scholarly journals Comparing the Field and Laboratory Curing Behaviour of Cold Recycled Asphalt Mixtures for Binder Courses

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4697
Author(s):  
Gilda Ferrotti ◽  
Andrea Grilli ◽  
Chiara Mignini ◽  
Andrea Graziani
Keyword(s):  
Mechanical Performance ◽  
Complex Modulus ◽  
Material Design ◽  
Asphalt Mixtures ◽  
Laboratory Simulation ◽  
Curing Time ◽  
Recycled Asphalt ◽  
Air Voids ◽  
Indirect Tensile

The cold recycling of reclaimed asphalt (RA) for the rehabilitation of end-of-life pavements is becoming very common. Cold recycled asphalt mixtures (CRAMs) are characterised by a curing time, required to reach the material design mechanical performance. Since the laboratory simulation of the long-term field curing is not yet a standardised procedure, a CRAM was laid as binder course in a full-scale trial section that was monitored for more than two years. The comparison between field curing and oven-curing in laboratory at 40 °C was performed by carrying out indirect tensile stiffness modulus (ITSM), indirect tensile strength (ITS) and complex modulus tests, as well as measurements of the air voids content. The evolution of the ITSM as a function of the curing time (field/oven-curing) was obtained for both gyratory specimens and cores taken from the trial section at different time periods. Results showed that the material stiffness development can be accelerated with a small effect on its long-term value if oven-curing is applied a few days/weeks after compaction. A linear relationship was found between the ITS measured on the cores and their air voids content. Finally, the complex modulus tests confirmed that CRAMs provide an intermediate behaviour between asphalt concrete mixtures and cement-bound mixtures.

A Balanced Mix Design Method for Selecting the Optimum Binder Content of Cold In-Place Recycling Asphalt Mixtures

2019 ◽  
Vol 2673 (3) ◽  
pp. 526-539 ◽  
Author(s):  
Ahmed Saidi ◽  
Ayman Ali ◽  
Wade Lein ◽  
Yusuf Mehta
Keyword(s):  
Complex Modulus ◽  
Cement Content ◽  
Design Method ◽  
Binder Content ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Air Voids ◽  
Foamed Asphalt ◽  
Indirect Tensile ◽  
Emulsified Asphalt

The objective of this paper is to present a procedure for designing cold in-place recycling (CIR) mixtures through balancing rutting and cracking for these mixtures. Four CIR mixtures were prepared using two recycling agents (foamed and emulsified asphalts), and compacted at two gyration levels (30 and 70 gyrations). The CIR mixtures were prepared at a constant water content of 3% and a constant cement content of 1% while curing of the compacted samples was conducted by placing them in an oven for three days at 140°F (dry curing). The CoreLok device was used for measuring air voids in compacted samples. The rutting susceptibility of these mixtures was then evaluated using the asphalt pavement analyzer (APA) and dynamic complex modulus (|E*|) while resistance to cracking was assessed using the indirect tensile strength (ITS) test and fracture energy as determined using the semi-circular bend (SCB-FE) test. A demonstration of how these tests were utilized to select a performance balanced optimum binder content for each of the four CIR mixes was also presented. The developed balanced mix design approach was used successfully for designing four CIR mixtures and selecting the optimum binder content for each mix. The results also showed that using a higher compaction level leads to increasing both foamed and emulsified asphalt CIR mixtures’ ability to resist rutting. In terms of cracking, SCB-FE results showed that foamed asphalt mixtures were better at resisting cracking than emulsified asphalt CIR mixtures.

scholarly journals Effect of bitumen emulsion on mechanical performance of cold asphalt mixtures

2014 ◽  
Vol 12 (2) ◽  
pp. 195-205
Author(s):  
Miomir Miljkovic
Keyword(s):  
Mechanical Performance ◽  
Asphalt Mixtures ◽  
Continuous Change ◽  
Bitumen Emulsion ◽  
Term Basis ◽  
Innovative Material ◽  
Indirect Tensile ◽  
Fracture Performance ◽  
Pavement Construction

Implementation of innovative material and evaluation concepts in pavement construction industry is important to reduce the negative environmental impacts. The objective of this paper is to review the recent scientific developments in characterising the effect of bitumen emulsion properties on the performance of cold asphalt mixtures. The experimental approach was based on the indirect tensile testing of the standardised bitumen emulsion mortar specimens. The major finding is that there is a continuous change in mechanical properties and the mode of fracture on the long-term basis. However, the ratios of the considered fracture performance-related parameters indicated that the change in the mode of fracture from ductile to brittle is not that direct, and the reason for this could be in the relation between the development of the adhesion and the residual binder viscosity. As a step towards fundamental understanding of the contribution of adhesion, further research should be focused on the interaction between cement hydration, binder droplets, and emulsifier.

scholarly journals Evaluation of Asphalt Mixtures Containing Metallic Fibers from Recycled Tires to Promote Crack-Healing

