- All bituminous materials permitted by A2, except those covered in A2.5, must be laid and compacted in accordance with the relevant requirements of A2, and Tables A2.5, A2.7 and A2.8, and A8.3.
- The in-situ air voids content for all bituminous materials as permitted in A2, must comply with the requirements shown in Table S10.1. The in-situ air voids content must be calculated as the average from all results obtained.
- Cores must be extracted as per BS EN 12697-27.
- The maximum density must be determined in accordance with BS EN 12697-5 Procedure A, in water.
- The bulk density must be determined in accordance with BS EN 12697-6 Procedure C sealed specimen.
- If two or more cores are retrieved from a reinstatement, wax sealing is the preferred method.
- If only one core is retrieved from a reinstatement, alternative sealing methods permitted in BS EN 12697-6 Procedure C such as using self-adhesive aluminium foil or vacuumed plastic wrap may be used.
- The maximum density and core bulk density must be used to determine air void content in accordance with BS EN 12697-8.
Table S10.1 In-situ air voids content requirements
Permitted air voids
Footways, Footpaths and Cycle tracks
AC6 dense surface course
AC10 close surface course 11 2* 11 2* HRA surface course 7 2 10 2 SMA surface course 8 2 10 2 AC binder course 10 2* 12 2* HRA binder course 9 2 12 2 SMA binder course 6 2 NP NP Permanent cold-lay surfacing materials (PCSM) 10 2 13 2 Any other bituminous materials within the specification No air-voids limits apply. Guidance on compaction contained in NGA8.3 NP = not permitted
* If the binder content is increased as per A2.3.5 and A2.3.6 the minimum air voids is 0.5%.
- All surface course materials used at binder course level must comply with the in-situ air voids content requirement for the relevant surface course material.
- To determine the in-situ air void content core samples must be taken at a rate of 1 per 6 m2 or part thereof. However, the undertaker should be given the opportunity to accept the results or to agree to further coring if they suspect that the results reflect localised areas of non-compliance. The average void content must be calculated for each reinstatement covered by a single notice. All core samples must be 95 mm minimum diameter with no part of any core being within 100 mm of any surface apparatus within the reinstatement. Where there is a potential to encounter the edge of the frame or apparatus, this distance should be increased accordingly.
- Unless agreed otherwise, all air voids testing must be carried out by a laboratory holding current UKAS accreditation for the specified test methods.
- Where core samples are recovered from a location overlaying an unbound substrate, trimming the bottom of a core sample is only permitted where it exceeds the specified length. Trimming the upper part of a core sample is not permitted. In any case, the length of core samples subjected to testing must comply with this Code.
- Where prevailing weather conditions or other site circumstances are considered likely to hamper the successful laying and compaction of any surfacing materials and the achievement of the required in-situ air voids content, consideration should be given to deferring the permanent surface reinstatement and, if necessary, to an agreed extension of the interim reinstatement period.