fill dry and cylinder dry density 2

[wmaperocho]

sirs,
im currently conducting tests on our subgrade for embankment and im a little confused between the calculation and the definition of;
a. fill dry density
b. cylinder dry density

admittedly, im still new in this field and needs all of the help you can extend. further may i know if my calculations are correct.

fill dry density=in place wet density/(1+water content at field
condition/100)

maximum dry density= max wet density/ (1+(in situ moisture
content+moisture content at graph/100))

cylinder dry density= converted wet density at 0 point in the graph/
(1+ insitu moisture content)

hope you can help me with this one. thank you in advance for the inputs...

 

[oldestguy]

I won't try.

First off, generally when comparing the results of compaction out on the job with a laboratory standard, the wet density's are converted to dry density, something like you apparently are doing. We pretty much drop the modifier "Dry", since we know it is dry and using wet can be confusing.

However, the use of the term "fill" dry density may be a local use there,but not here. I'd use the term Field Density.

then the use of the word "cylinder" may be because you may be using a drive cylinder to get a sample for determining the in-place density. If so, I'd drop the term "cylinder". I'd just call it "field density", as different from the lab standard.

How you got the Field Density usually is dropped from the report, unless there is something special about your method for finding that.

The result of comparing the field density to laboratory maximum density usually is then simply "percent compaction".

The term Maximum Density commonly is not found with a computation, but by viewing the graphical plot of moisture content versus dry density in the lab.

One of your local engineers may have found that your calculation produces that Maximum Density, but it is not something I am aware of after some 53 years in this endeavor.

I'm surprised you are out on a job trying to do the testing inspection and there has been no apparent training. Don't you have a boss that knows what is going on? If no knowledgeable supervision, I'd find me a text on the subject. Your employer may find a contractor ready to sue him for mistakes you may make.

 

[tain]

Maybe you can search through US Army Corps website and search for the item that you want or you can google up through internet for the item compaction and proctor test.

I strongly agree what oldestguy said about determination of field density test and laboratory test. This test will determine the MDD and OMC.

So,comparison from this two test will get you compaction degree of either 90%, 95% or 98% depends on criteria and specification needed for that particular layer

 

[Drumchaser]

wmaperocho

oldestguy's response is a great one and provides critical information.

Here is some practical application.

Soils- Many times I have seen folks get to caught up in the % compaction and moisture and forget that the embankment needs to be *stable.
Dependant on your material(s) ( especially the Plasticity Index )heavy clay has high P.I. , sand has a low P.I., your specifications, the type of weather conditions ( season )will mandate the type of equipment and amount of water to be applied during the "processing" of embankment.

I have been involed with several large embank. and excav. projects and only witnessed a couple of contractors who really knew how and were willing to perform compaction and manipulation necessary according to spec.s ....without heavy "persuation."

In our general area we have mongrel soils, which is to say you can run ten proctors out of ten different locations in your cut or pit areas and have ten differing Moisture Density Curves. And you cannot possibly have the exact M D curve to fit every test. Being familiar with your sources of embankment and their corresponding properties, colors, PI's, LL etc. will help in determining what is needed to process it correctly.

So my point is...during construction, if the embankment lift thickness is with-in spec.s, the amount of compactive effort is applied (equipment used and number of passes) and the moisture is there ( water truck(s) to add or disc to remove areas that are too wet ) and you are placing according to lines and grades on the plans, and the embankment is stable with no pumping or rutting ( only in high PI materials is this OK )
you are moving in the right direction.
Please don't interpret this to mean a passing % density is not important, it is, but.......sometimes your density will not pass and the fill is tight and the compactor is walking out ( riding on top of the vibratory teeth )and other times your % density will pass but your fill looks bad....rutting, pumping etc.

Having the right compactive effort (and moisture) applied is what the whole thing is about in my opinion.

Soils are not always an exact science in the field.

Working with honest people that have years of knowledge really helps with this.

When the motorgrader is "blue topping" or making the final grade on your subgrade watch his back wheels to see if there are any deflections or soft spots in your subgrade before the base course is placed, dig'em out or dry these areas out and reprocess as needed....even if you have passed density on a given area/section you may get rain showers on it and need to "proof" roll it.


Good luck.