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Should utility small excavation be subjected to air void testing. As A8.3 states that these should be compacted to the method specified in Table A8.3 and these would need to comply with the performance requirement of the SROH S2 performance requirements. All excavations outside A8.3 are to be compacted to in-situ air void requirement determined in accordance with SHW 937 sub-clause 32 & 33. SHW 937 only covers the testing of SMA binder course and regulating course, sub-clause 32-33 no longer exist following the revision of SHW 937 (08-08). SHW 937 refers to BS594987 for control by monitoring density and air void content. The following two quotes are taken from BS 594987.
9.1 note 2 End result compaction (core tests) is more appropriate for machine-laid work on major road contracts.
220.127.116.11 Note, This method (end result compaction) is applicable for works intended to carry heavy traffic. The scale of the works should be such as to justify the cost of testing and control.
Most core test carried out on utility works are on small excavations that are hand laid the, apx cost of reinstatement is £40 per m2 but the cost of testing is with some Authorities over £150 per core. Is it not more appropriate to use the performance requirement of SROH S2 to manage the performance of small reinstatements.
We have received high numbers of core failures where the failure is listed as (unacceptable level of limestone present in surface course). There is no indication as to the level of Limestone just that there is some present. There appears to be nothing wrong with Limestone in asphalt mixtures and BS EN 13108, PD6691 and the SROH all allow Limestone, however specified PSV rules seem to rule out Limestone in most surface course materials.
The presence of small amounts of limestone may cast doubt over the compliance of the material to reach the required PSV value but that is not the same as it failing. Wearing course materials will have been purchased with a given PSV value, is it not up to the testing body to prove that this has not been achieved by testing it. If a material passes a PSV test then is level of limestone irrelevant. Having spoken to tarmac manufactures it would seem to be unrealistic for them to exclude every partial of limestone from a hard stone mixture manufactured at a limestone quarry.
Reinstatement of HRASC?
The reinstatement of CGSC?
Reinstatement of SMA and thin surfacings?
Please give definitions on the phrases 'adjacent surface' and 'immediatley adjacednt surface'?
Are cold lay materials approved prior to the 2nd Edition of the Specification still approved?
Are Modules within the effective width to be removed and replaced?
Can materials categorised as Special materials for fill (SMF) be used as a base (road base) granular substitute if they meet the required CBR (+30%)?
Is it acceptable to use a 10 mm cgsc as a flexible footway binder course?
What are the surface course and binder course thickness?
Can over thick bituminous layers be applied without penalty?
We have recently received high numbers of core failures for Domestic Access depth.
Since the introduction of the Second Edition of the SROH, we have been selecting the option of reinstating with 2x30mm layers of 6mm hard stone in the footway (60mm total depth).
This is shown as an acceptable equivalent option to 50mm DBC & 30mm DSC (80mm total depth) in Appendix A7.1
Under S8.4.2 Domestic Access
1) Where a recognised domestic vehicle crossing or occasional emergency service vehicle etc crosses the footway the existing structure may include thicker layers higher quality material or other strengthening measures.
(in these cases we are assuming footway crossing is designed purely to support purely domestic vehicles as the accesses are typically only just sufficient to fit a car and adjoin residential properties)
The area of footway at the Domestic Access sites that have been failed under core sampling are those which have been constructed by the H.A. to a standard footway construction of 80mm.
We would believe this construction ( maximum of 80mm depth) is consistent along the full extent of the footway ( i.e. beyond the specific area of the “domestic access”) .
As such the footway has at no point included “ thicker layers, higher quality materials or other strengthening measures “as per the requirements of the SROH ( optional for “Domestic Access)
Therefore we would recognise this as standard footway construction, and accordingly we have used the standard option under Appendix A7 – that being a bituminous constructed depth of 60mm DSC.
Any Domestic Access that includes deliberately engineered thicker layers greater than 80mm in depth , or where higher quality materials have been used or other strengthening measures have been incorporated then we will ensure we match these as S8.4.2 2 with “similar or equivalent materials”.
Please note - At none of the alleged “Domestic Access” defect locations is there any performance issue with the reinstatement ( as would be deflectable under the visual aspects of the SROH) , the alleged defect is based purely on the Highway Authorities interpretation of the SROH
Is CGSC permitted in Road types 0, 1 and 2?