WSDOT Errata to FOP for AASHTO T 310

In-Place Density and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods
(Shallow Depth)

WAQTC FOP for AASHTO T 310 has been adopted by WSDOT with the following changes:

Procedure

Replace step 1 with below:

1. WSDOT requires test location selected per WSDOT SOP 615.

6. Place the gauge on the prepared surface so the source rod can enter the hole without
disturbing loose material.

Include note below:

Note: For alignment purposes, the user may expose the source rod for a maximum of ten
seconds.

10. Perform one of the following methods, per agency requirements:

a. Method A Single Direction: - Method not recognized by WSDOT.

11. Step not required by WSDOT.

12. Step not required by WSDOT.

Replace step 13 with below:

13. Determine the dry density by one of the following:

a. If the moisture content is determined by nuclear methods, use gauge dry density
readings directly.
b. If moisture content is determined by FOP for AASHTO T 255/T 265, compute dry
density by dividing the wet density from the nuclear gauge by 1 + moisture content
expressed as a decimal.

Percent Compaction

Determined using WSDOT SOP 615.

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IN-PLACE DENSITY WAQTC FOP AASHTO T 310 (20)

IN-PLACE DENSITY AND MOISTURE CONTENT OF SOIL AND SOIL-

AGGREGATE BY NUCLEAR METHODS (SHALLOW DEPTH)
FOP FOR AASHTO T 310

Scope
This procedure covers the determination of density, moisture content, and relative
compaction of soil, aggregate, and soil-aggregate mixes in accordance with AASHTO
T 310-19. This field operating procedure is derived from AASHTO T 310. The nuclear
moisture-density gauge is used in the direct transmission mode.

Apparatus
• Nuclear density gauge with the factory matched standard reference block.
• Drive pin, guide/scraper plate, and hammer for testing in direct transmission mode.
• Transport case for properly shipping and housing the gauge and tools.
• Instruction manual for the specific make and model of gauge.
• Radioactive materials information and calibration packet containing:
− Daily Standard Count Log.
− Factory and Laboratory Calibration Data Sheet.
− Leak Test Certificate.
− Shippers Declaration for Dangerous Goods.
− Procedure Memo for Storing, Transporting and Handling Nuclear Testing
Equipment.
− Other radioactive materials documentation as required by local regulatory
requirements.
• Sealable containers and utensils for moisture content determinations.

Radiation Safety
This method does not purport to address all of the safety problems associated with its use.
This test method involves potentially hazardous materials. The gauge utilizes radioactive
materials that may be hazardous to the health of the user unless proper precautions are taken.
Users of this gauge must become familiar with the applicable safety procedures and
governmental regulations. All operators will be trained in radiation safety prior to operating
nuclear density gauges. Some agencies require the use of personal monitoring devices such
as a thermoluminescent dosimeter or film badge. Effective instructions together with routine
safety procedures such as source leak tests, recording and evaluation of personal monitoring
device data, etc., are a recommended part of the operation and storage of this gauge.

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IN-PLACE DENSITY WAQTC FOP AASHTO T 310 (20)

Calibration
Calibrate the nuclear gauge as required by the agency. This calibration may be performed by
the agency using manufacturer’s recommended procedures or by other facilities approved by
the agency. Verify or re-establish calibration curves, tables, or equivalent coefficients every
12 months.

Standardization
1. Turn the gauge on and allow it to stabilize (approximately 10 to 20 minutes) prior to
standardization. Leave the power on during the day’s testing.
2. Standardize the nuclear gauge at the construction site at the start of each day’s work
and as often as deemed necessary by the operator or agency. Daily variations in
standard count shall not exceed the daily variations established by the manufacturer
of the gauge. If the daily variations are exceeded after repeating the standardization
procedure, the gauge should be repaired and/or recalibrated.
3. Record the standard count for both density and moisture in the Daily Standard Count
Log. The exact procedure for standard count is listed in the manufacturer’s
Operator’s Manual.
Note 1: New standard counts may be necessary more than once a day. See agency requirements.

