Appendix A9 Alternative Reinstatement Materials (ARMs)
Appendix A9 Alternative Reinstatement Materials (ARMs)
1) New or alternative materials have been, or may be, developed for use in road construction and maintenance. These materials may allow more rapid, reliable and cost-effective reinstatements, with less dependence on the skill and physical effort of the operators. These materials may also offer significant environmental or practical advantages, and/or cost benefits, compared with conventional materials, including various combinations of the following:
a) Reduced usage of virgin materials, by including recycled or secondary materials
b) Lower energy requirements during manufacture and/or laying
c) Reduced landfill requirements during construction or reconstruction
d) Self-cementing properties to improve performance, reliability of laying and compaction
e) Self-levelling or flowable, to avoid or reduce the need for compaction and to provide health and safety benefits
f) May be placed in fewer lifts
2) These materials are termed Alternative Reinstatement Materials (ARMs), and are categorised by this Specification into two generic groups:
a) Structural Materials for Reinstatements (SMRs)
This generic group is intended to include proprietary or alternative bound reinstatement materials that include a cementitious, chemical or hydraulic binder or are inherently self-cementing. SMRs are categorised as follows:
i) Foamed Concretes for Reinstatements (FCRs)
These are cement-bound materials that have been prepared off-site, generally as "prescribed" mixes, at an approved mixing plant and under appropriate quality control procedures. They are flowable in nature and should not require compaction when placed. Such materials manufactured under these conditions, and any foamed concretes conforming to Clause 1043 and with aggregates of the Specification for Highway Works are deemed to be approved for use as ARMs. FCRs do not necessarily incorporate a coarse aggregate. Layer thickness and compressive strength requirements shall be in accordance with Table A9.1.
In accordance with the SHW the composition of all Recycled aggregate and Recycled concrete aggregate shall be tested as specified in Clause 710 of the MCHW1. The content of other materials (Class X) shall not exceed 1% by mass or by volume, which ever is the greater.
FCR permissible constituents shall exclude potash and bottom furnace ash.
ii) Flowable SMRs (FSMRs)
These materials comprise any type and/or combination of aggregates and binders. They are flowable mixes that should not normally require compaction, and are capable of achieving strengths equivalent to FCRs. These materials may only be used on a trial basis by prior agreement with the road authority and following the approval trial procedure detailed in A9.5. Layer thickness and compressive strength requirements shall be in accordance with Table A9.1.
iii) Non-flowable SMRs (NFSMRs)
These materials comprise any type and/or combination of aggregates and binders. They are non-flowable mixes that will normally require compaction on site, and will be capable of achieving strengths equivalent to FCRs in their compacted state. These materials may be used on a trial basis by prior agreement with the road authority and following the approval trial procedure detailed in Appendix A9.5.
iv) Hydraulically bound mixtures (HBM)
Hydraulically bound mixtures (HBMs) are mixtures that set and harden by hydraulic reaction. They include:
cement bound materials (i.e. mixtures based on the fast setting and hardening characteristics of cement), and
slow setting and hardening mixtures made from industrial by-products such as fly ash (FA) and ground granulated blast furnace slag (GGBS).
These materials comprise any HBM specified in BSEN 14227-1, -2, -3, -5, -10, -11, -12, -13 & -14, and shall be produced, handled, transported, used and tested in accordance with the SHW 800 series. Although not called up in the SHW, the HBM types, SBM B4, FABM 4 and HRBBM 4 from BSEN14227-2, -3, & -5 respectively are also included since they are purposely suited for trench reinstatement work. HBMs therefore should be produced, constructed and tested in accordance with the SHW 800 series as if they were SBM B3, FABM 3 and HRBBM 4 respectively. Layer thickness and compressive strength requirements shall be in accordance with Table A9.1 except that the specified compressive strength requirement shall be deemed to apply at 28 days as detailed in Appendix A9.3.4. All of the SHW or BSEN14227 HBM types are deemed approved for use as ARMs without a trial.
b) Stabilised Materials for Fills (SMFs)
This generic group is intended to include materials derived from excavated spoil, virgin, secondary or recycled materials, or any combination thereof, that have been stabilised or modified by re-processing, re-grading and/or by the inclusion of a cementitious, chemical or hydraulic binder. SMFs are generally non-flowable and shall therefore normally require compaction.
