ATT-11/96, DENSITY, In-Place Nuclear Method

1.0 SCOPE

2.0 EQUIPMENT

3.0 PROCEDURE

3.1 General

3.2 Checkout Procedure

3.2.1 Troxler 3401 Gauge

3.2.1.1 Standards Counts3.2.1.2 Circuitry Check

3.2.2 Campbell Pacific MC-1 Gauge

3.2.2.1 Circuitry Check3.2.2.2 Standard Counts

3.3 Standard Counts Percent Drift

3.4 Site Preparation

3.4.1 Subgrade3.4.2 Cement Stabilized Base Course3.4.3 Granular Base Course3.4.4 Asphalt Concrete Pavement3.4.5 Seating Quality Experiment3.4.6 Direct Transmission Testing

3.5 Moisture and Density Counts

3.5.1 Troxler 3401 Gauge3.5.2 CPN MC-1 Gauge

3.6 Corrected Moisture

3.7 Wet Density

3.8 Dry Density and Moisture Content

3.9 Percent Compaction

3.9.1 Subgrade3.9.2 Granular Base Course3.9.3 Asphalt Concrete Pavement

4.0 HINTS AND PRECAUTIONS

ATT-11 1.0 Scope

ATT-11/96, DENSITY, In-Place Nuclear Method

1.0 SCOPE

This method describes the procedures for using nuclear moisture-density gauges:

a) to determine if the gauge's electronic circuits and detector tubes arefunctioning properly using the circuitry check and standard counts percentdrift, and

b) to operate the gauges in the backscatter and direct transmission modes todetermine the dry density and moisture content.

2.0 EQUIPMENT

nuclear moisture-density gauge: Troxler 3401, or Campbell Pacific MC-1AD/DC charger and timer (for gauges with Nicad batteries)

reference standard radiation placardscalibration tables documentationcarrying case scraper plateoperating instructions 2 locks and keys (for case and handle)log book 2 extra fuses (12 amp DC and 1-0.5 amp AC)1 pressure gauge (for granular base course projects)

Data Sheet: Nuclear Density Test, MAT 6-34, orDaily ACP Nuclear Density Report, MAT 6-6

3.0 PROCEDURE

3.1 General

Prior to using a gauge, ensure the gauge shows a charge. If a low battery charge isindicated, charge the Nicad battery pack overnight. A fully charged battery will last for300 h of normal operation, before needing recharging. Overcharging a Nicad batterywill not cause immediate damage to the power pack but repeated overcharge willultimately reduce the available stored power. Do not charge alkaline batteries. Whenalkaline batteries are discharged, send the gauge to the Laboratory for batteryreplacement.

The following table shows the order in which the basic steps in the operation of anuclear moisture-density gauge are performed. The corresponding ATT-11 sectionnumber per gauge type and model is also summarized.

ATT-11 3.2 Checkout Procedure(Troxler 3401)

Gauge Type and Model Troxler CPN3401 MC-1

ATT-11 Section

Checkout 3.2.1.1 3.2.2.2Procedure Calculate Standard Counts % Drift

Do a Circuitry Check (optional for Troxler 3401) 3.2.1.2 3.2.2.1Take 1 Moisture and 1 Density Standard Count

3.3 3.3

Use ofGauge Calculate Corrected Moisture 3.6 3.6

forTesting Calculate Wet Density 3.7 3.7

Prepare Test Site 3.4 3.4

Take 2 Moisture and 2 Density Readings 3.5.1 3.5.2

Calculate Dry Density and Moisture Content 3.8 3.8

Calculate % Compaction 3.9 3.9

Both gauges measure moisture and density simultaneously.

The nuclear moisture-density gauge must be calibrated at least once a yearand after all major repairs which may affect the instrument geometry. Thegauge calibration is described in ASTM D 2950, Annex and requires the useof calibration blocks of established densities.

3.2 Checkout Procedure

Each day, before taking density or moisture readings on the road, the CheckoutProcedure must be performed to determine if the nuclear moisture-density gauge isfunctioning properly.

The Checkout Procedure comprises of two tests: the "Circuitry Check" and the "DailyStandard Counts Percent Drift". The results of these two tests are recorded in the logbook supplied with the gauge so that a complete record of the gauge's performanceis kept. This record is used to identify and correct electronic and detector problems.

When the gauge is used most of the day, a set of moisture and density standardcounts should be taken in the morning and a second one in the afternoon, to detectany shift during daily use.

ATT-11 3.2.1 Troxler 3401 Gauge

3.2.1 Troxler 3401 Gauge

Figure 1 shows the front panel controls of the 3401 nuclear gauge.

3.2.1.1 Standard Counts

1. Ensure the gauge is charged. If the low battery warning "BAT" is displayed,turn the gauge on until the batteries are totally discharged and then chargethe Nicad batteries overnight.

