Concrete cube testing in Winchester.

No. Fresh concrete testing, meaning slump, flow and cube making at the pour, is only offered within about an hour’s drive of our laboratory in Milton Keynes, and that does not reach Winchester. Basingstoke is the closest town in the area and is still beyond it on most days, so ask, not assume. Your team or your readymix supplier makes the cubes, and we cure and test them.

By courier, by your own delivery up the A34 to Milton Keynes, or by collection when we are in Hampshire for CBR or plate bearing testing, if you tell us when you book. Wrap the cubes damp, pack them so they cannot knock together and send them to arrive before the first test age.

The ages your specification sets, usually 7 and 28 days, with conformity normally judged on the 28-day result. Early-age and 56-day tests can be scheduled where the specification calls for them. Give us the casting date and the ages and each cube is tested on the right day.

The cube is loaded to failure in a calibrated compression machine. The strength is the maximum load divided by the cross-sectional area, reported in newtons per square millimetre. Testing is usually specified to BS EN 12390-3. The report gives the reference, age at test, dimensions, failure load, strength and whether the failure pattern was satisfactory.

Only in part. Concrete in or near sea water is specified for durability as well as strength, with an exposure class that sets limits on cement type, cement content and water to cement ratio. A cube result confirms the strength class was achieved. It does not confirm the mix proportions, so the delivery tickets and the supplier’s mix design are part of the evidence too.

Chalk itself is usually benign, which makes foundations around Winchester simpler than on the sulfate-bearing clays elsewhere in the south. The exceptions are the clays of the Hampshire Basin towards Southampton and the coast, which can carry sulfates. The ground investigation sets the class for buried concrete. A cube test confirms strength, not sulfate resistance.

Check the specimen before the structure. Identification, age, curing history, dimensions and failure pattern can all explain a low figure. If the result stands, your engineer decides what follows, commonly a spare cube tested at a later age or cores from the element. We cut and test cores across Hampshire.

It is an early indicator, not a substitute. As a rough guide a CEM I mix reaches around two thirds of its 28-day strength by 7 days, but the proportion varies with cement type, additions, admixtures and curing temperature, and mixes with GGBS or fly ash gain more of their strength later. Treat a low 7-day result as a prompt to look closely.

Your specification sets the sampling rate, usually by reference to BS 8500 and BS EN 206, depending on the volume and importance of the pour. A set from each sample covering 7 and 28 days, plus a spare, is common. Make every cube in a set from the same sample.

100 mm cubes suit most structural concrete with 20 mm aggregate and are easier to courier. 150 mm cubes are needed where the aggregate is larger, because BS EN 12390-1 relates specimen size to maximum aggregate size. Use one size throughout a job.

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. Most of our soil and aggregate tests are on the schedule, and some concrete tests are still going through the accreditation process. If your specification or your client’s engineer requires accredited cube results, tell us when you enquire and we will confirm whether that method is on the current schedule before you book.

A unique reference marked on each cube and a matching schedule: site, element poured, supplier and mix reference, casting date and time, testing ages and who receives the results. Add slump or flow if it was measured. Clear references avoid delays and keep each result tied to its pour.

No. There is no Hixtra laboratory or office in Winchester or anywhere in Hampshire. The 01962 number rings through to the laboratory in Milton Keynes, where every cube is cured and crushed. We are in the area regularly for ground testing, so collection can often be tied in with a site visit.