These materials may be used on a trial basis by prior agreement with the Authority and following the approval trial procedure detailed in Appendix A9.5. or may be deemed to be approved for use without trial if manufactured and used in accordance with SHW clause 840 or BS EN 14227-11.
3) ARMs complying with the SHW or BS EN14227 (specific for HBM types) are deemed approved for use as ARMs without a trial.
A9.2 General Requirements for ARMs
1) With the exception of FCRs as described in Appendix A9.1.2 (a) (i, (which are deemed to be approved for use), ARMs shall only be used with the prior agreement of the Undertaker and the Authority on an approved trial basis and following the trial procedure described in Appendix A9.5.
2) The producer shall establish and maintain a Quailty System which includes policy and procedures for production control. Details that should be included in the manual may be found in the annexe of the appropriate part of BSEN 14227. ARMs shall be produced, handled, transported and used in accordance with the approved mix formulations and procedures proven by prior development and testing.
3) Alterations to the proven mix formulations, mix proportions, aggregate type, admixtures, etc. shall not be undertaken without confirmation of their suitability, obtained by further development and testing. The approval of the Authority is required prior to the use of any ARM, subject to the trial procedure, whose formulation has been altered.
4) ARMs used within 450 mm of the road surface shall be non-frost susceptible subject to the exceptions referred to in Section S5.3.1.
5) Where the Authority is aware of areas with drainage or groundwater problems, it should notify the Undertaker, and where an Undertaker exposes an area with drainage or groundwater problems, it should notify the Authority. Following such notification the Undertaker shall provide, at backfill and sub-base levels within trench reinstatements, ARMs that are permeable to a degree not less than the surrounding ground. A backfill layer of pea gravel, of 100 mm minimum thickness and surrounded by a geotextile filter fabric where appropriate, may by considered to offer equivalent drainage potential.
6) Where the Authority is aware of any site where high sulphate levels are known to occur, it should notify the Undertaker. Following such notification, any Ordinary Portland Cement based binders in the ARMs shall be replaced with cement having a high sulphate resistance.
7) Where an Authority demonstrates an engineering reason for not using an ARM, eg in Peat, the Undertaker shall not use the material without prior agreement.
8) Surfacing materials shall not be reinstated until the ARM has attained sufficient strength to allow adequate compaction of asphalt materials and to sustain adequate traffic loading. A simple penetration or indentation or bearing capacity test appropriate to the ARM is recommended to allow confirmation of adequate strength prior to surfacing. Any appropriate standardised test procedure may be used and, with prior experience, will indicate the earliest time at which surfacing should be carried out.
9) Fluid ARMs may flow into damaged drainage or ducting within, or adjacent to, the excavation. Where required, plastic sheeting etc. may provide adequate protection during pouring and curing.
A9.3 Structural Materials for Reinstatements (SMRs)
A9.3.1 Permitted Uses of SMRs
1) SMRs may be used in any combination of the following, regardless of the nature of reinstatement materials used above and below:
a) At any position within the surround to apparatus and/or backfill as the entire layer or combined with any other permitted backfill materials, in any proportion, within any reinstatement.
b) As a sub-base within any reinstatement.
c) As a combined sub-base and base within any reinstatement in Road Types 1, 2, 3 & 4 and as base within any reinstatement in Road Types 3 & 4.
d) As a combined sub-base and binder course, within any reinstatement in footways, footpaths and cycle tracks.
2) SMRs shall not be used in place of surface course materials.
