NUBIANFATKAL
Geotechnical
is there is a way to know that the soil density obtained by sand cone test is true?
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Sand cone test 2
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This test measures volume of a small excavation. You can use the method to find the volume of something similar, such as a deep sauce pan, etc. Make sure that you don't have any lips of the support plate hanging over the volume you are going to measure. Use as large a volume below the plate as you can. As I recall a CBR mold works for this.
The check on the test then is using some other method to measure the volume of the sauce pan.
You can play with things like using the rubber baboon method as another check. Don't forget to allow for thickness of the material of the support plate. Of course the volume of the cone also is in the field test.
A failing of the test in accuracy is when people use too small a hole dug. Minor variations in hole side disturbance and such will affect it, as well as variations in density of the sand itself. So, it is not a simple test, but works quite well when possible variations are checked as you go along with the program using it.
Some do a quick test of finding the weight of the sand in the cone as a rough calibration of the sand density. Being not very large a volume, that check can be misleading.
The main concern about this test is knowing the correct density of the sand you use, as well as good field practice to eliminate possible errors.
The check on the test then is using some other method to measure the volume of the sauce pan.
You can play with things like using the rubber baboon method as another check. Don't forget to allow for thickness of the material of the support plate. Of course the volume of the cone also is in the field test.
A failing of the test in accuracy is when people use too small a hole dug. Minor variations in hole side disturbance and such will affect it, as well as variations in density of the sand itself. So, it is not a simple test, but works quite well when possible variations are checked as you go along with the program using it.
Some do a quick test of finding the weight of the sand in the cone as a rough calibration of the sand density. Being not very large a volume, that check can be misleading.
The main concern about this test is knowing the correct density of the sand you use, as well as good field practice to eliminate possible errors.
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- #6
NUBIANFATKAL
Geotechnical
Thanks bigh i think you understand me but i want to chick that the insitu density is close or (suitable to the material used)at in the obtained water content .
As we've said, the sand cone test is as accurate as you are likely to give, if performed properly. As with all tests, there are limitations. For instance, if the moisture content of the surrounding soil is very high, it will affect the density value by increasing the amount of sand that will go into the hole from the sand cone jug. This will give you a higher weight of sand used, thus a higher volume calculation of the hole, resulting in a lower density in place. Vibration during the test will do the same thing.
As OG noted, the volume of the hole makes a difference. The smaller the whole, the less accurate the test. The whole volume should be at least comparable to the volume of a drive sleeve test cylinder (1/30th cf).
As for the moisture content, if it is determined properly and timely, it will not affect the determination of dry density (assuming the calculations are done properly).
What is your specific question? Do you suspect that the density results you have received are inaccurate or are you concerned that the in-place density is insufficient when compared to the laboratory standard (moisture-density relationship)?
As OG noted, the volume of the hole makes a difference. The smaller the whole, the less accurate the test. The whole volume should be at least comparable to the volume of a drive sleeve test cylinder (1/30th cf).
As for the moisture content, if it is determined properly and timely, it will not affect the determination of dry density (assuming the calculations are done properly).
What is your specific question? Do you suspect that the density results you have received are inaccurate or are you concerned that the in-place density is insufficient when compared to the laboratory standard (moisture-density relationship)?
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- #8
NUBIANFATKAL
Geotechnical
OK Ron lets say an example :
we have the following data to Agg.base coarse layer
1-Material specific gravity .
2-MDD - OMC & air void relationship .(M.proctor)
3-Sand cone test data (wet & dry density - moisture content - compaction % .
I heard about a relationship to know that the results of the sand cone test is represent the tested material .
finally i am so sorry about my language .
we have the following data to Agg.base coarse layer
1-Material specific gravity .
2-MDD - OMC & air void relationship .(M.proctor)
3-Sand cone test data (wet & dry density - moisture content - compaction % .
I heard about a relationship to know that the results of the sand cone test is represent the tested material .
finally i am so sorry about my language .
The relationship is whether or not the material tested in place is essentially the same as the material used for the MDD in the lab.
If your % compaction is more than about 103 to 105 percent, I would suspect that the material you are testing is out of the range of the moisture-density relationship done in the lab. The same is often true of materials showing less than 90 percent compaction, though is is much easier to get an actual compaction lower than 90% than it is to get a 105 % compaction.
Post all of your values for each of the items you noted. Perhaps we can tell you something from that.
If your % compaction is more than about 103 to 105 percent, I would suspect that the material you are testing is out of the range of the moisture-density relationship done in the lab. The same is often true of materials showing less than 90 percent compaction, though is is much easier to get an actual compaction lower than 90% than it is to get a 105 % compaction.
Post all of your values for each of the items you noted. Perhaps we can tell you something from that.
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