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5731
Author(s):  
Alvaro González ◽  
José Norambuena-Contreras ◽  
Lily Poulikakos ◽  
María José Varela ◽  
Jonathan Valderrama ◽  
...  
Keyword(s):  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Fiber Content ◽  
Crack Healing ◽  
Electrically Conductive ◽  
Air Voids ◽  
Indirect Tensile ◽  
Increasing Temperature ◽  
Metallic Fibers

This paper reports part of an international research project with the long-term aim of developing more sustainable asphalt mixture with crack-healing properties by the addition of recycled metallic waste from industrial sources. Specifically, this article presents an evaluation of the physical, thermophysical, and mechanical properties of asphalt mixtures with metallic fiber obtained from recycled tires for crack-healing purposes. Detailed results on the crack-healing of asphalt mixtures will be reported in a second article. Results showed a small reduction on the bulk density and increase in the air voids content was quantified with increasing fiber contents. The experimental results showed that mixing and compaction was more difficult for higher fiber contents due to less space for the bitumen to freely flow and fill the voids of the mixtures. Computed tomography (CT) results allowed to identify clustering and orientation of the fibers. The samples were electrically conductive, and the electrical resistivity decreased with the increase of the fiber content. Fiber content had a direct effect on the indirect tensile stiffness modulus (ITSM) and strength (ITS) that decreased with increasing temperature for mixtures and with increase in fiber content. However, the indirect tensile strength ratio (ITSR) was within acceptable limits. In short, results indicate that fibers from recycled tires have a potential for use within asphalt mixtures to promote crack-healing.

Sewage Sludge as Raw-Material in Asphalt Mixtures

2013 ◽  
Vol 664 ◽  
pp. 638-643 ◽  
Author(s):  
Maria del Pilar Durante Ingunza ◽  
Olavo Francisco dos Santos Júnior ◽  
Sayonara Andrade Medeiros
Keyword(s):  
Mechanical Performance ◽  
Environmental Parameters ◽  
Empty Space ◽  
Asphalt Mixtures ◽  
International Standards ◽  
Raw Material ◽  
Air Voids ◽  
The One ◽  
Consequent Increase ◽  
Space Volume

The aim of this study is to assess the volumetric and mechanical behavior of concrete asphalt mixtures, using natural sludge as a partial substitute for the tiny aggregate and calcined sludge as filler. This assessment was performed based on technical and environmental parameters, using laboratory tests obeying current Brazilian norms, according to international standards. The addition of natural sludge to the mixtures has increased stability, increased air voids contents of the mixtures. The addition has compromised mixture adhesiveness. With respect to the addition of calcined sludge to the mixtures, the mixtures with calcined sludge displayed the same behavior as those with cement. It was observed decrease in empty space volume of the mixtures and consequent increase in empty space-bitumen relation and increased stability. The mixture addition of natural sludge that has the best mechanical and volumetric performance is the one with 7.5% of natural sludge in the granulometric composition of the mixture. The mixture with 1% of calcined sludge had the best volumetric and mechanical performance.

scholarly journals Deformation Parameters and Fatigue of the Recycled Asphalt Mixtures

2015 ◽  
Vol 11 (2) ◽  
pp. 115-120
Author(s):  
Juraj Šrámek
Keyword(s):  
Complex Modulus ◽  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Test Method ◽  
Traffic Load ◽  
Bending Test ◽  
Recycled Asphalt ◽  
The Road ◽  
Dynamic Methods ◽  
Deformation Complex

Abstract The deformational properties of asphalt mixtures measured by dynamic methods and fatigue allow a design the road to suit the expected traffic load. Quality of mixtures is also expressed by the resistance to permanent deformation. Complex modulus of stiffness and fatigue can reliably characterize the proposed mixture of asphalt pavement. The complex modulus (E*) measurement of asphalt mixtures are carried out in laboratory of Department of Construction Management at University of Žilina by two-point bending test method on trapezoid-shaped samples. Today, the fatigue is verified on trapezoid-shaped samples and is assessed by proportional strain at 1 million cycles (ε6). The test equipment and software is used to evaluate fatigue and deformation characteristics.

Microstructural analysis of asphalt mixtures using digital image processing techniques

2014 ◽  
Vol 41 (1) ◽  
pp. 74-86 ◽  
Author(s):  
Ki Hoon Moon ◽  
Augusto Cannone Falchetto ◽  
Jin Hoon Jeong
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Microstructural Analysis ◽  
Asphalt Mixture ◽  
Material Model ◽  
Asphalt Mixtures ◽  
Recycled Asphalt ◽  
Air Voids ◽  
Processing Techniques

In this paper, the internal microstructure of asphalt mixture is analyzed through digital image processing (DIP) of two-dimensional asphalt mixture images. A set of 12 mixtures prepared with two binders, two air voids percentages, and different recycled asphalt pavement (RAP) contents is used. First, small asphalt mixture beams of the same size of bending beam rheometer specimens are prepared for the images acquisition. Then, based on mixture volumetric properties, a three-phase material model is obtained. Finally, 2- and 3-point correlation functions of the material phases are numerically evaluated. No significant differences were observed in the microstructure and spatial distributions of aggregates, asphalt mastic, and air voids for asphalt mixtures containing up to 40% of RAP. However, an increase in auto correlation length (ACL) was found for RAP mixtures in comparison with the conventional mixtures.