A9.3.2 General Requirements for SMRs
1) SMRs shall comply with the minimum layer thickness and compressive strength (Rc Class) requirements shown in Table A9.1.
| Layer | Road Type | Footway Footpath or Cycle Track | ||||
| 0 | 1 | 2 | 3 | 4 | ||
| Combined Binder Course & Sub-base | NP | NP | NP | NP | NP | 150mm C 1.5/2 |
| Base | NP | NP | NP | 300 mm C 1.5/2 | 200 mm C 1.5/2 | --- |
| Base | NP | 450 mm | 450 mm | 450 mm | 350 mm | |
| & Sub-base | C3/4 | C3/4 | C 1.5/2 | C 1.5/2 | --- | |
| Sub-base | 150 mm | 150 mm | 150 mm | 150 mm | 150 mm | 100 mm |
| &/or below | C 1.5/2 | C 1.5/2 | C 1.5/2 | C 1.5/2 | C 1.5/2 | C 1.5/2 |
| Crushing Strength at 28 days | C3/4 Minimum to C 9/12 Maximum |
|||||
Note to Table A9.1: NP = Not Permitted (see A9.3.1)
2) Where the total thickness of SMR laid exceeds 1000 mm, the minimum crushing strength requirement of C3/4 shall apply to the top 1000 mm only and a minimum of C1.5/2 below this depth.
A9.3.3 Particular Requirements for FCRs and FSMRs
1) The compressive strength shall be determined in accordance with the principles of BS EN 12390 part 3, with the following exceptions or options:
a) Test specimens may be prepared at the time of placement by casting within a test mould, or recovered from site after placement by the extraction of cores from the reinstatement.
b) Specimen shape and dimensions shall be in accordance with BS EN 12390 part 1 with the addition that specimens may also be manufactured with an aspect ratio of 1. Flowable SMR moulds may be manufactured from cellular foam (preferably polystyrene) and include a cellular foam lid. The samples shall not be compacted, except for minimal tamping to allow the mould to be filled without leaving excessive areas of voids.
c) Core test specimen top and bottom surfaces may be grouted to ensure flat, parallel loading surfaces.
d) Following preparation or recovery, the test samples shall be stored upright at either 20oC or 40oC, depending on the nature of the material, and tested in compression at 28 days after placement of the material on site.
2) Experience suggests that results obtained from 150 mm test cubes in moulds with cellular foam lids, stored at ambient temperature, are most representative of in-ground conditions.
3) FCRs and FSMRs shall not normally be tamped or compacted.
4) FCRs and FSMRs of density less than 1000 kg/m³ may not displace standing water. In excavations containing water, the minimum recommended density for foam concretes is 1050 kg/m³. FCRs may flow into, and block, damaged drainage or ducting within, or adjacent to, the excavation. Where required, plastic sheeting etc. may provide adequate protection during pouring and curing.
5) FCRs and FSMRs are unlikely to provide significant load bearing capacity for several hours after placement, depending on the ambient temperature. During this time, unguarded reinstatements may be a hazard to children and animals etc and should be protected.
A9.3.4 Particular Requirements for NFSMRs BS EN 14227
1 NFSMRs
The compressive strength of NFSMRs shall be determined in accordance with the principles of BS 1924 Part 2 Section 4.2, with the following exceptions or options:
a) Test specimens may be prepared at the time of placement by compaction of a sample of material within a test mould or, preferably, recovered from site after placement by the extraction of cores from the reinstatement.
b) Specimens prepared on site may be placed in conventional steel test cubes or in cylindrical moulds. Compaction shall be applied in order to achieve a specimen density between 100% +/- 5% of that achieved on site.
c) Core test specimen top and bottom surfaces may be grouted to ensure flat, parallel loading surfaces.
d) Following preparation or recovery, the test samples shall be stored upright at either 20oC or 40oC, depending on the nature of the material, and tested in compression at 28 days after placement of the material on site.
2) NFSMRs shall normally require compaction to ensure adequate strength. The compaction regime (i.e. details of plant type, weight category, lift/layer thickness and number of passes) shall be specified before the NFSMR is used, and should be obtained by prior development and testing.
