Sample Preparation for Marshall Compaction Test – ASTM D1559
A. Marshall Mix Design
Prepare representative samples of the field aggregates by following the procedure below:
(a) Dry the aggregate in an oven for approximately eighteen hours a 1050C to 1100C. Separate the aggregate into the individual specified sieve sizes by dry sieving. The sieve sizes will be established by the specified aggregate type.
(b) Recombine individual aggregate fractions in correct proportions to obtain the average stockpile gradation which is determined during the crushing of the aggregate. Proportioning will be for approximately 1200 g specimens.
(c) Combine trial percentages of each size, then run a wet sieve and compare the result to the stockpile average. Adjust the proportions of each size and repeat the procedure until the desired gradation is achieved. Use the final percentages of each size to produce Marshall specimens. If fillers or blenders are to be used in the mix, actual samples of field fillers/blenders must be used.
Place the asphalt cement in an oven for approximately two hours for pre-heating. The temperature of the asphalt cement should not exceed 1100C during the preheating.
B. Test Procedure
B.1. Marshall Mix Design
Weigh into separate pans for each test specimen the amount of each aggregatesize fraction required to produce a batch that will result in a compacted specimen 63.5 + 1.3 mm in height. Usually 1200 g of aggregate is required. Place the pans on the hot plate or in the oven. Remove one pan at a time from the oven and place on a hot plate. Form a crater in the dry blended aggregate and weigh the pre-heated required amount of asphalt cement into the mixture. Mix the aggregate and asphalt thoroughly, maintaining the required mixing temperature. Continue mixing until all particles are well coated. Remove pan and mix from the hot plate and continue mixing until the mix cools to the required compaction temperature. This is the temperature which results in an asphalt viscosity of 280 cst. Proceed with specimen preparation as described in B.3.
Compaction Procedure
B.2. Field Mix Specimens
Collect samples. Adjust the temperature of the mix for each specimen to the required compaction temperature.
B.3. Compaction Procedure
Place the entire batch in a previously prepared mold assembly, spade the mixture vigorously with a heated spatula or trowel 15 times around the perimeter and 10 times over the interior. Remove the collar and smooth the surface of the mix with a trowel to a slightly rounded shape. Temperatures of the mix immediately prior to compaction shall be within the limits of the specified compaction temperature.
Place two filter papers on the surface of the mix and replace the mold collar. Place the mold assembly on the compaction pedestal in the mold holder and unless otherwise specified, apply 50 blows with the compaction hammer. During compaction the operator will hold the axis of the compaction hammer by hand as nearly perpendicular to the base of the mold assembly as possible. Remove the base plate and collar and reverse and reassemble the mold. Apply the same number of compaction blows to the face of the reversed specimen. When compaction is completed, extrude the sample from the compaction mold. Carefully transfer the specimen to a smooth, flat surface and allow it to cool to ambient temperature before testing. The specimen should be extruded using a hydraulic jacking device to provide a gentle and constant pressure. Using hammers or other methods of impact loading to remove specimens from the mold is not acceptable. Mixtures that lack sufficient cohesion to retain the required cylindrical shape on removal from the mold immediately after compaction should be cooled in the mold in air until sufficient cohesion has developed to result in the proper cylindrical shape. Marshall briquettes which will be tested for stability and flow characteristics will be allowed to stand at room temperature overnight before any testing is conducted on them. The compacted specimen should be between 62.2 and 64.8 mm high. If the specimens are outside this range, adjust the amount of asphalt mix in subsequent tests.
Standards: EN 12697-10, 12697-30, comparable to: BS 598:107
This ruggedly constructed apparatus automatically compacts the bituminous sample and stops off the motor after the preset number of blows has been completed on the automatic digital display counter.
The trip mechanism is structured so that the sliding hammer falls at the same height at every blow.
The mould is held in position by a fast clamping device.
The compactor includes a vibrated concrete base where a laminate hardwood block is mounted.
Total weight of the compaction hammer (Rod + Foot + Sliding mass): 7850 ± 50 g
Sliding mass weight: 4535 ± 15 g
Free fall height: 457 ± 5 mm
Blow frequency: 50 blows in 55/60 seconds
When opened it stops automatically and cannot operate.
The control panel can be wall fixed or placed on a bench.
All moving parts are quickly/easily accessible for maintenance.
The compactor is supplied complete with mould.
Power supply: 230V 1ph 50Hz 300W
Dimensions: 500x500x1890 mm
Weight: 220 kg approx.