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    Flakiness & Elongation Test

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    Flakiness & Elongation Index Test – Method Statement Flakiness & Elongation Index Test Procedure • Apparatus • IS Sieve Table • Results format Contents Object Apparatus Theory Procedure IS Sieve & Gauge Table Observations & Formulae Result Notes & References OBJECT To determine the elongation index of the given aggregates To determine the flakiness index of the given aggregates APPARATUS The apparatus for the shape tests consists of the following: A standard thickness gauge A standard length gauge IS sieves of sizes: 63, 50, 40, 31.5, 25, 20, 16, 12.5, 10 and 6.3 mm A balance of capacity 5 kg, readable and accurate up to 1 g THEORY The particle shape of aggregates is determined by the percentages of flaky and elongated particles contained in it. For base course and construction of bituminous and cement concrete types, the presence of flaky and elongated particles is considered undesirable as these cause inherent weakness with possibilities of breaking down under heavy loads. Thus, evaluation of shape of the particles, particularly with reference to flakiness and elongation is necessary. The Flakiness Index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than three-fifths (0.6 times) of their mean dimension. This test is not applicable to sizes smaller than 6.3 mm. The Elongation Index of an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than nine-fifths (1.8 times) their mean dimension. This test is not applicable for sizes smaller than 6.3 mm. PROCEDURE Sieve the sample through the IS sieves (as specified in the table below). Take a minimum of 200 pieces of each fraction to be tested and weigh them, or take the maximum number available up to 200 pieces. To separate the flaky materials, gauge each fraction for thickness on a thickness gauge. The width of the slot used should be of the dimensions specified in column (4) of the table for the appropriate size of the material. Weigh the flaky material passing the gauge to an accuracy of at least 0.1% of the test sample. To separate the elongated materials, gauge the non-flaky material for length on a length gauge. The width of the slot used should be of the dimensions specified in column (6) of the table for the appropriate size of the material. Weigh the elongated material retained on the gauge to an accuracy of at least 0.1% of the test sample. … IS SIEVE & GAUGE TABLE Passing through IS Sieve, mm Retained on IS Sieve, mm Weight of fraction (200 pieces), g Thickness gauge size, mm Weight passing thickness gauge (Xi) Length gauge size, mm Weight retained on length gauge (Yi) 63 50 W1 23.90 X1 – – 50 40 W2 27.00 X2 81.00 Y1 40 31.5 W3 19.50 X3 58.00 Y2 31.5 25 W4 16.95 X4 – – 25 20 W5 13.50 X5 40.5 Y3 20 16 W6 10.80 X6 32.4 Y4 16 12.5 W7 8.55 X7 25.5 Y5 12.5 10 W8 6.75 X8 20.2 Y6 10 6.3 W9 4.89 X9 14.7 Y7 Total W = X = Y = OBSERVATIONS & FORMULAE Record every fraction’s weights clearly. Use at least two significant figures for percentages and record sample piece counts. Flakiness Index = ((X1 + X2 + …) / (W1 + W2 + …)) × 100 Elongation Index = ((Y1 + Y2 + …) / (W1 + W2 + …)) × 100 Fraction Total pieces taken (Wi) Flaky weight (Xi) Elongated weight (Yi) Remarks 63–50 mm 50–40 mm 40–31.5 mm 31.5–25 mm 25–20 mm 20–16 mm 16–12.5 mm 12.5–10 mm 10–6.3 mm Total RESULT I. Flakiness Index = X II. Elongation Index = Y NOTES & REFERENCES This document preserves the original technical content. Do not alter the definitions if your contract specification references a specific IS edition. Reference: IS:2386 (Part 1) — Methods of test for aggregates for concrete (shape tests). Use the latest edition for definitive gauge slot values. Record environmental conditions and the balance calibration status with every test batch for traceability. Document: • Generated: 20 Nov 2025 Enter Values to Calculate Indices W Values X Values Y Values Calculate Results: Flakiness Index: 0% Elongation Index: 0% Quick Reference: Flakiness & Elongation Index Test Applicable Aggregate Size: Only aggregates ≥6.3 mm are tested. Minimum Sample Count: 200 pieces per sieve fraction (or maximum available). Flakiness Index Criterion: Particles with thickness < 0.6 × mean size. Elongation Index Criterion: Particles with length > 1.8 × mean size. Required Gauges: Thickness gauge for flakiness; Length gauge for elongation. Accuracy: Weigh materials to at least 0.1% accuracy of sample weight. Outcome: FI = (Flaky Weight / Total Weight) × 100; EI = (Elongated Weight / Total Weight) × 100. Purpose: Ensures aggregates are suitable for pavement and concrete strength requirements. Top FAQs – Flakiness & Elongation Index Test What is the minimum aggregate size for these tests? Aggregates smaller than 6.3 mm are not tested. Why are flaky and elongated particles undesirable? They reduce pavement strength and break easily under heavy loads. How many aggregate pieces must be tested? A minimum of 200 pieces from each sieve fraction. Which gauges are required? A standard thickness gauge for flakiness and a length gauge for elongation. What are the formulas used? Flakiness Index = (Total Flaky Weight / Total Sample Weight) × 100; Elongation Index = (Total Elongated Weight / Total Sample Weight) × 100. Prepared by Kishor Kumar Related Aggregate Tests for Highway & Concrete Works Explore detailed test procedures, calculations and acceptance criteria as per IS, MoRTH & IRC specifications: ✅ Aggregate Impact Value (AIV) Test – Toughness of Aggregates ✅ Los Angeles Abrasion Test – Wear & Abrasion Resistance ✅ Aggregate Crushing Value (ACV) Test – Strength Evaluation ✅ Flakiness & Elongation Index Test – Shape Characteristics ✅ Water Absorption Test – Durability & Porosity Check 📌 Pro Tip: Use AIV, ACV, Los Angeles Abrasion, and Shape & Water Absorption Tests together to ensure aggregate suitability for bituminous layers & cement

