scholarly journals Evaluation of Test Specimen Geometry of Asphalt Mixes Tested with the Asphalt Mixture Performance Tester

2020 ◽  
Author(s):  
Abha Dwivedy
Keyword(s):  
Test Specimen ◽  
Asphalt Mixture ◽  
Specimen Geometry ◽  
Asphalt Mixes ◽  
Asphalt Mixture Performance Tester

scholarly journals Study of High-Temperature Properties of Asphalt Mixtures Used for Bridge Pavement with Concrete Deck

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4238
Author(s):  
Piotr Pokorski ◽  
Piotr Radziszewski ◽  
Michał Sarnowski
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Binder Content ◽  
Void Content ◽  
Concrete Bridge ◽  
Asphalt Mixes ◽  
Protective Layers ◽  
Concrete Bridge Decks ◽  
Air Void ◽  
Air Void Content

The paper presents the issue of resistance to permanent deformations of bridge pavements placed upon concrete bridge decks. In Europe, bridge asphalt pavement usually consists of a wearing course and a protective layer, which are placed over the insulation (waterproofing). Protective layers of bridge pavement are commonly constructed using low air void content asphalt mixes as this provides the suitable tightness of such layers. Due to increased binder content, asphalt mixes for bridge pavement may have reduced resistance to permanent deformations. The article presents test results of resistance to permanent deformations of asphalt mixes for the protective layers. In order to determine the composition of mixtures with low air void content and resistance to permanent deformation, an experimental design was applied using a new concept of asphalt mix composition. Twenty-seven different asphalt mixture compositions were analyzed. The mixtures varied in terms of binder content, sand content and grit ratio. Resistance to permanent deformation was tested using the laboratory uniaxial cyclic compression method (dynamic load creep). On the basis of experimental results and statistical analysis, the functions of asphalt mixture permanent deformation resistance were established. This enabled a determination of suitable mixture compositions for protective layers for concrete bridge decks.

scholarly journals Characteristics of asphalt mixes with FT additive

2012 ◽  
Vol 20 (1) ◽  
pp. 35-40
Author(s):  
S. Štefunková
Keyword(s):  
Energy Consumption ◽  
Low Temperature ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Environmental Effects ◽  
Asphalt Mixture ◽  
Working Environment ◽  
Gas Emissions ◽  
Asphalt Mixes ◽  
Save Energy

Characteristics of asphalt mixes with FT additiveThis article is focused on low-temperature asphalt mixture technologies using FT additive and RAP. The modern production and use of asphalt mixture technologies with reduced temperatures has many advantages. These advantages mainly help to save energy and the environment. Lower temperatures enable a reduction in energy consumption, a more acceptable working environment for workers, a reduction in negative environmental effects, such as greenhouse gas emissions, and an improvement in the workability of mixtures and a prolongation of their duration. This technology is currently becoming popular in many countries.

Laboratory Assessment of Workability of Asphalt Rubber Hot Mixes Using Warm Mix Technology

2012 ◽  
Vol 193-194 ◽  
pp. 452-457 ◽  
Author(s):  
Meng Yun Huang ◽  
Jing Hui Liu ◽  
Xi Zhang ◽  
Dan Ni Li
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Laboratory Assessment ◽  
Asphalt Mixes ◽  
Modified Asphalt ◽  
The Road ◽  
Asphalt Rubber ◽  
Synergy Effects ◽  
Save Energy

Using the waste crumb rubber modified asphalt to pave the road surface could reduce cost and save energy. However，in order to obtain adequate workability, the mixing temperature and compaction temperature of rubberized asphalt binder and its mixture is much higher than those of conventional asphalt mixtures. Warm Mix Asphalt (WMA) is the name given to certain technologies that reduce the production and placement temperatures of asphalt mixes. One of the main benefits advertised is the increased workability at conventional and lower compaction temperatures with the WMA addition. This paper evaluates whether there are any synergy effects of using warm mix technologies and Asphalt Rubber(AR) hot mixes. This paper summarizes a lab research to evaluate the workability of Asphalt Rubber hot mixes containing warm mix technologies. Both asphalt binder and asphalt mixture were evaluated and compared. The research suggests that combining WMA technology with Asphalt Rubber mixtures is a win-win.

