A new approach to laboratory roller compaction method and its influence on surface texture and permanent deformation of asphalt mixtures

This paper investigated the effects of aggregate mesostructures on permanent deformation behavior of an asphalt mixture using the three-dimensional (3D) discrete element method (DEM). A 3D discrete element (DE) model of an asphalt mixture composed of coarse aggregates, asphalt mastic, and air voids was developed. Mesomechanical models representing the interactions among the components of asphalt mixture were assigned. Based on the mesomechanical modeling, the uniaxial static load creep tests were simulated using the prepared models, and effects of aggregate angularity, orientation, surface texture, and distribution on the permanent deformation behavior of the asphalt mixtures were analyzed. It was proven that good aggregate angularity had a positive effect on the permanent deformation performance of the asphalt mixtures, especially when approximate cubic aggregates were used. Aggregate packing was more stable when the aggregate orientations tended to be horizontal, which improved the permanent deformation performance of the asphalt mixture. The influence of orientations of 4.75 mm size aggregates on the permanent deformation behavior of the asphalt mixture was significant. Use of aggregates with good surface texture benefitted the permanent deformation performance of the asphalt mixture. Additionally, the non-uniform distribution of aggregates had a negative impact on the permanent deformation performance of the asphalt mixtures, especially when aggregates were distributed non-uniformly in the vertical direction.

Download Full-text

Influence of the Compaction Method in the Volumetric Design of Cold Recycled Mixtures with Emulsion

Materials ◽

10.3390/ma14051309 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1309

Author(s):

Guillermo Flores ◽

Juan Gallego ◽

Lucía Miranda ◽

José Ramón Marcobal

Keyword(s):

Mechanical Properties ◽

Water Content ◽

Bulk Density ◽

Asphalt Mixtures ◽

Combined Effect ◽

Recycled Asphalt ◽

New Approach ◽

Two Factors ◽

Gyratory Compaction ◽

Compaction Method

Compaction of cold asphalt mixtures is a subject that has not been thoroughly studied, and, for this reason, requires new efforts from researchers to have a better understanding. Unlike hot mixtures, cold mixtures and mainly recycled mixtures require specific considerations for compaction. There is a lack of consensus about the methodology to select the optimum premix water and emulsion contents. In the absence of specific regulations, the use of soil tests or hot mixtures procedures is common. For these reasons, this investigation’s main goal was to evaluate two compaction methods used to design cold recycled mixtures with emulsion: the modified Proctor procedure and the gyratory compaction. It was concluded that both methods could be useful to study compactability since consistent results were obtained by applying the maximum bulk density criterion. However, the higher bulk densities achieved, the smaller specimens used, and the suitability of the gyratory specimens to be later tested for mechanical properties make them preferable to the modified Proctor samples. A new approach has been proposed using iso-density lines on dual-axis premix water content-emulsion content graphs that facilitates the study of the influence on compactability of these two factors combined. These contributions can alleviate the laboratory works during the design of cold recycled asphalt mixtures and contribute to a more in-depth knowledge of the combined effect of premix water and emulsion contents on the compactability of cold recycled mixtures with emulsion.

Download Full-text

Performance Evaluation of WMA Containing Re-Refined Acidic Sludge and Amorphous Poly Alpha Olefin (APAO)

Sustainability ◽

10.3390/su13063315 ◽

2021 ◽

Vol 13 (6) ◽

pp. 3315

Author(s):

Mansour Fakhri ◽

Danial Arzjani ◽

Pooyan Ayar ◽

Maede Mottaghi ◽

Nima Arzjani

Keyword(s):

Resilient Modulus ◽

Permanent Deformation ◽

Road Construction ◽

Moisture Damage ◽

Asphalt Mixtures ◽

Modified Bitumen ◽

Alternative Source ◽

The Road ◽

Marshall Test ◽

Alpha Olefin

The use of waste materials has been increasingly conceived as a sustainable alternative to conventional materials in the road construction industry, as concerns have arisen from the uncontrolled exploitation of natural resources in recent years. Re-refined acidic sludge (RAS) obtained from a waste material—acidic sludge—is an alternative source for bitumen. This study’s primary purpose is to evaluate the resistance of warm mix asphalt (WMA) mixtures containing RAS and a polymeric additive against moisture damage and rutting. The modified bitumen studied in this research is a mixture of virgin bitumen 60/70, RAS (10, 20, and 30%), and amorphous poly alpha olefin (APAO) polymer. To this end, Marshall test, moisture susceptibility tests (i.e., tensile strength ratio (TSR), residual Marshall, and Texas boiling water), resilient modulus, and rutting assessment tests (i.e., dynamic creep, Marshall quotient, and Kim) were carried out. The results showed superior values for modified mixtures compared to the control mix considering the Marshall test. Moreover, the probability of a reduction in mixes’ moisture damage was proved by moisture sensitivity tests. The results showed that modified mixtures could improve asphalt mixtures’ permanent deformation resistance and its resilience modulus. Asphalt mixtures containing 20% RAS (substitute for bitumen) showed a better performance in all the experiments among the samples tested.

