Flattening test

Asphalt mix compression test

The Asphalt Mix Compression Test is a laboratory test that is used to determine the compressibility of asphalt mix samples. This test allows engineers and construction practitioners to properly evaluate the compaction characteristics of asphalt mix for particular mix design, construction and pavement structure requirements. The test is carried out on cylindrical specimens that are straight-sided and short in length. It is a type of non-destructive evaluation (NDE) test and does not require destructive sampling.

The Asphalt Mix Compression Test involves applying force to a sample of asphalt mix at a specific rate of loading and measuring the samples response to that force. The applied force is typically in the form of a hydraulic jack and the stress being applied is usually maintained at a predetermined rate. The sample is placed in a container known as a Marshall frame which is designed to hold the specimen while measuring changes in size.

The sample is normally placed between two metal plates which form the bottom and top of the Marshall frame and the test piece is then compressed between the two plates with a series of strokes. The goal of the test is to measure the changes in height, thickness and weight of the test piece as force is applied. These measurements provide indications of the compressibility characteristics of the asphalt mix.

The Asphalt Mix Compression Test is usually conducted on cylindrical test specimens that are 4 inches (102 mm) wide and 2 inches (50 mm) high. The length of the specimen varies from 3 to 5 inches (75-125 mm) depending upon the intended usage of the asphalt mix. The specimen is normally placed between two metal plates that are 1 inch (25 mm) thick. A hydraulic jack is used to apply the load at a specific rate of strain. The maximum compressive load is either 5,000 or 10,000 lbf (4500-9000KN).

The test is usually divided into four phases: pre-loading, loading, post-loading and disassembly. During pre-loading, the specimen is placed into the Marshall frame and the height and thickness of the specimen is verified in order to ensure accuracy. During the loading phase, the hydraulic jack is used to apply the force and the rate of strain is monitored. The post-loading phase is used to verify the final height and thickness of the specimen along with any deformation that may have occurred. Finally, the specimen is removed from the Marshall frame and the results are interpreted and analyzed.

The data produced from the Asphalt Mix Compression Test is used to evaluate the compressibility of asphalt mixes and to characterize the materials in terms of their compressibility characteristics. The results can be used to evaluate the overall quality of the asphalt mix and to assess the suitability of a particular asphalt mix for a given application. Additionally, the results can be used to try to determine the mix design adjustments that may be necessary in order to achieve better performance characteristics.

Compressive test is a kind of test method of material structural strength, mainly used in metal materials. According to the test method, the specimen is placed in the middle of the upper and lower plates, and the upper and lower plates clamp the specimen at a certain pressing speed and a certain pressure, and the compressive strength is measured by the reinforcement pressure or deformation of the specimen.

For metal materials, when performing a compressive test, the commonly used testing machine is an electronic universal testing machine, which can realize accurate testing and high test efficiency, and at the same time, parameter control display and data acquisition can also control the test procedure. In addition, for materials that require high accuracy, professional strain sensors can also be used, which can achieve high accuracy and fast data acquisition.

In the test process, the operator should pay attention to the uniformity and stability of the specimen, control the speed of the upper and lower plates, ensure the normal pressure, observe whether the deformation process of the specimen is stable, and control the entire test process. If the test conditions are not good or the specimen quality is poor, it is easy to cause incomplete data or even false test, which will affect the accuracy of the results, so it is not advisable to use compressive test for materials with larger variability.