In this report, a summary of hands-on experience will be presented regarding the hot mix asphalt (HMA) preparation by Marshall method: Mixing, Compaction, and Stability and Flow.

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Summary of Hot Mix Asphalt Preparation by Marshall Method: Mixing,

Compaction, and Stability and Flow

Ahmed Hemida, amhbnc@mst.edu

Ph.D. Candidate, Department of Civil, Architectural, and Environmental Engineering, Missouri University of Science

and Technology (Missouri S&T), USA.

In this report, a summary of hands-on experience will be presented regarding the hot mix asphalt

(HMA) preparation by Marshall method: Mixing, Compaction, and Stability and Flow.

Mixing Process

Oven-dry a sufficient amount of different categories of aggregate (coarse and fine) at 110 ±5℃

until a constant mass achieved

Preheating different aggregates before combination

Determine the mixing and compaction temperatures using a rotational viscometer according to

ASTM D4402

Rotational Viscometer: Preheating the viscometer chamber, container, spindle, and asphalt binder to the initial testing

temperature (e.g., 135℃)

Mix the oven-dry aggregates with respect to the specification limits (e.g., BP-1) according to

MoDOT Section 401: Plant Mix Bituminous Base and Pavement, and place such a mix in the oven

at the mixing temperature plus no more than 28 ℃

Prepare the Marshall hammer and mold

o Clean

o Preheated at 95-150℃

Preheated Marshall Hammer, 95– 150℃

Preheat the mixing bowls to the mixing temperature

Preheat the asphalt cement, no more than one hour at the mixing temperature

Preheated Marshall Molds, asphalt binder, and mixing bowls

Weigh a sufficient amount of the mixed aggregate in the mixing bowl, and add the asphalt cement

to achieve the desired asphalt content in such a batch

Use a mechanical mixer (recommended) to mix aggregate with asphalt cement for about three

minutes or until you make sure that the asphalt has coated all aggregate particles (all black)

Sma ll Asphalt Mixer

Compaction Process

Mold Packing

o Place a paper disk on the mold bottom

Paper Disk

o Place the required asphalt mix amount in the mold (approximately 1.2 kg) with the collar

o Use a heated spatula/trowel to level the mix surface in the mold

o Place a paper disk on the top of the mix surface in the mold

Fix the mold in the mold holder

Marshal Compaction Base

Choose the required number of blows according to the traffic condition (35 blows for light traffic,

50 blows for medium traffic, and 75 blows for heavy traffic) with a free perpendicular fall by the

standard hummer from 457 mm height

Remove the base plate and the collar

Reverse and reassemble the mold (upside down)

Apply the same procedures for the reversed specimen

Rem ove the base plate and the paper disks

Cool down the specimen at room temperature in the mold (takes about 30–40 min)

Tak e the specimen (core) out of the mold by using an extrusion jack

Extrusion Jack

Place the core on a flat surface and leave it to cool down overnight before any consecutive tests

Compacted Asphalt Mixes: Cores

Marshall Stability and Flow Test

Marshall Stability and Flow Test Setup

Objective – To measure the resistance of plastic deformation of cylindrical specimen of a bituminous

mixture when the sample is loaded at a rate of loading of 5 cm/min.

Procedures

Recognize the specimen height to use the proper stability correlation factor according to ASTM

D6927

Place the mold in a water bath at 60 ℃ for 30–40 min

Set the compression machine with the ring and flowmeter on the zero set

All specimens must be tested with the same assembly. The specimen is supposed to have a diameter of

101.6±0.25 mm. otherwise, determine the initial and final readings of the flow.

Keep the inside surfaces of the testing heads clean before testing

Keep them at 21.1– 37.8 ℃ (the ro o m temperature is ok)

Make sure " no-load" position

Take the core from the water bath and dry its surface with a towel

Center the core on the lower head, and fit the upper head on it

Place the flowmeter over the marked guide rod

Apply a rate of loading of 51 mm/min until failure (max load obtained)

Marshall stability value = max force in Newton

In case of no auto flowmeter records, before load begins to decrease, remove immediately, take

readings, and record manually

The reading, in that case, is the flow value (units of 0.25 mm)

Example: a deformation of 3.8 mm corresponds to a flow of 15.

Note: the stability and flow test have to be done via 30 seconds after taking the core from the water bath.

Will be updated upon any adjustments required….

References

1. https://www.modot.org/sites/default/files/documents/2019_MO_Std_Spec_Gen_Supp_%28July

%202019%29_1.pdf.

2. ASTM International. D4402/D4402M-15 Standard Test Method for Viscosity Determination of

Asphalt at Elevated Temperatures Using a Rotational Viscometer. West Conshohocken, PA;

ASTM International, 2015. doi: https://doi.org/10.1520/D4402_D4402M-15.

3. ASTM International. D6926-16 Standard Practice for Preparation of Asphalt Mixture Specimens

Using Marshall Apparatus. West Conshohocken, PA; ASTM International, 2016.

doi: https://doi.org/10.1520/D6926-16.

4. ASTM International. D6927-15 Standard Test Method for Marshall Stability and Flow of Asphalt

Mixtures. West Conshohocken, PA; ASTM International, 2015. doi:

https://doi.org/10.1520/D6927-15.

ResearchGate has not been able to resolve any citations for this publication.

D6926-16 Standard Practice for Preparation of Asphalt Mixture Specimens Using Marshall Apparatus

  • Astm International

ASTM International. D6926-16 Standard Practice for Preparation of Asphalt Mixture Specimens Using Marshall Apparatus. West Conshohocken, PA; ASTM International, 2016. doi: https://doi.org/10.1520/D6926-16.

D4402/D4402M-15 Standard Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational Viscometer

  • Astm International

ASTM International. D4402/D4402M-15 Standard Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational Viscometer. West Conshohocken, PA;

D6927-15 Standard Test Method for Marshall Stability and Flow of Asphalt Mixtures

  • Astm International

ASTM International. D6927-15 Standard Test Method for Marshall Stability and Flow of Asphalt Mixtures. West Conshohocken, PA; ASTM International, 2015. doi: https://doi.org/10.1520/D6927-15.