Prediction of permeability for fully weathered granite amended with fly ash by fractal dimensions

Fully weathered granite (FWG) is a commonly used material for filling the subgrade of the highway. Existing conventional laboratory experiments indicated that it can be classified as sandy soil as per its particle diameter. Blending fly ash within FWG, referring to fly ash-amended fully weathered granite (FAFWG), seems to heighten its strength and bearing capacity. To estimate the optimal proportion of fly ash, the unconfined compressive strength (UCS) tests had been conducted on six categories of FWG specimens with different contents of fly ash and lime (as an activator) for optimization. The California bearing ratio (CBR) tests on the FWG specimens and those with the optimal proportion of fly ash (12%) and lime (4%) had been further conducted to evaluate the improvement effect of fly ash and lime on engineering properties. The permeability of FAFWG also is compliant with different blending ratios of fly ash and governs the durability of subgrades. For convenience, it was theoretically presented in terms of a fractal dimension of specimens by the image recognition technique. The rationality of the proposed method has been verified by the falling head permeability tests.