Abstract
Microscopic examination of a compressed sample, which is composed of air-dried awegates, has revealed that major differences exist in the macro-aggregate and which account for the cqmpaction characteristic of organic ash soil. Differences in the micro-aggregate are difficult to detect; in thin section, but the fracture of the macro-aggregate, especially 1-0. 5 mm in grain size, may be important for the interpretation of the compaction cure related to both dry and wet processes. Assuming that disturbance of the sample by cutting and grinding does not significantly disturb Balsam impregnated samples, the deformation process of the macro-aggregate is shown in Fig. 2 and Fig. 3. These figures indicate that successive variations initially occur by a deaease of 'structural pore spiice followed by collapse of the aggregate when the water content is low enough. Fracturing in conditions of natural water content may occur by the compression and separation within an aggregate.