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    Compressive Strength of Cube

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    Concrete Cube Casting & Compressive Strength Testing (IS:516) 1. Objective To prepare, cast, cure, and test concrete cube specimens of size 150 × 150 × 150 mm or 100 × 100 × 100 mm to determine compressive strength of concrete at specified ages (usually 7 days and 28 days). 2. Apparatus Required Cube moulds – 150 mm or 100 mm Mixing tray and scoop Tamping rod (16 mm diameter) Trowel Concrete mixer (if required) Curing tank (27 ± 2°C) Compression Testing Machine (CTM) 3. Preparation of Cube Moulds Clean moulds to remove dust and hardened mortar. Assemble moulds properly and tighten bolts. Apply thin uniform oil layer on internal faces. Check alignment and squareness of mould. 4. Sampling and Mixing of Concrete Sample concrete from freshly mixed batch. Mix thoroughly until uniform colour and consistency are achieved. Start casting immediately to avoid loss of workability. 5. Casting of Concrete Cubes Fill mould in three equal layers. Distribute concrete evenly around mould. 6. Compaction of Concrete Compact each layer by rodding or vibration. Manual compaction: 35 strokes per layer. Rods to penetrate into the previous layer. Tap mould sides gently to remove air voids. Finish top surface smoothly using trowel. 7. Identification and Initial Storage Date of casting Grade of concrete Cube number / location Store cubes undisturbed for 24 hours at 27 ± 2°C. 8. Curing of Concrete Cubes Demould cubes after 24 ± ½ hours. Immediately immerse in clean water. Maintain curing temperature at 27 ± 2°C. Continue curing till testing age. 9. Compression Testing of Cubes (IS:516) Remove cube from curing tank (SSD condition). Clean cube and CTM platens. Measure dimensions (nearest 0.2 mm). Place cube centrally on CTM platen. Apply load gradually at ≈140 kg/cm²/min. Record maximum load at failure. Note: Improper centring causes eccentric loading and wrong test results. 10. Calculation of Compressive Strength Compressive Strength (N/mm²) = Maximum Load at Failure ÷ Loaded Area 11. Cube Size – Area – Thumb Rules Cube Size Loaded Area 150 mm Cube 225 cm² 100 mm Cube 100 cm² Fast Site Calculation Rules 150 mm cube → Load (kg) ÷ 225 | Load (kN) ÷ 22.5 100 mm cube → Load (kg) ÷ 100 | Load (kN) × 10 12. Sampling Frequency (IS Practice – Simplified) Concrete Quantity No. of Samples Total Cubes 1 – 5 m³ 1 3 6 – 15 m³ 2 6 16 – 30 m³ 3 9 31 – 50 m³ 4 12 Each additional 50 m³ +1 +3 13. Reporting of Results Calculate strength of each cube. Round off to nearest whole number. Average of 3 cubes = representative strength. Variation limits must be satisfied. Concrete Strength Acceptance Criteria (±15% Rule Explained) Basic Rule For any set of 3 cubes (one sample): Calculate average strength Each cube must lie within: 0.85 × Average (−15%) 1.15 × Average (+15%) If even one cube is outside this range, the sample is REJECTED, irrespective of average strength. Key Strength Values – M25 Concrete