2. Turn the PWR TIME switch to SLOW, NORM or FAST approximately 20minutes before using the gauge to allow the regulators and detectors tostabilize.

NOTE: If the gauge is turned off between tests, then it is necessary to warmup the electronic circuitry for 20 minutes before the gauge can beused.

3. Ensure the reference standard and gauge bottom are clean.

4. Place the standard on flat, compacted soil, asphalt or concrete, (minimumdensity 1600 kg/m³) at least 3 m from any large object and at least 10 m fromany other nuclear gauge, preferably at the location and on the surface to betested.

5. Seat the gauge into the recessed area of the standard between the raisededges, with the scaler end against the metal plate.

FIGURE 1

ATT-11 3.2.1.2 Circuitry Check(Troxler 3401)

6. Ensure the gauge lock is removed, then place the source index handle in the

safe or stored position.

7. With the handle on the top notch of the index rod, lightly tap the handle downuntil it locks in the safe position.

8. Turn the PWR TIME switch to SLOW after the gauge has been on for 20minutes.

9. Press the START button and the gauge will start counting while displaying ERRand the count. ERR is displayed while counting or to indicate an error.

10. When the reading is complete (4 minutes), turn the DISPLAY switch toDENSITY. Record the displayed reading as Density Standard Count (line "H"),as shown in Figure 2.

11. Turn the DISPLAY switch to MOISTURE and record the displayed readingas Moisture Standard Count (line"A").

12. Proceed with the Standard Counts Percent Drift, Section 3.3.

3.2.1.2 Circuitry Check

The following procedure should only be performed when the daily standard countsmoisture and density percent drift results are out of the specified limits. The circuitrycheck is performed to check the oscillator and time base circuits, prescale circuits, dualaccumulators, multiplexing, decoding and display circuits.

The "circuitry check" is performed with the gauge in the same position used for takingstandard counts. If the gauge has been moved, set up the gauge as directed inSection 3.2.1.1 steps 1 to 7.

1. Remove the four corner screws and lift the front panel cover.

2. Turn the TEST-MEASURE slide switch located on the lower right corner of thecircuit board to TEST.

3. Return the front panel cover to the gauge body and replace the four cornerscrews.

4. Turn the PWR TIME switch to SLOW.

5. Turn the DISPLAY switch to DENSITY.

ATT-11 3.2.1.2 Circuitry Check(Troxler 3401)

6. Press the START button and the gauge will start counting while displaying thecount.

7. When the reading is complete (4 minutes) the gauge should display 8192±2,

8. Turn the DISPLAY switch to MOISTURE. The same reading should bedisplayed.

9. Turn the PWR TIME switch to NORM and press the START button.

10. When the reading is complete (1 minute) the gauge should display 8192±2.

11. Turn the DISPLAY switch to DENSITY and the reading should remainunchanged.

12. Turn the PWR TIME switch to FAST and press the START button.

13. When the reading is complete (15 seconds), the displayed reading should be8192±2,

14. Turn the DISPLAY switch to MOISTURE and the same reading should bedisplayed.

15. Remove the four corner screws and lift the front panel.

16. Turn the TEST-MEASURE slide switch to MEAS (measure).

17. Return the front panel to the gauge body and replace the four corner screws.

18. If the gauge displays 8192±2 for density and moisture for each of the timeperiods, the gauge circuits are functioning properly. In this case, take anotherset of Standard Counts as described in Section 3.2.1.1. If the % drift is still outof the specified limits, contact your main Laboratory and arrange for gaugerepairs or replacement.

19. If the gauge does not display 8192±2 for density or moisture in any of the timeperiods, there is a circuit malfunction. In this case, immediately send thegauge for repairs.

FIGURE 3

ATT-11 3.2.2 Campbell PacificMC 1 Gauge

3.2.2 Campbell Pacific MC-1 Gauge

The CPN MC-1 nuclear moisture-density gauge does not require a warm-up period.The MC-1 is ready for use when a display key is touched.

3.2.2.1 Circuitry Check

The following procedure tests the display and display command system, the digitalcircuitry and the performance of the memories. The circuitry check must be performedeach day before the gauge is used.

1. Ensure the gauge shows a charge. When the alkaline batteries aredischarged, send the gauge to the Laboratory for battery replacement.

2. Ensure the reference standard and the gauge bottom are clean. 3. Stand the shipping case on end with the CPN logo up-right, preferably at the

location and on the surface to be tested, at least 3 m from any large object andat least 10 m from any other nuclear gauge.

4. Place the reference standard across the protective strips on top of the case,

as shown in Figure 3.

5. Place the gauge on thereference standard withthe depressions in thebase of the gauge setdirectly over the threebuttons on the referencestandard.

6. Ensure the gauge lockis removed, then placethe index rod in the

safe or stored position.

