Innovative cementing agents, used as alternatives to conventional soil stabilisers

The paper studies innovative cementing materials and processes such as alkali-activated (AA) types of cement or enzymatically induced mineral precipitation for soil stabilisation, as alternatives to traditional binders such as Portland cement or lime. Parametric studies have been performed in the laboratory on two problematic fine-grained soils, treated by mixing with different activators at different molarities and dosages. Materials retrieved from waste have also been considered for both processes (i.e. as activators or as enzyme source). Tests included unconfined compressive strength (UCS) and p-wave velocity measurements using Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT). In general alkali-activated cements outperformed enzymatically induced mineral precipitation cements in terms of strength improvement. However the latter process has potential and is worth investigating further in order to gain a better understanding of the complex mechanisms involved. This can lead to the development of improved procedures that will give better results in terms of soil stabilisation.