Characteristic strength (fck) = 25 N/mm² Standard deviation (assumed) = 4 N/mm² Target mean strength = fck + 1.65 × S = 25 + (1.65 × 4) = 31.6 N/mm² CASE–1: Single Sample (Small Quantity Concrete) Concrete Quantity = 5 m³ As per IS practice → 1 sample (3 cubes) Acceptance Criterion (Special Case) When only one sample is available: Average strength ≥ fck + 4 = 29 N/mm² Cube Strengths (N/mm²) Average 0.85 × Avg 1.15 × Avg 19, 26, 16 20.3 17.3 23.3 Reasons for Rejection ❌ Average strength less than 29 N/mm² ❌ Cubes 26 and 16 N/mm² outside ±15% range Final Decision: ❌ CONCRETE REJECTED CASE–2: Multiple Samples (Normal Quantity Concrete) Concrete Quantity = 28 m³ Samples required = 3 samples (9 cubes) Acceptance Criteria Each cube ≥ fck − 2 = 23 N/mm² Overall average ≥ fck + 4 = 29 N/mm² ±15% variation satisfied for each sample Sample-wise Results Sample Cube Strengths (N/mm²) Average 0.85 × Avg 1.15 × Avg 1 33, 29, 32 31.3 26.6 36.0 2 24, 32, 28 28.0 23.8 32.2 3 25, 29, 32 28.7 24.4 33.0 Overall Average Strength (31.3 + 28.0 + 28.7) ÷ 3 = 29.3 N/mm² Acceptance Check (As per IS Acceptance Criteria) ✅ ±15% Variation Check: All individual cube strengths fall within the permissible range of 0.85 × Average to 1.15 × Average for their respective samples. This confirms uniformity in batching, mixing, compaction, and curing of concrete. ✅ Minimum Individual Strength Check: Each tested cube has achieved a compressive strength greater than or equal to fck − 2, i.e. 23 N/mm² for M25 concrete. No cube strength is below the minimum permissible limit. ✅ Average Strength Check: The overall average compressive strength of all samples is 29 N/mm² or higher, which satisfies the requirement of fck + 4 for acceptance of concrete under normal sampling conditions. ✅ Quality and Compliance Confirmation: Since variation, individual strength, and average strength criteria are all satisfied, the concrete meets the strength acceptance requirements prescribed under IS practice for M25 grade. Final Decision: ✅ CONCRETE ACCEPTED One-Line Site Memory Rules Single sample → Average ≥ fck + 4 Multiple samples → Each cube ≥ fck − 2 ±15% variation is compulsory Final Takeaway Concrete cube testing is the backbone of quality control. Correct casting, curing, testing, and acceptance checks ensure strength, durability, and compliance with IS standards. ✅ Why Concrete is ACCEPTED Uniform Strength: All cube test results lie within ±15% of their respective sample averages, indicating proper batching, mixing, compaction, and curing. Sufficient Individual Strength: No cube strength is below fck − 2 (23 N/mm² for M25), ensuring minimum safety at the individual specimen level. Adequate Average Strength: The overall average compressive strength is ≥ fck + 4 (29 N/mm²), satisfying IS acceptance requirements. Statistical Reliability: Multiple samples provide confidence that at least 95% of concrete will achieve the characteristic strength. ❌ Why Concrete is REJECTED (When Failure Occurs) One or more cube values fall outside ±15% of the sample

