« Previous | Contents | Next »
Listen
SPECIFICATION FOR THE REINSTATEMENT OF OPENINGS IN ROADS
Appendix A9
Alternative Reinstatement Materials (ARMs)
A9.1 Introduction
1) New or alternative materials have been, or may be, developed for use in road construction and reconstruction. 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, secondary or waste materials
b) Lower energy requirements during manufacture
c) Reduced landfill requirements during construction or reconstruction
d) Self-cementing properties to improve reliability of laying and compaction
e) Self-levelling or flowable, to avoid need for compaction
f) May be placed in fewer layers
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 of the Specification for Highway Works are deemed to be approved for use as ARMs. FCRs may not necessarily incorporate an aggregate.
ii) Flowable SMRs (FSMRs)
These materials comprise of any type and combination of aggregates and binders. They are flowable mixes that should not normally require compaction, and will be capable of achieving strengths equivalent to FCRs. These materials may only be used on a trial basis by prior agreement.
iii) Non-flowable SMRs (NFSMRs)
These materials comprise of any type and 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 only be used on a trial basis by prior agreement
b) Stabilised Materials for Fills (SMFs)
This generic group is intended to include materials derived from excavated spoil, virgin, secondary recycled or waste materials, or any combination thereof, that have been improved by re-processing, re-grading and/or by the inclusion of a cementitious, chemical or hydraulic binder. SMFs shall generally be non-flowable and shall therefore normally require compaction.
These materials may only be used on a trial basis by agreement.
A9.2 General Requirements for ARMs
1) With the exception of FCRs as described in A9.1.2 (a) (i) above, (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. A trial procedure scheme is described in A9.5.
2) ARMs shall be prepared and installed 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 whose formulation has been altered.
4) ARMs used within 450mm of the road surface shall be non-frost susceptible subject to the exceptions referred to in S5.3.1.
5) Where the Authority is aware of areas with drainage or groundwater problems it should notify the Undertaker. 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 an 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 sulphate resistant Portland cement based binders.
7) Surfacing materials shall not be reinstated until the ARM has attained sufficient strength to allow adequate compaction of bituminous materials and to sustain adequate traffic loading. A simple penetration or indentation test is recommended to allow confirmation of adequate strength prior to surfacing. Any standardised test procedure may be used and, with prior experience, can indicate the earliest time at which surfacing may be carried out.
8) 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 Usage of SMRs
1) SMRs may be used on a trial basis, by prior agreement, 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 combined sub-base and base (roadbase) within any reinstatement in Road Types 1, 2, 3 & 4.
d) As combined sub-base and binder course, within any reinstatement in footways, footpaths and cycletracks.
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 thicknesses and compressive strength requirements shown in Table A9.1
Layer | Road Type | Footway Footpath or Cycletrack |
0 | 1 | 2 | 3 | 4 |
Combined Binder Course & Sub-base | NP | NP | NP | NP | NP | 150mm C2 |
Base (Roadbase) Alone | NP | NP | NP | 300 mm C2 | 200 mm C2 | --- |
Base (Roadbase) & Sub-base | NP | 450 mm C4 | 450 mm C4 | 450 mm C2 | 350 mm C2 | --- |
Sub-base &/or below | 150 mm C2 | 150 mm C2 | 150 mm C2 | 150 mm C2 | 150 mm C2 | 100 mm C2 |
Crushing Strength at 90 days | C4 - 4 N/mm 2 Minimum to 10 N/mm 2 Maximum C2 - 2 N/mm 2 Minimum to 10 N/mm 2 Maximum |
Note to Table A9.1: NP = Not Permitted ref A9.3.1 |
Table A9.1 - SMR Minimum Layer Thickness and Compressive Strength Requirements
2) Where the total thickness of SMR laid exceeds 1000 mm, any minimum crushing strength requirement of 4N/mm 2 shall apply to the top 1000 mm only.
A9.3.3 Particular Requirements for FCRs and FSMRs
1) The compressive strength shall be determined in accordance with the principles of BS1881: Part 116 or Part 120, 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) Cast specimens may be conventional test cubes with a nominal side length of 150 mm, or they may be cylindrical with a diameter in the range 150 - 300mm and an aspect ratio of 1.0. 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 regions of voidage.
c) Core test specimens shall be cylindrical, with a diameter in the range 150 - 300mm and an aspect ratio of 1.0. The top and bottom surfaces of the test specimen may be grouted to ensure flat, parallel loading surfaces.
d) Following preparation or recovery, the test samples shall be stored upright, at ambient temperature until 90 days have elapsed from the placement of the material on site. Accelerated curing at temperatures exceeding 25ºC is not permitted.
2) Experience suggests that results obtained from 150 mm test cubes, in lidded cellular foam moulds, stored at ambient temperature, within the mould, are most representative of in-ground conditions.
3) FCRs and FSMRs shall not normally be tamped or otherwise compacted.