Overview
There are two methods for determining in-place density of soil / soil aggregate mixtures. See
agency requirements for method selection.
• Method A Single Direction
• Method B Two Direction

Procedure
1. Select a test location(s) randomly and in accordance with agency requirements. Test
sites should be relatively smooth and flat and meet the following conditions:
a. At least 10 m (30 ft) away from other sources of radioactivity
b. At least 3 m (10 ft) away from large objects
c. The test site should be at least 150 mm (6 in.) away from any vertical projection,
unless the gauge is corrected for trench wall effect.
2. Remove all loose and disturbed material and remove additional material as necessary
to expose the top of the material to be tested.
3. Prepare a flat area sufficient in size to accommodate the gauge. Plane the area to a
smooth condition so as to obtain maximum contact between the gauge and the
material being tested. For Method B, the flat area must be sufficient to permit
rotating the gauge 90 or 180 degrees about the source rod.

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4. Fill in surface voids beneath the gauge with fines of the material being tested passing
the 4.75 mm (No. 4) sieve or finer. Smooth the surface with the guide plate or other
suitable tool. The depth of the filler should not exceed approximately 3 mm (1/8 in.).
5. Make a hole perpendicular to the prepared surface using the guide plate and drive pin.
The hole shall be at least 50 mm (2 in.) deeper than the desired source rod depth and
shall be aligned such that insertion of the source rod will not cause the gauge to tilt
from the plane of the prepared area. Remove the drive pin by pulling straight up and
twisting the extraction tool.
6. Place the gauge on the prepared surface so the source rod can enter the hole without
disturbing loose material.
7. Lower the source rod into the hole to the desired test depth using the handle and
trigger mechanism.
8. Seat the gauge firmly by partially rotating it back and forth about the source rod.
Ensure the gauge is seated flush against the surface by pressing down on the gauge
corners and making sure that the gauge does not rock.
9. Pull gently on the gauge to bring the side of the source rod nearest to the
scaler / detector firmly against the side of the hole.
10. Perform one of the following methods, per agency requirements:
a. Method A Single Direction: Take a test consisting of the average of two, one-
minute readings, and record both density and moisture data. The two wet
density readings should be within 32 kg/m3 (2.0 lb/ft3) of each other. The
average of the two wet densities and moisture contents will be used to
compute dry density.
b. Method B Two Direction: Take a one-minute reading and record both density
and moisture data. Rotate the gauge 90 or 180 degrees, pivoting it around the
source rod. Reseat the gauge by pulling gently on the gauge to bring the side
of the source rod nearest to the scaler/detector firmly against the side of the
hole and take a one-minute reading. (In trench locations, rotate the gauge
180 degrees for the second test.) Some agencies require multiple one-minute
readings in both directions. Analyze the density and moisture data. A valid
test consists of wet density readings in both gauge positions that are within
50 kg/m3 (3.0 lb/ft3). If the tests do not agree within this limit, move to a new
location. The average of the wet density and moisture contents will be used to
compute dry density.
11. If required by the agency, obtain a representative sample of the material, 4 kg (9 lb)
minimum, from directly beneath the gauge full depth of material tested. This sample
will be used to verify moisture content and / or identify the correct density standard.
Immediately seal the material to prevent loss of moisture.
The material tested by direct transmission can be approximated by a cylinder of soil
approximately 300 mm (12 in.) in diameter directly beneath the centerline of the
radioactive source and detector. The height of the cylinder will be approximately the

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IN-PLACE DENSITY WAQTC FOP AASHTO T 310 (20)