Adjusted J-R Toughness Curve for Pipes Using J-A2 Crack Constraint of CT Specimens and 3D Crack Meshes

2019 ◽  
Author(s):  
Greg Thorwald ◽  
Ken Bagnoli
Keyword(s):  
Fracture Mechanics ◽  
Test Data ◽  
Crack Front ◽  
Test Specimen ◽  
Closed Form Solution ◽  
Form Solution ◽  
Specimen Geometry ◽  
Ductile Tearing ◽  
Two Parameter ◽  
Axial Surface

Abstract The objective of this paper is to use two-parameter fracture mechanics to adjust a material J-R resistance curve (i.e. toughness) from the test specimen geometry to the cracked component geometry. As most plant equipment is designed and operated on the “upper shelf”, a ductile tearing analysis may give a more realistic assessment of flaw tolerance. In most cases, tearing curves are derived from specimen geometries that ensure a high degree of constraint, e.g., SENB and CT Therefore, there can be significant benefit in accounting for constraint differences between the specimen geometry and the component geometry. In one-parameter fracture mechanics a single parameter, K or J-integral, is sufficient to characterize the crack front stresses. When geometry dependent effects are observed, two-parameter fracture mechanics can be used to improve the characterization of the crack front stress, using T-stress, Q, or A2 constraint parameter. The A2 parameter was be used in this study. The usual J-R power-law equation has two coefficients to curve-fit the material data (ASTM E1820). The adjusted J-R curve coefficients are modified to be a function of the A2 constraint parameter. The measured J-R values and computed A2 constraint values are related by plotting the J-R test data versus the A2 values. The A2 constraint values are computed by comparing the HRR stress solution to the crack front stress results of the test specimen geometry using elastic-plastic FEA. Solving for the two J-R curve coefficients uses J values at two Δa crack extension values from the test data. A closed-form solution for the adjusted J-R coefficients uses the properties of natural logarithms. The solution shows the adjusted J-R exponent coefficient will be a constant value for a particular material and test specimen geometry, which simplifies the application of the adjusted J-R curve. A different test specimen geometry can be used to validate the adjusted J-R curve. Choosing another test specimen geometry, having a different A2 constraint value, can be used to obtain the adjusted J-R curve and compare it to the measured J-R curves. The geometry of the component is also expected to have a different A2 constraint compared to the material test specimen. The example examined here is an axial surface flaw in a pipe. The A2 constraint for an axial surface cracked pipe is computed and used to obtain an adjusted J-R curve. The adjusted J-R curve shows an increase in toughness for the pipe as compared to the CT measured value. The adjusted J-R curve can be used to assess flaw stability using the driving force method or a ductile tearing instability analysis.

EVALUATION OF THE HIRSCH MODEL FOR DYNAMIC MODULUS ESTIMATION OF ASPHALT MIXTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Hassan Malekzehtab ◽  
Hamid Nikraz
Keyword(s):  
Western Australia ◽  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Recycled Asphalt ◽  
Asphalt Mixture Performance Tester ◽  
Comparison Of The Results ◽  
Asphalt Concrete Pavement ◽  
Cylindrical Samples ◽  
Do So

The dynamic modulus of the asphalt mixtures is an important factor in designing or analyzing an asphalt concrete pavement, but it is expensive and time consuming to measure. Therefore, it is important to develop a model to predict this value. In this regard, the Hirsch model is a popular model, however, it is developed based on a range of U.S. asphalt mixtures and standards. Therefore, it is not certain that it can be used for asphalt mixtures based on materials and codes other than U.S. This article investigated whether this model performs satisfactorily with two typical asphalt mixtures in Western Australia (WA) containing 0, 10, 20, and 30% of recycled asphalt pavement. To do so, cylindrical samples were made with materials and locally established standards in Western Australia and then tested in Asphalt Mixture Performance Tester (AMPT) machine to acquire their dynamic modulus and phase angle values in different loading frequencies (0.01 to 10 Hz) and temperatures (4 to 40°C). Meanwhile, the results are estimated by the Hirsch model using some properties of the mixture and binder. The properties of the binder in different test conditions are obtained using a dynamic shear rheometer. The comparison of the results showed that the dynamic modulus underestimation or overestimation error can reach to 50 and 280% respectively. Generally, this model did not perform well in this study.