7. With the handle in thetop notch of the indexrod, lightly tap the handledown until it locks in thesafe position.

ATT-11 3.2.2.1 Circuitry Check(CPN MC1)

¼ ,½ ,1 or 2 = SIMULTANEOUS COUNT OF BOTH CHANNELS

TEST + ANY DISPLAY = LAMP TEST (88888)TEST + LOCK = INTERNAL CHECK (65536)STD + LOCK = STANDARD COUNT (4 MINUTES)D - ONLY or M - ONLY = ONLY COUNT ONE CHANNELCLEAR = STOP COUNT (does not reset to zero)D - DATA or M - DATA = DISPLAY LAST FIELD COUNTD - STD or M - STD = DISPLAY LAST STD COUNT

FIGURE 4

8. Simultaneously press TEST and one of the display keys, e.g., DENSITY DATAor MOISTURE DATA or D STD or M STD. This is the "LAMP" test. The displayshould read 88888, if the display and display command systems arefunctioning properly.

Figure 4 shows the keyboard layout and description.

9. Press CLEAR. This cancels prior programs and clears out unwantedcommands.

10. Simultaneously press TEST and LOCK. This will erase all four memories andinitiate a ¼ minute count. If the gauge's digital circuitry is functioning properly,the display should be 65536.

ATT-11 3.2.2.2 Standard Counts(CPN MC-1)

11. If the circuitry check is satisfactory, proceed with the Standard Counts, Section3.2.2.2. If the circuitry check is not satisfactory, contact your main Laboratoryimmediately.

3.2.2.2 Standard Counts

Moisture and density standard counts are taken with the gauge in the same positionused for circuitry check at the location and on the surface to be tested. If the gaugehas been moved, set up the gauge as described in Section 3.2.2.1, steps 1 to 7.

1. Simultaneously press STD and LOCK. This will erase all 4 memories andinitiate a four minute count. Density and moisture standard counts are storedin the corresponding memories.

2. At the end of the count, press D STD. Record the displayed reading asDensity Standard Count in line "H" of the data sheet, as shown in Figure 5.

3. Press M STD and record the displayed reading as Moisture Standard Count(line "A").

4. Check the performance of the memories by pressing D STD and M STD andcomparing each displayed reading to the corresponding recorded standardcount. Corresponding counts must be equal.

5. Proceed with the Standard Counts Percent Drift, Section 3.3.

3.3 Standard Counts Percent Drift

1. Use the log book supplied with the gauge to record:

a) The density standard count (from line "H" of the data sheet) on thecolumn "A" of the log book, as shown in Figure 6.

b) The moisture standard count (from line "A" of the data sheet) oncolumn "D" of the log book.

2. Calculate the average of the last four density standard counts (column "A")shown in the four lines immediately above the present entry. Record asAverage of Previous Four Counts in column "B", in the same line as thepresent entry.

e.g. for count no. 10, average count numbers 6 to 9 inclusive and enter theaverage in column "B" in the same line as count no. 10.

ATT-11 3.3 Standard Counts Percent Drift

( B & A )

B

x 100 %

Diff . 'Ave . of Previous 4 Density Std . Counts & Present Density Std . Count

Average of Previous 4 Density Standard Counts

x 100

ATT-11 3.3 Standard CountsPercent Drift (cont'd)

EXAMPLE OF A CPN MC-1 GAUGEHow to complete the Record of Field Daily Standard Counts book.

Date Count No. Standard Previous Four

A B CDensity Average of % Difference

Count Counts

93.09.01 1 13 69993.09.01 2 13 85493.09.01 3 13 78193.09.01 4 13 60893.09.01 5 13 817 13 736 0.5993.09.02 6 13 614 13 765 1.10 * Failed 93.09.02 7 13 799 13 705 0.69 repeated93.09.03 8 13 772 13 710 0.45

GAUGE TRANSFERRED TO PROJECT SH 729 ON 93.09.10

93.10.03 1 13 80293.10.03 2 13 83893.10.03 3 13 78993.10.03 4 13 80693.10.03 5 13 763 13 809 0.3293.10.04 6 13 712 13 799 0.6393.10.05 7 13 637 13 768 0.95

GAUGE TRANSFERRED TO Main LABORATORY ON 93.10.07

NOTE: MOISTURE STANDARD COUNTS ARE COMPLETED IN SAME MANNER USING COLUMNS 'D", "E" & "F"

FIGURE 6

3. Calculate the day-to-day density shift in percent as follows:

Record the result as Density % Difference in column "C".

e.g. subtract count no. 10 from the average of counts 6 to 9, multiply theresult by 100, then divide the result by the average of counts 6 to 9.

4. Calculate the average of the last four moisture standard counts (column "D")shown in the four lines immediately preceeding the present entry. Record asAverage of Previous Four Counts in column "E" in the same line as the presententry.