Download Full-text

Effect of Rubberized Bitumen Blending Methods on Permanent Deformation of SMA Rubberized Asphalt Mixtures

Advances in Materials Science and Engineering ◽

10.1155/2016/4395063 ◽

2016 ◽

Vol 2016 ◽

pp. 1-14 ◽

Cited By ~ 4

Author(s):

Herda Yati Katman ◽

Mohd Rasdan Ibrahim ◽

Mohamed Rehan Karim ◽

Suhana Koting ◽

Nuha Salim Mashaan

Keyword(s):

Creep Behaviour ◽

Permanent Deformation ◽

Asphalt Mixtures ◽

Creep Model ◽

Materials Testing ◽

Wet Process ◽

Test Conditions ◽

Dynamic Creep ◽

Different Temperatures ◽

Stone Mastic Asphalt

This study aims at comparing the permanent deformation of Stone Mastic Asphalt (SMA) rubberized asphalt mixtures produced by the wet process. In this study, rubberized binders were prepared using two different blending methods, namely, continuous blend and terminal blend. To study the creep behaviour of control and rubberized asphalt mixtures, the dynamic creep test was performed using Universal Materials Testing Apparatus (UMATTA) at different temperatures and stress levels. Zhou three-stage creep model was utilized to evaluate the deformation characteristics of the mixtures. In all test conditions, the highest resistance to permanent deformation is showed by the rubberized mixtures produced with continuous blend binders. This study also reveals that the permanent deformation of rubberized mixtures cannot be predicted based on the characteristics of the rubberized binders.

Download Full-text

Use of Superpave Technology for Design and Construction of Rubberized Asphalt Mixtures

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1583-09 ◽

1997 ◽

Vol 1583 (1) ◽

pp. 71-81 ◽

Cited By ~ 9

Author(s):

H. Barry Takallou ◽

Hussain U. Bahia ◽

Dario Perdomo ◽

Robert Schwartz

Keyword(s):

Fatigue Behavior ◽

Permanent Deformation ◽

Performance Testing ◽

Fatigue Cracking ◽

Asphalt Mixtures ◽

Mix Design ◽

Asphalt Rubber ◽

Constant Height ◽

Overlay Design ◽

Gyratory Compaction

The effect of different mixing times and mixing temperatures on the performance of asphalt-rubber binder was evaluated. Four different types of asphalt-rubber binders and neat asphalt were characterized using the Strategic Highway Research Program (SHRP) binder method tests. Subsequently, mix designs were carried out using both the SHRP Levels I and II mix design procedures, as well as the traditional Marshall mix design scheme. Additionally, performance testing was carried out on the mixtures using the Superpave repetitive simple shear test at constant height (RSST-CH) to evaluate the resistance to permanent deformation (rutting) of the rubberized asphalt mixtures. Also, six rectangular beams were subjected to repeated bending in the fatigue tester at different microstrain levels to establish rubberized asphalt mixtures’ resistance to fatigue cracking under repeated loadings. The results indicate that the Superpave mix design produced asphalt-rubber contents that are significantly higher than values used successfully in the field. Marshall-used gyratory compaction could not produce the same densification trends. Superpave mixture analysis testing (Level II) was used successfully for rubberized asphalt mixtures. Results clearly indicated that the mixture selected exhibited acceptable rutting and fatigue behavior for typical new construction and for overlay design. Few problems were encountered in running the Superpave models. The results of the RSST-CH indicate that rubber-modified asphalt concrete meets the criteria for a maximum rut depth of 0.5 in.; and more consistent results were measured for fatigue performance analysis using the repeated four-point bending beam testing (Superpave optional torture testing). The cycles to failure were approximately 26,000 at 600 microstrain.

