the soil properties depend largely on the particles connection performance. In fact, Zhanjiang clay structure unit is actually many clay mineral plates stacked clay domain; the open flocculation structure combined with the free iron oxide as the main component of Zhanjiang clay is as a result of the cementation bond characteristics of the basic reason of the high sensitivity, strong structure. When stress level exceeds the structural yield stress, mechanical performance degrades rapidly; the structural unit body gradually transfers into aggregation and lamina of weak connection strength and strong dispersion. Studies also show that connection strength of soil particles, the structure morphology and its contribution to the structural strength are the essences of undisturbed soil and remolded soil properties difference; Zhanjiang natural clay is controlled by microstructure features, however, the remolded soil is controlled by clay mineral particles features.

Key words: cementation bond, Zhanjiang clay, microstructure, SEM, EDS, free iron oxide