scholarly journals Numerical Investigation to Quantify the Rate of Damage within Mortar Bituminous Materials: Modeling of Cracks Initiation and Propagation

2019 ◽  
Author(s):  
Yassine EL Haloui ◽  
Aziz Idrissi Bougrine ◽  
Mohamed EL Omari ◽  
El Khadir Lakhal ◽  
Fateh Fakhari Tehrani ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
Thick Layer ◽  
Stiffness Degradation ◽  
Damage Initiation ◽  
Coarse Aggregates ◽  
Applied Loading ◽  
Materials Modeling ◽  
Initiation And Propagation ◽  
Air Void ◽  
Cohesive Damage

Asphalt concrete is highly used to construct pavement layers in the civil engineering field. It is defined as a complex medium composed of aggregates (inclusions), mortar (matrix) and air void. The mortar itself is a mixture of fillers, sand and bitumen. Furthermore, mortar is the phase that links the coarse aggregates. In general, fracture of asphalt concrete occurs within mortar or among aggregate-mortar interface. Therefore, two types of fracture can be identified, i.e., adhesive and cohesive damages. The first type is occurred among the interface of aggregate-mortar. The second is taken place within the mortar. This paper presents numerical investigations of the damage initiation and stiffness degradation within the asphalt concrete matrix. Numerical simulations were carried out to investigate, firstly, how damage is initiated and developed, and then, to simulate how cracks can be initiated and propagated within this material. Cohesive finite elements method was adopted to simulate fracture. For adhesive damage, the model was represented by one rectangular aggregate that is linked to the asphalt concrete thanks to a thin layer of the mortar. For cohesive damage, the model was considered as a thick layer of the mortar in between two coarse aggregates. The applied loading was derived from the speed of traffic vehicle. A comparative analysis between four mortars was conducted. The effect of loading and the type of mortar on damage initiation and stiffness degradation will be shown. Moreover, the initiation and propagation of cracks as function of loading and stiffness modulus will be illustrated.

Image processing procedure to quantify the internal structure of porous asphalt concrete

2019 ◽  
Vol 15 (1) ◽  
pp. 206-226 ◽  
Author(s):  
Kabiru Abdullahi Ahmad ◽  
Norhidayah Abdul Hassan ◽  
Mohd Ezree Abdullah ◽  
Munder A.M. Bilema ◽  
Nura Usman ◽  
...  
Keyword(s):  
Internal Structure ◽  
Asphalt Concrete ◽  
Functional Performance ◽  
Resilient Modulus ◽  
Asphalt Mixture ◽  
Content Type ◽  
Porous Asphalt ◽  
X Ray ◽  
Air Void ◽  
Aggregate Interlock

Purpose In order to fully understand the properties of porous asphalt, investigation should be conducted from different point of views. This is from the fact that porous asphalt mixture designed with the same aggregate gradation and air void content can give different infiltration rate due to the different formation of the internal structure. Therefore, the purpose of this paper is to investigate the micro-structural properties and functional performance of porous asphalt simultaneously. Design/methodology/approach The aim is to develop imaging techniques to process and analyze the internal structure of porous asphalt mixture. A few parameters were established to analyze the air void properties and aggregate interlock within the gyratory compacted samples captured using a non-destructive scanning technique of X-ray computed tomography (CT) throughout the samples. The results were then compared with the functional performance in terms of permeability. Four aggregate gradations used in different countries, i.e. Malaysia, Australia, the USA and Singapore. The samples were tested for resilient modulus and permeability. Quantitative analysis of the microstructure was used to establish the relationships between the air void properties and aggregate interlock and the resilient modulus and permeability. Findings Based on the results, it was found that the micro-structural properties investigated have successfully described the internal structure formation and they reflect the results of resilient modulus and permeability. In addition, the imaging technique which includes the image processing and image analysis for internal structure quantification seems to be very useful and perform well with the X-ray CT images based on the reliable results obtained from the analysis. Research limitations/implications In this study, attention was limited to the study of internal structure of porous asphalt samples prepared in the laboratory using X-ray CT but can also be used to assess the quality of finished asphalt pavements by taking core samples for quantitative and qualitative analysis. The use of CT for material characterization presents a lot of possibilities in the future of asphalt concrete mix design. Originality/value Based on the validation process which includes comparisons between the values obtained from the image analysis and those from the performance test and it was found that the developed procedure satisfactorily assesses the air voids distribution and the aggregate interlock for this reason, it can be used.

Effects of asphalt concrete characteristics on cohesive zone model parameters of hot mix asphalt mixtures

2016 ◽  
Vol 43 (3) ◽  
pp. 226-232 ◽  
Author(s):  
S. Pirmohammad ◽  
H. Khoramishad ◽  
M.R. Ayatollahi
Keyword(s):  
Asphalt Concrete ◽  
Cohesive Energy ◽  
Cohesive Zone ◽  
Hot Mix Asphalt ◽  
Cohesive Zone Model ◽  
Experimental Tests ◽  
Model Parameters ◽  
Zone Model ◽  
Binder Type ◽  
Air Void

In this paper, the effects of the main asphalt concrete characteristics including the binder type and the air void percentage on the cohesive zone model (CZM) parameters were studied. Experimental tests were conducted on semi-circular bend (SCB) specimens made of asphalt concrete and the fracture behavior was simulated using a proper CZM. The CZM parameters of various hot mix asphalt (HMA) mixtures were determined using the SCB experimental results. Five types of HMA mixtures were tested and modeled to consider the effects of binder type and air void percentage on the CZM parameters. The results showed that as the binder in HMA mixture softened, the cohesive energy strength increased, whereas enhancing the air void percentage led to reduction of the cohesive energy and strength values. Among the studied HMA mixtures, the highest values of CZM parameters were found for the HMA mixture containing a copolymer called styrene-butadiene-styrene.

