Abstract

The presence of expansive clay often causes damage to infrastructure built on it. Expansive clay with great compressibility and swelling potential requires improvement or stabilization of the soil. It can be successfully done by mechanical and chemical compressibility effect of adding Polyamide (PA) fibre as the material for mechanical stabilization and nano SiO<inf>2</inf> as the material for chemical stabilization. Nano SiO<inf>2</inf> can be produced from waste from geothermal power plants. In the future, this material is very suitable for use in order to reduce waste that pollutes the natural environment. The expansive clay used in this study deployed a sample of clay containing mineral montmorillonite with the USCS classification in the high plasticity (CH) category. The mixed materials used include PA fibre with variations of 0%, 0.5%, 0.75% and 1% by dry soil weight and nano SiO<inf>2</inf> with variations of 0%, 1%, 2% and 3% by dry soil weight. To prove the effectiveness of using nano SiO<inf>2</inf>, this study compares the treatment with the use of micro SiO<inf>2</inf> materials under the same comparison variations. With inclusion of the polyamide fiber at the above ratio, the compression index decreased slightly of around 11%. But this is still better in comparison with inclusion of nano SiO<inf>2</inf> at the above ratio with the result of compression index of around 3%. With inclusion of the polyamide fiber at the best above ratio, the potential swelling decreased quite good of around 31%. Nano SiO<inf>2</inf> inclusions have achieved even better results at the best above ratio with the result of potential swelling of around 64%. The combination of these two materials results in a reduction in swelling potential of around 79%. The results of this test show that expansive clay which has been stabilized using PA fibers and nano SiO<inf>2</inf> is able to prevent potential swelling and reduce its compressibility.