IRC 44:2017 is the Indian Standard (IRC) for guidelines for cement concrete mix design for pavements. This IRC code outlines the methodology for designing cement concrete mixes for pavements, focusing on achieving specific strength and durability requirements. It details the selection of constituent materials (cement, aggregates, water, admixtures), the estimation of mix proportions based on target mean strength, and the control of workability and other performance indicators. The code emphasizes achieving a durable and cost-effective concrete pavement by considering factors like aggregate gradation, water-cement ratio, and the use of supplementary cementing materials. Engineers will find guidance on trial mix preparation, testing procedures, and adjustments necessary for field implementation to ensure pavement longevity and performance.
This document provides comprehensive guidelines for the proportioning of materials for the design of cement concrete mixes specifically for pavement applications. It covers the principles, procedures, and recommended values for achieving the desired strength, durability, and workability characteristics of concrete used in road and highway pavements.
Mix design for cement concrete pavements. Strength, w/c, cement content, admixtures.
| Reference | Value | Clause |
|---|---|---|
| Concrete grade — minimum highway pavement | M40 | Cl. 4.1 |
| Concrete grade — minimum heavy traffic / NH | M40 (with high modulus of rupture) | Cl. 4.1 |
| Modulus of rupture — minimum 90-day | 4.5 N/mm² | Cl. 4.2 (Table 1) |
| Modulus of rupture — design 28-day | 4.0 N/mm² | Cl. 4.2 (Table 1) |
| Cement content — minimum (PCC pavement) | 360 kg/m³ | Cl. 4.3 (Table 2) |
| Cement content — maximum | 425 kg/m³ | Cl. 4.3 (Table 2) |
| Maximum w/c ratio | 0.45 | Cl. 4.3 (Table 2) |
| Slump — slip-form paving | 20–40 mm | Cl. 7.2 (Table 4) |
| Slump — fixed-form paving | 30–50 mm | Cl. 7.2 (Table 4) |
| Maximum aggregate size | 31.5 mm typical | Cl. 5.2 |
| Coarse aggregate — flakiness + elongation | ≤ 30 % combined | Cl. 5.2 (Table 3) |
| Coarse aggregate — Los Angeles abrasion | ≤ 30 % | Cl. 5.2 (Table 3) |
| Coarse aggregate — water absorption | ≤ 1 % | Cl. 5.2 (Table 3) |
| Cement type | OPC 43 or OPC 53 or PPC (IS 1489) | Cl. 5.1 |
| Air entraining — required | for freeze-thaw exposure (Himalayan) | Cl. 5.4 |
| Trial mixes — minimum number | 3 (with ± 0.02 w/c variation) | Cl. 6.4 |
| Sample frequency — flexural strength | 1 sample per 150 m³ or per day | Cl. 8.2 |
| Acceptance — 28-day mean flex strength | ≥ design + 0.825 × σ | Cl. 8.4 |
| Curing duration — minimum | 14 days (extended for blended cement) | Cl. 7.7 |
| Joint cutting — initial sawing time | 6–18 hours after placement | Cl. 7.6 |
IRC 44:2017 provides guidelines for cement concrete mix design for pavements. It complements IRC 58:2015 (rigid pavement design) by specifying the concrete mix parameters required to achieve the flexural strength and durability needed for pavement concrete.
You use IRC 44 when: - Designing concrete mix for highway rigid pavements - Specifying pavement concrete for new state / national highway projects - Developing mix designs for industrial concrete roads (port access, warehouses) - Preparing tender specifications for concrete pavement work - Validating contractor mix designs during project execution
IRC 44:2017 is distinct from IS 10262:2019 (general concrete mix design) because pavement concrete has specific requirements — flexural strength (not just compressive) is the design basis, and durability in de-icing salt exposure (not applicable in most India but required for hill stations) is specified.