4) FCRs and FSMRs of density less than 1000 kg/m 3 may not displace standing water. In excavations containing water, the minimum recommended density for foam concretes is 1050 kg/m 3. 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 mixing, depending on the ambient temperature. During this time, unguarded reinstatements may be a hazard to children and animals etc and shall be protected.
A9.3.4 Particular Requirements for NFSMRs
1) The compressive strength of NFSMRs shall be determined in accordance with the principles of BS1881: Part 116 or Part 120, 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 with a nominal side length of 150mm, or in cylindrical steel moulds with a diameter in the range 150 - 300 mm and an aspect ratio of 1.0. Compaction shall be applied in order to achieve a specimen density between 95% and 105% of that achieved on site.
c) Core test specimens shall be cylindrical, with a diameter in the range 150 - 300 mm and an aspect ratio of 1.0. The top and bottom surfaces of the test specimen may be grouted to ensure flat, parallel loading surfaces.
d) Following preparation or recovery, the test samples shall be stored upright, at ambient temperature until a 90 days have elapsed from the placement of the material on site. Accelerated curing at temperatures exceeding 25ºC is not permitted.
2) NFSMRs shall normally require compaction to ensure adequate strength. The compaction regime (i.e. details of plant type, weight category, layer thicknesses 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 from virgin aggregates to prescribed mix formulations at an approved mixing plant, in accordance with approved preparation procedures and under approved quality control procedures. FCRs conforming to SHW Clause 1043 are deemed to be approved for use.
2) The wet density of the FCRs should be checked when required, prior to placement. Depending on the method of manufacture, the quality of any foam added at site should be checked prior to addition to the mix. Any on-site addition of foaming agents must be in accordance with the prescriptions of 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 A9.5), to the approved mix formulation(s) (obtained by prior development and testing), to achieve the required compressive strength. Binders, additives and admixtures may be included as agreed and 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 usage, 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.
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 by prior development and testing.
A9.4 Stabilised Materials for Fill (SMFs)
A9.4.1 Permitted Usage of SMF Materials
1) SMFs may be used in place of other materials on a trial basis by prior agreement, in the layers appropriate to their strength classification as defined by Table A9.2, and regardless of the nature of reinstatement materials used above and below, in any combination of the following:
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 surround to apparatus and/or backfill and/or sub-base, within any reinstatement.
2) SMFs shall not be used in place of the permanent binder course or surface course.
A9.4.2 Overall Requirements for SMFs
1) Each stabilisation method and formulation shall be classified as yielding SMF materials equivalent to one of the four defined classes of backfill material permitted in Appendix A1, as follows:
a) Class A SMF Material - equivalent to Class A Graded Granular Backfill Material,
or b) Class B SMF Material - equivalent to Class B Granular Backfill Material,
or c) Class C SMF Material - equivalent to Class C Cohesive/Granular Backfill Material,
or d) Class D SMF Material - equivalent to Class D Cohesive Backfill Material,
2) In addition stabilised materials that achieve CBR values in excess of 30% are designated class 'S' SMF materials and may be used as a combined backfill and sub-base.
3) The SMF material classification shall based on the "soaked" %CBR or equivalent value proven during the development and laboratory testing, in accordance with Table A9.2.
SMF Class | % CBR |
S | Over 30 |
A | 15 to 30 |
B | 7 to 15 |
C | 4 to 7 |
D | 2 to 4 |
Table A9.2 - SMF Strength Requirements
4) The %CBR value shall be determined by laboratory testing in accordance with the principles of BS1377, with the following exceptions or options:
i) Conventional test moulds may be unsuitable for some SMF materials, for which in-situ testing may need to be considered. The preparation of SMF test samples is not restricted and may include test cores extracted from site.
ii) Following preparation, the test samples shall be stored at ambient temperature until a period of 90 days has elapsed from the placement of the material on site.
iii) The laboratory CBR test shall performed on samples in a soaked condition.
iv) The test results shall be verified by a UKAS accredited laboratory.
v) On site, using a recognised appropriate direct or indirect test method.
A9.4.3 SMF Material Production
1) SMFs shall be prepared in accordance with the procedures set out in the Approval Trial Agreement ( see A9.5), to the approved mix formulation(s) (obtained by development and testing), to achieve the required strength classification. Binders, additives and admixtures may be included as agreed and based on prior development and testing.
2) SMFs shall normally be prepared on site from basic constituents or delivered to site as a ready-made fill material. However subject to experience gained by prior development testing, the mix may, by prior agreement, be transported SMF mixes may be prepared, wholly or partially, away from the site.
3) Mixing may be carried out using any equipment, adapted as necessary for the manufacture of SMFs in quantities appropriate to the intended usage, providing 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.
4) All binders, additives and admixtures, including diluted solutions should be stored according to the manufacturer's recommendations and used within the recommended shelf life.
5) SMFs shall be compacted in accordance with the manufacturer's recommendations or an agreed compaction regime obtained by prior development and testing.
A9.5 Outline Scheme for Approval Trials
A9.5.1 Introduction
1) It is anticipated that individual Undertakers or Authorities may wish to undertake or permit approval trials of ARMs for the purposes of development and/or performance assessment.