scholarly journals Analysis of Aggregate Morphological Characteristics for Viscoelastic Properties of Asphalt Mixes Using Simplex Lattice Design

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1908 ◽  
Author(s):  
Wensheng Wang ◽  
Yongchun Cheng ◽  
Guojin Tan ◽  
Jinglin Tao
Keyword(s):  
High Temperature ◽  
Viscoelastic Properties ◽  
Asphalt Mixture ◽  
Morphological Characteristics ◽  
River Sand ◽  
Asphalt Mixes ◽  
Coarse Aggregates ◽  
Lattice Design ◽  
Simplex Lattice Design ◽  
Simplex Lattice

Morphological characteristics of aggregates have direct impacts on performances of asphalt mixes. This paper aims to investigate the effects of the morphological characteristics of fine and coarse aggregates on the high-temperature viscoelastic properties of asphalt mortars and mixtures. For this purpose, an experimental proportion scheme was designed for asphalt mixes prepared with three different types of aggregates (basalt, andesite and pebble/river sand) based on the simplex lattice design (SLD) method. Three morphological parameters were chosen to characterize shape, angularity and texture of aggregates. Afterwards, the uniaxial compression creep test was conducted for asphalt mixes and the high-temperature viscoelastic properties were obtained based on Burgers model. The effects of fine and coarse aggregates on the viscoelastic properties are analyzed through asphalt mortars and mixtures, respectively. The results showed that aggregate morphological characteristics correlate with the high-temperature viscoelastic properties of asphalt mixes, especially for fine aggregates. Aggregates with complex morphological characteristics are conducive to improving the deformation recovery and anti-deformation of asphalt mixes. Furthermore, coarse aggregates can enhance the anti-deformation of asphalt mixture effectively due to its skeleton effect.

Evaluation Of Volumetric Properties And Resilient Modulus Performance Of Nanopolyacrylate Polymer Modified Binder (NPMB) Asphalt Mixes

2015 ◽  
Vol 73 (4) ◽  
Author(s):  
Ekarizan Shaffie ◽  
Juraidah Ahmad ◽  
Ahmad Kamil Arshad ◽  
Dzraini Kamarun
Keyword(s):  
Resilient Modulus ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Volumetric Properties ◽  
Modified Bitumen ◽  
Asphalt Mixes ◽  
Different Types ◽  
Potential Benefits ◽  
Modified Binder ◽  
Polymer Modified Bitumen

This paper presents the potential benefits of nanopolyacrylate (NPA) for the asphalt mixtures used on pavement. This research evaluates the resilient modulus performance of dense graded Superpave-designed HMA mix. Two different types of dense graded Superpave HMA mix were developed consists of unmodified bitumen mix (UMB) and nanopolyacrylate modified bitumen mix (NPMB). Nanopolyacrylate polymer modified bitumen was prepared from addition of 6 percent of NPA polymer into asphalt bitumen. Resilient modulus results from Resilient Modulus test were determined to evaluate the performance of these mixtures. Results showed that all the mixes passed the Superpave volumetric properties criteria which indicated that these mixtures were good with respect to durability and flexibility. The Resilient modulus result of NPMB demonstrates better resistance to rutting than those prepared using UMB mix. It was estimated that the average resilient modulus values for both UMB and NPMB mixtures are decreased by 80 percent when the test temperature increased from 25ºC to 40ºC.   In conclusion, the addition of NPA to the binder has certainly improved the bitumen properties significantly and hence increase the resistant to rutting of the asphalt mixture.

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