Pavement Mix Design Calculator
Optimized Mix 2026 — Rigid Pavement PQC, DLC Sub-base & Concrete Shoulder: Modulus of Rupture Design, IRC:58:2015 Compliance, IS 10262:2019 Absolute Volume, Low Slump for Slip-Form Paving & AEA for Freeze-Thaw
PQC — Pavement Quality Concrete
DLC Sub-base
MR ≥ 4.5 MPa
IRC:58:2015
IS 10262:2019
Slip-Form Paving
AEA Freeze-Thaw
🛣️ Pavement Concrete — Design Basis & Key Differences from Structural Concrete
IRC:58:2015
IRC:SP:62 (DLC)
IS 10262:2019
IS 516:1959 (Beam Test)
MORTH Spec. 2013
Rigid pavement concrete (PQC — Pavement Quality Concrete) is governed by an entirely different design criterion from structural building concrete. While structural concrete is designed to a compressive strength target (fck), PQC is designed to a Modulus of Rupture (MR) target — typically MR ≥ 4.5 MPa at 28 days per IRC:58:2015. Compressive strength is measured as a quality check but is not the governing design parameter.
This difference has profound implications for mix design — a mix achieving 40 MPa cube strength but only 3.8 MPa MR fails the pavement design criterion. PQC also uses very low slump (15–50mm for slip-form paving), larger aggregate size (31.5mm per IRC:58), and must consider air entrainment for Himalayan freeze-thaw exposure. The DLC sub-base beneath PQC uses an entirely separate, much leaner mix.
🛣️ PQC vs Structural Concrete — 5 Key Differences
1. Design Criterion: MR ≥ 4.5 MPa governs — not fck. Test by IS 516 beam (150×150×700mm).
2. Slump: 15–50mm for slip-form; 50–75mm for manual/highway paving. Much stiffer than structural.
3. Aggregate Size: IRC:58 specifies 31.5mm nominal max size for PQC — larger than most structural work.
4. Air Entrainment: Required in freeze-thaw zones (Himalayan highways) — 4.5–6.5% air target.
5. Joint Design: Transverse joints at 4.5–5m spacing; longitudinal joints at lane edges; dowel bars at transverse joints (IS 14595).
Step 1 — Select Pavement Layer Type
🛣️
PQC — Pavement Quality Concrete
MR ≥ 4.5 MPa | Slump 15–50mm | IRC:58
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DLC — Dry Lean Concrete Sub-base
≥ 10 MPa cube | Slump 0–25mm | IRC:SP:62
↔️
Concrete Shoulder / Median
MR ≥ 3.5 MPa | Slump 25–75mm
PQC — Pavement Quality Concrete
Top wearing course of a rigid pavement. Must achieve MR ≥ 4.5 MPa at 28 days (IRC:58:2015 Cl.7.1). Typical slab thickness 250–350mm for national highways. Placed by slip-form paver (preferred) at 15–50mm slump or by manual/fixed-form at up to 75mm. Aggregate: 31.5mm nominal max size per IRC:58.
Step 2 — Mix Design Parameters
Project Parameters
Used for batch quantity calculation
IRC:58 recommended 250–350mm for NH
Design & Environment
Cement & Aggregates
PQC slip-form: WRA or none only. PCE can cause stickiness in slip-form.
Ready to Calculate
Select pavement type, enter project and material parameters above, then click Calculate Pavement Mix. Results include MR prediction, IS 10262:2019 proportions, IRC:58 compliance, DLC sub-base design, batch quantities for your road project, and air entrainment for freeze-thaw zones.
📋 IRC:58:2015 PQC Concrete Requirements — Reference Table 2026
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| Parameter | IRC:58:2015 Specification | MORTH 5th Revision | Remarks |
|---|---|---|---|
| Minimum Flexural Strength (MR) | ≥ 4.5 MPa at 28 days | ≥ 4.5 MPa at 28 days | Governs slab design — 3-point beam test IS 516 |
| Equivalent Compressive Strength | ≈ M40 cube (30–45 MPa range) | M40 minimum | MR ≈ fck^0.5 × 0.7 (empirical correlation) |
| Maximum w/c Ratio | 0.45 | 0.45 | Lower w/c improves MR significantly |
| Minimum Cement Content | 360 kg/m³ | 360 kg/m³ | Higher cement improves flexural strength |
| MSA (Nominal Max. Aggregate Size) | 31.5mm | 31.5mm (some 25mm) | Larger MSA reduces cement demand; interlock in slab |
| Slump at Point of Placement | 15–50mm (slip-form) | Up to 75mm (manual) | Very low slump essential for edge stability in slip-form |
| Minimum Cover (to reinforcement) | 40mm (welded mesh in JRCP) | 40–50mm | Plain jointed pavements (JPCP) have no reinforcement except dowels |
| Air Entrainment | 4.5–6.5% (freeze-thaw zones) | As required by climate | Mandatory above 1500m altitude in Himalayas |
| Joint Spacing (transverse) | 4.5–5.0m (max) | 5.0m (max) | Shorter spacing reduces thermal cracking but increases joints |
| Curing Method & Duration | Curing compound THEN water curing 14 days | White pigmented compound immediately after finishing | PQC surface evaporation in open conditions — compound curing first 2 hours critical |
| Minimum DLC Sub-base Strength | ≥ 10 MPa cube at 28 days | ≥ 10 MPa | DLC provides rigid uniform support for PQC slab |