A9.3.5 SMR Material Production
A9.3.5.1 FCR Material Production
1) FCRs shall be produced to prescribed mix formulations by an approved mixing plant, in accordance with approved manufacturing processes under quality control procedures.
2) The wet density of the FCRs should be checked prior to placement. Depending on the method of manufacture, the quality of the foaming agent added at site should be checked prior to being incorporated in the mix. Any on-site addition of a foaming agent must be in accordance with the approved mix design.
A9.3.5.2 FSMR and NFSMR Material Production
1) FSMRs and NFSMRs shall be prepared in accordance with the procedures set out in the Approval Trial Agreement (see Appendix A9.5), to the approved mix formulation(s) (obtained by prior development and testing), in order to achieve the required compressive strength. Binders, additives and admixtures may be included based on prior development and testing.
2) FSMRs and NFSMRs may be delivered to site as ready-made materials or be prepared partly or wholly on site.
3) Mixing may be carried out using any equipment, adapted as necessary for the manufacture of FSMRs and NFSMRs in quantities appropriate to the intended use, provided the approved mixing procedure is used throughout. Mixing equipment should be maintained in accordance with the manufacturer's recommendations and checked regularly. All metering or weighing apparatus should be calibrated regularly according to a Quality Assurance Scheme.
4) All binders, additives and admixtures, including diluted solutions thereof, should be stored according to the manufacturer's recommendations and used within the recommended shelf life.
5) NFSMRs shall be compacted in accordance with the manufacturer's recommendations or an agreed compaction regime obtained from prior development and testing.
A9.4 Outline Scheme for Approval Trials
A9.4.1 Introduction
1) It is anticipated that an Undertaker or Authority may wish to undertake or permit approval trials of ARMs for the purposes of development and/or performance assessment.
Where an Undertaker wishes to use a particular ARM widely, undertaking trials with every Authority is undesirable. It is recommended that the need for trials is minimised by groups of Authorities working together. Parties are encouraged to involve Area RAUC's in organising these trials. It is for the parties to Approval Trial Agreements to specify how successful ARMs will be introduced but it is recommended that this will be across all participating Authorities.
Throughout section A9.5 the words "Authority" and "Undertaker" shall be taken to mean "Authority or Authorities" and "Undertaker or Undertakers" respectively.
2) Trials may be carried out by formal agreement between an Undertaker and Authority, under an Approval Trial Agreement. This section outlines a scheme under which trials of ARMs should be carried out.
Section A9.5.2.1 gives general guidance relating to the organisation of an Approval Trial.
Section A9.5.2.2 describes special conditions relating to the scale of an Approval Trial and its effect on organisational and reporting matters.
Section A9.5.2.3 outlines the intended duties of each party within the Approval Trial.
Section A9.5.3 comprises a list of headings that describe the key requirements and stages of an Approval Trial. The headings are considered to represent the minimum essential information required to ensure that the Approval Trials are carried out in a controlled and agreed manner. The additional information under each heading given in parentheses is for guidance only. The parties to an Approval Trial (normally an Undertaker (who would generally initiate or request the trial) and an Authority) may, by agreement with the other party, add, amend or omit any details that do not affect the legal standing of the Agreement.
A9.4.2 General Requirements, Special Considerations and Duties of Parties to Approval Trials
A9.4.2.1 General Requirements for Approval Trials
1) Approval Trials may be undertaken in any Road Category, with the prior approval of the Authority. No Approval Trials shall be undertaken in a high amenity or high duty footway, footpath or cycle track, or a Site of Special Scientific Interest.
2) Approval trials in carriageways should be conducted on a minimum of three separate sites, representing a range of traffic conditions. A range of positions within the carriageway (i.e. within and outside of a wheel track, longitudinal and transverse orientation (for trench reinstatements)) should also be considered.
