AREA No. 18

32 mm Pavers on Sand Bed with Hand-Tight Joints

8.2.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 765 x 384 x 32 mm units and 191 x 191 x 32 mm units, all with sawn edges. 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 "hand tight" joints between all paving units. The area was protected with plywood and mechanically vibrated after which fine sand was swept into the joints. A total of three iterations of the vibrating/sand filler procedure were completed.

8.2.B DATES

Installation of Granite Pavers: 23 October, 1995

Filling of Joints: 23 October, 1995

Traffic allowed on Pavement: 13 November, 1995

8.2.C OBSERVATIONS:

Area 18 has is similar to area 5, which failed almost immediately after traffic exposure. The differences between the two systems are the depth of the sand setting bed ( mm in area 5 and mm in area 18) and the joints (split-edge paving units with 20 mm joints were used in area 5 and sawn-edge paving units with "hand-tight" joints were used in area 18). The reduced depth of setting bed was expected to provide greater resistance to penetration of the paver corners, and the hand-tight joints were expected to prevent lateral displacement of the paving units. Observation in July, 1996, noted that paver alignment has been maintained without any significant problems. The area has settled significantly (nbsp;mm) du

May, 1997: Cracking in the perimeter pavers has continued to a total of 7 cracked units, while no additional field pavers have cracked. Chipping of the edges has not increased in the last 10 months. The settling of the area is severe, from 20 to 25 mm. The installation system is clearly not appropriate for the large perimeter pavers, but is a possible consideration for small pavers (up to 200 x 200 mm) with limited traffic loads.

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