1. Has the sod, topsoil and vegetation been removed?
All organic material must be removed before paving operations are performed.
2. Walk the site. Are there any pockets of peat, muck, soft soils or random fill?
All pockets of peat, muck, soft soils, or random fill must be undercut, properly back-filled and compacted with soil similar to the existing suitable subgrade soils (i.e. clay with similar clay, etc.) If these areas are excessively large or deep, then a soils engineer should be consulted.
3. Are there any wet areas in the subgrade?
When there are wet areas in the subgrade the water must be removed and a determination made to see if there are any soft spots. If there are soft spots then refer to solution No.2 above. If the soils under the wet area are firm and unyielding, but saturated with water, then the soils must be blended with adjacent soils, dried and re-compacted to create a uniform subgrade.
4. Are there any utility trenches within the area to be paved?
If there are utility trenches in the area to be paved, determine if proper backfill and compaction procedures have been used. If the trench areas are either soft and yielding or back-filled with soil that is not similar to the existing suitable subgrade soils then further corrective action may be necessary.
5. Will the pavement be placed over areas next to the building or other structures that have been excavated and back-filled?
If the pavement is to be placed over areas adjacent to a building or other structure that has been excavated and back-filled then the same solution is recommended as for utility trenches. See No.4.
6. Has there been fill placed in any portion of the area to be paved?
If there has been more than one (1) foot of fill placed in any areas of the subgrade then the same solution is recommended as for utility trenches. See the above solution No.4. If there is less than one (1) foot of fill, then special attention should be given to those areas during the test roll. If the fill material is not similar to the existing suitable subgrade soils, then refer to solution No.7 below.
7. Are the subgrade soils uniform (i.e. all clay, all sand)?
The areas between dissimilar soils should be excavated to a six (6) inch depth, blended and re-compacted to create a transition of approximately ten (10) feet from one soil type to the other.
As a preliminary check, you should now test roll the grade with a vehicle that has a minimum 5000 pound axle load.
8. Is there noticeable rutting of the subgrade during the test rolling?
In clay soils the areas of noticeable rutting must be excavated (disked), dried out, and re-compacted. In granular soils (sand) minor rutting should be anticipated and is normal. When there is deep rutting you must excavate (disk), dry out and re-compact the soil.
Before placing the concrete:
9. Has the final grade been prepared so that you may place a uniform thickness of concrete?
If the final grade has not been properly prepared then it must be fine graded to accomodate placement of a uniform thickness of concrete.
A second test rolling using a loaded dump truck should now be performed.
10. Is there any noticeable rutting or displacement of the subgrade?
Areas of noticeable rutting must be excavated, dried out, and re-compacted to create a stable and uniform subgrade.
11. Has a leveling course of sand or gravel been used?
If the subgrade soil is clay, a leveling course may trap water and additional under drainage may be required. The owner or his representative should be notified of this condition.
General Recommendation: Whenever one or more of the items in the checklist have not been met, the paving contractor shall notify the owner in writing of these conditions prior to concrete placement.
Disclaimer: This information is intended for the use of experienced personnel who are competent to evaluate the significance and limitations of its contents and who will accept responsibility for the application of the material it contains.
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