Testing of build materials
To ensure the roads and footpaths are built to our detail design, the materials used to build roads and footpaths shall be tested by a UKAS accredited laboratory that is specifically accredited for the tests required.
Details of the source and type of material being tested shall be required for all testing.
Capping and sub-base material testing
Plate Bearing and/or Light Drop Weight testing shall be conducted to assess the strength of the compacted capping and/or sub-base material prior to the laying of the binder course.
Plate Bearing testing shall use a mobile counterweight, known as a kentledge, with a minimum weight of 10 tonnes. The plate diameter should be between 100mm and 300mm depending upon the thickness of the material tested.
Light Drop Weight testing shall use a dynamic (light) plate loading technique such as Light Drop Weight Tester known as a Dynamic Plate Tester. Such devices should be calibrated against the plate bearing apparatus for the particular type of material tested. Evidence of this comparative testing could be requested.
Plate Bearing testing should be spaced between 50 metres and 100 metres apart and a minimum of 2 locations is required. The distance between Light Drop Weight tests should be no more than 20 metres.
A minimum value, known as the Modulus of Subgrade Reaction, shall be 30MPa on capping material and 35MPa on sub-base material.
The method of calculating the equivalent CBR value from the Modulus of Subgrade Reaction shall be detailed within the Test Procedure submitted for approval. The report should include first loading CBR% and EV1, second loading EV2 and the EV2/EV1 ratio (where EV = The Modulus of Deformation).
The testing shall be carried out:-
- To a procedure approved by us with details submitted prior to testing.
- In such a manner that the values obtained are representative of the full depth of capping and/or sub-base material.
- A minimum of 5 working days prior to the laying of the Binder Course.
- At a sufficient number of locations
The capping material shall achieve an equivalent CBR value of more than 15% and the sub-base material an equivalent CBR value of more than 30% at the surface of the finished layers as determined by the plate bearing test.
Surface water pipe testing
The integrity of surface water pipes shall be tested and all tests shall be witnessed by us. Surface water pipes means all or part of the sewer system agreed to be adopted by us.
Surface water pipes up to and including 750mm nominal diameter shall be tested by means of an air test and surface water pipes greater than 750mm nominal diameter by a visual examination. A visual examination may include a CCTV survey and/or walk-through inspection.
Surface water pipes to be air tested should be cleansed and have air pumped in by a suitable means until a pressure of 100mm head of water is indicated in a U-tube connected to the system. Surface water pipes will be accepted if the air pressure remains above 75mm head of water after a period of five minutes without further pumping, following a period for stabilisation.
CCTV surveys shall be required for all perforated pipe lines.
Notwithstanding the satisfactory completion testing, if there is any discernible flow of water entering the sewers of manholes which can be seen either by visual or CCTV inspection, appropriate measures shall be taken by the person building the road to stop such flow.
On completion of construction, and following cleansing of the surface water pipes, a CCTV survey shall be undertaken of all surface water pipes including gully pipes, and culverts. The CCTV survey should be reported in accordance with BS EN 13508-1:2012 and BS EN 13508-2:2003 + A1:2011 and submitted to us. The surface water pipes shall not be certified until any defects identified in the report are repaired by the person building the road.
Core sampling
Core sampling of the bituminous pavement shall be drilled in accordance with BS EN 12697-27:2017 with a diameter of 150mm to ensure the material contains an approved stone, laid to the correct thickness and compaction, and has a bond between bituminous layers.
The determination of thickness, compaction and bond shall be conducted in accordance with an approved in-house method.
Core densities should be determined on core specimens in a dried condition having been oven dried at 40oC to a constant mass and in accordance with BS EN 12697-6:2020.
Air voids shall be determined in accordance with BS EN 12697-8:2018.
The bond between bituminous layers shall be assessed from 150mm diameter cores cut into the material when cold and should be deemed to exist when detachment does not occur with the core suspended vertically for one minute. Compliance with this requirement shall be obtained at all times after laying and should be deemed to occur when no more than 1 in 10 cores taken from any area fail the test.
Bituminous layers will be certified when the material is sourced and supplied by an Approved Supplier and complies with the relevant Build tolerance.
Replacing failed material
When a new road or footpath does not comply with the Build tolerance, the non-compliant area shall be replaced.
For surface level or layer thickness this shall be achieved by at least partial removal and replacement of the existing binder course layer. This should be achieved by planing sufficient material to enable a replacement layer of binder course to be laid. For new roads the replacement binder course layer shall have a compacted thickness of a minimum 60mm. For footpaths the equivalent thickness is 50mm. There should be no regulating within the surface course layer.