Cooling cycle effects on low temperature cracking characteristics of asphalt concrete mixture (original) (raw)
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Procedia Engineering, 2016
Thermal strain causes transverse cracks in Asphalt Concrete (AC) pavements. In this study, thermal strain is determined by developing a three-dimensional Finite Element Method (FEM) model and validates the model with measured data using the field installed Horizontal Asphalt Strain Gauge (HASG) in Interstate 40 (I-40) located near the city of Albuquerque in the state of New Mexico. Materials' properties of the pavement section were determined by laboratory testing on field collected cores from the pavement section after the construction. Viscoelastic material properties of AC were determined from the creep test on the field cored samples. Coefficient of thermal expansion (CTE) and contraction (CTC) of AC were also determined in the laboratory and in the field. Results show that the FEM model can predict thermal strain with maximum variation of 6.0% compared to measured thermal strain in the field, which is very promising.
Self-healing of thermal cracks in asphalt pavements
Construction and Building Materials, 2019
h i g h l i g h t s Self-healing of thermal cracks in asphalt materials was investigated. Acoustic emission and disk-shaped compact tension testing approaches were utilized. The Felicity effect was observed indicating occurrence of self-healing in material. Healing Index parameter was introduced to assess extent of self-healing in material. Results showed occurrence of intrinsic healing at intermediate temperatures. 30% increase in HI% was observed due to 12 h of resting period between cooling cycles.
Assessment of Low-Temperature Cracking in Asphalt Materials Using an Acoustic Emission Approach
Journal of Testing and Evaluation, 2017
An acoustic emission (AE)-based approach to evaluate low-temperature cracking susceptibility of both asphalt binders and asphalt mixtures is presented. The AE binder testing approach consists of a thin film of asphalt binder bonded to a granite substrate exposed to decreasing temperatures ranging from 20 C to À50 C. Because of the differential thermal contraction between the granite substrate and the asphalt binder, thermal cracks develop in the asphalt binder. The initiation/propagation of these thermal cracks leads to a release of mechanical elastic energy in the material, i.e., acoustic emission activity that is recorded and used in determining the embrittlement temperature of the binder material. The AE-based embrittlement temperature showed excellent correlations with thermal cracking predictions based upon the binder rheological properties. Similar results were also obtained when asphalt concrete mixture samples were exposed to temperatures ranging from 20 C to À50 C. The AE-based approach for low-temperature characterization of binders and asphalt concrete mixtures is a rapid and reliable testing method that yields results with better repeatability (lower coefficient of variation) than the traditionally used methods based upon the binder rheological properties. Current results using AE source location also indicate that the AE approach could be used to quantitative evaluate the effectiveness of rejuvenators on aged asphalt pavements.
Differential Thermal Contraction of Asphalt Components
7th RILEM International Conference on Cracking in Pavements, 2012
Large differences between the coefficient of thermal contraction of mineral aggregate and binder has been associated with localised damage at the aggregate-binder interface at low temperatures. In this work, the coefficients of thermal contraction of different binders, aggregates and asphalt mixtures have been determined. Binder specimens were first produced by pouring hot bitumen into 200 x 50 x 50 mm 3 moulds. The specimens were conditioned at various temperatures ranging from 10 to-20 0 C. The change in length was then measured to determine thermal strains as a result of cooling. It was found that linear coefficients of thermal contraction varied between 115 and 175 x 10-6 mm/mm/ 0 C depending on grade and type of binder. Coefficient of thermal contraction of different aggregates was also determined. Rock specimens of the same dimension as the binder specimens were cut from large rock cores. The specimens were then conditioned at different temperatures and their change in length was measured. Three types of rocks namely limestone, granite and greywacke typically used in asphalt mixtures were employed. It was found that CTC of the aggregates varied between 7 and 10 x 10-6 mm/mm/ 0 C, thus, 10 to 25 times lower than those of the binders. The coefficient of thermal contraction of various asphalt mixtures was determined using a volumetric and a composite model. Furthermore, predicted values were compared with those determined experimentally using beam shaped asphalt specimens cut from roller compacted slabs manufactured in the laboratory.
Nondestructive Low-Temperature Cracking Characterization of Asphalt Materials
Journal of Materials in Civil Engineering, 2016
An acoustic-emission approach to evaluate the low-temperature cracking performance of asphalt binders is presented. The acoustic activity of a thin film of asphalt binder bonded to a granite substrate is monitored while the layer is exposed to decreasing temperatures from around 20°C to approximately −50°C. Results of eight different asphalt binders at three different aging levels, i.e., unaged (TANK), short-term aged (RTFO), and long-term aged (PAV), are presented. The acoustic emission (AE) embrittlement temperatures are found to be sensitive to binder type as well as binder aging level. Results show that for most binders, their AE-based embrittlement temperature is a few degrees lower than their bending beam rheometer (BBR) critical cracking temperatures.
Construction and Building Materials, 2013
Low-temperature cracking is a major form of distress that can compromise the structural integrity of asphalt pavements located in cold regions. A review of an Acoustic Emission (AE)-based approach is presented that is capable of assessing the low-temperature cracking performance of asphalt binders and asphalt pavement materials through determining their embrittlement temperatures. A review of the background and fundamental aspects of the AE-based approach with a brief overview of its application to estimate low-temperature performance of unaged, short-term, and long-term aged binders, as well as asphalt materials, is presented. The application of asphalt pavements containing recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) materials to thermal cracking assessment is also presented and discussed. Using the Felicity effect, the approach is capable of evaluating the self-healing characteristics of asphalt pavements and the effect of cooling cycles upon their fracture behavior. Using an iterative AE source location technique, the approach is also used to evaluate the efficiency of rejuvenators, which can restore aged asphalt pavements to their original crack-resistant state. Results indicate that AE allows for relatively rapid and inexpensive characterization of pavement materials and can be used towards enhancing pavement sustainability and resiliency to thermal loading.
Concrete strains under transient thermal conditions: A state-of-the-art review
Engineering Structures, 2016
Creep strain plus transient strain Drying creep strain Elastic strain ,0 Elastic strain at ambient temperature ℎ Strain developing during the heating phase of a load-then-heat test Components of the total strain tensor Load-induced thermal strain * Load-induced thermal strain without increment in the elastic strain Mechanical strain ℎ Shrinkage strain ℎ Thermal expansion strain Total strain Ultimate strain Transient strain Transient thermal creep strain Instantaneous stress-related strain Poisson's ratio Load-induced thermal strain Poisson's ratio Stress Initial compressive stress before heating