Paver Tests

Breaking load                       AS/NZS 4456.5

This test, also known as transverse strength, measures the force needed to break a paver in half. The paver is supported on two beams, 25 mm in from each end, and the force is applied via another beam in the centre. The results of this test are reported in kilonewtons (kN). They’re a measure of the paver’s ability to resist the stresses of handling, transporting and laying, and the loads likely to be encountered in service. Pavers with a breaking load of 2 kN or more are deemed to be strong enough to be transported and laid. Higher strengths (5kN and up) are needed for driveways, roads, etc. Normally the breaking load test is done on a sample of 10 pavers of the same size.

The breaking load test can also be used to measure the flexural strength of the material the pavers are made from (concrete, stone, fired clay), which can then be used to predict the breaking load of pavers of different dimensions.  For example, how much stronger will a paver that's twice as thick be?

Abrasion resistance     AS/NZS 4456.9

Pavers are generally subjected to abrasive wear on their top surface in use. This is typically from foot traffic (high-heeled shoes are particularly tough on pavers), but also from vehicular traffic.

The laboratory test for abrasion resistance involves bombarding the paver surface with hundreds of steel ball bearings. Sixteen pavers (or segments of pavers) are fixed to the outside of a drum containing the ball bearings, and as the drum rotates the ball bearings tumble and roll against the pavers through round holes in the drum. After an hour of this treatment, the pavers are weighed to measure the mass loss, which is then converted to a volume loss and reported as the abrasion index.

Pavers with an abrasion index of 3.5 or less are considered suitable for high-volume pedestrian traffic (eg shopping centre entrances & pedestrian malls). Up to 5 is OK for roads and low-volume public footpaths, and for domestic driveways around 7 is acceptable.

Salt attack resistance     AS/NZS 4456.10

In some situations, pavers can be attacked by salts from ground water, swimming pools , spas etc. How resistant a given paver is to the effects of salt crystallisation will depend on things like the porosity of the paver and the strength of the material the paver is made from, as well as the concentration and type of salt,and the ambient temperature. 

Pavers may be classed as Exposure Grade if they either have a history of coping with a salty environment, or have passed a laboratory test which simulates such conditions. The lab test puts small segments of paver through a series of 40 cycles of alternate soaking in a salt solution, then drying in an oven. If the specimens survive the 40 cycles with less than a specified loss in mass, they’ve passed the test.

The salt normally used in the test solution is sodium sulfate, as this is what causes most damage.  Sodium chloride may be used instead, for instance if the paving is to be laid within reach of wind-blown sea spray.

If the pavers are made of stone (basalt, limestone, sandstone, granite, etc) then a modified test is used, with different specimen dimensions and number of cycles.

Slip resistance         AS/NZS 4586 Appendix A

This is a topic of particular interest to local councils and operators of public areas such as shopping centres, because of the legal implications of pavements which may be slippery to pedestrians when wet.

The most common test for slip resistance involves sliding a rubber pad on the end of a pendulum across the wet paver surface and measuring how far the pendulum swings up on the other side. The more slippery the paver surface, the lower the test result, which is reported as “British Pendulum Number”. Depending on this value, the paver can be classified as Class V (least slippery) through to Class Z (most slippery).

Dimensions                                     AS/NZS 4456.3

Users of pavers will often want to know how much variation there is in the size of their pavers. Consistency of dimensions is important whenever patterns or straight lines need to be maintained in a paved area, particularly when pavers are butted up against one another.

Under this standard test, 20 pavers can be either measured individually for length, width and thickness, or they can be placed side by side, end to end, etc and their cumulative dimensions measured.

Potential to effloresce  AS/NZS 4456.6

Efflorescence is a deposit of salts, usually white, on the surface of pavers after being laid. The salts usually come from ground water or out of the bedding sand that the pavers are laid on, but may come from within the pavers themselves.

This test predicts the likelihood that the pavers will display such unsightly deposits from salts that they already contain.

Water absorption             AS/NZS 4456.14

A standard soaking-in-water test can determine the porosity of pavers, which can then be used as an indication of the potential for the development of problems related to the penetration of salts and other materials into the pavers, such as salt attack and efflorescence.