Engineer / Supervisor
- Deploy manpower, machinery, and materials as per plan.
- Execute work as per drawings and specifications.
- Maintain quality standards and site tolerances.
- Ensure safety compliance and housekeeping.
- Coordinate inspections with QA/QC and Consultant.
Land Surveyor
- Carry out setting out, alignment, and level checks.
- Maintain benchmarks and control points.
- Prepare and submit survey records.
- Establish reference points, benchmarks, and control points.
- Carry out setting out as per required levels and alignment.
- Check and record finished levels.
- Coordinate with Consultant for survey verification and approvals.
Material Manager
- Ensure availability of approved materials.
- Verify material quality before use.
- Maintain stock and issue records.
Safety Supervisor
- Ensure PPE compliance and safety implementation.
- Conduct toolbox talks.
- Identify hazards and take corrective actions.
- Ensure worker and site safety.
Helpers / Skilled Workers
- Assist in spreading, leveling, and compaction.
- Follow supervisor instructions.
- Maintain tools and cleanliness.
Material Manager
- Implement quality procedures as per approved Quality Plan.
- Ensure all materials meet specification requirements.
- Arrange and conduct required laboratory and field tests.
- Maintain test reports, records, and material documentation.
Safety Supervisor
- Ensure all activities are executed as per Project Safety Plan.
- Monitor use of PPE and safe working practices.
- Identify hazards and implement preventive measures.
- Ensure safe working environment for all personnel.
Materials
- Aggregates shall be produced from a multi-stage crushing and screening plant.
Physical Requirements
- Aggregates for WMM shall conform to grading requirements as per MoRTH Table 400-13.
- Los Angeles Abrasion Value ≤ 35% OR Aggregate Impact Value ≤ 30%.
- Combined Flakiness & Elongation Index ≤ 35%.
- Plasticity Index (PI) ≤ 6%.
- If Water Absorption > 2%, Soundness Test shall be conducted.
Table 400-11: Grading Requirements for Wet Mix Macadam
| IS Sieve Designation | % Passing by Weight |
|---|
| 53.00 mm | 100 |
| 45.00 mm | 95 - 100 |
| 26.50 mm | - |
| 22.40 mm | 60 - 80 |
| 11.20 mm | 40 - 60 |
| 4.75 mm | 25 - 40 |
| 2.36 mm | 15 - 30 |
| 600 Micron | 8 - 22 |
| 75 Micron | 0 - 5 |
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Wet Mix Macadam (WMM) – Construction Operations, Procedure & Compaction
Construction Operations
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Preparation of Base: The surface of the sub-base to receive the Wet Mix Macadam course shall beprepared to the specified grade and camber and cleaned of dust, dirt and other extraneous material. Any ruts or soft yielding places shall be corrected in an approved manner and rolled until firm surface is obtained.
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Provision for Lateral Confinement of Aggregates: While constructing WMM, arrangement shall be made for the lateral confinement of wet mix. This shall be done by laying materials in adjoining shoulders along with that of wet mix macadam layer and following the sequence of operations described in Clause 404.3.3.
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Preparation of Mix: WMM shall be prepared in an approved mixing plant of suitable capacity having provision for controlled addition of water and forced/ positive mixing arrangement likepug mill or pan type mixer of concrete batching plant.The plant shall have following features:
- a. Cold aggregates with minimum four bin feeders with variable speed motor
- b. Vibrating screen for removal of oversize aggregates
- c. Conveyor Belt
- d. Controlled system for addition of water
- e. Forced/positive mixing arrangement like pug-mill or pan type
- f. Centralized control panel for sequential operation of various devices and precise process control
- g. Safety devices
Optimum moisture for mixing shall be determined in accordance with IS:2720 (Part-8) after replacing the aggregate fraction retained on 22.4 mm sieve with material of 4.75 mm to 22.4 mm size. While adding water, due allowance should be made for evaporation losses. However, at the time of compaction, water in the wet mix should not vary from the optimum value by more than agreed limits. The mixed material should be uniformly wet and no segregation should be permitted.
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Spreading of Mix: Immediately after mixing, the aggregates shall be spread uniformly and evenly upon the prepared sub-base in required quantities. In no case shall these be dumped in heaps directly on the area where these are to be laid nor shall their hauling over a partly completed stretch be permitted.
