| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. SAMPLE DETAILS & PREPARATION | |||
| A1 | Sample identification & documentation Acceptance: All identifiers legible & traceable; depth documented; minimum sample mass ≥100 g dry weight | Sample ID, location, depth, borehole/pit reference clearly recorded | OK NC NA HOLD |
| A2 | Soil description & material assessment Acceptance: Description detailed enough for pre-test assessment; consistency checked against final gradation results | Visual description: color, texture, organic content, visible clay/silt/sand fractions; any prominent features noted | OK NC NA HOLD |
| A3 | Initial dry sample preparation Acceptance: Sample homogeneous; mass constant to ±0.5% between consecutive weighings; drying temperature documented | Sample air-dried (room temperature 20–25°C) or oven-dried at 110°C until constant weight; no grinding or crushing; clods gently broken; lumps <sieve opening | OK NC NA HOLD |
| A4 | Initial sample weight determination Acceptance: Weight recorded; accuracy verified; any moisture content or loss noted | Total dry sample mass weighed to ±0.1 g (balance accuracy ±0.1 g for m >100 g) | OK NC NA HOLD |
| A5 | Specific gravity reference (Gs) Acceptance: Gs value recorded with ±0.01 precision; used for particle diameter calculation (hydrometer) | Specific gravity determined per IS 2720 Part 3 (pycnometer or density bottle method); typical Gs 2.60–2.75 for mineral soils; value documented for hydrometer analysis | OK NC NA HOLD |
| B. SIEVE ANALYSIS — COARSE FRACTION (≥75 μm) | |||
| B1 | Sieve stack arrangement per IS 460 Acceptance: Sieves properly arranged; all sizes present & certified; mesh intact; no particles lost between sieves | IS 460 sieve sizes (from top): 75 mm, 40 mm, 20 mm, 10 mm, 4.75 mm (No. 4), 2.36 mm (No. 8), 1.18 mm (No. 16), 600 μm (No. 30), 300 μm (No. 50), 150 μm (No. 100), 75 μm (No. 200), pan. Sieves stacked in decreasing order; pan at bottom | OK NC NA HOLD |
| B2 | Dry sieving procedure Acceptance: Sieving duration adequate; material uniformly distributed on each sieve; no buildup or bridging; shaking thorough & consistent | Sample placed on top sieve; shaken mechanically (mechanical shaker per IS 2720 Part 4 Clause 5.2) or by hand (for quick assessment) for sufficient duration until material on each sieve stops flowing; typically 10–15 min mechanical or until variation <0.1% between consecutive 1-min intervals | OK NC NA HOLD |
| B3 | Weight retained on each sieve Acceptance: Weights sum to initial sample mass ±1% (loss ≤1% acceptable); no significant spillage or contamination | After sieving, material on each sieve weighed to ±0.1 g (or ±0.01 g if <10 g); weights recorded in grams. Pan contents (fines <75 μm) weighed separately | OK NC NA HOLD |
| B4 | Data tabulation — Weight retained & cumulative Acceptance: All values calculated correctly; cumulative % passing decreases uniformly; final % passing at pan ≤1% (or notes fine content) | Table columns: (a) Sieve size (IS 460 designation & mm/μm); (b) Weight retained (g); (c) Cumulative weight retained (g); (d) Cumulative % retained = cumulative weight ÷ initial sample mass × 100; (e) % passing = 100 − cumulative % retained | OK NC NA HOLD |
| B5 | Loss on sieving & material recovery Acceptance: Loss documented; if >1%, check for spillage, sieve damage, or adhesion; results flagged if loss significant | Loss (%) = (Initial mass − sum of weights on sieves & pan) ÷ initial mass × 100; acceptable loss ≤1% per IS 2720 Part 4 Clause 7.2 | OK NC NA HOLD |
| C. HYDROMETER ANALYSIS — FINE FRACTION (<75 μm, if applicable) | |||
| C1 | Hydrometer test applicability Acceptance: Decision to perform hydrometer documented; test scope (silt vs clay separation) defined | Hydrometer analysis per IS 2720 Part 4 Clause 6.2 applied if significant fines (<75 μm) present (typically >12% of sample); procedure: dispersed soil sedimentation in water column; hydrometer readings track particle size distribution | OK NC NA HOLD |
| C2 | Sample preparation — dispersion & deflocculation Acceptance: Dispersant concentration correct; soaking time adequate; soil dispersed (no visible clods); solution cloudy indicating particles in suspension | Fine soil fraction (<75 μm from pan) mixed with dispersant: sodium hexametaphosphate solution (33 g/L or per IS 2720 Part 4 Table 2) at 25 mL per 50 g soil; soaked for ≥12 hrs; then shaken/stirred to break particle flocculation | OK NC NA HOLD |
| C3 | Hydrometer apparatus & calibration Acceptance: Hydrometer certified; graduations clear; thermometer functional; apparatus clean & dry before test | Graduated cylinder (1000 mL, marked for 1000 mL reading); hydrometer Type 152 H or 151 H per IS 2720 Part 4 (calibrated for 20°C, ISM = 1.0); thermometer (±0.5°C accuracy); graduated rod (±1 mm); stopwatch | OK NC NA HOLD |
| C4 | Hydrometer reading procedure & timing Acceptance: Readings taken at correct times; hydrometer depth (immersion) consistent; temperature recorded; hydrometer removed between readings & replaced carefully | Dispersed soil poured into graduated cylinder, total volume made to 1000 mL with water; initial hydrometer reading at t=0 (immediately after mixing); subsequent readings at standardized times: 0.5, 1, 2, 4, 8, 15, 30, 60, 120, 240, 1440 minutes. For each reading: (a) Hydrometer reading (R); (b) Temperature (T°C); (c) Time (t in minutes) | OK NC NA HOLD |
| C5 | Hydrometer reading corrections Acceptance: All corrections tabulated; corrected reading = R + Cm + Ct + C0; table shows both raw & corrected readings | Corrections applied per IS 2720 Part 4 Clause 7.3: (a) Meniscus correction (Cm) — typically −0.5 for Type 152H hydrometer (read bottom of meniscus, then subtract 0.5); (b) Temperature correction (Ct) — from calibration table or formula; (c) Zero correction (C0) — from hydrometer calibration (typically 0–0.2) | OK NC NA HOLD |
| C6 | Effective depth & particle diameter calculation Acceptance: Effective depth table consulted for each corrected reading; D calculated correctly for each time interval; formula verified; viscosity & density at measured temperature used | Effective depth (H) in cm from hydrometer calibration (varies with corrected reading); particle diameter D (mm) = √[(30 × μ × L) / (g × (Gs − 1) × ρw × t)], where μ = viscosity of water (cP at T°C), L = effective depth (cm), g = 981 cm/s², Gs = specific gravity, ρw = water density (≈1 g/cm³), t = time (sec) | OK NC NA HOLD |
| C7 | Percent finer calculation Acceptance: Correction factor C1 determined (typically 5–10 for Na hexametaphosphate); factors a & m documented; % finer calculated for each reading; curve plotted | % finer than size D = (N − C1) / (a × m) × 100, where N = corrected hydrometer reading, C1 = correction for dispersant & pycnometer bottle, a = hydrometer bulb volume area factor, m = mass of soil solids (g) in suspension | OK NC NA HOLD |