The Marshall test method allows engineers to design effective, durable, and safe roads. By conducting the test, engineers are able to gauge the performance of an asphalt mixture and how much load it will be able to support.
Find out more about the Marshall method and the five basic steps to perform it.
An Introduction to the Marshall Test Method
The Marshall test method guides engineers to mix the ideal amount of asphalt binder at a density that satisfies the requirements for stability and flow value.
Although additional asphalt and bitumen tests have been created and improved alongside the Marshall test method, the Marshal method is still one of the most popular techniques for designing asphalt mixes worldwide.
Read More: Non-Destructive Testing (NDT) Methods & Benefits In Malaysia
The 5 Basic Steps of the Marshall Test Method
The steps of the Marshall Test Method are as the following:
1. Aggregate selection
To summarise, bitumen and aggregates are the two basic ingredients that make up asphalt. The former serves as a liquid binder that binds the aggregate mixture together and produces the finished product known as asphalt.
To choose an aggregate, you must test several physical characteristics, including durability, specific gravity, absorption, particle shape, gradation, and size. If you have more than one source of aggregates, conduct trial blending calculations until the ideal mix design is reached.
2. Asphalt binder selection
For the second step, most professionals will use the Superpave PG binder system as the Marshall test lacks a binder evaluation and selection procedure. Then, the engineers will determine the link between temperature and viscosity by performing some tests on the asphalt binder.
3. Sample preparation (including compaction)
The Marshall test method generally necessitates a variety of trial mixtures with varying amounts of binder content to find the appropriate bitumen-aggregate blend for an application.
There will typically be five bitumen-aggregate blends and three binder levels, bringing the total to 15 specimens. After consideration, engineers can choose the blend they believe best caters to the specific conditions to produce the ideal asphalt binder content.
Next, the specimens are heated to the predicted compaction temperature as part of sample testing. The samples are then compacted using a Marshall compaction tool, often a hammer, under continuous pressure.
4. Stability testing
At this step, the true Marshall test begins. Engineers can determine the maximum load a specific blend can support using Marshall stability test instruments like the Hveem stabilometer.
Specimens are loaded at 50.8 mm per minute (or approximately two inches per minute), and this gradually increases until the maximum capacity is reached. Also, a dial gauge will record the specimen’s plastic flow as a result of loading.
5. Density and voids calculations
Lastly, carry out gravity and air void tests to ensure the specimens comply with local and international standards. By doing this, you’ll obtain the ideal bitumen, aggregate, and air quantities, resulting in a top-notch finished product.
Prominent Asphalt & Bitumen Testing Services in Malaysia
High-quality asphalt and bitumen are essential in the construction of roads, highways, and more. As such, we offer various asphalt and bitumen testing services to ensure that your asphalt binder component fulfils the standards set forth for the construction of roads.
