Fly ash columns (FAC) as an innovative foundation technique for expansive clay beds

Abstract

Various innovative foundation techniques have been in practice to counteract the swell–shrink problems posed by expansive soils. Apart from techniques such as belled piers and under-reamed piles, chemical stabilisation of expansive soils has also met with considerable success. Lime, cement and fly ash are the various additives used in chemical stabilisation. This paper presents an innovative foundation technique in the form of fly ash columns (FAC) for expansive clay beds. Results from a laboratory experimental study on expansive clay beds reinforced with fly ash columns (FAC) are presented. Heave tests and compressive load tests were performed on expansive clay beds into which fly ash was introduced as compacted columns. Heave decreased significantly on reinforcing the clay beds with FACs. Stress-settlement characteristics of expansive clay beds also improved when reinforced by FACs. Curing of FAC-reinforced expansive clay beds improved stress-settlement characteristics.

Keywords:

• expansive soils
• belled piers
• chemical stabilisation
• fly ash columns (FACS)
• heave
• stress-settlement characteristics