A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
The Investigation of R-Curves of Asphalt Concrete
One of the primary distress mechanisms in asphalt concrete is cracking. Whether it is caused by fatigue, low temperature, or reflective mechanisms, the development of cracks in the pavement surface is undesirable. Currently, there are several performance tests that quantify cracking, including the four-point bending beam (fatigue), the Superpave Indirect Tension Test (low temperature), and the Texas Overlay Tester (reflective). Another type of test has gained traction in recent years in quantifying cracking of asphalt concrete: fracture testing. To date, most fracture testing has simply reported a single value, such as the stress intensity factor, the J-integral, or the fracture energy. However, when a single value is reported, valuable information about the crack initiation and crack propagation is lost. By using resistance curves, or R-curves, much of this information can be retained. This research introduces the concept of R-curves through two different methods: plotting the cumulative energy versus the crack mouth opening displacement (CMOD) and plotting the cumulative energy versus the crack length. Several laboratories are equipped to capture energy/CMOD data, but relatively few are able to capture energy/crack length data. Therefore, both methodologies are beneficial for discussion. The University of Arkansas has evaluated both of these methodologies at two test temperatures, two loading rates, and two test geometries on a single asphalt concrete mix. Not only has the fracture energy been calculated, but new information about the physical state of the material (linear elastic, inelastic, quasi-brittle, compliant, etc.), the development of the cumulative energy during testing over time, and the energy required to form the cohesive zone of asphalt concrete has been captured. With this preliminary data, the use of R-curves appears to have the capability of capturing new and vital data that furthers the understanding of how cracks develop and move through asphalt concrete.
The Investigation of R-Curves of Asphalt Concrete
One of the primary distress mechanisms in asphalt concrete is cracking. Whether it is caused by fatigue, low temperature, or reflective mechanisms, the development of cracks in the pavement surface is undesirable. Currently, there are several performance tests that quantify cracking, including the four-point bending beam (fatigue), the Superpave Indirect Tension Test (low temperature), and the Texas Overlay Tester (reflective). Another type of test has gained traction in recent years in quantifying cracking of asphalt concrete: fracture testing. To date, most fracture testing has simply reported a single value, such as the stress intensity factor, the J-integral, or the fracture energy. However, when a single value is reported, valuable information about the crack initiation and crack propagation is lost. By using resistance curves, or R-curves, much of this information can be retained. This research introduces the concept of R-curves through two different methods: plotting the cumulative energy versus the crack mouth opening displacement (CMOD) and plotting the cumulative energy versus the crack length. Several laboratories are equipped to capture energy/CMOD data, but relatively few are able to capture energy/crack length data. Therefore, both methodologies are beneficial for discussion. The University of Arkansas has evaluated both of these methodologies at two test temperatures, two loading rates, and two test geometries on a single asphalt concrete mix. Not only has the fracture energy been calculated, but new information about the physical state of the material (linear elastic, inelastic, quasi-brittle, compliant, etc.), the development of the cumulative energy during testing over time, and the energy required to form the cohesive zone of asphalt concrete has been captured. With this preliminary data, the use of R-curves appears to have the capability of capturing new and vital data that furthers the understanding of how cracks develop and move through asphalt concrete.
The Investigation of R-Curves of Asphalt Concrete
Yang, Shu (author) / Braham, Andrew (author)
2013 Airfield & Highway Pavement Conference ; 2013 ; Los Angeles, California, United States
Airfield and Highway Pavement 2013 ; 1064-1074
2013-06-18
Conference paper
Electronic Resource
English
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