Concrete cube testing in Manchester.

No. Fresh concrete testing, meaning slump, flow and cube making at the pour, is only available within about an hour’s drive of our laboratory in Milton Keynes, and Manchester, Salford, Stockport and Bolton are all well outside that. Your readymix supplier or your own trained staff will need to make the cubes. We cure and test them.

Usually by courier. Wrap each cube in damp hessian or cloth and polythene, pack them in a rigid box so they cannot knock together, and send them so they arrive before the first test age. If we are in the North West for plate bearing or CBR work, we can collect at the same time if you tell us when you book. You are also welcome to deliver them.

Yes. Give us the pour programme and the required ages, and each set of cubes is booked in by reference when it arrives and scheduled against its casting date. Results go to whoever you name as soon as each cube is crushed, so a 7-day result for level 12 is not waiting on anything else. A consistent referencing system on your side, by level and pour, is what makes a rolling programme work.

Yes, provided the cubes can reach us in time. Early-age tests at 1, 2 or 3 days are sometimes specified to support striking or post-tensioning. From Manchester the courier leg has to be allowed for, so talk to us about timing before the pour. Bear in mind that a cube cured in a tank does not match the temperature history of the slab, so your engineer may want a different approach for very early ages.

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

It can if the cubes are left out in it. In the first day a fresh cube is sensitive to temperature, and a cold, wet night on an exposed slab edge slows strength gain and can lower the result. Keep cubes in their moulds somewhere sheltered at around 20 °C, covered against drying and rain, for 16 hours to 3 days. After that they should be in water in a controlled tank, which is where ours go.

Look at the cube first. Identification, age at test, curing history, dimensions and failure pattern can all produce a low figure that says nothing about the structure. If the result stands, your engineer decides what follows, commonly a spare cube tested at a later age or cores cut from the element. We cut and test cores in Manchester, so the investigation can stay with the same laboratory.

No. A cube is compacted and cured under standard conditions and shows what the concrete as supplied can achieve. Concrete in a column or slab is placed and cured in place and is normally somewhat weaker. Cube results judge the conformity of the supply. In-place strength is assessed from cores.

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 all the cubes in a set from the same sample and tell us which are spares to hold.

100 mm cubes suit most structural mixes with 20 mm aggregate, and they are lighter and cheaper to courier. 150 mm cubes are needed where the aggregate is larger, because BS EN 12390-1 ties specimen size to maximum aggregate size. Keep to one size across the job and check whether your contract names one.

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 every cube and a schedule that matches it: site, level and 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. On a multi-storey frame, the level and pour reference is the piece of information most often missing.

No. Hixtra has one laboratory, in Milton Keynes, and every cube is cured and crushed there. The 0161 number rings through to the same team as our other numbers. We have no depot or staff in the North West, which is why cube testing for Manchester works by courier or by collection during a site visit.