3) The duration of all Approval Trials shall be two years - the final inspection shall be completed within one month following the end of the two-year test period. The Undertaker shall notify the Authority of the inspection date at least seven working days in advance. The Authority shall confirm their intention to attend, or otherwise, within seven working days of receipt of such notification. The inspection measures should be carried out on the notified date at an agreed time or an agreed alternative date. Where the Authority does not attend the final inspection, the Undertaker shall provide the Authority with a summary of the investigation within 28 days of the inspection. The Undertaker should keep a photographic record of the Approval Trial reinstatements at the time of inspection and send copies to the Authority.
4) Core sampling and interim inspections of any type may be carried out on Approval Trial reinstatements at any time. Where required, as part of the Approval Trial agreement, the Undertaker shall notify the Authority at least five working days in advance of such works. Any holes created during these activities shall be reinstated in accordance with the relevant requirements of this Specification.
5) Approval Trial reinstatements may be accidentally damaged during the trial and rendered unsuitable for accurate assessment. It is therefore recommended that trials should include duplicate sites for each road type, category, position, orientation, etc.
6) Where an Approval Trial reinstatement requires remedial action, regardless of the reason, the Undertaker shall provide the Authority with details of the remedial measures within one month of completion. Where practicable, records of surface measurements, photographs etc taken before and after the remedial work should be kept by the Undertaker and copies provided to the Authority.
7) With the written approval of the Authority further use of the ARM's under trial may be permitted before completion of the trial. Such approval shall only apply to works carried out within the boundary of the Authority. Further use of ARMs shall be only in Road Categories up to and including the highest category used for the Approved Trial.
8) On successful completion of the Approval Trial the results, audit trail and Factory Production Control or Quality System documentation should be shared with other Road Authorities from whom permission for further use is to be sought. By agreement between the parties involved, some or all of the details of the trials shall be forwarded to Regional HAUC or National HAUC to allow such details to be made available nationally. Further use of ARMs shall be only in Road Categories up to and including the highest category used for the Approved Trial.
9) After the successful completion of an Approval Trial permission for further use of the ARM shall not be unreasonably withheld by any other Authority and shall only be denied for engineering reasons. Where reasonable engineering concerns are expressed, the nature of which shall be stated, then additional assessment may be required by the Authority.
10) It is recognised that the scope, extent and duration of ARM approval trials may vary widely.
A9.4.2.2 Special Considerations for Approval Trials
1) For small-scale Approval Trials intended to take place on a small number of sites and over a fixed time period (e.g. for specially prepared Approval Trial excavations), the Undertaker shall notify the Authority at least one month in advance of the start of an Approval Trial.
Specially prepared excavations should be of similar depth and plan dimensions to the Undertaker's routine excavations, and generally not less than 500 mm by 500 mm in plan, or not less than 200 mm wide for trench excavations. The total combined surface area of all Approval Trial sites should not be less than 2 square metres.
The location and position of the Approval Trial reinstatements should represent as wide a range as possible (see Appendix A9.5.2.1 (2)). If specially prepared sites are to be used, the site locations may be jointly selected.
2) Approval Trials of a larger extent, (e.g. trials that use an Undertaker's routine excavation sites as Approval Trial sites) may take place over a longer time period and the Undertaker shall notify the Authority at least one month in advance of the start of the Approval Trial period. Arrangements for notification and attendance at these Approval Trials should be included in the Trial Agreement.
3) Any restrictions as to the size, location and position, total number of Approval Trial sites and/or the period during which the Approval Trial reinstatements may be carried out, should also be included in the Approval Trial agreement.
4) A two-year Approval Trial period shall apply to each Approval Trial site, commencing on its date of installation. An interim report on the Approval Trial should be provided within six months of the start date of the Trial. The final review or reporting need not be carried out until the final Approval Trial site has reached an age of two years.
A9.4.2.3 Duties of Parties to Approval Trials
1) The initiator (usually the Undertaker) would be expected to have carried out documented development work to ensure a high level of confidence in the proposed process before the commencement of the Approval Trial. The results of such development work should not be unreasonably withheld from the Authority.