Diff . 'Average of Previous 4 Moisture Std . Counts & Present Moisture Std . Count

Average of Previous 4 Moisture Standard Counts

x 100

ATT-11 3.3 Standard Counts Percent Drift (Cont'd)

For each project, this step and step no. 6 below are only performed afterstandard count no. 5. Columns "E" and "F" are left blank for the first fourcounts on each job.

5. Calculate the moisture day-to-day shift in percent as follows:

Record the result as Moisture % Difference in column "F".

6. If the % Difference is less than 2% for moisture and 1% for density, proceedwith Site Preparation, Section 3.4. If the % Difference exceeds those limits,proceed with step 7 below.

7. If the % Difference is greater than 2% for moisture or 1% for density, there isa possibility of a gauge malfunction or operator error in placing the gauge onthe standard. Since the radiation statistics may on occasion cause this degreeof shift, a second attempt to acquire useable standard counts is permissible.In this case:

a) Take a second set of moisture and density standard counts, ensuringthe gauge shows a charge and the rod is properly set in the safeposition.

b) Continue with the Standard Counts Percent Drift Section 3.3, steps 1to 5 if the first set was obtained with the gauge properly set up, theprocedure was properly performed and the gauge batteries were notlow in charge. If not, repeat steps 1, 3 and 5 and use the Average ofPrevious Four Counts already calculated in steps 2 and 4. Do notinclude the first set in the average, as they may be the cause ofexcessive variation.

c) If the % Difference is acceptable, proceed with the Site Preparation,Section 3.4. If excessive variation still persists, contact a nucleartesting equipment repair facility.

8. If, over a period of several months, the accumulative shift in standard countsexceeds 6% for moisture or 3% for density, the gauge should be recalibratedon standard calibration blocks.

9. If repetitive readings vary greater than normal radiation statistics, or if suddenlarge variations in data are encountered, contact a nuclear testing equipmentrepair centre immediately.

ATT-11 3.4 Site Preparation

3.4 Site Preparation

Proper site preparation is the most important step in the in-place nuclear density testprocedure. The presence of excess surface voids seriously affects the obtainedvalues. Surface voids must be reduced to a minimum, and the gauge should sit solidlyon the prepared site without rocking. A minimum of amount of native fines should beused to fill surface voids. The use of excess fines does not compensate for poor sitepreparation and gives poor results.

1. Once the test site has been chosen, obtain and record the station, locationand depth below grade or lift of the test side in the heading section of the datasheet corresponding to the vertical column to be used to record the test data.

2. Prepare the test site as directed in either of the following sections, dependingthe type of material on which the test is to be performed.

3.4.1 Subgrade

1. Use a pick and flat nose spade to remove the top 50 mm of soil or until arepresentative moisture condition is reached. The excavated area must beslightly larger than the base of the gauge.

2. Once a representative moisture content is reached, use the guide plate andgarden trowel to level the surface. Avoid tearing out pieces of the soil andcreating voids.

3. Remove all loose stones or soil.

4. Use a flat part of the guide plate to lightly tamp the prepared site. Thisremoves roughness and provides a good base for the gauge.

5. Shake locally obtained "fines" through a 1250 Fm sieve onto the preparedsurface. Ensure the fines are at the same moisture content as the sitesurface.

6. Slide the plate as required to move the fines and fill any visible surface voids.

NOTE: Use the minimum amount of fines. Fines are not to be used as asubstitute for poor site preparation.

7. Place the gauge on the prepared site and test the seating of the gauge. Thegauge must sit solidly on the prepared site, without rocking. Make correctionsif seating is irregular.

ATT-11 3.4.2 Cement Stabilized Base Course

3.4.2 Cement Stabilized Base Course

1. If the mat is a flat, freshly laid sand base cement stabilized base course, verylittle surface preparation is required other than levelling the site.

2. If the mat is rutted, rippled, or uneven, prepare the surface as for subgrade,ensuring all loose stones are removed, the surface voids are filled with - 1250Fm native fines and the gauge sits level.

3.4.3 Granular Base Course

1. Remove dried or loose soil and stones to form a level surface for the gauge.

2. Fill the surface voids with native fines. The native fines should be at the samemoisture content as the site surface.

3. If the topsize of the aggregate is 25 000 Fm or less and the base course layeris thicker than 100 mm, the direct transmission method may be used on thismaterial. However, avoid overly disturbing the aggregate when punching theaccess hole.

3.4.4 Asphalt Concrete Pavement

1. Select test locations away from excessively voided or rough surface areas.

2. If required, fill the surface voids with - 1250 Fm native fines.

3.4.5 Seating Quality Experiment

This experiment is used to determine the effort required to obtain good seating:

1. Before preparing the site, take a backscatter density reading as directed inSection 3.5.1 for Troxler 3401 or Section 3.5.2 for CPN MC-1 gauges.

