The Importance of Bedding Course Sands in Heavily Trafficked Pavements
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The Importance of Bedding Course Sands in Heavily Trafficked Pavements

Technical advice

The Importance of Bedding Course Sands in Heavily Trafficked Pavements
The Importance of Bedding Course Sands in Heavily Trafficked Pavements

It is established that the best bedding course sands for flexible clay pavements are naturally occurring silica sands from the quaternary geological series and sea-dredged sands. Crushed rock sands should only be used in domestic applications.

Crushed stone with excessive fines, such as dolomitic ‘crusher dust’, are unsuitable because although they can be compacted, they fail to provide a capillary break.

Water entering this material carries with it fines providing a ‘lubricant’ for further breakdown of particles in heavily trafficked channelized areas which may result in eventual bedding course failure.  

Pavements subjected to heavily channelized traffic, such as a bus lane, require a sand of high stability-a Category 1A or 1B sand.

The Importance of Bedding Course Sands in Heavily Trafficked Pavements
Category Application
 
1A Pavements receiving severely channelized traffic
Aircraft pavements
Bus stations
 
1B Industrial pavements
Loading bays
 
II Adopted highways and other roads
                Petrol station forecourts
                Pedestrian areas with regular heavy traffic
                Car parks receiving some heavy traffic
                Footways regularly overridden by vehicles
 
III Pedestrianisation schemes receiving only occasional heavy traffic
                Car parks receiving no heavy vehicles
 
IV Private drives
Areas receiving pedestrians only
                Footways likely to be overridden by no more than occasional
                vehicular traffic

 

The Importance of Bedding Course Sands in Heavily Trafficked Pavements
Moisture content of bedding course
 
The moisture content of the bedding course should be uniform and moist without being saturated. Stockpiled material should be covered.
 
Bedding sand thickness
 
Following compaction, the bedding sand should be uniformly 35mm thick with a maximum specified of 50mm and a minimum of 25mm. 

 

The Importance of Bedding Course Sands in Heavily Trafficked Pavements
Bedding sand construction
 
This is best prepared by spreading the sand in a loose uncompacted layer and then compacting it with a vibrating plate compactor. The compacted sand is then screeded to level to receive the pavers and must not be disturbed as any disturbance to this sand layer may lead to final surface undulations.
 
Edge restraints must be provided around the perimeter of the area to be paved. The restraint construction, together with any haunching, should be mature before any vibration of the paving takes place. Gaps between edge restraints or at the intersection with other pavements should be sealed to avoid loss of bedding sand.
 
For further advice on the laying of Vande Moortel clay Paving please contact info@vandemoortel.co.uk