Charpy Impact Test Data for Asphalt Mixtures – Ductile-to-Brittle Transition Evaluation
Description
This dataset contains results from Charpy impact tests conducted on asphalt mixture specimens to evaluate whether the material exhibits a ductile-to-brittle transition (DBTT) as temperature decreases. The impact energy absorbed before fracture was quantified and normalized by the specimen cross-sectional area to calculate toughness, enabling direct comparison of fracture resistance across different temperatures and mix samples. The dataset supports research on asphalt performance in cold environments and the applicability of DBTT concepts (commonly studied in metals) to asphalt materials. The DBTT was evaluated by examining the effect of temperature variation on notched bar impact work and analyzing different mixture compositions. Results indicate that, like metals, the energy required to fracture asphalt materials increases with temperature, exhibiting brittle behavior at low temperatures and ductile behavior at high temperatures. A significant change in impact energy absorption was observed within a narrow temperature range, confirming that DBTT is a suitable test for assessing asphalt mixture behavior. Contents: Mix Sample / Test ID: Unique identifier for each tested specimen. Temp (°C): Test temperature. Wnbi (J): Notched bar impact work (impact energy absorbed). Dimensions (L, H, h, W, mm): Geometrical measurements of specimens. A0_mm2 (mm²): Cross-sectional area of the notched specimen. Snbi (J/mm²): Normalized impact toughness, calculated as energy divided by cross-sectional area. Key Use: Identifying the ductile-to-brittle transition temperature (DBTT) in asphalt mixtures. Comparing fracture energy across mixtures and temperatures. Supporting material selection for cold climates. File format: Excel (.xlsx), multiple sheets with results from different test series.
Files
Steps to reproduce
For this experiment, the additional weights were removed so the hammer has a work capacity of 15 J. The impact energy measured during the test was recorded using the WP 400.20 system for data acquisition, which logs the output into a CSV file. The data collected was analyzed to determine how energy behavior varies with temperature and at which temperature the material shows an energy shift. To make small beam samples for the test, a lapidary saw cut tested Bending Beam Rheometer (BBR) beams (6.25 x 12.5 x 127 mm) into smaller sizes. The Charpy impact test requires beams with a length of 55 mm. For this purpose, BBR samples with 127 mm length were cut into two beams of 55 mm length. L is the length (55 mm), H is the height (12.7 mm ± 0.25 mm), w is the thickness (6.35 ± 0.25 mm), and h is the cross-sectional height area of the specimen before fracture (residual surface of the specimen in the notch base). To cut the specimens to the correct length, a set of specimens available as an accessory for the Charpy experimental unit was used to guide the cutting and to produce the notch in the middle of the sample. Calipers measured the dimensions of each sample after cutting: The length (L), height (H), thickness (w), and cross-sectional height (h). The samples were cut and separated for testing at seven different temperatures (40°C , -30°C, -20°C, -10°C, 0°C, 10°C, 20°C). A chest freezer was used to keep the samples in before testing. The samples were placed in an aluminum container filled with sand, and a temperature probe was inserted into a designated sample. This sample with a temperature probe was used to monitor the internal temperature of the asphalt mixture beams to be tested. Once the sample with the probe reached the target temperature, it was assumed that the remaining samples, subjected to the same conditions, had also achieved thermal equilibrium. To ensure uniform cooling, the container holding all the samples was placed in a freezer for two hours, ensuring the samples reached the desired temperature within the sand. The hammer will impact the sample in a gap of 40 mm of distance between the two supports. After the impact, the beam is destroyed, and the energy transfer of the hammer to the specimen is measured in Newton meters (Nm) and represented in Joules (J) (1 Nm = 1 J)
Institutions
- University of Utah