2. Perform a minimum of surface work, then take another reading.

3. Perform more work, such as clearing, smoothing, etc. and take anotherreading.

4. The readings will drop as the density increases if the gauge is seated betterand better. When readings cease to change, the gauge is properly seated.This is then an index of the work required to obtain good seating.

ATT-11 3.4.6 Direct TransmissionTesting

3.4.6 Direct Transmission Testing

The shutter cavity of some gauges has been plugged up to prevent dirt build up andsubsequent problems in lowering and raising the source rod, and cleaning the shuttercavity.

Testing in the direct transmission mode is not available with some gauges. Consultantsmay use the Direct Transmission method to test subgrade as follows:

1. After the surface measurements have been taken (if required), place the guideplate on the prepared site, ensuring the hole in the plate is at the point wherethe source was placed during the surface measurements.

2. Insert the drill rod through the hole in the guide plate, place one foot on theplate and use the hammer to punch or drill an access hole perpendicular to theprepared test surface.

3. When the hole is at least 50 mm deeper than the direct transmission depth tobe used, remove the rod by pulling straight up. Avoid disturbing the accesshole.

4. In heavy clay, lightly tap or rotate the rod to loosen it as it is being pulledupward, or use a rod jack to retrieve the rod. Make sure the area surroundingthe hole is not disturbed excessively. Do not use the guide plate as aretraction device, as it will damage the top of the guide hole.

5. Position the gauge on the prepared site and align the source rod with the hole.With Troxler gauges, this can easily be accomplished by tilting the gaugeslightly to one side and pushing the index handle down until the source rod isthrough the bottom of the gauge.

6. Align the source rod of CPN MC gauges with the hole as follows:

a) With the left hand hold the gauge by the source rod handle and bringthe gauge closer to the hole.

b) With the body safely above the gauge, brace the right elbow on theright knee and use the right hand to lift the lip located on the front ofthe bottom casting, as shown in Figure 7.

c) Lower the source rod until it is between 50 and 100 mm through thebottom of the gauge.

(d) Let go of the source rod handle and grasp the guide tube above thehandle.

(e) Raise the gauge until the source rod is visibly going into the hole.Peak under the gauge.

FIGURE 7

ATT-11 3.5 Moisture and Density Counts

7. Lower the source rod into the holeby pushing the index handle downto the desired depth. Increments of50.8 mm (2") are clearly marked onthe detent rod at 51, 102, 152 and203 mm (2", 4", 6" and 8").

8. Slide the gauge horizontallytowards the scaler end until thesource rod makes contact with theside of the hole. Ensure the gaugeis seated firmly on the surface tobe tested.

9. Record DT (direct transmission)followed by the depth of the sourcerod in the Mode line (line "G") ofthe data sheet.

10. Proceed to Section 3.5.1 forTroxler3401 gauges or Section 3.5.2 forCPN MC1 gauges.

3.5 Moisture and Density Counts

When the nuclear moisture-density gauge is set to read "moisture", it actually picks offthe hydrogen content of the material. As water and asphalt contain hydrogen, theactual moisture content obtained in any material containing both of those elements isincreased by the percentage of asphalt in it. On the other hand, if the amount of waterin an asphalt mix is negligible, the gauge would pick off the approximate asphaltcontent of the mix when in the "Moisture" mode. In conclusion, the gauge may be usedfor moisture measurements on all construction materials with the exception of asphaltbound soils or aggregate.

When a gauge is set to read density, it actually reads wet density. Only wet densitiesmust be taken on asphalt bound materials because the density of asphalt boundmaterials includes the weight of the asphalt.

Both Troxler 3401 and CPN MC-1 gauges take moisture and density readingssimultaneously. Calculations are performed manually and moisture and density tablesare included with the equipment.

The gauge calibration data is ratioed to standard moisture and density counts madein the field on the reference standard supplied with the gauge. To compensate forcomponent aging and drift within the instrument the gauge calibration is checked oncea year by an approved Laboratory by taking readings on blocks of known density.

ATT-11 3.5.1 Troxler 3401 Gauge

3.5.1 Troxler 3401 Gauge

1. Once a standard count has been taken as directed in Section 3.2.1.1, preparethe test site as directed in Section 3.4.

2. Seat the gauge on the prepared site and lower the index handle to therequired depth. Use the backscatter (BS) notch which is the first detent belowthe safe position or one of the direct transmission modes. Record the modeas BS or DT on line "G". If using DT, also enter the depth of measurement.

3. Set the PWR TIME switch to NORM (1 minute position).

4. Press the START button and the gauge will display ERR and the count. ERRis displayed while counting or to indicate an error.

5. After one minute the gauge will stop counting. Turn the DISPLAY switch toDENSITY and record as Density Display Reading as shown in column 1 ofFigure 2.

