MSEdesigns
Civil/Environmental
Which Compaction method is best suitable for specifying the compaction requirements on a Segmental retaining wall reinforced with poliester geogrids. Material specified for the reinforced zone is A-2-4 or better.
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Best compaction specification for MSE Walls
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MSEdesigns
Civil/Environmental
I'm talking about the test. Should I specify 95% Standard or 90% Modified Proctor. What difference it makes on the final compacted material?
casimmons
Geotechnical
- May 21, 2003
- 35
This varies with soil type, but 95% standard is roughly equivalent to 90% modified. Just make sure that the compaction and soil type you specifiy will give the soil properties you used for design. It would be a good idea to perform triaxial or direct shear testing to verify this.
MSEdesigns,
The following is from the guide specification for MSE walls with segmental concrete facing elements, as presented in FHWA NHI-00-043:
Backfill shall be compacted to 95 percent of the maximum density as determined by AASHTO T-99, Method C or D (with oversize corrections as outlined in Note 7 of that test). For backfills containing more than 30 percent retained on the 19 mm sieve, a method compaction consisting of at least four passes by a heavy roller shall be used. For applications where spread footings are used to support bridge or other structural loads, the top 1.5 m below the footing elevation should be compacted to 100 percent AASHTO T-99.
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State DOTs that I have worked for (as my "ultimate" client) have their own guide specifications which may or may not contain jurisdiction-specific compaction standards that will likely exceed or regurgitate the guide specs mentioned above. All that I have seen to date, however, incorporate by reference the AASHTO Standard Specifications for Highway Bridges, which in turn incorporates by reference the FHWA publication indicated above. Download a copy of the FHWA guide from
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
The following is from the guide specification for MSE walls with segmental concrete facing elements, as presented in FHWA NHI-00-043:
Backfill shall be compacted to 95 percent of the maximum density as determined by AASHTO T-99, Method C or D (with oversize corrections as outlined in Note 7 of that test). For backfills containing more than 30 percent retained on the 19 mm sieve, a method compaction consisting of at least four passes by a heavy roller shall be used. For applications where spread footings are used to support bridge or other structural loads, the top 1.5 m below the footing elevation should be compacted to 100 percent AASHTO T-99.
-----
State DOTs that I have worked for (as my "ultimate" client) have their own guide specifications which may or may not contain jurisdiction-specific compaction standards that will likely exceed or regurgitate the guide specs mentioned above. All that I have seen to date, however, incorporate by reference the AASHTO Standard Specifications for Highway Bridges, which in turn incorporates by reference the FHWA publication indicated above. Download a copy of the FHWA guide from
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
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