A failed compaction lift triggers a stop-work order. Rework, re-test, and re-inspection costs average $8,500+ per event — and that does not include schedule impact to follow-on crews. Sitemark logs nuclear gauge compaction tests lift-by-lift, station-by-station, and generates DOT-formatted QC records that pass first review.
State DOT quality control plans for road construction are governed by AASHTO standards and enforced through project specifications. Every federally funded road project requires a written QC plan submitted and approved before construction begins. The QC plan specifies compaction methods, testing frequency, acceptance criteria, corrective action procedures, and documentation requirements — all of which the contractor must follow and document on every lift.
The foundational compaction standards are AASHTO T99 (Standard Proctor) and AASHTO T180 (Modified Proctor). Road subgrade typically requires 95% of Standard Proctor maximum dry density (T99). Base course requires 98% of Modified Proctor (T180). Subbase may be specified at either 95% T99 or 95% T180 depending on the DOT. Using the wrong reference standard — T99 results when T180 is specified — is a common documentation error that results in a passing record on a failing lift.
Per AASHTO QC plan requirements, each compaction test record must capture: date and time of the test, station and offset of the test location, lift number and material type, test method (T99 or T180), nuclear gauge serial number and calibration date, field moisture content, field wet density, dry density, maximum dry density from the Proctor test, percent compaction, pass/fail status, and the technician name and certification number.
Testing frequency requirements vary by state and project type. Typical minimums: one test per 500 cubic yards of fill, one test per lift per 200 linear feet of road subgrade, or one test per 2,500 square feet of fill area. DOT inspectors may request additional tests at any location — the QC plan must include a provision for this. Records must be retained for the duration of the project and submitted at closeout. Many state DOTs now require digital submittal through their project management portals.
Lift thickness documentation is a parallel requirement. Most state DOTs specify maximum loose lift thickness of 6–8 inches for fine-grained soils and up to 12 inches for granular material. The QC record must confirm that specified lift thickness was not exceeded. Lifts that are too thick cannot achieve adequate compaction at depth regardless of surface test results — a failure mode that leads to premature pavement distress and warranty claims.
On a well-run road project, compaction documentation is an active process, not a closeout task. The QC technician follows the compaction roller and takes nuclear gauge tests at each required interval as the material is placed. This means tests happen while the crew is still on site and corrections — more passes, moisture adjustment — can happen before the next lift goes down.
The sequence starts at subgrade. After the subgrade is graded to plan elevation and compacted, the QC technician takes tests at the specified frequency by station. If all tests pass, the inspector signs off on subgrade and base course placement begins. The subgrade record is locked and archived. Base course goes down in specified lift thicknesses, gets compacted, gets tested. Each lift is its own discrete record set. When all base course lifts pass, paving begins.
The critical documentation discipline is never advancing a lift before the previous lift is documented and passes. On paper-based systems, this discipline breaks down constantly — crews place the next lift before the test records are even written up, tests fail after the fact, and the project has a documentation gap that cannot be retroactively resolved. Digital logging at the point of test prevents this: the test result is recorded immediately, pass/fail is calculated automatically, and no lift advancement can occur without a record.
When a test fails, the corrective action process must also be documented. The QC record for a failed test must include: the failure date, time, and location; the identified failure cause; the corrective action taken (additional passes, moisture adjustment, lift removal); the re-test date, time, and result; and the technician signature on both the failed and the passing record. DOT inspectors reviewing the record at closeout look specifically for this chain — a passing test without a preceding failed test is not a concern, but a gap in the record where a known failure was not followed by documented re-test is grounds for rejection.
Station-based documentation — recording tests at 0+00, 0+50, 1+00 station format — ties every compaction record to a specific physical location on the roadway. This matters for closeout because DOT reviewers will spot-check records against their own field observations. A compaction test at station 14+75 that shows 98.2% compaction on base course must be locatable in the field and must correspond to the actual lift that is now buried under pavement.
