In-Situ Construction Materials Testing

Originally developed by the California Division of Highways in the 1930s and covered within British Standard BS1377, the California Bearing Ratio test – or CBR test – is designed to assess the load-bearing capabilities of roads, pavements, driveways and so on. It is widely accepted as being the ‘go to’ test for the simulation of traffic, providing useful information on the effects such activity might have upon component layers.

A penetration test critical for road design and materials calculations, in basic terms, the CBR test involves a piston of a known size being applied to a sample of soil at a specified rate. The CBR value is then calculated, in part, based upon the ease with which the piston penetrates the soil.

Whilst CBR testing can be used when a change of use is being considered (e.g. heavier or increased traffic), it is also commonly utilised to assess the volume of materials required should contractors be looking to construct a new road.

One of our more popular construction materials testing services, we carry out incremental plate load testing on sites throughout the UK, providing our clients with project-critical information, often in real time.

Described in detail within British Standard BS1377 : Soils for Civil Engineering Purposes, due to its ability to assess conditions at the surface, this test is predominantly used in conjunction with temporary works.

It’s no surprise, therefore, that we’re commonly asked to…

• Prove pile mats
• Prove crane mates prior to plant arriving on site, thus ensuring safety
• Prove slabs prior to the installation or design of particularly heavy plant

The incremental plate loading test itself involves applying kentledge – a counterweight – to the ground in question, typically in the form of a 13t+ tracked excavator. Our team will provide insight into the size of plate needed to simulate the loads required, with the design/safe working load then being applied to the plate in equal increments. Any deformation will be recorded with reports available there and then to avoid delays on site.

At Perry Testing, we use a Dynamic Core Penetrometer (or DCP) to obtain an indicative CBR value without the need for expensive downtime such as plant and operator costs.

Generally applied to the ground via specially created trial pits or core holes, DCP testing is carried out by dropping a weight from a known distance onto the cone. The resultant movement measured can then be read directly from the instrument.

DCP testing is typically used to measure road and pavement condition and stiffness. That said, we can also use the dynamic cone penetrometer to measure the strength of in-situ soils as well as to determine both the thickness and location of underlying soil layers.

Hand shear vane testing involves the application of an instrument in order to determine the undrained shear strength of cohesive soils.

The result can be given in Kn/M² or it can be given as a vane shear strength using the calculation given in British Standard BS 1377. Either of these results can be provided instantly on site by our knowledgeable engineers.

Experts in our field, Perry Testing offers a comprehensive sand replacement density testing service, designed to measure the in-situ density of natural soils or imported materials using sand pouring cylinders.

The in-situ density is normally used for highway or pavement design purposes, providing designers and engineers with the relevant ‘degree of compaction’ (required for highway and site specifications). This allows our clients to be confident in the compaction of the material before proceeding with final layers.

Sand replacement density testing is fully described in British Standard BS 1377: Soils for Civil Engineering Purposes: Part 9 and is both an efficient and accurate way of accessing the density of most materials.

It is worth noting that, unlike other methods, with SRD testing there is no need for time consuming and expensive calibration of equipment for every site and material type.

Core cutter density testing is used for almost the same purpose as SRD testing (covered above). This time, however, it is used solely for cohesive materials (e.g. clay). As with the former method, this is an extremely effective way of both quickly and accurately checking compaction on site.

Once collected, the samples can then be used for further tests such as triaxial or permeability assessments.

Not all testing is carried out there and then on site. Many of the tests we most commonly carry out involve a physical sample being taken on site, with that sample then being transported to one of our UKAS-accredited partner laboratories for in-depth analysis.

For more information on these services, visit our laboratory testing services page. Alternatively, why not get in touch?