Mechanical Properties Stabilization of Low Plasticity Kaolin Soil Using Fly Ash and Hydrated Lime

Kaolin soil is found in various places in Egypt, such as the Sinai Peninsula, Al-Galala, and Aswan. The need to improve kaolin soil is urgent because of its low to moderate bearing capacity. The effect of fly ash on the enhancement of low-plasticity kaolin soils is the main purpose of this work. Since fly ash requires alkali activation to enhance its pozzolanic reactivity, a small amount of hydrated lime (3%) has been added to fly ash. The behaviour of untreated and treated kaolin soil with fly ash proportions ranging from 5 to 20% by dry weight of soil is studied and analysed. Unconfined compressive strength (UCS), Atterberg limits, compaction, and California bearing ratio (CBR) tests are conducted on low-plasticity Kaolin clay and binder mixtures. Results of more than 120 tests indicate that the optimum moisture content (OMC) decreases while the maximum dry density (MDD) increases by adding binders to kaolin soil. It is also noticed that the maximum improvement of the CBR occurs by adding 3% lime and 10% fly ash to kaolin soil. The results of the UCS test show that using 5% and 10% fly ash with 3% lime gives low UCS compared to adding only 3% lime for all curing periods. On the other hand, using 15% and 20% fly ash with 3% lime gives a significant increase in UCS compared with other studied cases.