Sitemark's compaction test logger is built around the data requirements of DOT QC plans. The field interface prompts for every required field in sequence: station, offset, lift number, material type, test method (T99/T180), moisture content, wet density, and gauge info. Dry density and compaction percentage are calculated automatically. Pass/fail appears immediately based on the project's specified compaction requirement.
Each test is linked to the job and lift, creating a sortable, filterable record set. The project dashboard shows compaction coverage along the route — which stations have been tested, which have passing records, and which have open failures awaiting re-test. QC managers can see the coverage map in real time from the office while the crew works in the field.
Failed tests stay in the record and are linked to their re-tests. The corrective action field captures what was done between the failed test and the re-test. This complete chain — failure, correction, passing re-test — is exactly what DOT reviewers look for. No record can be deleted; only annotated. The audit trail is permanent.
At project closeout, Sitemark generates a DOT-formatted QC summary report that includes: a compaction test log table sorted by date/station/lift, a pass/fail summary by lift, a station coverage map showing test locations, the Proctor test reference data, gauge calibration records, and the QC manager's signature block. This is the document format DOT closeout reviewers recognize and accept. Many state DOTs now allow digital submittal — Sitemark exports to PDF and CSV for portal upload.
Grade verification runs alongside compaction in the same job. Sitemark's shot logger captures station-based grade shots, compares actual to design grade, and flags out-of-tolerance locations. The grade verification report and the compaction QC report are generated together — a single closeout package covering both documentation requirements.
Compaction test records missing at required intervals — especially around bridge approaches, drainage structures, and utility crossings. Sitemark's coverage tracker shows exactly which stations need tests.
Using T99 max dry density when T180 is specified results in a passing record on a failing lift. Sitemark locks the Proctor reference to the specification at job setup.
A failed test without a documented corrective action and passing re-test is an open finding that blocks acceptance. Sitemark flags open failures and requires re-test linkage before closure.
Nuclear gauge calibration must be current (typically within 12 months) and the calibration date must appear in every test record. Sitemark's equipment registry tracks calibration dates and alerts before expiry.
Placing material thicker than the specified maximum loose lift and compacting to surface spec leaves under-compacted material at depth. Document and comply with lift thickness at placement.
Nuclear gauge operators must be certified. The technician's certification number must appear in the compaction test record. Sitemark captures this at the user level, auto-populating it on every test.
DOT QC plans require: test date/time, station and offset, lift number and material, test method (T99 or T180), gauge serial number and calibration date, moisture content, wet density, dry density, Proctor maximum dry density, percent compaction, pass/fail, and the technician's name and certification number. Sitemark captures all of these fields and generates the formatted report.
A failed test triggers stop-work on the affected station range. The contractor identifies the failure cause, takes corrective action (add moisture, additional passes, remove and replace material), re-compacts, and re-tests. Both the failed test and the passing re-test — with corrective action documented — must be in the QC record. Missing the corrective action chain blocks project closeout.
AASHTO T99 (Standard Proctor) uses lower compaction energy and is specified for subgrade — typically 95% T99 minimum. AASHTO T180 (Modified Proctor) uses 4.5x more energy and is specified for base course — typically 98% T180 minimum. Using T99 results when T180 is specified will show passing when the material may actually be failing. Always verify which standard your DOT specification references.
Typical DOT tolerances: subgrade ±0.05 ft from design grade; base course ±0.03 ft; paving ±0.02 ft. Tolerances vary by state DOT and project type. Sitemark flags every grade shot outside tolerance in the as-built report so out-of-tolerance locations are addressed before the inspector's review.
Yes. Sitemark's compaction test logger and shot logger are both available in the same job. Log your station-based grade shots, then add nuclear gauge compaction tests at the same stations. Both data sets are linked to the same job and lift, and included in the final QC submittal package.
Sitemark captures lift-by-lift compaction data in the field and generates DOT-formatted QC records that hold up at closeout review — no paper, no gaps, no surprises.