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    Profile Corrective Course DBM

    Leave a Comment / Highway Construction Methodology /

    🚧 Profile Corrective Course (DBM) Construction Methodology Profile Corrective Course (DBM) Construction Methodology This work involves preparing an existing road surface (granular or bituminous) and laying a bituminous mix, typically 50 mm to 100 mm thick, to correct the pavement profile and strengthen the surface. 1.0 Scope and Preparation The Profile Corrective Course (PCC) is a layer of varying thickness designed to correct the existing pavement profile (e.g., local depressions, sags, or incorrect camber/super-elevation) before the main overlay. Existing Bituminous Surface Repair: Existing potholes and cracks must be repaired and sealed according to relevant specifications (MoRT&H Clauses 3004.2 and 3004.3). Scarifying: Where specified, the existing bituminous layer is carefully removed without disturbing the underlying layers. The exposed base is reworked, compacted, and primed (Clause 502) if needed. Tack Coat: After preparation, a Tack Coat (bituminous emulsion) is applied to the surface before laying the new DBM. Existing Granular Surface All loose materials are removed, and the surface is prepared to be firm and clean. If the PCC is bituminous, the granular surface must be primed (Clause 502) after removing loose material. The surface must be free from dust and capable of being swept by a mechanical broom. Pre-Laying Checks Before and after scarifying/preparation, the existing road top levels must be checked and recorded by the Engineer’s representative. 2.0 Resource Arrangement: Plant & Equipment Sl. No. Name of Equipment Nos. 1 Batch Type Hot Mix Plant (Capacity 200 TPH) 01 2 Sensor Paver (Automatic Screed Control) 01 3 Pneumatic Tyred Roller (PTR) 01 4 Tandem Vibratory Roller 02 5 Bitumen Sprayer (for Tack Coat) 01 6 Compressor / Hydraulic Broom 01 7 Water Tanker 01 8 Tipping Trucks As Required 3.0 Materials and Mix Production 3.1 Materials Aggregates: Coarse and fine aggregates from approved quarries. Bitumen: VG-30 or VG-40 grade from approved sources. Tack Coat: Rapid setting Bituminous Emulsion from approved sources. 3.2 Job Mix Formula (JMF) The JMF determines the precise proportions of coarse aggregates, fine aggregates, bitumen, and mineral filler/additives. It is designed in the site laboratory and must be approved by the Independent Engineer (AE/IE)/PMC. The process is the same as we do for DBM & BC mix designs. 3.3 Hot Mix Plant Operation Storage: Bitumen (VG-30/VG-40) stored in automatic temperature-controlled tanks (150°C to 165°C). Aggregates: Separate cold bins and feeders proportion the aggregates and dust into the dryer. Drying: Dryer continuously heats and dries aggregates (150°C to 170°C) minimizing fuel consumption and dust release. Mixing: Aggregates and binder combined in an inert, steam-laden atmosphere. Bitumen Temp: 150°C–165°C, Aggregate