A compaction log submitted to a DOT must contain specific data fields or it will be rejected outright. Here is exactly what must appear on every nuclear gauge compaction log, how calibration requirements work, and what state-specific formats look like in Texas, Colorado, and Florida.
What data must appear on a DOT nuclear gauge compaction log?
A DOT compaction log must include: test date, station and offset, lift number, test method (AASHTO T99 or T180), moisture content (%), dry density (pcf), maximum dry density from the proctor test, percent compaction, pass/fail determination, and inspector certification number.
DOT compaction log requirements vary by state but share a common core set of required fields. Missing any of these fields is grounds for log rejection — regardless of whether the compaction results are passing. Test methods are standardized under AASHTO T99 (Standard Proctor) and T180 (Modified Proctor), which define the maximum dry density reference for all compaction compliance calculations.
Nuclear density gauges are radioactive devices subject to federal licensing under the Nuclear Regulatory Commission (NRC) and state radiation control programs. The calibration requirements for compaction testing purposes are layered:
Every nuclear gauge must be calibrated annually by an accredited laboratory or returned to the manufacturer for calibration. The calibration certificate must be on file at the project office and available for inspection at any time. The certificate number must appear on every compaction log submitted using that gauge. A gauge whose annual calibration has lapsed — even by one day — renders all tests recorded with it invalid under most DOT specifications.
Before each day of field testing, the gauge operator must perform a standard block check using the calibration reference block supplied with the gauge. This verifies that the gauge is reading correctly relative to known standards. The daily block check results must be logged. If the daily check shows drift beyond acceptable limits, field testing must stop until the gauge is recalibrated or replaced.
Nuclear gauge operators must hold a current radiation worker certification. This is typically obtained through a one-day training course and is renewed every few years depending on the state. The operator's certification number must appear on the compaction log. Some DOTs require a copy of the operator's certification to be on file at the project office.
While the required data fields are largely the same across states, the required form format varies. Many DOTs require contractor use of specific forms — submitting equivalent data on a non-approved form is grounds for rejection even if all the required data is present.
TxDOT Form 2073 is the Nuclear Density Test Report. It requires the district and county codes in addition to the standard required fields. TxDOT also requires that the field lab report reference the specific proctor test number assigned by the district materials lab — generic proctor references are not accepted. The form must be submitted within 24 hours of testing on federally-funded projects.
CDOT Form 418 is the Nuclear Gauge Density Test Report. Colorado adds a requirement for the gauge depth setting (backscatter or direct transmission mode) to be recorded. CDOT also requires a project engineer signature on the weekly summary, not just the daily test records. Electronic submission is accepted if the form layout matches the official Form 418 exactly.
FDOT Form 675-030-17 is the Density Log for Nuclear Gauge. Florida adds a requirement for the roadway designation (US, SR, I, CR) and the direction of travel (NB, SB, EB, WB) on each test record. FDOT also requires the signed and sealed proctor test report to be attached to the first density log referencing that proctor — not just referenced by number.
Based on DOT materials engineer review patterns, these are the most frequent reasons compaction logs are rejected:
Test recorded at "subgrade" with no station or offset. Inspector cannot locate the test geographically on the project. Entire log page rejected.
Log references Proctor Report #2024-1145 but the test at that station was performed on a different material type than what the proctor represents. Cross-reference fails review.
Annual calibration expired before the test dates on the log. All tests with an expired-cert gauge are invalid and must be retested.
Crossed-out numbers without initials, correction fluid over original entries, or pencil-smudged data that cannot be read clearly. DOTs require single-line strikethrough with initials and date for corrections.
Log shows AASHTO T99 but contract requires AASHTO T180 for base course. Results may pass T99 but would fail T180 — method mismatch means the test cannot be used for compliance.
Digital compaction logging eliminates most of these rejection reasons by enforcing required fields at data entry time. See how Sitemark's road and highway QC platform handles compaction documentation. You can also check percent compaction in real time with the compaction percent calculator.
Sitemark enforces required fields at entry, tracks gauge calibration status, and generates DOT-format compaction logs ready for submission.
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Shop at Express Tools →At minimum: test date, project number, station and offset, lift number, material type, gauge serial number, test method (T99 or T180), moisture content, dry density, maximum dry density from proctor, percent compaction, pass/fail, inspector certification number, and inspector signature. Missing any field is grounds for rejection.
T99 is Standard Proctor (12,375 ft-lb/ft³ compaction energy) and T180 is Modified Proctor (56,250 ft-lb/ft³). T180 produces a higher maximum dry density and is specified for base course and high-traffic applications. The proctor method specified in the contract must match what is recorded on the compaction log — a T99 result cannot be used to meet a T180 specification.
Annual calibration by an accredited lab is required, with the certificate number on every test log. Daily standard block verification checks are also required before field testing. An expired annual calibration invalidates all tests performed with that gauge.