scholarly journals Effect of Aging on the Properties of Asphalt and Asphalt Mixtures

2015 ◽  
Vol 19 (2) ◽  
pp. 89
Author(s):  
Carlos Hernando Higuera Sandoval ◽  
Xiomara Vanessa Camargo Amaya ◽  
Edwin Alexander Suárez Molano
Keyword(s):  
Tensile Test ◽  
Dynamic Modulus ◽  
Work Values ◽  
Asphalt Mixtures ◽  
Indirect Tensile Test ◽  
Aged Asphalt ◽  
Indirect Tensile ◽  
The Stability

This article presents the results of the analysis of the effect of aging on the properties of asphalt and asphalt mixtures. The objective of this study was to compare the properties of the original asphalt and aged asphalt and the dynamic modulus of asphalt mixtures. The long-term aging was simulated by using Pressure Asphalt Vessel (PAV). Marshall and RAMCODES methodologies were used to determine the formula of work; values of dynamic modulus of designed mixtures were obtained by the indirect tensile test, using the Nottingham Asphalt Tester (NAT). The results showed an increase in the rigidity of the aged asphalt. Also, an increase of the stability and a decreased flow in the mixtures made with this type of binder was found. The dynamic modulus values of the mixtures containing aged asphalt showed an increase up to three times compared with those elaborated with original asphalt mixtures.

scholarly journals Investigation on the Combined Effect of Fibers and Cement on the Mechanical Performance of Foamed Bitumen Mixtures Containing 100% RAP

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Ehsan Ashouri Taziani ◽  
Emanuele Toraldo ◽  
Filippo Giustozzi ◽  
Maurizio Crispino
Keyword(s):  
Research Study ◽  
Mechanical Performance ◽  
Asphalt Pavement ◽  
Construction Materials ◽  
Recycled Asphalt ◽  
New Methods ◽  
Dynamic Creep ◽  
Indirect Tensile ◽  
The Common ◽  
Foamed Bitumen

Concerns about virgin aggregate sources and increasing demands for construction materials of transport infrastructures as the key parameters in development are the most important reasons, which convinced pavement engineers to develop new methods in order to use higher amount of recycled asphalt pavement (RAP). One of the common methodologies to produce mixtures containing RAP is foamed bitumen mix (FBM). In addition, according to previous research studies, incorporating various types of fibers and hydraulic binders such as cement could significantly improve the mechanical performance of mixtures. The present research study evaluated FBM containing 100% RAP and two types of fiber and Portland cement. Dynamic modulus, unconfined dynamic creep compression, and indirect tensile strength were evaluated in the laboratory at optimum moisture content, which was investigated in this research. Both types of fiber and cement proved to enhance specific properties of mixtures.

Impact of Aging on the Viscoelastic Properties and Cracking Behavior of Asphalt Mixtures

2019 ◽  
Vol 2673 (6) ◽  
pp. 406-415 ◽  
Author(s):  
Runhua Zhang ◽  
Jo E. Sias ◽  
Eshan V. Dave ◽  
Reyhaneh Rahbar-Rastegar
Keyword(s):  
Viscoelastic Properties ◽  
Complex Modulus ◽  
Fatigue Cracking ◽  
Compact Tension ◽  
Asphalt Mixtures ◽  
Fatigue Properties ◽  
Cracking Behavior ◽  
Stiffness Reduction ◽  
Fracture Tests

Aging can significantly affect the viscoelastic properties and cracking behavior of asphalt mixtures, causing increase in stiffness, reduction in relaxation capability, and increase in brittleness. Eleven mixtures are evaluated using different laboratory conditioning protocols to evaluate how the properties of asphalt mixtures, including viscoelastic properties, fatigue, and fracture behavior will change over time. Comparisons between different aging levels and mixtures are conducted by using complex modulus (E*) (field cores are included), simplified viscoelastic continuum damage (S-VECD) approach, semi-circular bending (SCB), and disk shaped compact tension (DCT) fracture tests. The climatic aging index developed by the NCHRP 09-54 project is utilized in this study to calculate the appropriate field aging duration corresponding to the different laboratory aging protocols. Pavement evaluation tools FlexPAVETM and IlliTC are also used to predict and compare the fatigue and thermal cracking performance of these mixtures. The results of E* and S-VECD tests indicate that the mixtures are more prone to fatigue cracking with aging, and the two long-term conditioning protocols induce statistically similar changes in linear viscoelastic and fatigue properties. However, prediction of fatigue performance from FlexPAVE TM does not show a consistent trend once pavement structure and traffic are considered. Fracture tests and IlliTC predictions show the virgin mixtures and those with soft base binders will have better capability to resist cracking after long-term aging. In this study, the two mixtures with the largest difference between high and low temperature performance grade (PG) show the largest change in fracture and fatigue properties with aging.

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