6. Turn the DISPLAY switch to MOISTURE and record as Moisture DisplayReading.

7. With the gauge in the same location, take a second moisture and densityreading by repeating steps 4 to 6.

8. Proceed with Section 3.6, Corrected Moisture. If testing asphalt boundaggregates, proceed with Section 3.7, Wet Density.

3.5.2 CPN MC-1 Gauge

The BS position should be used on soils and asphalt concrete, to obtain backscatterdensity counts because the AC position is not as accurate. On Department ownedgauges, the AC position has been blocked off and cannot be used.

1. Once a standard count has been taken as directed in Section 3.2.2.2, preparethe test site as directed in Section 3.4.

2. Seat the gauge firmly on the prepared site.

3. Release the source rod by pulling back on the handle latch pin and pressingdown on the handle.

4. Place the rod in the proper detent. Visually check and ensure that the latchpin is in its full forward location. Record the density mode as "BS" forbackscatter or "DT" for Direct Transmission on line "G". Also enter on line "G"the depth of the direct transmission.

Moisture Count Ratio 'Average Moisture Count

Moisture Standard Count

ATT-11 3.6 Corrected Moisture

5. Press 1 MIN.

6. When the count is completed, press DENSITY DATA. Record as DensityDisplay Reading as shown in column 1 of Figure 5.

7. Press MOISTURE DATA and record as Moisture Display Reading.

8. With the gauge in the same location obtain a second reading, by repeatingsteps 5 to 7.

9. Return the source rod to the safe position.

10. Proceed with Section 3.6, Corrected Moisture. If testing asphalt concretepavement, proceed with Section 3.7, Wet Density.

3.6 Corrected Moisture

1. Calculate the average of the two moisture readings and record as AverageMoisture Display, (line "B").

2. Calculate the Moisture Count Ratio (line "C") as follows:

3. Use the Moisture Calibration Table to determine the Moisture in kg/m³ (line"D"). Make sure that the calibration tables supplied correspond to the serialnumber of the gauge.

4. Record on Line "E" the Moisture Correction Factor in kg/m³ obtained in ATT-48, CORRECTION FACTORS, Nuclear Moisture-Density Measurements.

5. Calculate the Corrected Moisture in kg/m³ (line "F") using the formula:

= Moisture from Tables + Moisture Correction Factor

If the moisture correction factor is negative:

= Moisture from Tables - Moisture Correction Factor

e.g. Moisture from Table = 215 kg/m³Moisture Correction Factor = - 12 kg/m³Corrected Moisture = 215 - 12 = 203 kg/m³

Density Count Ratio 'Average Density Count

Density Standard Count

Moisture Content ( % ) 'Corrected Moisture i n kg / m ³

Dry Density i n kg / m ³

x 100 %

ATT-11 3.7 Wet Density

3.7 Wet Density

1. Calculate the average of the two backscatter or direct transmission densityreadings and record as Average Density Display (line "I").

2. Calculate the Density Count Ratio (line"J") using the formula:

3. Use the proper Density Calibration Table to determine the Wet Density inkg/m³ (line "K").

4. Record on line "L" the Density Correction Factor in kg/m³ obtained in testmethod ATT-48, CORRECTION FACTORS, Nuclear Moisture-DensityMeasurements.

5. Determine the Corrected Wet Density kg/m³ (line "M") as follows:

= Density (from Tables) + Density Correction Factor

If the density correction factor is negative:

= Density (from Tables) - Density Correction Factor

If testing asphalt concrete pavement, proceed with Section 3.9.3.

3.8 Dry Density and Moisture Content

1. Calculate the Dry Density in kg/m³ (line "N") using the formula:

Dry Density (kg/m³) = Corrected Wet Density - Corrected Moisture

2. Calculate the Field Moisture Content in percent (line "Q") using the formula:

When testing asphalt bound aggregates, the Field Moisture Content in percent(line "Q") is the approximate mix asphalt content. This is because theCorrected Moisture (line "F"), represents the weight of asphalt and a negligibleamount of moisture per cubic metre of mix and the dry Density (line "N")represents the weight of dry aggregate per cubic metre of mix.

ATT-11 3.9 Percent Compaction

3.9 Percent Compaction

3.9.1 Subgrade

To determine the actual degree of compaction of a soil in which a nuclear densitygauge was used to establish the dry density, the following rock correction must beperformed.

1. Use a garden trowel to excavate the soil located at the test site from the sourcerod hole to where the detector tube sat, to the depth that the source rod waslowered.

