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TRENCH REINSTATEMENTS |
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The prevalence for distress to either the surface seal or the foundation layers of roadways in proximity to trench reinstatements becomes more apparent as roadways age. The distress is primarily due to inadequate waterproofing of the surface reinstatement. |
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Development of the Failure |
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Surfaced roadways are excavated to install services such as water, sewer, gas pipelines and telephone, electrical and television cables. These services are placed in roadways due to spatial limitation in the road reserve.
After the service has been installed, the trench is reinstated using a compacted backfill material similar to that which was excavated. An asphalt layer is then constructed to protect the foundation layers and to provide a wearing course.
It is impossible to re-compact the trench reinstatement to exactly the same compaction density as the surrounding layer works and as such differential settlement will occur. The result of this settlement is the foundation of a crack along the interface of the existing and new asphalt layer. This crack allows moisture ingress which in turn leads to fine particles in the foundation layer being "pumped" to the surface. This situation causes the failure of the foundation layers adjacent to the reinstatement and ultimately the collapse of the roadway. |
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Preventative Measures |
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The backfill material and its compaction density in the reinstatement should be as similar to the existing material and its compaction density as is possible.
A flexible seal should be used to seal off the reinstatement. For this purpose BRP Road Patch is used to cover the entire reinstatement ensuring a minimum 100mm overlap on to the existing surface.
If the seal has been constructed using materials other than BRP Road Patch and distress is showing around the interface, strips of BRP Crackseal are used to seal off any cracking. |
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EDGEBREAK REPAIRS |
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These repairs fail due to either a lack of maintenance or erosion at the shoulder break point, cracking at the vertical joint or transverse cracking. |
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Additional Advantages |
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- Compact base up to existing surface level.
- Not necessary to break back existing asphalt to a straight edge.
- In the event of differential settlement between the existing base and the new shoulder area BRP Road Patch will accommodate the settlement and not result in interface cracking.
- In the event of deterioration to the new edge occurring, BRP Road Patch will flex and hold the edge.
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