scholarly journals Numerical Simulation on Reflective Cracking Behavior of Asphalt Pavement

2021 ◽  
Vol 11 (17) ◽  
pp. 7990
Author(s):  
Houzhi Wang ◽  
You Wu ◽  
Jun Yang ◽  
Haopeng Wang
Keyword(s):  
Crack Propagation ◽  
Mechanical Response ◽  
Asphalt Pavement ◽  
Entropy Method ◽  
Base Layer ◽  
Internal Crack ◽  
Bottom Surface ◽  
Propagation Mechanism ◽  
Cracking Behavior ◽  
Pavement Base

Cracks are one of the main problems that plague road workers. A correct understanding of the internal crack propagation mechanism of asphalt pavement will help road workers evaluate the road’s working status more comprehensively and make more reasonable decisions in design, construction, and maintenance work. This paper established a three-dimensional asphalt pavement layered model using the software ABAQUS and fracture mechanics theory and the extended finite element method were used to explore the mechanical response of the pavement base layer’s preset reflective cracks. This paper investigated the influence of the modulus of each layer, vehicle load on the principal stress, shear stress, J-integral, and two stress intensity factors (K1, K2) during the predetermined crack propagation process of the pavement base layer, and the entropy method was used to analyze the above-mentioned mechanical response. The results show that the main factor affecting the propagation of reflective cracks on asphalt pavements is the modulus of the bottom surface layer. However, from a modeling perspective, the effect of increasing load on crack growth is obvious. Therefore, in terms of technical feasibility, the prevention of reflective cracks should still be achieved by controlling the driving load and prohibiting overloading.

scholarly journals Wood Fly Ash Stabilized Road Base Layers with High Recycled Asphalt Pavement Content

2021 ◽  
Vol 16 (2) ◽  
pp. 1-15
Author(s):  
Peteris Skels ◽  
Viktors Haritonovs ◽  
Edvards Pavlovskis
Keyword(s):  
Fly Ash ◽  
Asphalt Pavement ◽  
Pilot Project ◽  
Base Layer ◽  
Freezing And Thawing ◽  
Recycled Asphalt Pavement ◽  
Recycled Asphalt ◽  
Road Base ◽  
Proctor Test ◽  
Pavement Base

Wood fly ash stabilised road base layers with high recycled asphalt pavements content was studied both at the laboratory and in-situ. The original recipe was chosen based on an actual stabilised pavement base layer design with cement CEM II/B-T 42.5R but optimised using wood fly ash. The existing road base layer from gravel was mixed with dolomite aggregate and recycled asphalt pavement, adding cement and wood fly ash at different proportions. The mixture was compacted at optimal water content according to the Standard Proctor test and further conditioned. Resistance to freezing and thawing of hydraulically bound mixtures was checked after 28 days of conditioning. Even 50 cycles of freezing and thawing were used. Test results indicated wood fly ash as an effective alternative to the typically used cement for road base stabilisation, including recycled asphalt pavement material. Three hydraulically bound mixtures were chosen for test sections in the pilot project. The project includes five different sections with three different hydraulic binder recipes. The performance of each section was evaluated.

scholarly journals Parameter Optimization of Graded Macadam Transitional Layer for Inverted Asphalt Pavement Based on the Mechanical Response and Strength Standard

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chen Zhang ◽  
Yong Lei
Keyword(s):  
Shear Stress ◽  
Surface Layer ◽  
Tensile Stress ◽  
Parameter Optimization ◽  
Mechanical Response ◽  
Asphalt Pavement ◽  
Maximum Shear Stress ◽  
Base Layer ◽  
Transitional Layer ◽  
Cold Regions

To improve the durability of asphalt pavement with heavy traffic conditions in cold regions, the parameter optimization of graded macadam transitional layer (GMTL) for the inverted asphalt pavement based on the mechanical response and the strength standard was studied. The stress distribution laws of GMTL were studied with different loads by means of BISAR3.0. The influences of the thickness and the modulus of GMTL on the pavement stress were analyzed. The optimal thickness and the modulus range of the GMTL were determined. Combined with a self-developing real-time data acquisition and a processing system for aggregate attitude (RDAPS), the strength control standard of the GMTL was established. Finally, the performance of the optimized inverted asphalt pavement structure was verified through the MEPDG design method. The results show that the tensile stress at the bottom of the surface layer reduced by about 58%, and the shear stress in GMTL increased by about 17% when the modulus of GMTL increases from 300 MPa to 800 MPa. However, the change in modulus has no significant influence on the maximum shear stress in the asphalt surface layer and the tensile stress in the base layer bottom. When the thickness of GMTL increases from 12 cm to 20 cm, the tensile stress in the bottom of the base layer reduced by about 31%. Based on the mechanical results from simulation calculation and the technical indicator required in the field, the recommended optimal parameters of GMTL are the modulus of 700 MPa and the thickness of 18 cm. In addition, the spatial attitude angle ΦN of wireless intelligent attitude aggregate (WIAA), the compressive strength Rc standard, and the California Bearing Ratio (CBR) standard were analyzed, and the strength control standard of inverted asphalt pavement with GMTL was proposed, namely, CBR ≥ 354%, Rc ≥ 1.06 MPa, and ΦN ≤ 3°. A significant improvement in the resistance to crack can be seen in the inverted asphalt pavement when the optimized structure was applied. Taking the 20-year service life as an example, the top-down cracks reduced by 29.3% and the bottom-up cracks reduced by 32.6% in comparison to the original structure. The recommended structural parameters of GMTL could be used to guide the construction and design of inverted asphalt pavement in cold regions.

