On the swelling potential of remolded clays compared with undisturbed clays

The vertical swell per centages and the vertical swelling pressures obtained for undisturbed clay specimens are different from those obtained for remolded specimens utilizing the same ASTM 4546 Method B and Method C testing procedures. This comparison refers to the same source of clay for which both the undisturbed and the remolded specimens possess the same characteristics, such as density, moisture, liquid limit, etc. Thus there is an engineering need to know the value of the remolded-clay swell ratio, defined as the ratio of the vertical swell per centage under a given vertical pressure to that of undisturbed specimens. The remolded swell ratio is reflected in the calculation of the expected heave for any given pavement, based on (a) an expansive clay subgrade and (b) a fill that contains a swelling clay core. According to both literary sources and local specific individual tests, the value of this ratio is greater than 1.0. It is clear that for any given project, the value of this ratio can be determined from local specific tests; however, in the absence of such tests, use can be made of the analysis presented in this paper. This analysis applies to the swelling-pressure characteristics (the general swelling model), developed elsewhere, of Israeli clay; to some local swelling data; as well as to some other data taken from the technical literature. As a general evaluation, the value of this ratio can amount to 1.5 and more.