| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. SAMPLE DETAILS & CLASSIFICATION | |||
| A1 | Sample ID assigned — unique identifier for traceability (e.g., S-01, S-02, etc.) Acceptance: Sample ID marked on all specimen containers and test records; ID consistent across all phases of testing | Mandatory | |
| A2 | Sampling location documented — exact site location with coordinates or reference; boring/pit ID if from investigation Acceptance: Location description clear; enables sample traceability to source; filed with project records | Mandatory | |
| A3 | Sample depth recorded — depth from ground level (GL) in meters; depth recorded in testing report Acceptance: Depth noted; used to interpret bearing capacity relative to overburden | Mandatory | |
| A4 | Sampling date recorded — calendar date sample extracted; time lag between sampling and testing noted Acceptance: Date recorded; testing date noted; storage conditions (sealed container, kept moist) documented | Mandatory | |
| A5 | Testing date — date testing started; time from sampling to testing noted (typically <2 weeks for accurate results) Acceptance: Testing date recorded; if >2 weeks from sampling, sample may have changed; condition noted | Mandatory | |
| A6 | Soil classification per IS 1498 — soil type identified (sand, silt, clay); plasticity (non-plastic, low, high) determined Acceptance: IS 1498 classification determined (e.g., Medium sand, Silty clay); Atterberg limits tested for fines >12% | Mandatory | |
| A7 | Natural moisture content determined — oven-dried sample weighed; moisture % = [(wet-dry)/dry]×100 Acceptance: Natural moisture content measured; value noted; used to assess sample condition and interpret compaction results | Mandatory | |
| B. SPECIMEN PREPARATION & COMPACTION | |||
| B1 | Mould dimensions — diameter 150mm ±1mm, height 127.3mm ±1mm (5 inches ±0.04 inches per IS 2720 Part 16 Cl. 4.1) Acceptance: Mould dimensions verified; certificate of calibration filed; mould not damaged or worn | Mandatory | |
| B2 | Specimen height — built to 127.3mm (5 inches) above collar; specimen measured before and after compaction Acceptance: Height measured to 0.1mm precision; recorded before soaking and test | Mandatory | |
| B3 | Compaction method — 3 layers compacted separately; each layer receives specified number of blows (56/25/10 for heavy/medium/light) Acceptance: Compaction effort documented (heavy/medium/light); blow count per layer recorded; method per IS standard | Mandatory | |
| B4 | Heavy compaction (56 blows/layer) — for well-compacted subgrade; generates high dry density (typically >1.80 t/m³) Acceptance: If heavy effort selected, 56 blows applied to each of 3 layers; rammer mass 4.89 kg, drop height 450mm | Conditional | |
| B5 | Medium compaction (25 blows/layer) — for moderately compacted layers; typical for site work Acceptance: If medium effort selected, 25 blows per layer applied; MDD typically 1.65-1.80 t/m³ | Conditional | |
| B6 | Light compaction (10 blows/layer) — for loosely compacted soil; generates lower dry density (~1.50-1.65 t/m³) Acceptance: If light effort selected, 10 blows per layer; represents poorly compacted subgrade | Conditional | |
| B7 | Moisture content at compaction — soil moisture adjusted to optimum for selected effort (from Proctor test or field estimation) Acceptance: Moisture at compaction noted; ideally at OMC for maximum density; recorded for each specimen | Mandatory | |
| B8 | Dry density achieved — specimen weighed after compaction; dry density calculated = (weight)/(volume), recorded in t/m³ Acceptance: Dry density measured and recorded; typically 3 specimens per test condition; values tabulated | Mandatory | |
| C. SOAKING (IF SOAKED CBR TEST) | |||
| C1 | Soaking duration — specimens submerged in water for 96 hours (4 days) minimum per IS 2720 Part 16 Cl. 6.1 Acceptance: Soaking period documented; start and end dates recorded; specimens fully submerged throughout | Conditional | |
| C2 | Surcharge weight during soaking — 4.54 kg (10 lbs) weight placed on specimen to simulate overburden (per IS standard) Acceptance: Surcharge weight verified (4.54 kg ±0.05 kg); placed on specimen before soaking; maintained throughout | Conditional | |
| C3 | Swell reading — initial specimen height measured before soaking; final height after 96 hours measured; swell recorded Acceptance: Initial height and final height measured to 0.1mm; swell height = final - initial; recorded for each specimen | Conditional | |
| C4 | Swell percentage — calculated as: swell % = (final-initial)/127.3 × 100; acceptable <2% for subgrade per IS 1904 Acceptance: Swell % tabulated; if >2%, material may be unsuitable for subgrade; engineer approval required | Conditional | |