Rigid clay pavements can be utilised in a wide variety of applications.
The most popular areas using the Rigid Paving method are:- * domestic pathways
- * patio areas
- * pool surrounds
- * domestic driveways
- * pedestrian areas
Testing carried out by the Clay and Brick Pavers Institue has shown that clay pavers used in rigid pavement are suitable for use where heavy vehicle loading is expected. Testing has shown that this method withstands the forces that may sometimes induce movement or "shunting" in a flexible pavement.
Laying:
Subgrade:
The considerations with regards to the subgrade for a rigid pavement are the same as those for a flexible pavement.In every case, the pavement designer and/or the contractor must consider all measures necessary to determine the site conditions that will impact on the long term performance of the pavement including, but not limited to:
- * Loadbearing capacity of the subgrade.
- * Subgrade drainage.
- * Removal and replacement of unsuitable material.
Base Course:
The base course for a rigid pavement is a concrete slab having the following properties:- * Strength to be consistent with expected trafficloading and subgrade strength but,
- in general terms, should always exceed an ultimate strenght of 20 MPa.
- * Thickness to satisfy predicted loadings.
- * Reinforced, if required, due to predicted loading.
- * Finished to a smooth surface with a "helicopter trowel".
- * Allowed to harden overnight before the pavers are laid.
Paver Laying:
Pavers should be selected as to their suitability for the intended application. Pavers should be laid once the concrete slab base course has hardened to resist deformation, usually overnight.The perimeter pavers are laid first, generally as a header course around the job. They are bonded to the hardened slab either by a strong cement/sand mix (1:3 or 1:3.5) or by an adhesive.
Once the permimeter pavers have been installed, the main body of the pavement can be laid in the chosen pattern. For rigid pavements that will be used for vehicular traffic, it is strongly recommended that a 45 or 90 degree herringbone pattern is used.
The gaps that are essential between pavers in a flexible pavement, are not necessary in a rigid pavement. The can be used if this is an aesthetic requirement, but gaps are not essential to the performance of a rigid pavement.
It must be noted that with this system, there is no allowance for the variation in the depth or height of the pavers, as they are being laid on a hardened concrete base. Therefore, any variation in height of the units will show up in the finished pavement. Pavers that have a bevelled or rounded arris can disguise this variation.
Expansion Joints
Expansion must be considered when laying a rigid pavement. The gaps between pavers in a flexible pavement allow for thermal and long-term moisture expansion of clay pavers to be taken up. In a rigid pavment this does not occur. Therefore expansion joints are required in rigid pavements.
The paver manufacturer should be consulted for advice on the location of such expansion joints.
Joint Filling
Once all the full and cut pavers have been laid it is time to fill the joints. The jointing mix is 1:3 cement:fine sand mixed with sufficient water to turn it into a fluid slurry. Themixture must be sufficiently fine so that the slurry mix can flow around any gaps in the paver and fill any voids underneath them.Finally, once the slurry filling of the joints is complete, the surface of the pavers should be hosed down using a high-pressure, fine moist spray to remove the excess slurry.
Vehicular traffic should be prevented from traversing the pavement for at least four days.