Temp: 150°C–170°C, Mixture Max Temp: 165°C. 4.0 Laying and Compaction 4.1 Transportation of Mix Mix loaded into tipping trucks (up to 20 MT). Beds sprayed with release agent. Covered with tarpaulin to maintain temperature. Temperature at loading: 155°C to 165°C. 4.2 Application of Tack Coat Applied using a mechanical sprayer. Rate: 0.25–0.30 Kg/m². Emulsion Temp: 20°C–70°C. Allow tack coat to cure before DBM layer is laid. 4.3 Spreading and Finishing Sensor wire fixed over brackets at 10m intervals. Paver guided to achieve designed finished levels. Laying temperature (Min): 125°C. Paver uses fully activated screed with tampers/vibrators. Loose thickness allowance: 25%. Manual methods for irregular areas. 4.4 Compaction Equipment: Vibratory Tandem Roller + PTR. Rolling sequence: From lower end to higher side. Passes determined on-site. Density: Rolling until specified density achieved or no further movement. Transverse joints cut full thickness; edges painted with hot bitumen/tack coat. 5.0 Quality Control and Traffic Core Cutting: After 24 hours to check density. Bitumen Testing: Softening Point, Penetration, Ductility for each consignment. Surface Finish: Must conform to Clause 902 of MoRT&H. Opening to Traffic: Minimum 24 hours after laying. Traffic diversion with cones, caution boards, flagmen. Top FAQs – DBM Profile Corrective Course What is PCC? A layer to correct existing pavement profile before overlay. When is it required? For depressions, potholes, uneven camber or sags. Typical thickness? 50–100 mm per layer. Materials used? Aggregates, VG-30/VG-40 bitumen, mineral filler, tack coat. Surface preparation? Scarify, repair cracks/potholes, broom sweep, prime or tack coat. Compaction method? PTR + Tandem Vibratory Rollers until specified density. Joints? Full-depth transverse cut, edges coated with hot bitumen/tack coat. Traffic opening? Minimum 24 hours after laying. QC measures? Core density, bitumen tests, surface level checks. Bridge paving? Yes, temperature ≤145°C unless approved. 🏗️ Highway Construction Methodology Hub Standard construction methodologies for highway works as per MoRTH 5th Revision and IRC Specifications. ✅ Earthwork Methodology ✅ Clearing & Grubbing Methodology ➡️ ✅ Embankment Construction Methodology ➡️ ✅ Flyash Embankment Construction Methodology ➡️ ✅ Subgrade Construction Methodology ➡️ ✅ Granular Work Methodology ✅ Granular Sub-Base (GSB) Methodology ➡️ ✅ Wet Mix Macadam (WMM) Methodology ➡️ ✅ Bituminous Work Methodology ✅ Prime Coat Application Methodology ➡️ ✅ Tack Coat Application Methodology ➡️ ✅ Dense Bituminous Macadam (DBM) Methodology ➡️ ✅ Bituminous Concrete (BC) Methodology ➡️ ✅ Profile Corrective Course of DBM ➡️ ✅ Use of Waste Plastic in Bitumen ➡️ ✅ Use of Waste Plastic in Road Construction ➡️ ✅ Thermoplastic Road Marking Methodology ➡️ ✅ Concrete Methodology ✅ Dry Lean Concrete (DLC) Methodology ➡️ ✅ PQC Road Construction Methodology ➡️ ✅ Kerb Construction Methodology ➡️