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

scholarly journals Material parametrization of natural rubber based compound and characterization of crack propagation under consideration of dissipative effects

2021 ◽  
Author(s):  
Dan Pornhagen ◽  
Konrad Schneider ◽  
Markus Stommel
Keyword(s):  
Energy Dissipation ◽  
Crack Propagation ◽  
Natural Rubber ◽  
Experimental Tests ◽  
Material Behavior ◽  
Prony Series ◽  
Material Forces ◽  
Cracking Behavior ◽  
Dissipative Effects

AbstractMost concepts to characterize crack propagation were developed for elastic materials. When applying these methods to elastomers, the question is how the inherent energy dissipation of the material affects the cracking behavior. This contribution presents a numerical analysis of crack growth in natural rubber taking energy dissipation due to the visco-elastic material behavior into account. For this purpose, experimental tests were first carried out under different load conditions to parameterize a Prony series as well as a Bergström–Boyce model with the results. The parameterized Prony series was then used to perform numerical investigations with respect to the cracking behavior. Using the FE-software system ANSYS and the concept of material forces, the influence and proportion of the dissipative components were discussed.

Influence of Hole Size on Crack Propagation Mechanism of Nano-Single Crystal Copper

2013 ◽  
Vol 328 ◽  
pp. 679-683
Author(s):  
Ge Li ◽  
Xian Qin Hou ◽  
Zhi Min Liu
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Hole Diameter ◽  
Propagation Mechanism ◽  
Hole Size ◽  
Single Crystal Copper ◽  
Dislocation Glide ◽  
Hole Position ◽  
Crack Propagation Mechanism ◽  
Dynamics Method

By molecular dynamics method, the tensile processes of nanosingle crystal copper with the crack front existence hole were simulated, and the effect of different hole size on crack propagation mechanism was analyzed. The results indicate that as the hole position remain unchanged, the hole diameter was more bigger, the atomic staggered and the crack tip deactivation were more obvious under tensile loads caused more dislocation glide appeared, meanwhile the number of slide-line was more and the trend of crack branch extend to hole position was more obvious.

Mechanical Response Analysis of the Composite Asphalt Pavement

2014 ◽  
Vol 1023 ◽  
pp. 28-31
Author(s):  
Li Min Li
Keyword(s):  
Service Life ◽  
Mechanical Response ◽  
Asphalt Pavement ◽  
Road Construction ◽  
Pavement Design ◽  
Rigid Base ◽  
Response Analysis ◽  
Early Failure ◽  
Short Service Life ◽  
Design Software

With the constant increasing of traffic flow and axle load, the early failure of semi-rigid base asphalt pavement is increasingly serious in China. The bad durability and short service life of pavement have become main obstacles in road construction development. Based on the experience of successful application, the early failure of semi-rigid base asphalt pavement is solved, and the service life of pavement is increased by using of the composite asphalt pavement. To solve the design problem of the composite asphalt pavement , its mechanical properties influence results of are obtained by the factors, such as shear strain, shear stress, compression strain on top of subgrade, etc, by a lot of calculation using Shell pavement design software. These provide theoretical basis for durable asphalt pavement design based on rut-resistance property.

Mitigation of permanent deformation in base layer containing recycled asphalt aggregates

2013 ◽  
Vol 40 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré ◽  
Jonas Depatie
Keyword(s):  
Asphalt Concrete ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Design Procedure ◽  
Base Layer ◽  
Repeated Loading ◽  
Recycled Asphalt ◽  
Thickness Increase ◽  
Permanent Strain ◽  
Pavement Base

The use of recycled asphalt pavement (RAP) aggregates as replacement for new materials in the pavement base weakens the layer in regards to the resistance to permanent deformation under repeated loading. A mechanistic based design procedure is proposed to ensure that base layers containing RAP particles have a similar rutting behaviour to base layers made of virgin aggregates. The design procedure allows calculating an asphalt concrete thickness increase that is based on permanent deformation behaviour of base materials. The calculation approach is based on multistage triaxial permanent deformation tests performed on granular material samples with varied RAP content. The tests allowed proposing an equation that relates permanent strain rate, RAP content, and deviatoric stress, which is the basis of the design procedure. Design charts are proposed to select adequate thickness increase for the asphalt concrete layer according to the expected RAP content in the base layer and asphalt concrete modulus.

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