2) Trials may be carried out by the agreement of an Undertaker and Authority, in the form of an Approval Trial Agreement. This section outlines a scheme under which trials of ARMs can be carried out.
Section 9.5.2.1 gives general guidance relating to the organisation of an approval trial.
Section 9.5.2.2 describes special conditions relating to the scale of an approval trial and its effects on organisational and reporting matters.
Section A9.5.2.3 outlines the intended duties of each party to 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 the approval trials (normally an Undertaker (who would generally initiate or request the trial) and an Authority) may, by agreement, add, alter or omit any details that do not affect the legal standing of the Agreement.
A9.5.2 General Requirements, Special Considerations and Duties of Parties to Approval Trials
A9.5.2.1 General Requirements for Approval Trials
1) No approval trials shall be undertaken within a Type 0 or 1 road or high amenity or high duty footway, footpath or cycletrack, or a site of Special Engineering Difficulty.
2) Approval trials in carriageways should be conducted on a minimum of two separate sites, representing a range of traffic conditions. A range of positions within the carriageway (i.e. within and outside the 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 being 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 14 days in advance. The inspection measures should be carried out on the notified date or an agreed alternative date, regardless of whether the Authority has confirmed its attendance. Where the Authority does not attend the final inspection, the Undertaker shall provide the Authority with a summary within 28 days of the inspection. The Undertaker should keep a photographic record of the approval trial reinstatements at the time of inspection.
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 days in advance of such works. Any holes created during these activities should 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.
7) On completion of the Approval trial, and by agreement of the parties, some or all of the details of the trials may be forwarded to Area RAUC and or RAUC Scotland.
8) The further use of ARMs on the successful completion of the Approval trial shall be permitted only with the specific written approval of the relevant Authority. Such approval shall not be unreasonably withheld.
A9.5.2.2 Special Considerations for Approval Trials
It is recognised that the scope, extent and duration of ARM Approval trials may vary widely.
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 its start of the 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 A9.5.2.1 2)). If specially prepared sites are to be used, the site locations may be selected to achieve this.
The Authority shall confirm their intention to attend, or otherwise, within seven days of receipt of such notification from the Undertaker. The approval trial should commence on the notified date, or a mutually agreed alternative date, regardless of whether the Authority has confirmed attendance. Where the Authority does not attend, the Undertaker should keep a photographic record of the approval trial.
2) Approval trials of a larger extent, (e.g. trials that use an Undertaker's routine excavation sites as the 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.
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.
The two-year approval trial period shall apply to each approval trial reinstatement, commencing on its date of installation. Any final review or reporting need not be carried out until the final approval trial site has reached an age of two years.
Any approval trial shall be completed within 6 months.
A9.5.2.3 Duties of Parties to Approval Trials
1) The initiator (usually the Undertaker) would be expected to have carried out documented development work to ensure 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 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 of any matter relating to the approval trial. Such a request must not be unreasonably refused by the other party
A9.5.3 Suggested Information for Inclusion in Approval Trial Agreement
Prior to the commencement of the trials, the following information should be considered by both parties for inclusion in the Approval Trial Agreement.
A9.5.3.1 General Information
Parties to trial - names of Undertaker and Authority agreeing to approval trial
Confidentiality - parties (if any) to whom trial information may be divulged
Geographical extent of trial - county or district border, utility region or area boundary
Scope of approval trial - time period or total number of trial reinstatements
Start date/time limit for trial - start/end dates or maximum number of sites
Determination - conditions under which agreement may be ended, notice of termination etc
Signatories/witnesses - approved officers of appropriate seniority who are permitted to commit their organisation to the terms of the approval trial
A9.5.3.2 Procedural Information
Contemporary records - details of records required, responsibility for record-keeping
Notification details - notice periods, arrangements contacting relevant persons
Attendance at trials - parties who may attend, whether compulsory or voluntary
Review periods/meetings - dates, attendees, procedures for calling ad hoc meetings
Reporting requirements - organisations or persons responsible
Post-construction assessment - arrangements for periodic surveying, sampling, etc
A9.5.3.3 Technical Information
Type of trial site - routine utility excavations or specially excavated approval trial sites
Location of trial site - footway, cycletrack, (including road classification 0 to 4) etc.
Positioning of trial site - "as excavated" or within wheeltrack, etc
ARMs to be trialled - SMR or SMF
ARM details - Mix formulation(s), binder details, other additives, mix formulation dependencies on site conditions or excavated/base material type and condition, details of prior development work.
ARM preparation - batching, mixing and placement procedures.
Quality control on site - any tests to be applied to ensure that the ARM has been prepared to the required formulation
Compaction regime - normally for NFSMRs and SMFs only
Sampling requirements - types of samples and sampling frequency
Testing laboratories - contact details of accredited laboratories
Remedial measures for "failed" sites - replacement with ARM or approved materials
Future of trial sites - remove after trial completion or leave in place, future monitoring
« Previous | Contents | Next »