Numerical and digital image correlation analysis of tensile behavior of thin-ply hybrid laminates with discontinuous carbon sandwiched by continuous glass and carbon

2021 ◽  
pp. 002199832110565
Author(s):  
Amos Ichenihi ◽  
Wei Li ◽  
Li Zhe
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Element Model ◽  
Image Correlation ◽  
Continuous Glass ◽  
Damage Initiation ◽  
3D Digital Image Correlation ◽  
Initiation And Propagation ◽  
Hybrid Laminates ◽  
Strain Increase

Thin-ply hybrid laminates of glass and carbon fibers have been widely adopted in engineering pseudo-ductility. In this study, a Finite Element model is proposed using Abaqus to predict pseudo-ductility in thin-ply laminates consisting of three materials. These materials comprise continuous carbon (CC) and continuous glass sandwiching partial discontinuous carbon (DC). The model adopts the Hashin criterion for damage initiation in the fibers and the mixed-mode Benzeggagh-Kenane criterion on cohesive surfaces for delamination initiation and propagation. Numerically predicted stress–strain results are verified with experimental results under tensile loading. Results show pseudo-ductility increases with the increase in DC layers, and pseudo-yield strength and strain increase with the increase in CC layers. 3D-Digital Image Correlation results indicate delamination growth on pseudo-ductile laminates, and the calculated Poisson’s ratios show pseudo-ductility occurs below 0.27. Moreover, Poisson’s ratio decreases with an increase in pseudo-ductility.

Specimen Geometry Study for Direct Tension Test Based on Mechanical Tests and Air Void Variation in Asphalt Concrete Specimens Compacted by Superpave Gyratory Compactor

2000 ◽  
Vol 1723 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Ghassan R. Chehab ◽  
Emily O’Quinn ◽  
Y. Richard Kim
Keyword(s):  
Asphalt Concrete ◽  
Tensile Testing ◽  
Complex Modulus ◽  
Specimen Geometry ◽  
Uniaxial Tensile ◽  
Void Content ◽  
Uniaxial Tensile Testing ◽  
Superpave Gyratory Compactor ◽  
Air Void ◽  
Air Void Content

Reliable materials characterization and performance prediction testing of asphalt concrete requires specimens that can be treated as statistically homogeneous and representative of the material being tested. The objective of this study was to select a proper specimen geometry that could be used for uniaxial tensile testing. Selection was based on the variation of air void content along the height of specimens cut and cored from specimens compacted by the Superpave gyratory compactor (SGC) and on the representative behavior under mechanical testing. From measurement and comparison of air void contents in cut and cored specimens, it was observed for several geometries that sections at the top and bottom and those adjacent to the mold walls have a higher air void content than do those in the middle. It is thus imperative that test specimens be cut and cored from larger-size SGC specimens. Complex modulus and constant crosshead-rate monotonic tests were conducted for four geometries—75 × 115, 75 × 150, 100 × 150, and 100 × 200 mm—to study the effect of geometry boundary conditions on responses. On the basis of graphical and statistical analysis, it was determined that there was an effect on the dynamic modulus at certain frequencies but no effect on the phase angle. Except for 75 × 115 mm, all geometries behaved similarly under the monotonic test. From these findings and other considerations, it is recommended that the 75- × 150-mm geometry, which is more conservative, and the 100- × 150-mm geometry be used for tensile testing.

Damage Progress Simulation in Unidirectional Composites by Extended Finite Element Method (XFEM)

2010 ◽  
Vol 152-153 ◽  
pp. 73-76 ◽  
Author(s):  
Huai Wen Wang ◽  
Qing Hua Qin ◽  
Hong Wei Zhou ◽  
Hui Miao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Independent Solution ◽  
Single Fibre ◽  
Extended Finite Element ◽  
Damage Initiation ◽  
Initiation And Propagation ◽  
As Stress ◽  
Element Method

Damage initiation and propagation in unidirectional glass fibre reinforced epoxy matrix composites under tension load were simulated in this study. Cell models with either single fibre or multiple fibres were modelled by extended finite element method (XFEM). The damage progress in the cells was investigated and then the nominal stress-strain curves as well as stress distributions in the fibre and matrix were obtained. Results presented here indicate that the extended finite element method is an effective modelling technique to study the initiation and propagation of a crack along an arbitrary, mesh-independent, solution-dependent path.

Electrical, Thermal and Induction Heating Properties of Dense Asphalt Concrete

2013 ◽  
Vol 723 ◽  
pp. 303-311 ◽  
Author(s):  
Alvaro Garcia ◽  
Jose Norambuena-Contreras ◽  
Manfred N. Partl
Keyword(s):  
Induction Heating ◽  
Asphalt Concrete ◽  
Asphalt Mixture ◽  
Void Content ◽  
Steel Wool ◽  
Electrically Conductive ◽  
Wool Fibers ◽  
Conductive Fibers ◽  
Different Diameters ◽  
Air Void

Induction heating consists in adding electrically conductive fibers to the asphalt mixture and heating them with an induction heating device. But still, the factors that affect the increase of temperature are not well-known. With this purpose, 25 different mixtures, with the same aggregates distribution and amount of bitumen, but with 2 different lengths, 4 different quantities, and 4 different diameters of steel wool fibers have been considered. The influence of fibers on the air void content, electrical and thermal conductivity and on the induction heating of dense asphalt concrete has been studied. It was found that steel wool fibers increase slightly the electrical and thermal conductivities of dense asphalt concrete. Finally, it has been observed that the temperature reached due to the induction heating, increases with the number of fibers in the mixture and with their diameter.

Sign in / Sign up

Export Citation Format

Share Document