Maximum dry density of poorly-graded gravel
Maximum dry density of poorly-graded gravel
(OP)
We recently had a gravel material be tested by a soils lab for sieve and proctor. he sieve results classified it as "Poorly-graded gravel w/sand & silt", which does make sense once you compare the grain-size distribution. However, when they ran the proctor, they claimed they came up with an uncorrected value of 155.3 pcf. Now, I know that most engineers when designing with concrete usually take values from 145 pcf to 150 pcf. Looking at these results, I can't help but think that there may have been an error somewhere.
Has anyone ever encountered a material that the maximum dry density tests out heavier than concrete? Is this truly feasable?
Bear in mind this is 1/2" processed material, no reclaimed concrete or asphalt.
Thanks all.
Extras: ASTM D1557 Method C for compaction. ASTM D422 for washed sieve was used.
Has anyone ever encountered a material that the maximum dry density tests out heavier than concrete? Is this truly feasable?
Bear in mind this is 1/2" processed material, no reclaimed concrete or asphalt.
Thanks all.
Extras: ASTM D1557 Method C for compaction. ASTM D422 for washed sieve was used.





RE: Maximum dry density of poorly-graded gravel
RE: Maximum dry density of poorly-graded gravel
According to what they have,
Coarse Aggregate SG = 3.20 (granite?? Extremely high for this region, Southern New England)
Fine Aggregate SG = 2.94 (again extremely high for any type of "common" sand around here).
Based on 53% retained on the #4 sieve, the weighed specific gravity turned out to be 3.07.
Still...something seems rather fishy to me, especially having now looked at these specific gravities. What do you think?
RE: Maximum dry density of poorly-graded gravel
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RE: Maximum dry density of poorly-graded gravel
RE: Maximum dry density of poorly-graded gravel
RE: Maximum dry density of poorly-graded gravel
RE: Maximum dry density of poorly-graded gravel
Perhaps some form of lab vibration test is in order instead.
RE: Maximum dry density of poorly-graded gravel
Post test gradation will confirm what oldest guy suggests.
Maximum density by vibratory may or may not be greater than impact compaction, but with post test gradation will answer the question of breakdown.
Match the lab test with gradation from samples of field compacted material to select lab method.
RE: Maximum dry density of poorly-graded gravel
On the retest of the specific gravity, it came up at 2.8 instead of 3.0. I witnessed this second specific gravity get completed, so all steps were correct, and I feel more confident with this new sp. gr.
Also, the new proctor value in relation to this retest became 144.9 uncorrected, with the same exact sieve breakdown as the previous sample.
I want to thank everyone for their responses and say I am very glad I joined this forum site.
RE: Maximum dry density of poorly-graded gravel