ZZj than ouuigtunut o-teenThe device consists of a glass or plastic jar with a metal -attached at its top (Figure 5.14). The jar is lled with vety ttnirotm dry Ottawa sand. The weight or the jar. the con, and the h lling the jar is determined (w1). In the field. a small hole is excavated in the area where the soil has been compacted. If the weight of the moist soil excavated from the hole (W3) is determined and the moisture content of the excavated soil is known. the dry weight of the soil (Wt) can be found as

w = -W~ (S 25)

w ( 96) 'I +I00

when: w - moisture content.

After excavation of the hole. the X with the --filled jar attached to it is invettedand placed over the hole (Figure 5.|5 . - is allowed to ow out of the jar into the holeand the Once the hole and are tilled. the weight of the jar. the -. and theremaining - in the jut is detennined (W4). so

W5 = W. - W4 (5.26)

whete w, = weight of I to till the hole and IThe volume of the hole excavated can now be determined as

V = (5.27)

COMPARISON OF NUCLEAR AND I-LI}

METHODS OF DENSITY

ML

AND MOISTURE DETERMINATIONS FOR FOURNEW YORK STATE SOILS

BY SIDNEY Mr.\rrz1-:tt'

This report summarizes and compares the results of density and moisture content measurements made on compacted embankments by the nuclear or radiation and by the -mi The latter has been utilized as a standard for many years for such measurements by the Bureau of Soil Mechanics, New York State Department of Public Works. The tests were performed on three highway projects under construction, and involved four basic soil types. The tests were performed on Aug. 24 and 25, 1959.

The d/M (density-moisture) gage manufactured by the Nuclear-Chicago Corp. was utilized for the nuclear portions of the test. The instrument was operated and the readings interpreted by Jack Templeman of the aforementioned rm. The density and moisture content determinations using the Tan 9- were performed by personnel of the Bureau of Soil Mechanics under the supervision of the author.

The testing described represents the preliminary phases of a program to investigate the suitability and adaptability of the nuclear if for embankment compaction control under the various conditions prevailing in New York State. Since the tests described represent the preliminary phase of this program, no conclusions are included.

Associate Soil: Engineer, Bureau of Soil Mechanics. New York State Department of Public Works, Albany, N. Y.

The results obtained from the tests are presented for information purposes to indicate the trend of the program and as a guide for further investigation.

DESCRIPTION or we Two .\/In-woos

Density - Moisture Gage Moisture and Density Surface Probes:

The density-moisture gage used consisted of a model P-21 surface moisture probe, a model P-22 surface density probe and a model 2800 scaler. The approximate time required for a complete moisture or density measurement was 2 min. The probe was placed on the surface of the layer to be tested, the timer set to the desired time interval, and the scaler read for the count. This count was then located on a calibration chart, from which the moisture content or wet density was obtained, the value being indicated in pounds per cubic foot.

The P-21 moisture probe measures a semispherical volume of material, the depth of which varies from approximately 5 to 15 in., while the P-22 density probe measures to a depth of approximately 3 to 8 in.

The principle of operation of the density-moisture gage is based on the degree to which radioactivity is scattered when placed in contact with materials of different moisture content or density. After the equipment has been calibrated for various moistures and densities, measurement of the resulting scatter

provides a for determining moisture content or density of the soil layer being tested.

The P-21 surface moisture probe contains a radioactive radium-beryllium source of fast neutrons, and the P-22 surface density probe a cesium-137 gamma ray source. Each probe contains a detector system sensitive to radioactive scatter. The count of impulses received from the probe is registered on the P-2800 scaler glow-tube registering system; this count is then located on the calibration chart and the moisture content in pounds per cubic foot, or wet density, also in pounds per cubic foot, read directly from the chart. The dry density is obtained by subtracting the moisture measurements from the density measurements. Per cent of moisture content by dry weight is obtained by dividing the dry density into the pounds per

cubic foot of water.

Bureau of Soil Mechanics-V-Field Compaction-Conlrol-Dcnsily Test:

The eld compaction test of the Bureau of Soil Mechanics, New York State Department of Public Works, utilizes a calibrated apparatus for determination of density. The test procedure consists of measuring the actual wet density of the compacted material in the eld by removing a sample of soil from the layer and determining the actual volume of the hole from which the soil was removed. All of the soil removed from the hole is retained and, knowing the weight of the soil and the volumen the soil occupied in the test hole, the wet density is computed.

The moisture content of the soil isdetermined by taking a sample of thewet soil, drying it to constant weight ina laboratory oven at 110 C, and then ob-taining the ratio of the water in the sam-ple to the dry weight of soil, expressedas a percentage. The dry density is de-

Nucu-ma Mr:'ruons roa Son. DENSITY AND MOISTURE

termined by correcting the wet densityfor the moisture content of the sample.

The Bureau of Soil Mechanics @-wan Iretliilu is in conformance withASTM Tentative of Test forDetermining Density of Soil in Place bythe li-$9 ihtil.

Tssr Pnocsnuru-:

In-place eld density and moisturemeasurements were first made using thedensity-moisture gage on several care-fully leveled locations at each site. i-cone measurements were made at eachidentical spot immediately after thedensity-moisture gage was moved to thenext location. The soil extracted fromeach hole was sealed in air-tight jars for moisture determination atthe laboratory.

Tests were performed on the followingproiects:

Projca Soil Ty):Interstate Route 502-GlensFalls Bypass. FISH 58-19

(saratoga County) . . . . . . . . brown 1. trace

of siltAmsterdam North-South Ar-terialFAC 58-I6 (Mont-gomery County) . . . . . . . . .. brown silt andclayBallston SpaScotch ChurchI-ARC 58-I31 (Schenec-tady County) . . . . . . . . . . .. brown T andgravel. somesilt. trace ofclayBallston SpaScotch Churchl-ARC 58-13] (Schenectady County . . . . . . . . . . . .. brown glacial till

T1-:s-r RESULTS

Materials representing some predominant soil types utilized in highway construction in New York State were selected to obtain a general comparison and evaluation of the two methods. The characteristics of the four soil types

Tentative UK of Test for Density ofSoil in Place by the Ii-D T (DI556-581'), 1958 Book of ASTM Standards,Part 4. D. 1171.

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