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    Water Absorption Test

    Leave a Comment / Aggregate /

    Water Absorption Test of Coarse Aggregate — Objective, Procedure & Calculation Water Absorption Test of Coarse Aggregate The Water Absorption Test determines the percentage of water absorbed by coarse aggregates, providing an indication of pore structure, density, and suitability for high-quality concrete and asphalt works. Objective To determine the Water Absorption (%) of a coarse aggregate sample using SSD and Oven-dry mass values. Apparatus Required Tray or suitable container Balance (Capacity ≥ 3 kg, Accuracy 0.5 g) Oven (100–110°C) Cotton cloth Test Procedure 1. Immersion (Saturation) Take at least 2000 g (2 kg) of aggregate. Immerse in clean water for 24 hours to fill internal pores. 2. Saturated Surface Dry (SSD) Condition Remove the sample and wipe gently with a cotton cloth. Ensure no visible free water film remains on the surface. Weigh the sample → SSD Mass (A). 3. Oven Drying Place SSD sample in oven at 100–110°C for 24 hours. Cool it and weigh → Oven‑Dry Mass (B). 4. Repeat Trial Repeat the procedure on another sample and take the average. Calculation Water Absorption (%) = (A − B) / B × 100 Where: A = SSD Mass of aggregate B = Oven‑Dry Mass of aggregate Example If: A (SSD Mass) = 2045 g B (Oven-Dry Mass) = 2000 g Water Absorption (%) = (2045 − 2000) / 2000 × 100 = 45 / 2000 × 100 = 2.25% Importance in Construction Mix Design Adjustments: Highly absorptive aggregates steal mix water → affects workability. Durability: Higher absorption = higher porosity → weaker freeze-thaw and weathering resistance. ✔️ Typical Acceptable Limits Aggregate Type Max Water Absorption (%) Coarse Aggregate (Normal concrete) ≤ 2% Fine Aggregate (Sand) ≤ 3% For high-performance or severe exposure concrete, stricter limits may apply. Background & Standard Reference The Water Absorption Test is covered under IS 2386 (Part 3) – Specific Gravity, Density, Voids, Absorption and Bulking. This test provides insight into the internal pore structure of aggregates, which directly affects concrete durability, water demand, and long‑term performance. Aggregates with excessive pores tend to absorb more water, which may lead to reduced compressive strength and increased shrinkage. By determining absorption, engineers calibrate mix water content accurately to achieve the target workability and strength parameters. Factors Affecting Water Absorption Aggregate Type: Crushed rock typically has lower absorption than natural aggregates. Surface Texture: Rough, angular particles may retain more surface moisture. Pore Structure: Aggregates with interconnected pores have higher absorption levels. Weathering: Older, weathered aggregates tend to be more porous. Mineral Composition: Some minerals inherently exhibit higher porosity. Significance of SSD Condition The SSD (Saturated Surface Dry) condition is critical because it represents the state where internal pores are full of water while the exterior surface is dry. This allows mix water calculations to remain accurate. If aggregates are not brought to SSD before batching, they either absorb mix water (leading to lower workability) or contribute excess water (making the mix too wet). The SSD condition ensures correct water‑cement ratio, the single most important factor governing concrete strength. Impact on Concrete Performance Water absorption is directly linked to aggregate quality. Aggregates with low absorption are denser and more durable, making them suitable for high‑strength and long‑life structures. On the other hand, aggregates with high absorption may lead to increased permeability, reduced freeze‑thaw resistance, and potential durability issues. Additionally, when absorption is high, the concrete mix becomes unpredictable without proper adjustments, affecting slump, cohesiveness, and compaction. Precautions Ensure aggregates are completely submerged during the 24‑hour soaking period. Wipe surface moisture gently—over‑drying may lead to inaccurate SSD readings. Do not exceed oven temperature beyond 110°C to avoid thermal damage. Use a calibrated balance for precise mass measurements. Allow oven‑dry samples to cool in a desiccator if available, to prevent moisture uptake from air. Notes for Field Engineers In site conditions, aggregates stored in open yards exhibit varying levels of moisture. Regular absorption testing helps determine free moisture correction during batching to maintain consistent mix quality. For automated batching plants, entering accurate absorption values ensures the batching software adjusts water content correctly. This prevents issues such as plastic shrinkage, excessive bleeding, or segregation in fresh concrete. IS Code References IS Code Description IS 2386 (Part 3) Methods of Test for Aggregates – Specific Gravity, Density, Voids & Water Absorption IS 383 Specification for Coarse and Fine Aggregates for Concrete IS 456 General concrete requirements & material quality guidance Frequently Asked Questions (FAQ) 1. What is a good water absorption value for coarse aggregates? For most concrete works, water absorption should be ≤ 2%. Lower values indicate denser and more durable aggregates. 2. Why is SSD condition important? SSD ensures that aggregate pores are filled without free surface water. This prevents errors in mix design water calculations. 3. Can high water absorption affect concrete strength? Yes. Aggregates with high absorption draw water from the concrete mix, reducing effective W/C ratio and causing poor workability and potential strength loss. 4. How often should this test be performed? Typically during material approval and periodically during construction to ensure consistent aggregate quality. 5. Do different rocks have different absorption characteristics? Yes. Dense rocks like basalt and granite have low absorption. Porous rocks like sandstone and lightweight aggregates have higher absorption. Related Aggregate Tests for Highway & Concrete Works Explore detailed test procedures, calculations and acceptance criteria as per IS, MoRTH & IRC specifications: ✅ Aggregate Impact Value (AIV) Test – Toughness of Aggregates ✅ Los Angeles Abrasion Test – Wear & Abrasion Resistance ✅ Aggregate Crushing Value (ACV) Test – Strength Evaluation ✅ Flakiness & Elongation Index Test – Shape Characteristics ✅ Water Absorption Test – Durability & Porosity Check Pro Tip: Use AIV, ACV, Los Angeles Abrasion, and Shape & Water Absorption Tests together to ensure aggregate suitability for bituminous layers & cement concrete as per MoRTH Section 400 & 500.

