Lime and cement stabilisation can be utilised to enhance the strength and stiffness characteristics of soils. This form of stabilisation is recognised in Series 600 of the Specification for Highway Works Series as a method of providing capping replacement layers. The technique can be used to provide a cost-effective alternative to imported stone capping layers under road pavements and hardstandings. The design strength can be varied to meet specified project requirements, however CBR values in excess of 15% are commonly achievable.
We also have extensive experience in applying these techniques for temporary works. A soil stabilised piling mattress can offer an alternative to the import of aggregates, and often the later disposal of the same or the equivalent volume of displaced soil. Construction laydowns, compounds, crane pads and temporary haul roads can all be constructed predominantly using the existing soils found on-site. We can provide a full design service for temporary works and can deliver designs that are certified by our own chartered engineers.
Utilising site-won soils in this manner will nearly always reduce the total requirement for imported aggregate and disposal of surplus materials off site. The benefits not only include cost savings but they also enhance the project’s environmental credentials and provide improved safety standards through the reduction of heavy vehicle movements.
Prior to stabilisation, the formation is initially prepared for grading using a GPS machine control dozer that allows us to achieve the required grades and crossfalls.
The required dose of lime or cement binder is then spread over the materials that are undergoing treatment using a computer-controlled binder spreader. The type and quantity of binder that is required for each project is determined through initial design testing that is undertaken prior to site start and then on an ongoing basis to allow for variations in the ground.
Mixing then takes place to incorporate the binder into the soil. Our Wirtgen self-propelled stabilising machines can mix to a depth of up to 500mm in a single pass.
Materials are graded to ensure the correct layer thickness is maintained for compaction and then compacted with the specified number of passes with a heavy soil compactor.
Any soft spots identified during compaction are over-excavated and replaced with engineered materials to the same performance as the stabilised materials.
The surface is then final trimmed and the last compaction takes place.
Testing is carried out to confirm that the specified project requirements have been met.