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Compaction: After the mix has been laid to the required thickness, grade and cross-fall/camber the same shall be uniformly compacted to the full depth with suitable roller. If the thickness of single compacted layer does not exceed 100 mm, a smooth wheel roller of 80 to 100kN weight may be used. For a compacted single layer up to 200 mm, the compaction shall be done with the help of vibratory roller of minimum static weight of 80 to 100kN with an arrangement of adjusting frequency and amplitude. The speed of the roller shall not exceed 5km/h.
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Setting & Drying: After final compaction of wet mix macadam course, the road shall be allowed to dry for24 hours.
Procedure
- Wet mix macadam shall be prepared, as per the approved design proportion, in the pug mill plant with controlled addition of water.
- Gradation of the mix shall be checked as the production starts for the days the site laboratory itself.
- Generally 1.0 to 2% extra moisture shall be maintained in the mix to compensate the evaporation losses depending upon the lead and ambient temperature.
- Mix shall be transported from the plant to the laying site dumpers.
- Water shall be sprinkled on the entire GSB surface, before placing the WMM.
- Single layer thickness shall be maximum of 150mm and this can be increased to 200mm based on site trail and with the approval of engineer.
- Before laying and spreading of material the shoulder on both sides shall be constructed in avarice. This will laterally confine the wet mix macadam while compacting.
- The wet mix shall be spread uniformly and evenly upon the prepared granular sub base by a paver finisher /motor grader with the approval of engineer.
- The required camber, grade, and thickness shall be checked. The high and low spots are to rectified by removing or adding new material.
- The number of heavy vibratory passes shall be established after doing trail stretch to achieve required density.
- Vibratory pass shall overlap1/3 of preceding pass. And make sure the speed of the roller shall not exceed 5km/hr. the places not accessible to roller shall be compacted with mechanical tampers or by a plate compactor.
- The moisture content of wet mix at the time of compaction shall be between 85% to 115% of OMC.
- All the depressions and segregated portions if any will be rectified during initial rolling itself.
- After the rolling is completed the stretch is to be tested for degree of compaction with respect of MDD of design mix of WMM.
- Field compaction test shall be conducted as per MoRT&H clause No.406.3.5
Detailed Compaction
After the mix has been laid to the required thickness grade and cross fall /camber the same shall be uniformly compacted to the full depth with vibratory roller. For a compacted single layer up to 200mm, the compaction shall be done with the help of vibratory roller of minimum static weight of 80 to 100 KN Equivalent vibratory roller.
The speed of the roller shall not exceed 5km/hr in portions having unidirectional cross fall/super-elevation, rolling shall commence from the lower edge and progress gradually towards the upper edge.
Thereafter roller should progress parallel to the center line of the road, uniformly overlapping each preceding track by at least one third width until the entire surface has been rolled. Alternate trips of the roller shall be terminated in stops at least I m away from any preceding stop.
In portions in camber, rolling should begin at the edge with the roller running forward and backward until the edge have been firmlycompacted. The roller shall then progress gradually towards the center parallel to the center line of the road uniformly overlapping each of the preceding track by at least one-third width until the entire surface been rolled.
Any displacement occurring as a result of reversing of the direction of a roller or from any other cause shall be corrected at once as specified and/or removed and made good along forms, kerbs, walls or other places not accessible to the roller, the mixture shall be thoroughly compacted with mechanical tampers or a plate compacter.
Skin patching of an area without scarifying the surface to permit proper bonding of the added material shall not be permitted. Rolling should not be done when the sub grade is soft or yielding or when it causes a wave like motion in the sub-base base courses or sub grade. If irregularities develop during rolling which exceed 12 mm when tested with a 3 meter straight edge, the surface should be loosened and permitted material added or removed as required before rolling again so as to achieve a uniform surface conforming to the desired grade and cross fall. In no case should the use of unmixed material be permitted to make up the depression rolling shall be continued till the density achieved is at least 98 percent of the maximum dry density for the material as determined by the method outlined in IS 2720 part-8.
After completion, the surface of any finished layer shall be well-closed, free from movement under compaction equipment or any compaction planes, ridges, cracks and loose material. All loose segregated or otherwise defective areas shall be made good to the full thickness of the layer and re compacted.
- Surface level will be maintained as per table no 900-1. And recorder in the specified format.
- All the field density readings/results will be recorded in the specified format.