Three key differences from IS 10262 building concrete:
1. Flexural strength is the design basis. Rigid pavement slabs bend under wheel loads; bottom-up cracking from flexural stress is the primary failure mode. Target flexural strength 4.5 MPa minimum for highway pavement per IRC 44, corresponding to M40 grade compressive.
2. Stricter aggregate gradation. Pavement aggregate must be cleaner, tougher, and graded more strictly than building aggregate. Angular coarse aggregate (basalt, granite) preferred over rounded (river gravel). Soundness, Los Angeles abrasion, and impact value tests per IS 2386 Parts 4-5.
3. Controlled cement content. Not too low (insufficient strength, durability), not too high (excess shrinkage, thermal cracking in pavement slab). IRC 44 specifies 350-400 kg/m³ cement for highway pavement concrete, with water-cement ratio 0.45-0.50.
Typical mix proportions per IRC 44: - Cement: OPC 43 or OPC 53 (M40 concrete target) - Water-cement ratio: 0.45-0.50 - Coarse aggregate: 20 mm nominal MSA, angular, soundness ≤ 12%, LA abrasion ≤ 35%, impact value ≤ 30% - Fine aggregate: Zone II or III per IS 383, preferably M-sand - Admixture: water-reducer / superplasticizer, 0.5-1.0% of cement weight - Air entrainment: 4-6% (for freeze-thaw zones, per IRC 44 Clause 5.3 — not mandatory for plain India)
Project: 50 MSA highway concrete pavement, 250 mm slab, design life 25 years. M40 pavement concrete per IRC 44:2017.
Step 1 — Target flexural strength: f_flex,target = 4.5 × 1.1 (10% buffer for site variability) = 4.95 MPa
f_ck,target (compressive) from f_flex = 0.7 × √f_ck: 4.95 = 0.7 × √f_ck → f_ck = 50 MPa target mean
Step 2 — Characteristic strength required: f_ck,char (for M40) = 40 MPa
Standard deviation for pavement concrete (IRC 44 Table 3): σ = 5 MPa
Target mean (IRC 44 Eq 3.1): f_ck + 1.65 × σ = 40 + 1.65 × 5 = 48.25 MPa
This is close to our 50 MPa design target. Use 50 MPa as the mix design target.
Step 3 — Water content and cement: For 20 mm MSA, slump 50 mm (pavement spec, less slump = drier mix), with superplasticizer: Water = 180 × 0.85 (admixture reduction) = 153 kg/m³
Water-cement ratio = 0.45 (per IRC 44 Table 4 for M40 pavement): Cement = 153 / 0.45 = 340 kg/m³
But check minimum! IRC 44 Clause 5.2 requires minimum cement 350 kg/m³ for highway rigid pavement.
Use Cement = 350 kg/m³. Adjust water: W = 350 × 0.45 = 158 kg/m³ (slightly higher than calculated, slump will be ~65 mm — accept).
Step 4 — Aggregate volumes: From mass-volume balance (concrete volume = 1 m³):
Volume of cement = 350 / 3,150 = 0.111 m³ Volume of water = 158 / 1,000 = 0.158 m³ Volume of entrained air = 0.015 (1.5%, lower than building) Volume of aggregates = 1.000 − 0.111 − 0.158 − 0.015 = 0.716 m³
For 20 mm MSA and Zone II fine aggregate, per IS 10262 Table A-3: coarse volume fraction = 0.62.
Coarse aggregate: 0.716 × 0.62 × 2,700 = 1,198 kg/m³ Fine aggregate: 0.716 × 0.38 × 2,650 = 721 kg/m³
Step 5 — Final mix (kg/m³): - Cement OPC 43: 350 - Water: 158 - Coarse aggregate (20 mm): 1,198 - Fine aggregate (Zone II or M-sand): 721 - Superplasticizer: 2.1 (0.6% of cement)
Mix ratio by mass: 1 : 2.06 : 3.42, W/C 0.45
Step 6 — Trial batch verification: Must test for: - 28-day compressive strength (3-cube sample) per IS 516 - 28-day flexural strength (3-beam sample) per IS 516 Part 2 - Slump per IS 1199 - Density ≥ 2,400 kg/m³
Target flexural at 28 days: ≥ 4.5 MPa (design minimum). If first trial gives 4.2 MPa, adjust cement or W/C and retrial.
