Highways

A12 Margaretting Concrete Trials

As part of the Highways England Concrete Road Innovations Project, TAG was employed by Graham to replace two defective concrete bays on the A12 Margaretting southbound, the first time CSA concrete had been used on this stretch of highway. The trial was designed to test how the material performed and cured under genuine overnight maintenance conditions.

The works were planned across two nights: Friday to saw cut and core the bays ready for removal, Saturday night to carry out the replacements and reinstate the joint sealant. That sequencing was deliberate, minimising the risk of the road being handed back late on a first-of-its-kind material for Highways England, Graham and TAG alike.

Both bays were reinstated with Eastern Concrete's Rapid Set P400 CSA concrete, which cured to the required 25N/mm² inside two and a half hours even in low temperatures. The trial didn't go entirely to plan: an issue with the first bay put the works two hours behind schedule, delaying the second pour until 2:30am on a section of the A12 only two junctions from the M25, where a late reopening would have caused real disruption. The P400 CSA still cured to over 25N/mm² by the 05:00 deadline, and the road opened on time.

All material removed from site was recycled through TAG's local partner SRC Aggregates, and the trial's results fed directly into how CSA concrete was specified on later Highways England schemes.

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