depth of measurement. When organic material or large aggregate is removed during

this operation, disregard the test information, and move to a new test site.
12. To verify the moisture content from the nuclear gauge, determine the moisture
content with a representative portion of the material using the FOP for AASHTO
T 255/T 265 or other agency approved methods. If the moisture content from the
nuclear gauge is within ±1 percent, the nuclear gauge readings can be accepted.
Moisture content verification is gauge and material specific. Retain the remainder of
the sample at its original moisture content for a one-point compaction test under the
FOP for AASHTO T 272, or for gradation, if required.
Note 2: Example: A gauge reading of 16.8 percent moisture and an oven dry of 17.7 percent are within
the ±1 percent requirement. Moisture correlation curves will be developed according to agency
guidelines. These curves should be reviewed and possibly redeveloped every 90 days.
13. Determine the dry density by one of the following.
a. From nuclear gauge readings, compute by subtracting the mass (weight) of the
water (kg/m3 or lb/ft3) from the wet density (kg/m3 or lb/ft3) or compute using
the percent moisture by dividing wet density from the nuclear gauge by
1 plus the moisture content expressed as a decimal.
b. When verification is required and the nuclear gauge readings cannot be
accepted, the moisture content is determined by the FOP for AASHTO
T 255/T 265 or other agency approved methods. Compute dry density by
dividing wet density from the nuclear gauge by 1 plus the moisture content
expressed as a decimal.

Percent Compaction
• Percent compaction is determined by comparing the in-place dry density as determined
by this procedure to the appropriate agency density standard. For soil or soil-aggregate
mixes, these are moisture-density curves developed using the FOP for AASHTO
T 99/T 180. When using maximum dry densities from the FOP for AASHTO T 99/T 180
or FOP for AASHTO T 272, it may be necessary to use the Annex in the FOP for
T 99/T 180 to determine corrected maximum dry density and optimum moisture content.
For coarse granular materials, the density standard may be density-gradation curves
developed using a vibratory method such as AKDOT&PF’s ATM 212, ITD’s T 74,
WSDOT’s TM 606, or WFLHD’s Humphres.
See appropriate agency policies for use of density standards.

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Calculation

Calculate the dry density as follows:

𝜌𝜌𝜌𝜌𝑤𝑤𝑤𝑤 𝜌𝜌𝜌𝜌𝑤𝑤𝑤𝑤
𝜌𝜌𝜌𝜌𝑑𝑑𝑑𝑑 = � � × 100 𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 𝜌𝜌𝜌𝜌𝑑𝑑𝑑𝑑 = 𝑤𝑤𝑤𝑤
𝑤𝑤𝑤𝑤 + 100 +1
100
Where:
ρd = Dry density, kg/m3 (lb/ft3)
ρw = Wet density, kg/m3 (lb/ft3)
w = Moisture content from the FOP’s for AASHTO T 255 / T 265, as a
percentage

Calculate percent compaction as follows:

𝜌𝜌𝜌𝜌𝑑𝑑𝑑𝑑
% 𝐶𝐶𝐶𝐶𝑜𝑜𝑜𝑜𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑜𝑜𝑜𝑜𝐶𝐶𝐶𝐶 = × 100
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐴𝐴𝐴𝐴 𝑑𝑑𝑑𝑑𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑑𝑑𝑑𝑑𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑

Where:
ρd = Dry density, kg/m3 (lb/ft3)
Agency density standard = Corrected maximum dry density
from the FOP from T 99/T 180 Annex

Example:

Wet density readings from gauge: 1948 kg/m3 (121.6 lb/ft3)

1977 kg/m3 (123.4 lb/ft3)
Avg: 1963 kg/m3 (122.5 lb/ft3)

Moisture readings from gauge: 14.2% and 15.4% = Avg 14.8%

Moisture content from the FOP’s for AASHTO T 255/ T 265: 15.9%

Moisture content is greater than 1 percent different so the gauge moisture cannot be used.

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Calculate the dry density as follows:

1963 𝑘𝑘𝑘𝑘𝐴𝐴𝐴𝐴⁄𝐶𝐶𝐶𝐶3 𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 122.5 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙⁄𝑓𝑓𝑓𝑓𝐶𝐶𝐶𝐶 3 1963 𝑘𝑘𝑘𝑘𝐴𝐴𝐴𝐴⁄𝐶𝐶𝐶𝐶3 𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 122.5 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙⁄𝑓𝑓𝑓𝑓𝐶𝐶𝐶𝐶 3
𝜌𝜌𝜌𝜌𝑑𝑑𝑑𝑑 = � � × 100 𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 𝜌𝜌𝜌𝜌𝑑𝑑𝑑𝑑 =
15.9 + 100 15.9
+1
100
= 1694 𝑘𝑘𝑘𝑘𝐴𝐴𝐴𝐴⁄𝐶𝐶𝐶𝐶3 𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 105.7 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙⁄𝑓𝑓𝑓𝑓𝐶𝐶𝐶𝐶 3

