Code of Practice - Specification for the Reinstatement of Openings in Highways. (Second Edition, 2002)
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Q0013 - 'Air Void testing in Small Excavations'
Date Submitted: Tuesday 21st July 2009
Answer:
For Small Excavations (generally trenches <300mm width and other openings of surface area <2m2) Air Voids limits set down in Table S10.1 should be achieved through the Minimum Passes method indicated in Table A8.3. Utilities should be testing their own works to meet these standards, and it is indeed appropriate and necessary for HAs to carry out their own tests. From the HAs perspective, without this level of control of placement quality, there would be a dis-service to the public, as compaction is fundamentally a contributory control of durability (the effects of ageing and weathering, as well as on performance through deformation). By implication, durability is also an essential component of sustainability (returning to repair defects).
In terms of guidance on the method of testing air voids, under S10.2.3(2), it is known that the current SHW Clause 937 has changed since the publication of the 2nd Edition SROH CoP in June 2002. This has been addressed in the proposed 3rd Edition, thus:
“S10.2.3(2) The in-situ air voids content for all bituminous materials as permitted in Appendix A2 shall comply with the requirements shown in Table S10.1. The in-situ air voids content shall be calculated as the average from all results obtained. The maximum density shall be determined in accordance with EN 12697 – 5 Procedure A, in water. For reference purposes and in the event of dispute the bulk density shall be determined in accordance with EN12697 – Procedure C sealed specimen. The maximum density and core bulk density shall be used to determine air void content in accordance with EN12697-8.”
The Working Party recommends that the above is used for testing Air Voids.
Q0012 - 'Limestone in Surface Course'
Date Submitted: Wednesday, 21st July 2009
Answer:
Generally, limestone in a Surface Course mix will not provide the minimum PSV required by Table 2.7 of the SROH CoP. We believe the query probably relates to instances of Surface Course materials mixed using other suitable aggregates (providing the requisite PSV), but which has some limestone present, most probably through some contamination.
Contamination of mixes is known to occur through: (a) Contamination at the batching plant - contamination of the stockpiles, ground feed hoppers mixer, bins or delivery vehicle - all down to poor control & not acceptable in any case (b) Contamination of the collect load vehicles/hotboxes – this is more prevalent when split loads are picked up, which is common in utility work. Both instances are substantially avoidable through improved handling/control practices. However, it is recognised that some contamination will still be a possibility. The issue therefore is whether a permitted level of limestone contamination is actually detrimental to the key Surface Course property driver – PSV, being a key safety matter for road users.
The Working Party consider that very small quantities of limestone present in the Surface Course (due to contamination) are unlikely to materially affect the intended PSV. In this regard, where it is clear that the Surface Course mix demonstrably contains the intended aggregate (needed to give the required PSV), that the occasional presence of limestone (at levels of approximately 5% or less) should not constitute a defect under the PSV requirements of S2.6.3 of the Code.
Q0011 - 'Reinstatement of HRASC'
Date Submitted: Monday, 12th December 2005
Answer:
No cannot be allowed because of texture differences and the fact that S.6.4.1 precludes anything other than HRASCs in HRA surfaced roads.
Q0010 - 'reinstatement of CGSC?'
Date Submitted: Monday, 12th December 2005
Answer:
As question 0009, satisfactory in 2s, 3s and 4s roads.
Q0009 - Reinstatement of SMA and Thin Surfacings
Date Submitted: Monday, 12th December 2005
Answer:
Whilst SMA PCMs were not anticipated under SROHv2 (June 2002), they should not be precluded just because a manufacturer had gone through the BBA/HAPAS approvl process as such it is considered satisfactory that SMA PCSMs can be used in both SMA and thin surfacing applications in 2s, 3s and 4s roads.
Q0008 - 'immediately adjacent surface'
Date Submitted: Tuesday 1 July, 2003
Answer:
It is impossible to be fully prescriptive on some matters and the intention is to convey the undersatinding and application.
In this case, the fixed features S2.3 at an 'adjacent surface' is intended to mean the edge of the existing surface that has been broken into. 'Immediately adjacent surfaces' are the surfaces within the reisnstatement in which the fixed feature is laid.
Q0007 - Cold lay materials
Date Submitted: Tuesday 1 July, 2003
Answer:
Yes, however we would expect these materials to be put forward to HAPAS and covered by the HAPAS scheme and renewal requirements.
Q0006 - Modules
Date Submitted: Tuesday 1 July, 2003
Answer:
Yes
Q0005 - SMF be used as a base?
Date Submitted: Tuesday 1 July, 2003
Answer:
No, this material cannot be used in this way, if it were there would be no difference between it and SMR's. The distinction between SMF and Structural Material for Reinstatement (SMR) is that the SMF is categorised by CBR and used as a fill material and SMR by cube strength used in structural layers.
Q0004 - 10 mm cgsc
Date Submitted: Tuesday 1 July, 2003
Answer:
It is not acceptable to use a 10 mm binder course in flexible footways. The standard construction for these layers is 20 mm cgbc for the binder course and 6 mm cgsc for the surface course. In small openings (less than 2 metre square) a single material of 6 mm cgsc can be used for the binder and surface course. The use of 6 mm material as a binder course in small openings is a concession to facilitate the use of a single material.
Q0003 - surface course and binder course thickness
Date Submitted: Tuesday 1 July, 2003
Answer:
Thickness of surface courses and binder courses are detailed in Appendix A3 to A7. All surface courses on flexible roads are 40 mm thick as shown in the Appendices. All binder courses within flexible roads finish 100 mm below the surface and are 60 mm thick.
However, the bituminous structural courses may extend below this and become part of the base (road base). The line on the diagrams A3 to A7 differentiating between the binder course and base (road base) was shown to clarify where foam concrete could be used as part of the base (road base) as per table A9.1 in Appendix 9.
Q0002 - Over thick bituminous layer.
Date Submitted: Tuesday 1 July, 2003
Answer:
Yes, Section A2.5 has removed the upper tolerance for structural layers. Over thick layers can be constructed but these will not count towards other structural layers and each layer must meet the minimum thickness limit.
Q0001 - Is CGSC Permitted in Road Types 0, 1 and 2?
Date Submitted: Wednesday 13 November, 2002
Answer:
Reinstatements in close graded surface course (CGSC) material to BS4987 are permitted in type 0, 1 and 2 roads where this material already exists. Section 6.4 outlines the permissible options.
The table A11.2 dealing with bitumen binder equivalence issued as an errata slip will need to be modified in due course to reflect the permitted use of CGSC.