LAUSR

Abstract Cohesive soils are often mixed in situ with cementitious binders to serve as a deep foundation. However, there is limited research on cemented stiff clay in applications where high soil strength is required. The present research is aimed to determine the mechanical properties of soilcrete produced with Edmonton stiff clay. The equivalent cement content is high, between 18 and 30%. Two cementitious binders were used: 100% ordinary Portland cement and a mix of 90% cement and 10% fly ash. Unconfined compressive strength tests were carried out at different curing ages. Scanning electron microscopy images were taken to inspect soilcrete texture and examine the effects of fly ash. Results showed that soilcrete behaves similar to an overconsolidated clay; the specimens reach peak strength at strain lower than 1% at mature age (>56 days). The peak strength decreases with increasing water to cement ratio. The measured moduli range widely from 30 to 270 MPa; the initial and secant moduli have a linear relation. The residual strength is nearly linearly related to the peak strength. SEM images show that addition of 10% fly ash helps disperse the cement and reduce cement clusters; the damage on soilcrete occurs along the failure plane due to crushing of cement clusters.