The principle of CEDEC® footpath gravels is to form a firm but porous structure that retains moisture yet allows any excess to flow through. The materials used are specially graded decorative aggregates ideal for areas where the traffic is too heavy for grass but where a natural appearance is desired.

CEDEC® footpath gravels comprise granite and quartzite, which are chemically inert and durable and will not affect the pH value of the surrounding soil. This is important where newly planted trees or pH-sensitive plants are sited. Its porous nature is good for trees generally.

In order to function effectively, CEDEC® needs to be rained upon and walked upon. It will not be effective indoors or under permanent shelter.

Coverage of CEDEC® is approximately 10m² per tonne, compaction being about 25%.

The following specification is based on best practice and may vary according to the particular situation.

Specification and Maintenance - Foundation

The foundation layer should be laid to a uniform crossfall or crown as required on the finished path. This layer should be firm enough to take the subsequent layers and compacting machinery without deformation and a geotextile should be used if ground conditions so indicate.

The thickness of the base layer will depend on the maximum vehicle weight likely to cross the footpath gravel but a compacted 150mm is suitable for pedestrian and light maintenance vehicle use. A free draining layer of specially graded 28-0mm from the same source as the surface layer is the best practice, however other inert materials with similar sizing may be suitable. A 1500kg non-vibratory roller should be used, but being careful to avoid damage to irrigation systems if installed. If any irregularities are found in the base layer, these should be rectified with the correct base layer material and not the surface material.

CEDEC® footpath gravel should be supplied in a thoroughly mixed and moist state. It must not be laid if dry and should be laid to a thickness of 50mm after compaction. Initial compaction should be carried out BEFORE watering takes place and by at most two passes of non-vibratory roller not exceeding 500kg in weight. After initial compaction, which should be sufficient to prevent fines being washed through the surface, thorough saturation is necessary with water by a hose fitted with a rose sprayer, or similar method, taking care to prevent disturbance of the top layer.

Final compaction of the saturated surface (5 or 6 passes) is to be with a non-vibratory roller with a 500kg axle weight on the saturated surface. A short delay (up to 30 minutes) may be necessary after watering to prevent pick-up on the roller. Two further cycles of watering and rolling (5 or 6 passes each) should take place within one week after lying.

Maintenance of CEDEC® Footpath Gravel

A: New (up to 3 months)

Correct maintenance for the newly laid footpath gravel is essential and damage must be repaired promptly. If the new surface is allowed to dry out there is a possibility that the surface may tend to break up through lack of bonding. Regular maintenance by watering with a hose fitted with a rose sprayer, or similar method, plus rolling with a non-vibratory roller, maximum axle weight 500kg (5 or 6 passes) will be necessary until the surface is entirely consolidated. Drag matting or brushing should be carried out if necessary. Any depressions should be lifted and made good additional surfacing material as necessary.

NEVER ROLL A DRY SURFACE

B: Established Surface

A mature surface will require a different regime of maintenance to a newly laid one. It will be mostly to prevent potholes and to repair erosion. If potholes do occur, it is advisable to cut out the affected areas and replace them with new footpath gravel, rolling with a 500kg non-vibratory roller.

Collect large litter with a spiked litter collector. Raking with a springbox rake will pick up small pieces of litter, cigarette ends, chewing gum, twigs, leaves etc. As an indication a man should clean about 150 square metres in an hour.

In areas of particularly heavy use, the surface may become too hard. Should this occur and there be some puddling, thoroughly spike the surface with a fork to improve drainage.

The base layers and surfaces both use graded aggregates therefore non-vibratory rollers only must be used. Any area of CEDEC® must always be constrained by a raised surround. As an example, where used adjacent to paving always make the surface of the CEDEC® at a lower level than the paving to prevent migration of the loose chips onto the paving. As with any loose material, CEDEC® will be picked up to some degree by shoes, especially in damp conditions. If being used near a building entrance, ensure that adequate foot cleaning areas or transitional areas are provided.

Because CEDEC® relies on its own binding qualities for stability, it is best as a level surface. It should not normally be laid on a slope greater than 1 in 25. If appropriate, steps should be used to reduce the steepness of the slope.

CEDEC® is not recommended where lateral forces are applied to the compacted surface by frequent wheeled traffic. Loss of cohesion of the surface, and hence friability leading to erosion, can occur where any wheeled traffic is accelerating, slowing down or turning. CEDEC® is currently available as CEDEC® Red, CEDEC® Gold and CEDEC® Silver.

For further information concerning CEDEC® or a location where CEDEC® is available for viewing, please call one of our four nationwide depots; also to be consulted are the descriptive notes. These notes complement the laying instructions by providing some insight to how CEDEC® works and should be used.

Issue Date: 30 December 2004