2. Identify the soil as directed in ATT-29, SOILS IDENTIFICATION, Hand Method.

3. In the Remarks section of the form on the numbered line corresponding to thevertical test column number being used, record the following:

a) the tests of the hand method test,

b) a description of the soil in common terms, e.g., dark brown sandy claywith some small white pebbles,

c) a description of the origin of the soil, e.g., common excavation atstation 21+090.

d) any evidence of stratification of any kind, e.g., moisture content, soiltype, or density, and

e) any problems encountered in the test, e.g., equipment problems, rocksin hole, etc.

4. In the Visual Description section of the form, on the numbered linecorresponding to the vertical test column number, enter the following:

a) The unified soil classification on the Material Type line, based on theHand Method test results, e.g. CL.

b) Estimate the moisture content of the in-place soil and express it as arelationship between actual moisture content and estimated optimummoisture content based on the plastic limit test, e.g., 1% wet, 2% dry,etc. Enter the results on the Estimated Moisture Content line.

c) Estimate the percent compaction of the in-place soil and record thevalue on the Estimated Percent Compaction line, knowing the relativemoisture content of the soil.

5. Establish the percent of rock in the density zone as follows:

% % 20 000 F m 'Wt . % 20 000 F m Rock

Wt . of Collected Soil

x 100 %

ATT-11 3.9.1 Subgrade% Compaction

a) Weigh the collected soil (minimum 7000 g) and record the weight.

b) Separate the +20 000 Fm rock from the soil.

c) Weigh the +20 000 Fm rock and record the weight.

d) Perform a moisture content test on the - 20 000 Fm material. Recordas Field Moisture Content (line "Q").

e) Calculate the percent of +20 000 Fm rock using the formula:

f) If there is more than 30% of the +20 000 Fm material, disregard thedensity test results. If there is less than 10% of the +20 000 Fmmaterial, a rock correction is not necessary.

6. Use test method ATT-20, MOISTURE DENSITY RELATION, One Point toestablish the maximum dry density and optimum moisture content (line "P") ofthe -20 000 Fm soil. If rock correction is not required, record the maximum drydensity on Line "S" of the data sheet.

7. Subtract the optimum moisture content (line "P") of the one point moisture-density relation test from the field moisture content (line "Q") determined instep 5 (d). Record as ± Moisture Difference from Optimum (line "R") .

8. If the amount of +20 000 Fm is greater than 10% and less than 30%, adjust themaximum dry density established in test method ATT-20 as follows:

MAXIMUM DENSITY CORRECTED FOR ROCK 3 AGG. ADJUSTMENT

A % +20 000 Fm _____ % +20 000 Adjustment

B % -20 000 Fm (100 - A) _____ 10 - 20 1.00

C Density of +20 000 Fm g/cm³ 2.600 21 - 25 0.99

D +20 000 Fm Ratio (A / 2.6 3) _____ 26 - 30 0.98

E Max. Dry Density of -20 000 Fm _____

F -20 000 Fm Ratio (1000 B/ E) _____

G Correction Factor (D + F) _____

H Corrected Max. Dry Density (100 000 / G) kg/m³ _____

Transfer the Corrected Maximum Density (line "H", above) to line "S" of thedata sheet.

'Road Dry Density ( l ine

))N

)))

Maximum Dry Density ( l ine))

S))

)

x 100 %

ATT-11 3.9.2 GBC and ASBC% Compaction

9. Calculate percent compaction (line "T") as follows:

Use the corrected maximum dry density (line "H" of the table shown in theprevious page), if the value was calculated.

3.9.2 Granular and Asphalt Stablized Base Courses

Refer to ATT-58, DENSITY, GBC, Control Strip Method for further testing of granularbase course materials.

ATT-66, DENSITY, ASBC, Control Strip Method, describes the procedure for testingasphalt stabilized base courses.

3.9.3 Asphalt Concrete Pavement - Quality Control Testing

If cores are not being obtained, nuclear wet densities may be used for quality controlof ACP contracts. This procedure must be followed to satisfy the Specifications' QualityControl Testing Requirements. If this procedure is not followed, cause for an appealmay not be allowed.

The percent compaction obtained using this procedure may be allowed as "Cause foran Appeal" of quality assurance test results if, prior to an appeal, the contractorsubmits to the Project Manager the following documentation:

1. A copy of the most recent calibration data using calibration blocks (as outlinedin Section 3.2), the date of the calibration and the name of the company whichperformed the calibration.

2. A copy of the log book showing the field daily standard counts percent drift.

3. A copy of the applicable density correction factor data (as outlined in ATT-48).

A copy of each Stratified Random Test Sites data sheet (MAT 6-82) completed for thelot must be submitted with the appeal request.

A copy of each density correction factor performed for the project must be submittedto the Project Manager as obtained.

When quality control and quality assurance percent compaction differ and an appealis being considered, the contractor may be required to confirm the nuclear densitydata with core densities before the appeal process is allowed.

ATT-11 3.9.3 ACP % Compaction

When taking moisture readings, nuclear moisture-density gauges pick off the hydrogencontent of materials and do not differentiate between the hydrogen in water or asphalt.

