IS 1199 Part 7 : 2018Methods of sampling and analysis of concrete - Part 7: Determination of the slump

IS 1199 (Part 7) specifies the method of sampling and analysis of fresh concrete — analysis of fresh concrete (washing-out / washout method). The IS 1199 multi-part series is the comprehensive Indian standard for fresh concrete testing.

The IS 1199:2018 series: - Part 1: Sampling methods + slump test (most common) - Part 2: Determination of density of fresh concrete - Part 3: Vee-bee consistometer (workability) - Part 4: Compacting factor test (workability) - Part 5: Flow test (high-flow concrete) - Part 6: Determination of bleeding - Part 7 (this code): Analysis of fresh concrete (cement content + w/c ratio determination by washing) - Part 8: Determination of air content

Use IS 1199 Part 7 when: - Verifying actual cement content in delivered concrete - Forensic investigation of low-strength concrete (was correct cement dosed?) - Audit / dispute resolution on RMC quality - Mix-design vs delivered-mix validation - Quality-control benchmark for in-house RMC plant

The washout method separates fresh concrete into its components (cement + water + aggregate) by washing — directly verifies cement content per cubic metre and water content per cubic metre.

1. Sample fresh concrete per IS 1199 Part 1:2018 — minimum 5-10 kg from point of placement. 2. Mass measurement — record total mass of fresh sample + container. 3. Initial sieving — pass through 4.75 mm sieve under running water; collect fines (cement + sand) + retain coarse aggregate. 4. Coarse aggregate analysis — wash, oven-dry, weigh; gives coarse aggregate content. 5. Fine fraction (cement + sand) analysis — separate cement from sand by: - Settling: cement settles slower than sand; decant - Filtration: through 75 µm sieve under water - Centrifuging: for precise separation 6. Cement content — dried mass of cement fraction × correction factor 7. Water content — by mass balance: total mass − (coarse aggregate + cement + sand) 8. Calculations: - Cement content (kg/m³) = mass of cement / volume of concrete sample - Water content (kg/m³) = mass of water / volume - w/c ratio = water / cement - Aggregate-cement ratio

Volume measurement: by direct displacement or computed from density × mass.

Reporting: - Cement content (kg/m³) - Water content (kg/m³) - w/c ratio - Aggregate proportions (coarse + fine) - Comparison with design mix - Deviation from design (acceptable: ±5 % of cement content, ±3 % of w/c)

Acceptance criteria (typical for project audit): - Cement content within ±5 % of design value - Water content within ±3 % of design - w/c ratio within ±0.05 of design

Typical mix ratios (M30 example): - Cement: 380 kg/m³ - Water: 175 kg/m³ (w/c = 0.46) - Fine aggregate: 700 kg/m³ - Coarse aggregate (20 mm): 1100 kg/m³ - Total: ~2355 kg/m³ (concrete density)

Washout result should match within tolerance.

When to run IS 1199 Part 7: - Source qualification of new RMC supplier - Routine audit (per 1000 m³ or per supplier change) - Investigation of low cube strength - Spot-check on delivered batches - Cross-validation against batching plant records

Test cost (typical 2026): - ₹3000-8000 per test (NABL lab) - Higher than routine cube test (which is ~₹500); lower than full mix-design verification

Test cadence (recommended for QC): - Source qualification: 3-5 tests on representative samples - Routine: 1 per 500-1000 m³ for high-volume projects; per supplier change - Investigation: as needed when problem suspected

Compared to other QC methods: - Cube strength (IS 516 Part 1 Sec 1:2021): indirect — measures outcome (strength), not inputs (cement, water) - Slump (IS 1199 Part 1:2018): workability, indirect indication of w/c - Density (IS 1199 Part 2:2018): indirect indication of mix proportions - Washout (this code, Part 7): direct measurement of cement + water + aggregate

Washout is the most rigorous + most expensive on-site QC; usually reserved for source qualification + dispute resolution.

• IS 1199 Parts 1-8 — fresh concrete sampling + testing series.
• IS 1199 Part 1:2018 — sampling + slump (most common).
• IS 1199 Part 2:2018 — fresh concrete density.
• IS 516 Part 1:2021 — compressive strength on cubes.
• IS 456:2000 — RCC code.
• IS 10262:2019 — concrete mix design.
• IS 4926:2003 — Ready-Mixed Concrete specification.
• IS 4925:2004 — concrete batching plant specification.
• IS 8112:1989 / IS 12269:2013 — cement standards.
• IS 383:2016 — aggregates.
• IS 9103:1999 — admixtures (modify washout interpretation slightly).
• ASTM C172 — international counterpart for fresh concrete sampling.
• ASTM C173 / C231 — air content.

1. Sample too small. Affects accuracy of separation; especially for coarse aggregate. Use ≥ 5-10 kg sample. 2. Sample from mixer outlet only. Workability + segregation may differ at placement. Sample from point of placement. 3. Cement-sand separation incomplete. Some cement particles trapped in sand fraction; cement reads low. Use centrifuge or longer settling. 4. Water content by mass balance imprecise. Small errors compound; can't detect ± 5 % water variation reliably. Direct water measurement (pre-weigh sample, dry and re-weigh) more accurate. 5. Plant operator pre-warned. Knowing audit happening, plant produces good batch (Hawthorne effect). Random / unannounced audit. 6. Single test extrapolated. One test result doesn't characterise plant; need ≥ 3 samples for meaningful average. 7. No comparison to plant batching record. Result without context; can't identify drift. Compare to supplier's batch print + design mix. 8. Test in lab, days after sample taken. Concrete hardens; impossible to wash. Test must be on FRESH concrete within hours. 9. No written audit protocol. Ad-hoc test; results disputed. Document procedure + acceptance + reporting. 10. No follow-up if anomaly found. Test reveals 10 % under-cement; no action. Mandatory follow-up: investigate root cause, increase sampling, reject batches if needed.

Concrete QA cascade:

1. Source qualification (one-time): - Mix design (cement, w/c, aggregate proportions) - Trial mix verification (strength, workability) - Washout analysis (this code, IS 1199 Part 7) on trial batches — verify mix proportions deliver as designed - Cube tests at multiple ages

2. Routine QA (per delivery): - Slump test (IS 1199 Part 1) - Cube casting + 7d/28d testing - Visual inspection (uniformity, segregation)

3. Periodic audit (per 500-1000 m³): - Washout analysis to verify cement content + w/c - Density test

4. Investigation (on demand): - When cube fails: washout to determine if cement was correct - When workability drifts: washout to determine if water added on-site

5. Documentation: - Per-batch records: design mix, plant batch, slump, cube - Periodic washout reports - Trends + anomalies tracked

IS 1199 Part 7 is the deep-dive QA tool — invoked when indirect QA (cube strength, slump) raises concerns or for source qualification of new suppliers. For routine production QC, slump + cube cover 95 % of needs; washout fills the remaining 5 % of high-stakes verification.