Tests have been carried out to determine the potential use of Class F fly ash in stabilising a highly expansive clay. The unconfined compression test was found to be ineffective in determining the gain in strength due to the development of micro cracks within the specimens. However, the soaked CBR test results showed that the addition of Class F fly ash alone could not improve the performance of the soil. On the other hand, the use of 12 percent fly ash and 4 percent lime reduced the swelling by 33 percent while the soaked CBR value was more than doubled. The most significant improvement produced by the lime-fly ash stabilisation is that the swell pressure of the clay was reduced by a factor of up to 10, to a value of about 40-50 kPa. This suggests that a road embankment of 2 to 3 metres high built on the stabilised clay would not experience problems with swelling. The use of pressure injection was attempted as an alternative to soil mixing. However, it was observed that this technique could not produce the same efficiency as soil mixing in terms of strength improvement and swell reduction. (a)
Samenvatting