CBR testing in Nottingham.

Same-day and next-day dates are often available, subject to the schedule. Nottingham is about an hour and a half from our laboratory by the M1, which leaves a full working day on site, and Derby, Loughborough and Leicester are a similar run or shorter. We do not guarantee an attendance time. If the capping is due and the formation is trimmed, ring 0115 786 5656 and we will tell you what is possible.

It swings with moisture. A freshly trimmed, dry mudstone formation can give a good in-situ value. After rain and site traffic the weathered surface softens quickly, and soaked laboratory values are commonly in the low single figures. Designers at West Bridgford, Edwalton, Gedling and Clifton normally work to the soaked figure and allow a capping layer. A low result is information for the design, not a failure.

Usually, yes. Sherwood Sandstone weathers to a dense sand that drains freely, so CBR values are higher and much less sensitive to the weather. The thing to watch is where the boundary runs. A site around the edge of the city centre, or out towards Arnold, can have sandstone at one end and mudstone at the other, and a single design CBR should not be stretched across both.

Send us the specification or tell us what the result is for. Adoptable estate roads normally need an in-situ CBR at formation level, often with a soaked laboratory CBR for design. Yards on capping or recycled fill are more often checked by plate bearing with a derived CBR. The methods are not interchangeable, and the report should state which was used.

Where the material is fine enough, yes, but expect scatter. The plunger suits material up to about 20 mm, so coarse spoil, burnt shale with large fragments or rubble backfill will not give a reliable value, and plate bearing is the better test. On any filled ground, results vary between positions because the fill does. Ask for more positions, and consider a DCP profile to see how strength changes with depth.

South and east of Nottingham, towards Gotham, East Leake, Cropwell Bishop and Newark, the Mercia Mudstone contains gypsum. If a high sulfate clay is stabilised with lime or cement, the treated layer can heave, sometimes months after it achieved its CBR. Sulfate and related chemical tests on formation samples are run in our laboratory and should reach the designer before the binder is chosen. The chemistry takes longer than a site test, so ask early.

Yes, significantly on the mudstone and much less on the sandstone. CBR is strongly influenced by moisture content, and a result describes the formation on the day it was tested. Test soon after trimming, protect the formation afterwards, and where the design must allow for the wettest likely condition, use a soaked laboratory CBR instead of choosing a dry day.

Your specification or the adopting highway authority sets the number. Where they are silent, it depends on the length of road and how variable the ground is. Positions are spread along the formation so that weak areas are found, and each test is made at the level the design relates to. In-situ testing is commonly carried out in accordance with BS 1377-9. Send the layout and we will suggest a number.

Yes. We take a bulk disturbed sample at formation level while we are on site, and it travels back to the laboratory in Milton Keynes with the technician. The specimen is remoulded into a 152 mm mould at the compaction and moisture condition the specification calls for, soaked where required, and tested under surcharge discs, commonly to BS 1377-2. Confirm the quantity with us before sampling.

No. A CBR plunger stresses only the top of the formation. It will not find a sandstone cave under a plot near the city centre or a shallow working under a site at Bilborough, Eastwood or Ilkeston. Those are questions for the desk study, the cave records, the Coal Authority report and the ground investigation. CBR testing describes the surface the road is built on.

Hixtra holds UKAS accreditation to ISO/IEC 17025 under schedule number 8996. Accreditation is granted method by method, not to the company as a whole, so it applies only to the tests listed on our current schedule. Most of our soil tests are on it. If your specification or the adopting authority requires accredited results, name the CBR method when you enquire and we will confirm whether it is on the schedule before you book. We would rather you asked than assumed.

Every visit is quoted from the site postcode. The price depends mainly on the number of positions and the time on site. Digging to test level, restricted access, standby time and out-of-hours working add to it. We can often combine a Nottingham visit with work in Derby, Loughborough or Leicester, which keeps travel down. Send the postcode, positions and dates and we will quote.

No. Hixtra has one laboratory, in Milton Keynes, and every Nottingham visit is run from there. The 0115 number rings through to the same team as our other numbers, and we keep no staff, vehicles or depot in the East Midlands. With the M1 between us, that makes little practical difference to dates, and samples for laboratory CBR go back with the technician the same day.