Concrete cube testing in Birmingham.

No. Slump, flow and cube making at the pour are only offered within about an hour’s drive of our laboratory in Milton Keynes, and Birmingham and the Black Country are beyond that. Your own team or your readymix supplier will need to make the cubes. We then cure and test them, and we are happy to talk your team through making and storing them properly.

Three ways. Deliver them to the laboratory in Milton Keynes, about an hour and a half down the M6 and M1. Send them by courier, packed so they stay damp and cannot knock together. Or have us collect them while we are in the West Midlands for site testing, if you tell us when you book. Whichever you choose, get them to us in good time before the first test age.

The ages your specification sets. Most structural concrete is tested at 7 and 28 days, and conformity is normally judged at 28 days. Where formwork striking or post-tensioning depends on early strength, 1, 2 or 3-day tests are sometimes added, and mixes with GGBS or fly ash are sometimes tested at 56 days. Give us the casting date and the ages and we schedule each cube.

Each cube is loaded to failure in a calibrated compression machine, and 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, dimensions, failure load, strength and whether the failure pattern was satisfactory, because an unsatisfactory failure points to a problem with the specimen.

Start with the cube, not the structure. Identification, age, curing history, dimensions and the failure pattern can all explain a low figure. If the result stands, your engineer decides the next step, which commonly means testing a spare cube at a later age or coring the element to establish the in-place strength. We cut and test cores across Birmingham, so both steps can stay with one laboratory.

No. A cube is made, compacted and cured under standard conditions, so it shows what the concrete as supplied can achieve. Concrete in the structure is placed, compacted and cured in place and is normally somewhat weaker. Cube results judge the conformity of the concrete supplied. Where the question is what the structure is achieving, that is assessed from cores.

Your specification sets the sampling rate, usually with reference to BS 8500 and BS EN 206, according to the volume and importance of the pour. A common arrangement is a set from each sample covering 7 and 28 days, plus a spare. Make every cube in a set from the same sample, and tell us which are spares to be held.

It affects what should have been specified. Mercia Mudstone east of the city can carry gypsum, and the made ground across Birmingham and the Black Country, with its ash, slag and industrial residues, can be aggressive to buried concrete. Foundations are designed to a sulfate and aggressive ground class from the ground investigation. A cube test confirms strength, not chemical resistance, so check the delivery ticket matches the specified mix.

100 mm cubes suit most structural concrete with 20 mm aggregate. Where the aggregate is larger, 150 mm moulds are needed, because BS EN 12390-1 relates specimen size to maximum aggregate size. Use one size throughout a job so results compare like with like, and check whether your contract names a size.

Send them anyway and tell us. We record the condition they arrive in, test them and report the conditioning history with the result, stating any deviation from the standard method. Standard curing is in water at 20 ± 2 °C. Cubes that dried out, froze or sat in a hot cabin can give a result that does not represent the concrete, and your engineer needs to know that when reading it.

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 schedule that matches: site, element poured, supplier and mix reference, casting date and time, required testing ages and who receives the results. Include the slump or flow if it was measured. With several Birmingham pours running at once, clear references are what stop results being attached to the wrong element.

No. Hixtra has one laboratory, in Milton Keynes, and all cubes are cured and crushed there. The 0121 number rings through to the same team as our other numbers. We are in the West Midlands regularly for ground testing, so collection can often be tied in with a site visit.