Therefore, when a nuclear gauge is used to test asphalt concrete pavements, only thewet density must be determined and used as the site dry density. However, thepavement surface must be dry at the time of testing. Also no tests should be takenwithin 24 hours of rain fall, as surface and absorbed water affect the reading.

3.9.3.1 Quality Control Nuclear Densities on ACP

Each segment is divided into three areas or Sub-Segments. A nuclear backscatter wetdensity is taken for each Sub-Segment at a random station and a random location, asdirected in ATT-56, Part II.

The lift thickness and the surface texture of each density site must be similar to thatof the test sites used to establish the correction factor determined in ATT-48.

The average corrected segment nuclear backscatter wet density may then be used toreplace the segment core dry density. The procedure is as follows:

1. Use form MAT 6-82, Stratified Random Test Sites and test method ATT-56, Part II, to calculate the station line "H" and location (line "K") ofeach of the three sub-segment test sites.

2. Transfer to form MAT 6-6, Daily ACP Nuclear Density Report, the calculatedstations (column "A") and locations (column "B") as shown in Figure 8.

3. Take a Density Standard Count at the road as directed in Section 3.2.1.1 forTroxler 3401 gauges and Section 3.2.2.1 for CPN MC-1 gauges. Record thecount in line "E".

4. For each test site of each segment:

a) Prepare the site by filling the surface voids with a minimum amount ofnative fines.

b) Take two backscatter density readings on each site as directed inSection 3.5.1 for Troxler 3401 gauges or Section 3.5.2 for CPN MC-1gauges. Record as Reading (line "C").

5. For each segment, calculate the average of the six backscatter densityreadings and record as Average Reading (line "D").

If the gauge gives direct readout, transfer the result to line "I" and proceed tostep 8.

Density Count Ratio 'Average Backscatter Density Reading ( l ine

))D

)))

Density Standard Count ( l ine))

E))

)

ATT-11 3.9.3 ACP % Compaction(cont'd)

FIGURE 8

6. Calculate the segment backscatter Density Count Ratio (line "H") using theformula:

7. Use the backscatter density Calibration Table to determine the segment'sNuclear Wet Density in kg/m³ (line "I").

8. Plot the segment's nuclear wet density on the vertical axis of the ACP DensityCorrection Factor Graph (ATT-48), as shown in Figure 9.

9. Proceed horizontally to where it intercepts the curve.

10. Proceed vertically and pick off the horizontal axis the corresponding core drydensity. Record as the segment's Corrected Nuclear Wet Density (line "J").

'Corrected Nuclear Backscatter Wet Density

Lot Average Marshall Dry Density

x 100 %

'Lot Average Corrected Nuclear Wet Density

Q . A . Lot Average Marshall Dry Density

x 100 %

ATT-11 3.9.3 ACP % Compaction(cont'd)

FIGURE 9

11. Repeat steps 6 to 10 for the remaining four segments.

12. Record in line "G" the Lot Average Marshall Dry Density as established by theQuality Assurance testing program.

13. Calculate the Segment Percent Compaction (line "K") using the formula:

14.Calculate the Lot Average Corrected Nuclear Wet Density (line"L") byaveraging the segment densities (line "J").

15. Calculate the Lot Average Percent Compaction (line "M") as follows:

ATT-11 4.0 Hints and Precautions

4.0 HINTS AND PRECAUTIONS

1. Operators must be trained in the safety, operation and proper care of nuclearmoisture-density gauges. The training requirements are outlined under theAtomic Energy Control Board licensing requirements.

2. Correction factors (ATT-48) must be determined and used for each significantconstruction material to be tested.

3. Poor site preparation will affect all density and moisture measurements,especially counts obtained using the Backscatter operating mode, as this isstrongly influenced by surface density.

4. Any material of non-representative moisture such as a chunk of mud or drycrust must be removed before starting the test, because it will affect moisturemeasurements.

5. Ensure that the index handle is locked securely in the proper depth detentbefore taking the measurements. Push the handle down to the desired depththen pull upwards slightly and push down until a definite click is heard.Improper positioning of the rod will give incorrect readings and erroneousdecisions may be made based on these results.

6. When using the direct transmission method, be certain that the depth selectedfor the test does not exceed the thickness of the lift on which the density isdesired.

7. Where maximum accuracy is not required, take ½ or ¼ minute readings tospeed up the test procedure; for example, take ¼ minute readings for rollingpattern measurements on hot asphalt test strips.

8. The gauge can be placed on a hot asphalt pavement. Surface temperaturesare generally low enough for the nuclear gauge not to experience excessivetemperature rise. Do not leave the gauge on a hot mat for a long period oftime. If the gauge becomes uncomfortably hot to the bare hand, allow a coolingperiod between readings.