A distribution centre off the A47 was loading articulated lorries onto a yard that had cracked within two seasons. The original design assumed uniform ground support, but the subgrade across the eastern end sat on a pocket of softened chalk with silt infill, and the slab had no transition detailing. In our Norwich laboratory, we see this pattern often: a rigid pavement is treated as a standard section when the ground below is anything but standard. Getting the concrete slab thickness, joint spacing, and base course specification right depends first on taking proper cores and performing plate load testing at formation level. The chalk terrain across the wider Norwich area, from the river valleys to the plateau edge, creates abrupt stiffness contrasts that feed directly into curling stresses at slab corners. A design that works on the first 50 metres may be under-designed 100 metres further along if the ground investigation skips the transition zones.
A rigid pavement transfers wheel loads across a wide footprint, but only if the ground beneath it has a consistent stiffness profile — something the chalk and glacial drift around Norwich rarely provide naturally.
Methodology applied in Norwich
Local geotechnical conditions in Norwich
Norwich sits atop the Upper Chalk formation, and across the city and its fringes the chalk is riddled with dissolution features — pipes, swallow holes, and soft putty-chalk seams that can settle abruptly under repeated loading. The Environment Agency’s mapping shows several areas classified as moderate to high susceptibility to groundwater-related dissolution, particularly where the chalk is close to the surface and overlain by less than three metres of cover. A rigid pavement concentrates differential movement at the joints, so even 10 mm of localised settlement across a dissolution feature will trigger faulting, slab rocking, and eventual corner breaks. We carry out dynamic probing and rotary coring to map the chalkhead profile across the entire footprint before committing to a slab design. Where there is any doubt, the design incorporates a geogrid-reinforced granular platform to bridge weak zones and maintain the design k-value under the slab.
Our services
We deliver the full engineering workflow for rigid pavements in and around Norwich, from initial ground investigation through to mix design verification and construction-phase testing.
Rigid pavement structural design
Full analytical design of jointed unreinforced concrete pavements for highways, industrial yards, and port pavements. We use Westergaard-based edge-loading analysis and finite element modelling where thermal gradients are critical, calibrated against actual ground stiffness from on-site testing rather than assumed values.
Concrete durability and quality control testing
UKAS-accredited laboratory testing covering compressive strength, flexural strength, water absorption, and freeze-thaw resistance per BS EN 12390. We also perform on-site cube sampling, air content monitoring, and joint sealant verification during construction.
Questions and answers
How much does a rigid pavement design package cost for a Norwich project?
For a typical industrial yard or access road in the Norwich area, the complete design package — including ground investigation, laboratory testing for subgrade stiffness and concrete flexural strength, and the structural design report — falls between £1,430 and £4,700. The range depends on the size of the paved area, the number of boreholes or trial pits required, and whether dynamic plate load testing is needed across multiple formation levels.
When is a rigid pavement a better choice than a flexible pavement for Norwich's ground conditions?
A rigid pavement becomes the better choice when the subgrade is weak but uniform, because the slab distributes loads over a wide area and reduces pressure on the formation. On the chalk and silt profiles around Norwich, we recommend rigid pavements for industrial yards with frequent turning movements, bus depots, and areas where fuel or oil spillage would soften an asphalt surface. The key is verifying that the subgrade support is consistent; where it is not, we design a reinforced ground platform beneath the slab to bridge the variation.
What ground investigation is needed before designing a rigid pavement in the Norwich area?
We typically combine cable percussion boreholes to the chalkhead with dynamic probing to map the stiffness profile continuously. In Norwich, identifying dissolution features and soft chalk zones is essential, so we include rotary coring where the chalk is within three metres of formation. Plate load testing at formation level gives us the in-situ k-value, and laboratory testing on recovered samples determines the moisture sensitivity and frost heave potential of the glacial silts.