IS 1199 Part 2 : 2018Fresh Concrete - Methods of Sampling and Testing - Part 2: Determination of Slump

IS 1199 (Part 2) specifies the method for determining density of fresh concrete — direct measurement of fresh concrete density (kg/m³). Density is a critical fresh-concrete property: it indicates compaction quality, helps detect mix proportion drift, and validates yield (volume of concrete delivered vs design).

Use IS 1199 Part 2 when: - Yield verification (e.g., RMC delivers 8 m³ — does it weigh 8 × density of fresh concrete?) - Detection of mix proportion drift (low density may indicate excess water or air entrainment) - Quality acceptance for high-density / low-density specialty concrete - Source qualification of new mix design or supplier - Air-entrained concrete verification (lower density indicates higher air content)

The IS 1199:2018 series: - Part 1: Sampling + slump - Part 2 (this code): Density of fresh concrete - Part 3: Vee-bee - Part 4: Compacting factor - Part 5: Flow test - Part 6: Bleeding - Part 7: Washout analysis - Part 8: Air content

Typical fresh concrete densities: - Standard M20-M30 concrete (no admixture): 2350-2400 kg/m³ - High-performance M40+ with HRWR: 2400-2450 kg/m³ - Lightweight aggregate concrete: 1500-1900 kg/m³ - Air-entrained concrete (4-6 % air): 2250-2350 kg/m³ - Heavy concrete (with magnetite / barite for shielding): 3000-4500 kg/m³

Equipment: - Calibrated container (cylindrical, 5-15 L; volume known precisely) - Tamping rod (16 mm dia, 600 mm long) - Balance (capacity ≥ 30 kg, accuracy 0.01 kg) - Strike-off plate / trowel

Procedure: 1. Determine container volume V (calibrated by water filling at known temperature). 2. Sample fresh concrete per IS 1199 Part 1:2018. 3. Fill container in 3 layers; tamp 25 strokes per layer with rod. 4. Strike off top surface flush with container rim; smooth. 5. Wipe outside of container clean. 6. Weigh full container (M_full). 7. Subtract container empty mass (M_empty). 8. Density (kg/m³) = (M_full − M_empty) / V

Sampling: - Sample at point of placement (not mixer outlet) per IS 1199 Part 1 - Fresh sample (test within 30 minutes of mixing) - Concrete representative of full batch (avoid first / last slug)

Reporting: - Volume of container (L) - Mass of empty + filled container (kg) - Density (kg/m³) - Date, time, batch reference, ambient temperature

Tolerance: - Test repeatability: ± 1 % (typical) - Acceptance: per project specification (typically 2350 ± 50 kg/m³ for standard concrete)

Test cadence: - Source qualification: every trial mix - Routine: 1 per 50-100 m³ for high-volume RMC - Critical: 1 per truck (high-stakes pours like dam or bridge)

Density acceptance criteria:

| Concrete type | Expected density (kg/m³) | Acceptance tolerance | |---|---|---| | Standard M20-M30 | 2350-2400 | ±50 | | M40+ | 2400-2450 | ±50 | | M60+ with silica fume | 2450-2500 | ±50 | | Air-entrained (4-6 % air) | 2250-2350 | ±50 | | Lightweight (aggregate-driven) | 1500-1900 | ±100 | | Heavy concrete (shielding) | 3000-4500 | ±100 |

Density used for yield calculation: - Yield = batch mass / fresh density - Design batch: 1 m³ of concrete should weigh ≈ design density × 1 m³ - Actual yield = (sum of materials supplied) / actual density - Yield ratio: actual / design (should be ≈ 1.0; deviations indicate mix proportion error)

Density vs other QC tests: - Density alone doesn't measure strength (a low-density concrete may still meet strength target) - Density helps identify: mix proportion error, air entrainment level, sand content variation - Combined with cube strength + slump + (occasionally) washout = comprehensive QC

Typical project usage: - Routine RMC project: density tested occasionally (1-2 per 1000 m³ delivered) - High-stakes project (dam, bridge, raft foundation): every truck or every 50 m³ - Lightweight / heavy concrete project: every batch (density is the headline acceptance criterion) - Air-entrained concrete: density verifies air content indirectly

Cost: - Test takes 5-10 minutes; cost ≤ ₹500 - One of the cheapest QC tests; should be used liberally

• IS 1199 Parts 1, 3-8 — fresh concrete tests series.
• IS 1199 Part 1:2018 — sampling and slump (most common companion).
• IS 1199 Part 7:2018 — washout analysis (when density anomaly investigated).
• IS 516 Part 1:2021 — compressive strength on cubes.
• IS 456:2000 — RCC code.
• IS 10262:2019 — concrete mix design (target density per design).
• IS 4926:2003 — Ready-Mixed Concrete.
• IS 4925:2004 — concrete batching plant (yield verification).
• IS 9103:1999 — admixtures (air-entraining changes density).
• IS 383:2016 — aggregates (specific gravity affects density).
• IS 8112:1989 / IS 12269:2013 — cement standards.
• ASTM C138 — international counterpart for fresh concrete density.

1. Container volume not calibrated. ±2-5 % volume error → ±2-5 % density error. Calibrate annually with water at known temperature. 2. Inadequate compaction. Voids in container reduce mass; density reads low. Tamp 25 strokes per layer. 3. Strike-off with wedge motion. Pulls aggregate up; surface not flush. Use straight strike-off motion. 4. Sample from one truck used to characterise batch. Variation between trucks; need multiple samples. 5. Test late after mixing. Concrete partly set; density changes. Test within 30 minutes of mixing. 6. Container not clean / dry before test. Residue affects mass. Clean + dry. 7. Balance not calibrated. ±5 % balance error → ±5 % density. Calibrate; weight check before test. 8. No comparison with design density. Result reported but not interpreted; no action taken. Compare to design ± tolerance. 9. Single anomaly ignored. One low density may signal trouble; investigate (mixer water excess?). Don't dismiss. 10. Air-entrained concrete tested without air content correlation. Density reads low; may be due to air, not water excess. Test air content (Part 8) for clarification. 11. No record-keeping. Density results trend lost; can't detect drift. Log per batch. 12. Yield calculation skipped. Density alone provides yield insight; don't skip the calculation.

Routine concrete QA cascade:

1. Per-batch tests: - Slump (IS 1199 Part 1) — workability - Density (this code, IS 1199 Part 2) — proportions check - Cube casting for 7d / 28d strength 2. Periodic tests (per 500-1000 m³): - Washout analysis (IS 1199 Part 7) — direct cement / water verification - Flexural strength on beam (for PQC) 3. Investigation (on anomaly): - Strength fail → washout, cement source check - Workability drift → admixture, water addition check - Density drift → mix proportion verification 4. Documentation: - Per-batch log - Trend tracking - Statistical control charts for high-volume operations

Density is one of the cheapest + fastest fresh-concrete QC tests; under-utilised in routine practice. Standard mix should hit 2350-2400 kg/m³; deviations beyond ±50 kg/m³ warrant investigation. Combined with slump + cube tests, density rounds out a robust QC programme without significant cost.