8.1 INSTALLATION OF AREA No. 17

76 mm Pavers over Sand Setting Bed

8.1.A INSTALLATION PROCEDURE

A course gravel mixture of approximately 150 mm depth was placed over the existing grade material and mechanically vibrated to approximately 90% compaction. A layer of washed sand was placed over the gravel, screeded to an approximate thickness of 25 mm, and mechanically vibrated. The granite pavers were a combination of 756 x 375 x 76 mm sawn edge units and 172 x 172 x 76 mm split edge units. The pavers were hand selected from a larger lot to provide a thickness tolerance of approximately ...........5 mm. The granite pavers were placed directly on the sand setting bed without any bonding agent. The pavers were aligned and leveled maintaining 10 mm joints between sawn edges and 20 mm joints between split edges. The area was protected with plywood and mechanically vibrated. Fine sand was swept into the joints after which it was vibrated a second and third time. Fine sand was swept into the joints a final time to make the joint filler level with the paving surface.

 

8.1.B DATES

Installation of Granite Pavers: 20 October, 1995

Filling of Joints/Vibrating: 20 October, 1995

Traffic allowed on Pavement: 13 November, 1995

8.1.C OBSERVATIONS:

This area is essentially the same installation system as area 9, which failed almost immediately after traffic exposure. The only differences between the two areas is the thickness of the sand setting bed (which was mm in Area 9 and mm in Area 17) and the additional vibrating done to area 17 after installation of the pavers. The reduced setting bed depth apparently provides better resistance to penetration of the pavers corners, as the "tipping" of the paving units demonstrated in area 9 has not been evident in area 17. In July, 1996, after 10 months of weather and traffic exposure, the paving units appear to have maintained alignment quite well with only minor displacement ( mm) of the paving uni

May, 1997: The condition of the area after 20 months of exposure, is essential unchanged from above.

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