Asphalt exhibits a gradual transition in mechanical behavior as temperature decreases, shifting from a visco-plastic state to an elastic-brittle state. The Fraass breaking point is defined as the temperature at which a thin asphalt film coated on a metal plate begins to crack under specified bending conditions.This instrument is designed to simulate this low-temperature behavior by continuously bending a coated metal strip in a precisely controlled cooling environment. When cracking occurs, the corresponding temperature is recorded as the Fraass breaking point, which is used to evaluate the low-temperature brittleness of asphalt materials.

I. Product Introduction

The Automatic Low Temperature Bitumen Fraass Breaking Point Tester is designed and manufactured in accordance with GB/T 4510-2006 “Test Method for Determination of Bitumen Breaking Point” and JTG E20-2011 “Standard Test Methods of Bitumen and Bituminous Mixtures for Highway Engineering (T 0613 Fraass Method)”. It is specifically used to determine the Fraass breaking point of bituminous materials under low-temperature conditions.

In addition to Chinese standards, this equipment also complies with widely recognized international standards such as:

EN 12593 – Bitumen and bituminous binders — Determination of the Fraass breaking point

DIN EN 12593 – European standardized test method for Fraass breaking point

IP 80 – Institute of Petroleum standard for Fraass breaking point determination

JIS K2207 – Japanese industrial standard for petroleum asphalt materials

These international standards ensure that the test results are reliable, comparable, and accepted in global asphalt and petroleum testing laboratories.

II. Key Technical Features

1. The system consists of a Fraass breaking point tester and a low-temperature circulating bath. The Fraass breaking point tester serves as the main testing unit, while the low-temperature circulating bath is used to cool the refrigeration system of the tester.

2. The freezing chamber provides a controlled cooling environment with a temperature reduction rate of 1°C per minute.

3. The electric bending mechanism automatically loads the specimen, causing it to bend once per minute (adjustable).

4. Microcomputer control is adopted to automatically regulate the cooling rate and perform timed bending of the specimen. A color LCD screen displays test data in real time, and a built-in printer outputs the test results.

III. Main Technical Parameters and Specifications

Power supply: AC (220 ± 10%) V, 50 Hz

Cooling rate: (1 ± 0.5) °C/min (adjustable range: 0.5–3 °C/min)

Temperature range: Room temperature to -40 °C

Temperature measurement error: ±0.5 °C

Bending speed: 0.5–50 mm/min (adjustable)

Bending stroke: 0.1–15 mm (adjustable)

IV. Instrument Application and Working Principle

Asphalt materials gradually change from a visco-plastic state to an elastic-brittle state as temperature decreases. As a result, their plasticity decreases while brittleness increases. This instrument is used to determine the Fraass breaking point of asphalt at low temperatures.

The test is performed by coating a thin asphalt film onto a specified metal strip. The specimen is placed in a temperature-controlled insulated bath equipped with a cooling system. The bending device continuously bends the metal strip, and as the temperature decreases, the asphalt film temperature also drops. When a certain temperature is reached, the asphalt film cracks under the specified bending conditions. The temperature at the moment of cracking is recorded as the Fraass breaking point.

The machine supports simultaneous testing of three specimens and can directly calculate the average breaking point temperature. It is also capable of storing up to 500 sets of test data, with functions for individual data deletion and printing.

V. Instrument Structure

The equipment consists of a refrigeration module, environmental chamber, servo specimen clamping system, and electrical control system.

The refrigeration module provides a low-temperature range from room temperature to -40°C. It is equipped with dual fin-type heating tubes to provide temperature compensation for stable cooling control. The system adopts a dual-stage vibration reduction design to reduce noise and ensure stable operation.

The environmental chamber has internal dimensions of 180 × 150 × 180 mm (L × W × H). It is equipped with a temperature sensor, air circulation fan system, and lighting system. The exterior features a 4 cm thick thermal insulation layer and a three-layer glass observation window.

The servo clamping system consists of a driving mechanism, stainless steel screw rod, upper and lower pressing clamps, and an adjustable handwheel.

The control system adopts a 10.1-inch touchscreen display with real-time temperature curve monitoring. Lighting, air circulation, refrigeration, and heating functions can all be operated through the touchscreen interface.

VI. Test Method

1.Prepare the specimens according to the testing standards. Install three groups of specimens into the fixture, and adjust the handwheel to bring the specimens into a slightly pre-bent state.

2. Place a desiccant pack inside the environmental chamber; normally one pack is sufficient.

3. Install the loaded fixture into the chamber and connect the aviation plug properly.

4. Turn on the refrigeration and lighting systems. When the temperature drops below zero (or approximately 10°C above the estimated breaking point), activate the heating function to control the cooling rate, typically set at 1°C/min.

5. Press the test button. The fixture will begin bending the specimens according to the preset speed and parameters.

6. When specimen cracking is observed or heard, press the value recording button. The current temperature will be recorded as the breaking point temperature of the first specimen.

7. pressing the value recording button three times, the system will calculate the average breaking point temperature of the three specimens, and the test is completed.

8. data can be saved via the menu button. The system supports storage of up to 500 test records, with functions for deletion and printing.

VII. Conclusion

The Automatic Low Temperature Bitumen Fraass Breaking Point Tester provides a precise, intelligent, and fully automated solution for determining the low-temperature brittleness of asphalt materials. With advanced microcomputer control, high-precision temperature regulation, and compliance with both Chinese and international standards, it is an ideal choice for road construction laboratories, material testing centers, and research institutions worldwide.