Lime stabilisation of road subgrades benefits and receptive soil types

Soil stabilisation is not new in New Zealand having been practised some thirty years or more. Lime stabilisation, however, is only now being considered as a primary option in the process of road construction.

Lime reacts with clay to varying degrees depending on the mineral composition of the clay. Plastic soils whether they are fine grained clay or gravel-clay in nature are responsive to lime, whereas organic soils and soils with a low Plasticity Index (P.I.) are generally not.

The advantages of lime treatment is that it leads to reduction in the construction time and cost if carried out correctly. It this makes it imperative to recognise when it is a viable option. Simple tests can identify lime responsive soils, but further laboratory tests are required to enable a cost efficient result to be achieved.