Given:
ρw = 1963 kg/m3 or 122.5 lb/ft3
w = 15.9%

Calculate percent compaction as follows:

105.7 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙/𝑓𝑓𝑓𝑓𝐶𝐶𝐶𝐶 3
% 𝐶𝐶𝐶𝐶𝑜𝑜𝑜𝑜𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑜𝑜𝑜𝑜𝐶𝐶𝐶𝐶 = × 100 = 95%
111.3 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙/𝑓𝑓𝑓𝑓𝐶𝐶𝐶𝐶 3

Given:

Agency density standard = 111.3 lb/ft3

Report
• On forms approved by the agency
• Sample ID
• Location of test, elevation of surface, and thickness of layer tested
• Visual description of material tested
• Make, model and serial number of the nuclear moisture-density gauge
• Wet density to the nearest 0.1 lb/ft3
• Moisture content as a percent, by mass, of dry soil mass to the nearest 0.1 percent
• Dry density to the nearest 0.1 lb/ft3
• Density standard to the nearest 0.1 lb/ft3
• Percent compaction the nearest 1 percent
• Name and signature of operator

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PERFORMANCE EXAM CHECKLIST

IN-PLACE DENSITY AND MOISTURE CONTENT OF SOIL AND SOIL-

AGGREGATE BY NUCLEAR METHODS (SHALLOW DEPTH)
FOP FOR AASHTO T 310

Participant Name ______________________________ Exam Date ______________

Record the symbols “P” for passing or “F” for failing on each step of the checklist.

Procedure Element Trial 1 Trial 2

1. Gauge turned on 10 to 20 minutes before use? _____ _____
2. Calibration verified? _____ _____
3. Standard count taken and recorded in accordance with
manufacturer’s instructions? _____ _____
4. Test location selected appropriately 10 m (30 ft.) from other
radioactive sources, 3 m (10 ft.) from large objects, 150 mm (6 in.) away
from vertical projections? _____ _____
5. Loose, disturbed material removed? _____ _____
6. Flat, smooth area prepared? _____ _____
7. Surface voids filled with native fines (-No. 4) to 3 mm (1/8 in.) maximum
thickness? _____ _____
8. Hole driven 50 mm (2 in.) deeper than source rod depth? _____ _____
9. Gauge placed and source rod lowered without disturbing loose material? _____ _____
10. Method A:
a. Gauge firmly seated, and gently pulled back so that the source rod is against
the side of the hole toward the scaler / detectors? _____ _____
b. Two, one-minute reading taken; wet density within
32 kg/m3 (2.0 lb/ft3)? _____ _____
c. Density and moisture data averaged? _____ _____
11. Method B:
a. Gauge firmly seated, and gently pulled back so that the source rod is against
the side of the hole toward the scaler / detectors? _____ _____
b. A minimum of a one-minute reading taken; density and moisture
data recorded? _____ _____
c. Gauge turned 90° or 180° (180° in trench)? _____ _____

OVER

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Procedure Element Trial 1 Trial 2

d. Gauge firmly seated, and gently pulled back so that the source rod is against
the side of the hole toward the scaler / detectors? _____ _____
e. A minimum of a one-minute reading taken; density and moisture
data recorded? _____ _____
f. Wet densities within 50 kg/m3 (3.0 lb/ft3 )? _____ _____
g. Density and moisture data averaged? _____ _____
12. Representative sample (4 kg or 9 lb) obtained from test location? _____ _____
13. Sample sealed immediately to prevent moisture loss? _____ _____
14. Moisture content correctly determined using other means than the nuclear
density gauge reading? _____ _____
15. Dry Density calculated using proper moisture content? _____ _____
16. Percent compaction calculated correctly? _____ _____

Comments: First attempt: Pass Fail Second attempt: Pass Fail

Examiner Signature _______________________________WAQTC #:_______________

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