2) The Undertaker shall provide as much notice of the Approval Trial reinstatement operation(s) (e.g. location, date/time, excavation, mixing, reinstatement, sampling, post-construction activities etc) as practically possible, in accordance with the requirements of Appendix A9.5.3.1 of the Approval Trial agreement.
3) The Undertaker shall not unreasonably withhold information relating to any aspect of the Approval Trial from the Authority.
4) The Authority shall not unreasonably obstruct the commencement, progress, or cause the termination of the Approval Trials provided they are carried out in accordance with the terms of the Approval Trial agreement.
5) Either party shall have the right to request confidentiality on any matter relating to the Approval Trial.
A9.4.3 Suggested Information for Inclusion in Approval Trial Agreement
Prior to the commencement of an Approval Trial, the following information should be considered by both parties for inclusion in the Approval Trial Agreement.
A9.4.3.1 General Information
1) Parties to trial - names of Undertaker and Authority agreeing to Approval Trial
2) Confidentiality - parties (if any) to whom trial information may be divulged
3) Geographical extent of trial - county or district border, utility region or area boundary
4) Scope of trial - total number of trial reinstatements or maximum number of sites
5) Time limit for trial - start/end dates
6) Termination criteria - conditions under which agreement may be ended and notice of termination
7) Signatories/witnesses - approved officers of appropriate seniority who are permitted to commit their organisation to the execution of the Approval Trial and who can approve the terms and conditions of the trial.
A9.4.3.2 Procedural
1) Contemporary records - details of records required, responsibility for record-keeping
2) Notification details - notice periods, arrangements for contacting relevant parties to an Approval Trial
3) Attendance at trials - parties who may attend an Approval Trial
4) Review periods/meetings - dates, attendees, procedures for calling ad hoc meetings
5) Post-construction assessment - test methods to be employed and arrangements for periodic surveying, sampling, etc
6) Outcome - The criteria for assessing the success or failure of the Approval Trial
A9.4.3.3 Technical
1) Type of trial site - routine utility excavations or specially excavated Approval Trial
2) Location of trial site - non high-amenity or non high-duty footway, cycle track, (including road classification Type 2 to 4) etc
3) Positioning of trial site - "as excavated", within wheel track, etc
4) ARMs to be trialled - generic SMR or SMF materials
5) ARM details - Mix design, binder details, additives, dependencies on site conditions or excavated/base material type and condition, details of prior development work
6) ARMs preparation - batching, mixing and placement procedures.
7) Quality control on site - any tests to be applied in order to ensure that an ARM has been prepared to the required design
8) Compaction regime - NFSMRs and SMRs only
9) Sampling requirements - types of samples and sampling frequency
10) Testing laboratories - contact details of accredited laboratories or otherwise
11) Remedial measures for "failed" sites - replacement with an alternative SMR or SMF material or other approved material or remove from the Approval trial Agreement
12) Future of trial sites - remove after trial completion or leave in place, future monitoring and/or testing
A9.5 Recording of Approval Trials and Local Agreements
A9.5.1 General
Approval Trials and Local Agreements shall be recorded in a central register made available through the website of the Office of the Scottish Roadworks Commissioner or in any other place agreed by RAUC Scotland.
1) Once an Appendix A9 Approval Trial Agreement has been signed the initiator (usually the Undertaker) shall record the trial on the central register and keep the record updated.
2) The record shall include a summary of the materials under trial, the parties to the Agreement, the start date and the duration.
3) On conclusion the success or failure of the trial shall be added to the record
4) New materials approved shall be listed on the register along with all those Authorities who permit their use and the relevant restrictions and specifications
5) Authorities who subsequently approve new materials following a trial to which they were not a party shall add their approval to the register.
1) Local agreements between Authorities and Undertakers may be made under S1.6.1. provided they are signed by approved officers of appropriate seniority permitted to commit their organisation to the terms
2) The terms and parties to a local agreement shall be recorded on the central register