Success in the Use of Recycled Aggregate
Despite being the Highway Authority with the largest U.K. network, (some 12900 km) and having reputedly one of the strictest Street Works regimes in England; Devon County Council have been very receptive to the correct use of SMR Soil Stabiliser by Utility Companies since its introduction in late 1999.
Initial trials were carried out by John Kennedy (Civil Eng) Ltd, (now Balfour Beatty Utility Solutions Ltd) on behalf of South West Water and under strict monitoring by Devon County Materials Laboratory. The trials encompassed numerous laboratory and field tests including C.B.R. and compressive strength testing, frost heave susceptibility tests and air void testing of wearing course applied onto SMR reinstatements. In all of the tests carried out, the SMRreinstatements were proven to outperform control reinstatements using Type 1 GSB.
Following these trials, permission was granted to South West Water for use of SMR in footway reinstatements under clause S1.5 of the SROH, New Roads and Street Works Act 1991, (more commonly referred to as the HAUC spec).
Based on the success of SMR in use in footway reinstatements and further trials in carriageway, the approval to South West Water was extended in December 2000 to include reinstatements in Type 3&4 carriageway.
The approvals permit SMR treated spoil to be used as a replacement for traditional materials up to and including Roadbase levels. Under the revised SROH introduced in June 2002, performance criteria set down for alternative materials in Appendix A9 to be used at these levels deem the material to be classified as an NFSMR (non flowable structural material for reinstatement).
To date, SMR has been used by South West Water on approx 100,000 reinstatements within the footways and carriageways of Devon
The fact that use of SMR mixed with excavated spoil eliminates the need for imported backfill material and eliminates the need to remove spoil to landfill since it is re-used, means that the following environmental benefits have been realised.
- Approx 150,000 Tonnes of Landfill Capacity have been preserved.
- Approx 150,000 Tonnes of Primary Aggregate have been preserved.
- Approx 300,000 Tonnes of Material movements have been avoided, reducing both pollution and disruption to the road going public.
In addition to the substantial environmental benefits, both South West Water and Devon County Council are more than happy with the performance of the SMR reinstatements, since nearly 5 years and 100,000 completed reinstatements on, there is still to be a single reported failure. Zero failure means zero remedial works = no further disruption.
Major financial benefits are also achieved, typically a saving of £40.00 per cubic metre is enjoyed by Utility Companies using SMR when compared to traditional methods, and these savings can be further increased should the Utility Co. adopt a 1st time – single visit – permanent reinstatement policy.
The successful use of SMR in the UK is not limited to Devon and South West Water, although both must be considered as pioneers in the adoption of this highly sustainable and environmentally ideal technique. SMR is currently approved for use by in excess of 130 Local Highway Authorities nationally and has been used, without a single reported failure, on over 400,000 reinstatements, saving close to a million tonnes of landfill capacity and a similar quantity of primary aggregate. As word spreads, and the success stories increase, breaking down the industry’s “traditional approach” and its inherent resistance to change, more and more Utility Companies, Contractors, and Highway Authorities will adopt SMR as their first option on footway and carriageway reinstatements.