The clay mineral composition, the Atterberg limits and the potential expansiveness of eleven residual soil profiles from five basic igneous rocks are given. The relationship between clay mineral composition, clay content and potential expansiveness of the soil is discussed.
The paper contains a descriptionption of some practical problems with regard to concreting technique and ground water encountered in forming large diameter bored underreamed piles. Some experiences in inspecting underreams and methods adopted to ensure sound construction throughout are descriptionbed.
The paper descriptionbed a method for estimating the heave to be expected under a building by using a simple formula based on the results of Atterberg limit and particle size determinations. It was shown how the results of these tests may be used to classify the soil into four degrees of potential expansiveness to each of which a figure for potential heave under normal conditions may be assigned. Because the amount of heave decreases with depth below the surface, reduction factors are introduced and hence the potential heave of any layer may be calculated. The summation of the results for the whole profile gives the estimated total heave for the site accurately enough for the purposes of foundation and structural design.