Step 7 — Field mix adjustments: Allow for aggregate moisture correction, slump variation with ambient temperature, supplier consistency. Establish a tolerance band around the approved mix; typical variance ±5% on cement, ±10% on aggregate proportions acceptable.
1. Using IS 10262 building mix for pavement. Building mix targets compressive strength; pavement requires flexural strength. The ratio f_flex / f_c is 0.7 × √f_ck — a mix designed for compressive strength alone may fall short on flexural. Always verify flexural test result separately.
2. Inadequate aggregate quality tests. Pavement concrete sees extreme abrasion, impact, and weathering. Missing Los Angeles abrasion test (max 35%), impact test (max 30%), or soundness test (max 12%) leads to pavement wear-out in 10-15 years instead of 25-30.
3. Wrong cement content specification. Below 350 kg/m³: inadequate durability. Above 400 kg/m³: excessive shrinkage cracking. IRC 44 Clause 5.2 narrows the range — both limits matter.
4. Ignoring shrinkage / thermal cracking prevention. Pavement slabs crack from day-night temperature cycling, shrinkage, and sub-base friction. Mix design should minimize paste volume (fewer fines, lower cement), use angular aggregate (lower shrinkage), and specify proper joint spacing per IRC 58:2015.
5. Skipping trial batch flexural testing. Labs routinely test compressive strength (cube) but skip flexural (beam) test because beams are more expensive and time-consuming. For pavement mix, flexural IS the design basis — test it per IS 516 Part 2.
6. Using non-potable water. IS 456 Clause 5.4 + IRC 44 Clause 4.2 specify water quality. Seawater, turbid water, water with high chloride/sulphate is banned. Many rural pavement projects use locally-available water without testing — leads to long-term durability issues.
IRC 44:2017 is the current pavement mix design standard, updated from IRC 44:2008 primarily to align with IRC 58:2015 and incorporate SCM provisions (fly ash, GGBS).
Indian pavement concrete reality: - NH / expressway projects use IRC 44-compliant M40 mix with flexural strength 4.5-5.0 MPa. Ready-mix concrete preferred with batching plant QC. - State highway projects increasingly use IRC 44 specs but quality varies. Site-mixed concrete on smaller projects struggles with consistency. - Low-volume rural roads (village roads, PMGSY) use IRC SP 62:2014 specs — M25-M30, lower cement content — for economy.
Fly ash / GGBS in pavement mix (IRC 44 Clause 5.4): - Fly ash replacement up to 25% (PPC or OPC + fly ash): acceptable - GGBS replacement up to 35%: acceptable - Reduces cement cost and long-term chloride penetration - But early-age strength is slower — not ideal for fast-track projects - Curing period must extend (21 days vs 14 days for pure OPC)
A revision of IRC 44 is expected 2026-2027, likely adding: - Self-compacting concrete for pavement (faster construction, consistent finish) - Fiber-reinforced concrete provisions (crack control in thin slabs) - Sulphate resistance classes for inland-saline regions (Rajasthan, Kutch) - High-performance concrete (M60-M80) for specialty applications like toll plaza pavements
For any IRC 44 mix design submission, include: 1. Target flexural strength with 10% buffer 2. Trial batch plan with 3 cube + 3 beam samples each 3. Aggregate source approval with test certificates 4. Cement mill certificates 5. Field mix tolerance specification
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Target Mean Strength Calculation | |||
| Maximum Water-Cement Ratio | |||
| Minimum Compressive Strength | |||
| Aggregate Quality Requirements |