Download Full-text

Estimation of Service Life of Mechanical Engineering Components

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.799.71 ◽

2019 ◽

Vol 799 ◽

pp. 71-76

Author(s):

Oskars Linins ◽

Ernests Jansons ◽

Armands Leitans ◽

Irina Boiko ◽

Janis Lungevics

Keyword(s):

Service Life ◽

Service Time ◽

Surface Texture ◽

Mechanical Engineering ◽

Friction Pair ◽

Theory Of Elasticity ◽

New Approach ◽

Material Fatigue ◽

Texture Parameters ◽

3D Surface Texture

The paper is aimed to the methodology for estimation of service life of mechanical engineering components in the case of elastic-plastic contact of surfaces. Well-known calculation methods depending on physics, theory of probability, the analysis of friction pair’ shape and fit include a number of parameters that are difficult or even impossible to be technologically controlled in the manufacturing of mechanical engineering components. The new approach for wear rate estimation using surface texture parameters as well as physical-mechanical properties and geometric parameters of components is proposed. The theoretical part of the calculations is based on the 3D surface texture principles, the basics of material fatigue theory, the theory of elasticity and the contact mechanics of surfaces. It is possible to calculate the service time of the machine, but the process of running-in of the components is relatively short (less than 5%), therefore, the service time is mainly determined by a normal operating period, which also was used to evaluate this period. The calculated input parameters are technologically and metrologically available and new method for calculating the service time can be used in the design process of the equipment. The results of approbation of the method for estimation service time of mechanical engineering, which prove the applicability of mentioned method, are offered as well.

Download Full-text

Functional and environmental performance of plant-produced crumb rubber asphalt mixtures using the dry process

Materials and Structures ◽

10.1617/s11527-021-01790-y ◽

2021 ◽

Vol 54 (5) ◽

Author(s):

M. Bueno ◽

R. Haag ◽

N. Heeb ◽

P. Mikhailenko ◽

L. Boesiger ◽

...

Keyword(s):

Environmental Performance ◽

High Performance ◽

Large Scale ◽

Fatigue Behavior ◽

Permanent Deformation ◽

Asphalt Mixture ◽

Crumb Rubber ◽

Asphalt Mixtures ◽

Gaseous Emissions ◽

Dry Process

AbstractIncorporating crumb rubber (CR) using the dry process, directly in the asphalt mixture rather than into the bituminous binder requires no plant retrofitting, and therefore is the most practical industrial method for CR incorporation into asphalt mixtures. Nevertheless, very few large scale studies have been conducted. This work uses a holistic approach and reports on the functional and environmental performance of asphalt mixtures with different concentrations of CR fabricated employing the dry process in asphalt plants. Gaseous emissions were monitored during the production and laboratory leaching tests simulating the release of pollutants during rain, was conducted to evaluate the toxicology of both the CR material alone and the modified asphalt mixtures. In addition, laboratory compacted samples were tested to assess their fatigue behavior. Furthermore, noise relevant surface properties of large roller compacted slabs were evaluated before and after being subjected to a load simulator (MMLS3) to evaluate their resistance to permanent deformation. The results confirm that comparable performance can be achieved with the incorporation of CR using the dry process for high performance surfaces such as semi-dense asphalt, which usually require the use of polymer modified binders. Environmental performance improvement can be achieved by a washing step of the CR material that could remove polar CR additives which have commonly been used as vulcanization accelerator during rubber production.

Download Full-text

Effect of Coarse Aggregate Morphology on the Resilient Modulus of Hot-Mix Asphalt

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105192900101 ◽

2005 ◽

Vol 1929 (1) ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Tongyan Pan ◽

Erol Tutumluer ◽

Samuel H. Carpenter

Keyword(s):

Surface Texture ◽

Coarse Aggregate ◽

Resilient Modulus ◽

Asphalt Binder ◽

Aggregate Size ◽

Asphalt Mixtures ◽

Maximum Aggregate Size ◽

Asphalt Mixes ◽

Aggregate Morphology ◽

The Relationship

The resilient modulus measured in the indirect tensile mode according to ASTM D 4123 reflects effectively the elastic properties of asphalt mixtures under repeated load. The coarse aggregate morphology quantified by angularity and surface texture properties affects resilient modulus of asphalt mixes; however, the relationship is not yet well understood because of the lack of quantitative measurement of coarse aggregate morphology. This paper presents findings of a laboratory study aimed at investigating the effects of the material properties of the major component on the resilient modulus of asphalt mixes, with the coarse aggregate morphology considered as the principal factor. With modulus tests performed at a temperature of 25°C, using coarse aggregates with more irregular morphologies substantially improved the resilient modulus of asphalt mixtures. An imaging-based angularity index was found to be more closely related to the resilient modulus than an imaging-based surface texture index, as indicated by a higher value of the correlation coefficient. The stiffness of the asphalt binder also had a strong influence on modulus. When the resilient modulus data were grouped on the basis of binder stiffnesses, the agreement between the coarse aggregate morphology and the resilient modulus was significantly improved in each group. Although the changes in aggregate gradation did not significantly affect the relationship between the coarse aggregate morphology and the resilient modulus, decreasing the nominal maximum aggregate size from 19 mm to 9.5 mm indicated an increasing positive influence of aggregate morphology on the resilient modulus of asphalt mixes.

Download Full-text