### **SECTION 120 NUCLEAR GAGES**

**120-01** **TESTING.** When the specifications provide for nuclear gage
acceptance testing of material for Items P-152, P-154, P-208, and P-209,
the testing shall be performed in accordance with this section. At each
sampling location, the field density shall be determined in accordance
with ASTM D 2922 using the Direct Transmission Method. The nuclear gage
shall be calibrated in accordance with Annex A1. Calibration and
operation of the gage shall be in accordance with the requirements of
the manufacturer. The operator of the nuclear gage must show evidence of
training and experience in the use of the instrument. The gage shall be
standardized daily in accordance with ASTM D 2922, paragraph 8.

Use of ASTM D 2922 results in a wet unit weight, and when using this
method, ASTM D 3017 shall be used to determine the moisture content of
the material. The moisture gage shall be standardized daily in
accordance with ASTM D 3017, paragraph 7.

The material shall be accepted on a lot basis. Each Lot shall be divided
into eight (8) sublots when ASTM D 2922 is used.

**120-02.** When PWL concepts are incorporated, compaction shall
continue until a PWL of 90 percent or more is achieved using the lower
specification tolerance limits (L) below.

The percentage of material within specification limits (PWL) shall be
determined in accordance with the procedures specified in Section 110 of
the General Provisions.

The lower specification tolerance limit (L) for density shall be:

Specification Item Number Specification Tolerance (L) for Density,
(percent of laboratory maximum)

Item P-152 90.5 for cohesive material, 95.5 for non-cohesive

Item P-154 95.5

Item P-208 97.0

Item P-209 97.0

If the PWL is less than 90 percent, the lot shall be reworked and
recompacted by the Contractor at the Contractor\'s expense. After
reworking and recompaction, the lot shall be resampled and retested.
Retest results for the lot shall be reevaluated for acceptance. This
procedure shall continue until the PWL is 90 percent or greater.

**120-03 VERIFICATION TESTING.** (For Items P-152 and P-154 only.) The
Engineer will verify the maximum laboratory density of material placed
in the field for each lot. A minimum of one test will be made for each
lot of material at the site. The verification process will consist of;
(1) compacting the material and determining the dry density and
moisture-density in accordance with \[ASTM D 698 for aircraft gross
weights less than 60,0000 pounds\] \[ASTM D 1557 for aircraft gross
weights 60,000 pounds or more\], and (2) comparing the result with the
laboratory moisture-density curves for the material being placed. This
verification process is commonly referred to as a \"one-point Proctor\".
If the material does not conform to the existing moisture-density
curves, the Engineer will establish the laboratory maximum density and
optimum moisture content for the material in accordance with \[ASTM D
698 for aircraft gross weights less than 60,0000 pounds\] \[ASTM D 1557
for aircraft gross weights 60,000 pounds or more\].

Additional verification tests will be made, if necessary, to properly
classify all materials placed in the lot.

The percent compaction of each sampling location will be determined by
dividing the field density of each sublot by the laboratory maximum
density for the lot.

**END OF SECTION 120**

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