The Mastic Asphalt Mixture Penetration Test is an important laboratory method used to evaluate the deformation behavior and structural stability of mastic asphalt under specified temperature and loading conditions. It is widely applied in the performance assessment of waterproof pavement systems and steel bridge deck paving materials. By measuring the penetration or indentation response over time, this test provides key data for analyzing the high-temperature stability, consistency, and durability of mastic asphalt mixtures, ensuring reliable quality control in engineering applications.

1. Purpose and Scope

This method is used to determine the penetration value and penetration increment of asphalt mixtures, in order to evaluate the high-temperature stability of mastic asphalt mixtures.

2. Apparatus and Materials

2.1 Mold: A rectangular steel mold with an internal side length of 70.7 mm ± 0.5 mm, consisting of a base plate, four frames, and fasteners, which can be assembled.

2.2 Penetration Testing Apparatus:

2.2.1 Weights

The weight is approximately 490.5 N. It is applied vertically onto the specimen through the penetration rod. The total mass of the weight, penetration rod, and loading platform is 515.0 N ± 9.8 N.

2.2.2 Penetration Rod

The penetration rod is made of steel. The combined weight of the penetration rod and loading platform is approximately 24.5 N. The bottom end is a flat-ended cylinder with a height not less than 20 mm and a diameter of 25.2 mm ± 0.1 mm. The side surface and bottom of the flat cylinder shall be smooth and flat.

Two ball bearings shall be used to ensure minimum friction during testing. Except for the ball bearings, all components shall maintain a minimum clearance of 1 mm from the penetration rod.

2.2.3 Dial Gauge

A dial-type or digital dial gauge with a resolution of 0.01 mm shall be used. The deformation of the gauge shall not exceed 0.01 mm when load is applied or removed. A displacement sensor may also be used as an alternative.

2.2.4 Water Bath

The water bath shall maintain controlled temperatures of 50 ± 1 °C, 55 ± 1 °C, and 60 ± 1 °C during testing. Temperature control is achieved using an external thermostatic water bath with a capacity of approximately 7.5 L.

2.3 Electric Heating Blast Drying Oven

The electric heating blast drying oven shall be capable of maintaining a constant temperature of 250 ± 10 °C and shall meet the requirements specified in T0602, Clause 2.1.

2.4 Thermometers

Two thermometers shall be used:

One with a range of 0–100 °C and a division value of 1 °C;

One with a range of 0–300 °C and a division value of 2 °C.

2.5 Timer

A stopwatch or electronic timer shall be used, with a minimum division value of 0.1 s and a maximum permissible error of ±0.10 s/h.

2.6 Calibration Block

The hardness of the rubber block shall be determined in accordance with GB/T 39693.2 “Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: International rubber hardness (10 IRHD to 100 IRHD)”, GB/T 39693.5 “Portable international rubber hardness test method — Indentation hardness”, or GB/T 531.2 “Rubber, vulcanized or thermoplastic — Determination of indentation hardness — Part 2: Portable IRHD hardness method”.At 23 °C, the hardness shall be 58 IRHD ± 5 IRHD.

2.7 Others

Scraper (approximately 30 mm wide) and mixing equipment.

3. Calibration of Penetration Tester

3.1For new equipment or after every 6 months of use, calibration shall be carried out.

3.2The calibration block shall be used in place of the asphalt mixture specimen for testing. A load of 515.0 N ± 9.8 N shall be applied for 5 minutes, and the penetration depth shall be measured. The test shall be conducted for 10 consecutive times.The coefficient of variation of the 10 measured values shall not exceed 5%.

4. Methods and Steps

4.1 Specimen Preparation

4.1.1Prepare mastic asphalt mixture specimens indoors according to Method T0740, or obtain hot mastic asphalt mixture specimens from field sampling.

4.1.2Assemble the molds and preheat them in an oven to 100–150 °C. Before pouring the specimen, apply a thin layer of release agent inside the mold and place it on a flat platform.

4.1.3Pour the mixed specimen into the preheated mold and ensure that all four corners are fully filled. Compact the mixture vertically around the mold edges manually to improve specimen density; do not tamp the center of the specimen. Trim the surface so that the center is slightly higher. After cooling for approximately 15 minutes, level the surface using a heated scraper.

4.1.4Store the specimens at room temperature of 23 ± 5 °C for not less than 48 hours. The maximum storage time shall not exceed 7 days.

4.2Remove the bottom plate of the mold containing the specimen. Place the specimen with its bottom surface facing upward as the testing surface, and immerse it in a water bath maintained at the test temperature for 60 minutes. The test temperature shall be set to 50 ± 1 °C, 55 ± 1 °C, or 60 ± 1 °C according to relevant requirements.

4.3Adjust the penetration tester so that the penetration rod is aligned with the center of the specimen surface. Lower the penetration rod vertically until it makes contact with the specimen surface.

4.4Lower the penetration rod and start the timer simultaneously. Apply an initial load of 24.5 N (the self-weight of the penetration rod and loading platform). After 10 minutes, record the dial gauge reading as the zero deformation value.

4.5Gently place the 490.5 N weight onto the loading platform, avoiding any impact, and restart timing. Record the dial gauge readings at 1 min, 2 min, 3 min, 5 min, 10 min, 20 min, 30 min, and 60 min.

4.6Each test group shall include at least three parallel specimens for testing.

5. Data Processing

5.1 The difference between the dial gauge reading at 30 minutes and the zero-point deformation is recorded as the penetration depth of a specimen. The difference between the dial gauge reading at 60 minutes and the dial gauge reading at 30 minutes is recorded as the penetration increment of a specimen.

5.2 The arithmetic mean of the three measured values is taken as the test result for both penetration depth and penetration increment, accurate to 0.1 mm.

6. Permissible Error

The allowable relative error for repeatability tests of mastic asphalt mixture penetration shall be 28% of the average value. The allowable relative error for reproducibility tests shall be 55% of the average value.

7. Report

7.1 Test Item Name and Applicable Standard.

7.2 Sample Receipt Date and Sample Description.

7.3 Test Date, Name, Model, and Serial Number of Instrument/Equipment.

7.4 Test Temperature, Specimen Placement Time, Penetration Measurement Value and its Average Value, Penetration Increment Measurement Value and its Average Value.

7.5 Other Matters Requiring Explanation.

Notice:There may be some errors in the compilation process of our unit. This is for reference only. We recommend purchasing the genuine test standard.