Spikma kerbing is manufactured by special machines that were largely developed in-house. Very high-quality concrete is used for the kerbing. This guarantees low moisture absorption and good resistance to frost and road salt. The concrete’s compressive strength is a full 60 MPa and is checked daily along with flexural strength (6 MPa). Most of our kerbing also has a cast-in 5 mm reinforcement bar.
Frost heave and heavy traffic often cause a degree of movement in road surfaces. Kerbing must be able to take up this movement flexibly without coming loose. Through flexible fastening within reasonable limits, Bender Spikma kerbing achieves this. Pin penetration into the asphalt can be modified without affecting the kerbing’s ability to take up lateral stresses.
“Benders’ pinned kerbing has the only pinned kerb stones on the market. We use virtually nothing else. Primarily because it is more durable than bonded stones and is easier to adjust,” Anders Hansson, foreman, Skanska Asfalt.
Spikma pinned kerbing has pre-fitted pins. This saves a lot of work. Each pin is a robust manganese steel alloy, 4.5 mm thick and 70 mm long, fitted in a polyethylene bushing. The pin’s shearing strength is 115 kp/mm2, i.e. a full 2.3 tonnes per pin. Pin and bushing are captive in the kerbing, an arrangement that is advantageous from the health and safety perspective.
The lip on Spikma kerbing holds the captive pin, provides a stable footprint on the substrate and further anchors the kerbing in the backfill material. To avoid joints opening in the front face when laying large convex radiuses, the lip is somewhat shorter than the kerbing element itself.
Double tongue and groove ends
To facilitate laying, each kerbing element has both a tongue and a groove at each end. The element’s ability to take up lateral forces is thereby increased by 50%.
The ends also have spacing shoulders. These give each kerbing element the space it needs to take up linear expansion and movement in the substrate.
Bevelled end edges
To reduce corner damage, all Spikma kerbing has bevelled end edges. This also “conjures away” minor unevenness when laying – yet another advantage!