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    Aggregate Crushing Value Test

    Leave a Comment / Aggregate /

    Aggregate Crushing Value Test — Procedure, Calculation & Limits | QC for Pavements Aggregate Crushing Value (ACV) Test — Procedure, Calculation & Acceptance Limits Quick lab method for QC of aggregates used in concrete pavements — Field & Lab Overview The Aggregate Crushing Value (ACV) test measures the resistance of an aggregate sample to crushing under a gradually applied compressive load. The result helps determine suitability of aggregates for different pavement layers and wearing surfaces. Apparatus Item Specification / Notes Steel cylindrical measure Internal diameter 115 mm, height 180 mm Plunger / piston Diameter 150 mm (for main apparatus) Tamping rod Diameter 16 mm (rounded end), length 450–600 mm Balance Capacity ≈ 3 kg with 0.01 g accuracy Compressive testing machine 40 tonnes capacity, uniform loading rate 4 tonnes/min IS sieves 12.5 mm, 10 mm, and 2.36 mm Sample Selection & Preparation Use aggregate passing 12.5 mm and retained on 10 mm IS sieve. Ensure the aggregates are surface-dry (no visible free moisture). Sample weight: as required by the cylinder capacity — record dry weight (W1). Procedure (Step-by-step) Fill the cylindrical measure in three approximately equal layers. Tamp each layer 25 times using the rounded end of the tamping rod. After the third layer, level off the surface using the tamping rod as a straight edge. Insert the plunger carefully so it rests level on the sample surface. Place the cylinder & plunger assembly on the compression testing machine. Apply load at a uniform rate of 4 tonnes per minute until the total load reaches 40 tonnes, then release the load. Remove crushed material and sieve through a 2.36 mm IS sieve; collect fines that pass the sieve. Weigh the portion passing 2.36 mm (W2). Repeat the test on a second sample and record both W2 values. Calculation Aggregate Crushing Value (ACV) is the percentage ratio of crushed fines to the total sample weight. Aggregate Crushing Value = (W2 / W1) × 100 Where: W1 = Total dry weight of sample W2 = Weight of material passing 2.36 mm IS sieve Report: Mean of two test results Results & Reporting Report the mean of the two test values as the final ACV for the aggregate sample. Include: Sample identification and date Apparatus used and calibration status W1 and W2 values for both trials and the mean ACV Any deviations from standard procedure Acceptance Limits Application Maximum ACV (%) Cement concrete pavements 30 Wearing surfaces 45 Frequently Asked Questions Why do we use a 2.36 mm sieve for fines? 2.36 mm is the standard IS limit for defining crushed fines in this test — it provides a consistent basis to compare strength characteristics across aggregate sources. What if my aggregate grading differs? If grading is outside the specified range (12.5–10 mm) use a representative fraction or follow the standard practice for coarse/fine fractions as specified in the relevant code. Notes & Best Practices Always run two trials and report the mean to reduce random error. Ensure the compression machine platen and the plunger are clean and parallel before applying load. Record ambient conditions and any visible degradation of sample during handling. Quick Checklist Aggregate: 12.5–10 mm Tamping: 25 blows/layer Loading: 4 t/min to 40 t Sieve for fines: 2.36 mm Acceptable ACV: <=30% (concrete pavements) Useful snippets <strong>ACV = (W2 / W1) × 100</strong> Use this procedure Related Aggregate Tests for Highway & Concrete Works Explore detailed test procedures, calculations and acceptance criteria as per IS, MoRTH & IRC specifications: ✅ Aggregate Impact Value (AIV) Test – Toughness of Aggregates ✅ Los Angeles Abrasion Test – Wear & Abrasion Resistance ✅ Aggregate Crushing Value (ACV) Test – Strength Evaluation ✅ Flakiness & Elongation Index Test – Shape Characteristics ✅ Water Absorption Test – Durability & Porosity Check 📌 Pro Tip: Use AIV, ACV, Los Angeles Abrasion, and Shape & Water Absorption Tests together to ensure aggregate suitability for bituminous layers & cement concrete as per MoRTH Section 400 & 500.

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