- Any ratification in WMM layer will be done after scarifying the layer proper bonding.
Acceptance Criteria
- The field dry density shall be more than 98% of MDD.
- The tolerance on the surface level shall be +10mm to -10mm
- The top width shall be as per drawing +25mm
| Layer | Inspection Stage | Test / Parameter | Standard | Frequency | Acceptance Criteria |
|---|
| Wet Mix Macadam (WMM) / Cement Treated Base (CTB) | Inspection at Source | Aggregate Impact Value | IS: 2386 (Part 4) | 1 Test / 1000 m³ | 30% (Max) |
| Combined Flakiness & Elongation Index | IS: 2386 (Part 1) | 1 Test / 500 m³ | 35% (Max) |
| Water Absorption Value | IS: 2386 (Part 3) | As & when Required | 2% (Max) |
| Soundness Test (If water absorption value more than 2%) | IS: 2386 (Part 5) | As & when Required |
12% max with Sodium Sulphate
18% max with Magnesium Sulphate |
| Gradation | IS: 2386 (Part 1) | 1 Test / 200 m³ | | IS Sieve | % Passing |
|---|
| 53 mm | 100 | | 45 mm | 95 – 100 | | 22.4 mm | 60 – 80 | | 11.2 mm | 40 – 60 | | 4.75 mm | 25 – 40 | | 2.36 mm | 15 – 30 | | 600 micron | 8 – 22 | | 75 micron | 0 – 5 |
MoRTH 5th Revision Table 400-13 |
| Plasticity Index | IS: 2720 (Part 5) | 1 Test / 200 m³ | 6% (Max) |
| Abrasion Value | IS: 2386 (Part 4) | As & when Required | 40% (Max) |
| % Age of Fractured Face | IS: 2386 (Part 1) | As & when Required |
90% material retained on 4.75 mm sieve shall have at least 2 fractured faces |
| Modified Proctor | IS: 2720 (Part 8) | Every Month | As per MoRTH Specification |
| In-process Inspection | Control of Compaction (Field Density) – Sand Replacement Method | IS: 2720 (Part 28) |
0 – 1000 m² = 1 Set
1 Set = 3 Tests | 98% (Min.) |
| Control of Compaction (Field Density) – Nuclear Density Gauge Method | AASHTO T310 |
1 – 1000 m² = 2 Sets
1 Set = 3 Tests | 98% (Min.) |
| Control of Compaction (Field Density) | IS: 2720 (Part 28) | Each & every layer | As per MoRTH 5th Rev. Clause 903.2.2 |
| Acceptance Criteria | Tolerance in Surface Level | Standard Survey Practice | As per MoRTH Specification | Machine Laid ±10 mm |
| Surface Regularity | IRC: SP:16 | As & when Required | 8 mm |
| Strength of Concrete | IRC: 37-2012 | Minimum 3 Samples for Each Day Work | 4.5 – 7.0 MPa at 7 Days |
Inspection Plan & Testing
| S.No | Activity | Inspection | Testing | Remarks |
|---|
| 1 | GSB Top Approval | Yes | Yes | Joint level & density check |
| 2 | Spreading | Yes | - | Method control |
| 3 | Final Layer | Yes | Yes | Joint survey record |
| 4 | Density Check | Yes | Yes | After compaction |
Safety Measures
- No person shall travel on loaded dumpers during transportation.
- Material spillage shall be cleared immediately.
- Water tanker sprinkler system shall be properly maintained to avoid potholes.
- All safety practices shall comply with approved EHS Plan.
Top 10 FAQs – WMM
- What is WMM? Base layer of flexible pavement, mixed with water, compacted to dense mass per MoRTH 406.
- Purpose of WMM? Stable, well-drained foundation for bituminous layers.
- Materials? Crushed stone aggregates, LA ≤40%, Flakiness ≤35%.
- Grading? MoRTH Table 400-13, continuously graded.
- OMC? Determined by modified Proctor (IS:2720 Pt 8).
- Mixing method? Mechanical plant with controlled water, uniform mixing.
- Compaction requirement? ≥98% MDD using vibratory roller.
- QC tests? Aggregate impact, grading, flakiness, PI, field density per Table 900-3.
- Surface tolerance? Longitudinal ±15 mm, Cross slope ±0.3%.
- Minimum layer thickness? 75–200 mm per lift; multiple lifts if thicker.
