NEW PROCTOR/SOIL CALIBRATION 2

[LJB1955]

thread261-252795 Does anyone know where a new to the soils person could obtain a book/isbn # or web site explaining on how to get the proctor # of a soil to input into the machine. Thank you

 

[Ron]

The "Proctor" number is the laboratory moisture-density relationship of the particular soil you're dealing with. It is a laboratory test that is site specific to the soil.

Since you are in the US, the standards for the moisture-density relationship are ASTM D1557 (Modified Proctor) and ASTM D698 (Standard Proctor). Their approximate equivalents for roadway work are AASHTO T180 (Modified) and AASHTO T99 (Standard). The difference between a modified Proctor and a standard Proctor is primarily the amount of compactive effort exerted on the soil (there are some procedural differences as well).

The result of the Proctor test will be a maximum dry density (probably somewhere between 95 and 135 pcf, depending on soil type) at a particular optimum moisture content (usually between about 9 and 13 percent by weight). Those are the values you will enter into the more sophisticated nuclear density gauges. It will then measure the in-place density and compare the two values to give you a compaction percentage.

I would encourage you to learn the process manually before you depend on the "black box". It will give you an appreciation for the process and help you to understand if the results you are getting from the gauge are off for some reason (and there are several reasons that they can be off).

Learn the drive sleeve (drive cylinder) method of in-place density testing, as well as the Sand Cone method. Learning those two methods will help teach the volumetric characteristics of the compaction process.

 

[msesi]

Hi LJB1955,to answer your question regarding inaccurate of the nuclear desinty gauge,you are required to demonstrate it on site.Choose a road section where you are intending to carry the field density test say 1km stretch.Carry out both tests by the use of sand replacement method and by the use of nuclear density gauge.Plot the obtained test results and compare the test results.Find the reduction factor for the nuclear density gauge.Then you can work with the nuclear density gauge by multiplying the results by the obtained correction factor.Hopefully,this will be the best way.