Safety Testing & Certification for Property Developers in Bristol

The specification should come from the engineer and follow BS 8500 and BS EN 206, which set out how concrete is specified by strength class, exposure class and other requirements. Exposure class matters for elements in contact with the ground, where sulfates in the soil can attack concrete, so the site investigation findings must reach the concrete specification. Ready-mixed concrete arrives with a delivery ticket recording the mix, batching time and quantity, and those tickets should be checked on arrival and kept. Water should not be added on site to ease placing unless the specification allows it, because it reduces strength.

On-site testing usually includes a consistence test, often a slump test, on delivery, and making test cubes to be cured and crushed at a laboratory, commonly at 7 and 28 days, following the BS EN 12350 and BS EN 12390 series. The sampling frequency is set by the specification. Cubes must be made, stored and transported correctly, because a badly handled cube can fail even when the concrete in the structure is sound. Ask who will make the cubes, where they will be stored and which laboratory will test them.

Inspections before concrete goes in matter as much as tests afterwards. Building control needs notice at key stages, including foundation excavations before they are concreted, and the engineer or warranty inspector may want to see reinforcement, cover spacers, membranes and formwork before a pour. Build those inspections into the programme and record them with dated photographs, so there is evidence of what sits inside the concrete once it is hidden.

Weather and curing need their own records. Cold weather slows strength gain and frost can damage fresh concrete, while hot, windy conditions cause rapid drying and cracking, and night-time temperatures matter as much as daytime ones. The pour record should note air temperature, protection used and curing method, such as curing compounds, insulated blankets or wet hessian. If test results come back low, those records help the engineer decide whether further investigation, such as coring, is needed.

Collate everything into a pour register as work proceeds: the location of each pour, date, delivery tickets, test results, inspection records, photographs and any non-conformances with how they were resolved. On larger schemes the principal contractor's quality system may already require this, but on smaller developments it often falls to the concrete subcontractor. The register becomes part of the handover information and supports the health and safety file under the Construction (Design and Management) Regulations 2015.

When comparing proposals from the concrete contractors and testing firms you are introduced to, check how sampling and cube making are priced and who is responsible for them, how soon laboratory results are reported, what happens if a result falls below specification, and the format of pour records at handover. Ask for a sample pour register from a previous project.