Marshall Mould Casting & Marshall Stability Test (MoRTH 2025 Guide)
This complete HTML guide explains mould casting using sieve-wise aggregate proportioning, sample preparation, Marshall Stability Test procedure, calculations, limits, and field tips.
Simple Explanation: How to Weigh Material for DBM Mould Casting
When preparing a DBM Marshall sample, you must weigh the correct amount of each aggregate size based on JMF percentages. Think of it like a recipe:
- Each sieve size = one ingredient
- Percentage retained = how much of that ingredient is needed
Materials Required
- Coarse aggregates
- Fine aggregates
- Mineral filler (cement/lime/stone dust)
- Bitumen (VG30 / VG40)
Example Sheet for Marshall Mould Casting
DBM MOULD CASTING PROCEDURE BY INDIVIDUAL SIEVE RETAINED MATERIAL
| IS Sieve (mm) | Passing % | % Retained | Weight for Different Bitumen % (g) |
|---|
| | | 4.00 | 4.25 | 4.50 | 4.75 | 5.00 | 5.25 | 5.50 | 5.75 | 6.00 |
|---|
| 26.5 | 100 | 0.0 | 0.0 |
| 19 | 98.1 | 1.9 | 22.8 | 22.7 | 22.7 | 22.6 | 22.6 | 22.5 | 22.4 | 22.4 | 22.3 |
| 13.2 | 72.1 | 26 | 312 | 311.2 | 310.4 | 309.6 | 308.8 | 307.9 | 307.1 | 306.3 | 305.5 |
| 9.5 | 61.5 | 10.6 | 127.2 | 126.9 | 126.5 | 126.2 | 125.9 | 125.5 | 125.2 | 124.9 | 124.6 |
| 4.75 | 44.3 | 17.2 | 206.4 | 205.9 | 205.3 | 204.8 | 204.3 | 203.7 | 203.2 | 202.6 | 202.1 |
| 2.36 | 37 | 7.3 | 87.6 | 87.4 | 87.1 | 86.9 | 86.7 | 86.5 | 86.2 | 86.0 | 85.8 |
| 1.18 | 25.9 | 11.1 | 133.2 | 132.9 | 132.5 | 132.2 | 131.8 | 131.5 | 131.1 | 130.8 | 130.4 |
| 0.6 | 17.6 | 8.3 | 99.6 | 99.3 | 99.1 | 98.8 | 98.6 | 98.3 | 98 | 97.8 | 97.5 |
| 0.3 | 12.3 | 5.3 | 63.6 | 63.4 | 63.3 | 63.1 | 62.9 | 62.8 | 62.6 | 62.4 | 62.3 |
| 0.15 | 8.4 | 3.9 | 46.8 | 46.7 | 46.6 | 46.4 | 46.3 | 46.2 | 46.1 | 45.9 | 45.8 |
| 0.075 | 3.8 | 4.6 | 55.2 | 55.1 | 54.9 | 54.8 | 54.6 | 54.5 | 54.3 | 54.2 | 54.1 |
| PAN | 2 | 1.8 | 21.6 | 21.5 | 21.5 | 21.4 | 21.4 | 21.3 | 21.3 | 21.2 | 21.2 |
| Filler | 0 | 2 | 24 | 23.9 | 23.9 | 23.8 | 23.8 | 23.7 | 23.6 | 23.6 | 23.5 |
Step-by-Step: DBM Marshall Sample Preparation
STEP 1 — Know Total Weight
- Total mix weight: 1250 g
- Total aggregates: ~1200 g
- Bitumen weight: 4–6%
STEP 2 — Convert % Passing → % Retained
Example:
- 13.2 mm retained = 26% → 312 g
- 9.5 mm retained = 10.6% → 127.2 g
STEP 3 — Formula
Weight = (% retained / 100) × total aggregate weight
STEP 4 — For Different Bitumen %
Aggregate reduces slightly with more bitumen.
STEP 5 — Weigh each sieve separately
- Keep separate bowls
- Add filler separately
- Add bitumen lastly
Marshall Stability & Flow Test – Step-by-Step Procedure (IS/ASTM) | Bituminous Mix Design
Reference Standards
| Standard | Description |
|---|
| IS: 1201 – 1220 | Methods for testing tar and bituminous materials |
| IS: 73 | Paving Grade Bitumen Requirements |
| ASTM D6927 | Marshall Stability and Flow Test |
| MoRTH Section 500 | DBM & BC Acceptance Criteria |
Objectives of the Marshall Test
- Determine Stability & Flow
- Determine OBC
- Evaluate VMA, VFB, density
- Ensure MoRTH/ASTM/IS compliance
Apparatus Required
- Marshall mould
- Compaction hammer
- Water bath (60°C)
- Marshall testing machine
- Flow meter
- Oven
- Sieves & balance
Sample Preparation (Bituminous Mix)
1. Heating
- Aggregates: 170–175°C
- Bitumen: 150–160°C
- Moulds: 120–140°C
2. Mixing
Mix uniformly with complete coating.
3. Filling
Filter paper → Pour mix → Level top.
4. Compaction
- 75 blows (heavy traffic)
- 50 blows (medium traffic)
5. Cooling & Extraction
Cool → Extract using jack.
6. Density Measurement
- Air weight
- SSD
- Water weight
Curing & Conditioning
Place in 60°C water bath for 30–40 min.
Marshall Stability & Flow Test Procedure
- Place sample in loading frame.
- Attach flow meter.
- Apply load @ 50.8 mm/min.
- Record stability & flow.
- Plot for OBC determination.
Marshall Calculations
Stability
Maximum load (kN).
Flow
Deformation at failure (mm).
Bulk Density
Density = Air wt / (SSD – Water wt)
Air Voids (Va)
Va = [(Gmm – Gmb) / Gmm] × 100
VMA
VMA = [1 − (Gmb × Ps / Gsb)] × 100
VFB
VFB = [(VMA − Va) / VMA] × 100
MoRTH — DBM Requirements (Table 500-11)
| Property | Viscosity / Grade | Modified Bitumen (Hot) | Modified Bitumen (Cold) | Test Method |
|---|
| Compaction Level | — | 75 blows each face | — |
| Minimum Stability (kN) | — | 12.0 | 10.0 | AASHTO T245 |
| Marshall Flow (mm) | — | 2.5–4 | 3.5–5 | AASHTO T245 |
| Marshall Quotient | — | 2.5–5 | — | MS-2 |
| Air Voids (Va) | 3–5% | MoRTH |
| VFB | 65–75% | MoRTH |
| Coating | 95% min | — | IS 6241 |
| TSR | ≥ 80% | — | AASHTO T283 |
| VMA | Refer MoRTH Table 500-12 | MoRTH |
Comparison — Standard vs Modified Marshall
| Parameter | Standard Marshall | Modified Marshall |
|---|
| Max Aggregate Size | 26.5 mm | 38 mm |
| Diameter | 101.6 mm | 152.4 mm |
| Blows | 50/75 | 112 (1.5×) |
| Batch Weight | 1200–1500 g | 4050 g |
| Flow | 2–4 mm | 3–6 mm |
Frequently Asked Questions
Q1: Minimum stability?
12 kN (hot), 10 kN (cold)
Q2: When to use Modified Marshall?
For aggregates > 26.5 mm
Q3: Air voids & VFB?
Va = 3–5%, VFB = 65–75%
Q4: VMA values?
See MoRTH Table 500-12
Summary
The Marshall Test determines the optimum bitumen content and mix strength. A properly prepared sample gives accurate, reliable results used for DBM and BC mix approval in national highway works.
