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Introduction (NGA9.1)

Promoters of alternative reinstatement materials (ARMs) and alternative technologies (ATs) are likely to be undertakers, contractors or manufacturers of proprietary products, plant or equipment. However, the benefits of ARMs and ATs extend to a wide range of stakeholders with positive impacts on safety, congestion, the environment, the asset and the wider benefits of efficient working.

The SROH also includes provision for Product Acceptance Schemes. Where appropriate, ARMs and ATs should be developed with a view to being covered under a Product Acceptance Schemes or included within a subsequent revision of the SROH. For guidance, the process for obtaining a Product Acceptance Scheme certificate should apply the same level of safety, practical and technical rigour as is applied when assessing ARMs and ATs.

Treated materials for fill (TMF) covers a range of materials that are treated before use. The purpose of the treatment is improvement, not necessarily stabilisation. Improvement includes treating wet or cohesive materials to enable placement and compaction. The performance characteristics of TMF are lower than SMR and are based on their mechanical performance post immersion in water (soaking). This means the performance of the TMF (SMF Class B to D) is typically dictated by the nature of the compacted soil and aggregate mix. SMF Class A could either be a granular material similar to the above, or a predominately fine-grained material including clay that has been stabilised. Particular care and attention is required to ensure it is a stabilised product (see description under SMR).

TMF may be trialled for use as surround to apparatus, backfill or sub-base. If used as a surround to apparatus, particular care is required to avoid damage during placement and compaction.

Non flowable structural material for reinstatement (NFSMR) is an SMR designed to provide a stabilised product. Stabilisation is a process that obtains a homogenous mixture of soil or graded granular material using treating agents and, optionally, water. When properly compacted, it significantly changes the characteristics of the material in a way that renders it stable, particularly with respect to the action of water and frost.

Flowable structural material for reinstatement (FSMR) is an SMR designed to provide a flowable product that hardens during curing. It does not require compaction.

Structural material for reinstatement (SMR) may be trialled for use as surround to apparatus, backfill, sub-base, base or binder (subject to road category). If used as a surround to apparatus, particular care is required to avoid any damage during placement and compaction.

HBMs have an extensive track record in highways in the UK going back to civils works in the 1960s and include a wide range of different constituents and categories of performance. A10.2 HBMs are most akin to NFSMR; including an upper limit on strength. However, standardised requirements; including constituents, test methods, testing regimes, mixture and production control requirements apply to HBM.  These requirements mean that A10.2 HBMs do not require an A9 trial and are only typically achieved with static production facilities (see A10.2).

The mixture test requirements for SMR and TMF are not suitable for all material types and applications. An example of non-suitability is bituminous based mixtures (asphalt) that are classified based on a different suite of testing than that included for SMR and TMF. Reference should be made to the appropriate British Standards (BS) or European (BS EN), and this Code for materials proposed as ARMs that do not fall under the SMR and TMF categories.

Using the example of an ARM that is a bituminous based mixture, it is anticipated that reference would be made to standards including those for aggregate (BS EN 13043), bitumen (BS EN 12591 or BS EN 14023 for polymer modified bitumen), mixture (BS EN 13108), UK specific guidance (e.g. PD6691) and British Standard specifications (e.g. BS 594987).

For these materials a higher level of technical input and expertise is anticipated in the development and support of ARMs through the A9 process.