scholarly journals Monitoring Micro Crack Healing Phenomena in Recycled Asphalt Concrete

2020 ◽  
Vol 1 (4) ◽  
pp. 1-6
Author(s):  
Saad Issa Sarsam
Keyword(s):  
Service Life ◽  
Carbon Black ◽  
Asphalt Concrete ◽  
Permanent Deformation ◽  
Styrene Butadiene Rubber ◽  
Shear Stresses ◽  
Crack Healing ◽  
Recycling Process ◽  
Recycled Asphalt ◽  
Testing Techniques

Asphalt concrete usually practices cracking and distress during its service life. However, recycling process as well as crack healing phenomena can enhance the physical properties and extend the pavement service life. This investigation is concerned with monitoring the microcrack healing of recycled asphalt concrete through its influence on deformation measurement under three testing techniques, repeated (compressive, tensile and shear stresses). Reclaimed asphalt concrete mixture was recycled with [carbon black-asphalt] and [Styrene Butadiene Rubber (SBR)-asphalt] rejuvenators. Specimens have been tested with the aid of the pneumatic repeated load system (PRLS). The repeated loading of the three testing techniques was terminated after 1000 load repetitions, and the specimens could heal by external heating at 60°C for 120 minutes. Specimens were returned to the (PRLS) and subjected to another run of repeated stresses application after healing. It was concluded that the deformation increases after recycling process while it declines after microcrack healing regardless of the testing technique adopted. The deformation declines by (31.8, 5.8 and 19)%, (43 ,49 and 24 )% and (44 ,10 and 13 )% under three level of repeated compressive stresses of (0.068, 0.138, and 0.206) MPa at (40 °C) after healing cycle for reclaimed and recycled mixture with (carbon black-asphalt) and (SBR-asphalt) respectively when compared with permanent deformation before the healing cycle. The permanent deformation under repeated punching shear and indirect tensile stresses declines after microcrack healing by (32, 26 and 25.7) % and (73, 78.7 and 78.2) % for reclaimed, recycled with (carbon black-asphalt) and recycled with (SBR-asphalt) mixtures respectively.

scholarly journals Influence of Additives on Permanent Deformation and Resilient Modulus of Recycled Asphalt Concrete

2020 ◽  
Vol 26 (2) ◽  
pp. 159-175
Author(s):  
Mustafa Shakir Mahdi ◽  
Prof. saad Isa Sarsam
Keyword(s):  
Carbon Black ◽  
Compressive Stress ◽  
Asphalt Concrete ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Styrene Butadiene

Tests were performed on asphalt concrete specimens with (101.6 mm in diameter and 101.6 mm in height), and the results were implemented for calculating permanent deformation and resilient modulus under repeated compressive stress with different levels of stresses (0.068, 0.138 and 0.206) MPa at 40 ºC. Two types of additives namely (carbon black-asphalt) and (SBR-asphalt) were tried as rejuvenators with three percentages of (0.5, 1 and 1.5) % by weight of asphalt cement along with two ratios of AC (1 and 2) % have been implemented as rejuvenator and blended with the reclaimed asphalt concrete. Aged materials were obtained from the site. 100% Reclaimed Asphalt Pavement material from the reclaimed mixture is implemented. A set of (3) specimens were prepared for every mixture; three specimens were tested under (repeated compressive stress) at each level of stress. The objective of this work was to study the effect of two types of additives (Styrene-Butadiene-Rubber (SBR) and carbon black) on the performance of recycled asphalt concrete mixture. It was concluded that the Resilient modulus (Mr) at (0.138 and 0.206) MPa stress level decreases by (14, 22 and 8) % and (22, 34 and 11) for reclaimed and recycle mixtures with (carbon black-asphalt and SBR-asphalt) respectively when compared with that at 0.068 MPa. Permanent deformation for recycled mixtures with (carbon black-asphalt and SBR-asphalt) increased by (65.9, 4.54) %, (146.6, 27.2) % and (79, 5.5) % at level of stresses (0.068, 0.138 and 0.206) MPa respectively when compared to reclaimed mixture.

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.

scholarly journals Ensuring the shear resistance of asphalt mixtures in the pavement of highways

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Zelgedin Mevlidinov ◽  
Tatiana Levkovich ◽  
Anastasia Bilсko
Keyword(s):  
Carbon Black ◽  
Asphalt Concrete ◽  
Residual Deformation ◽  
Shear Resistance ◽  
The State ◽  
Shear Stresses ◽  
Concrete Mixtures ◽  
Concrete Mix ◽  
Used Car ◽  
The Impact

Studying the state of the issue on the shear resistance of asphalt concrete mixtures in the pavement, the authors reviewed the currently available technical reference literature. The state of the streets of the city of Bryansk and the highways of the Bryansk region by measuring the depth of the tracks and flows was also examined. The asphalt concrete samples were tested in laboratory conditions taking into account the rate of deformation, temperature and stress-strain state using the device manufactured at the Department of «Highways» of the Bryansk state engineering and technological University. As additives in asphalt concrete mix introduced: rubber crumb from used car tyres, wheels automobiles, carbon black (powder form) and definiltely thermoplastics. The conducted researches on samples of asphalt concrete mix with use of divinyl-styrene thermoplastics (DST) showed that at increase in the polymer content from 2 to 5 % there was some increase in durability of asphalt concrete on tension in 1,06…1,16 times at 0 °C (smaller value corresponds to the smaller number of DST). Compressive strength at a temperature of «plus» 50 °C increased by 1.04…1.08 times and the module of residual deformation at «plus» 50 °C increased by 1.18…1.23 times. In General, with an increase in the content of DST from 2 to 5 %, the shear resistance increased almost 1.27 times (with the introduction of 5 % DST over the mass of bitumen). The conducted research allows to conclude that to reduce the impact of shear stresses in asphalt concrete mixtures it is necessary to introduce modifying additives, the properties of asphalt concrete depend on the presence of additives, as well as on the quality of the stone aggregate, bitumen and other materials. With the introduction of certain additives (DST, carbon black, rubber c hips), the shear resistance of asphalt concrete increases.

Extending the service life of asphalt concrete pavements through the addition of conductive metallic waste particles for induced crack healing

2020 ◽  
pp. 1-14
Author(s):  
Lucas Cenci Aragão ◽  
Eduarda Fontoura ◽  
Luiza Carbunk Godoi ◽  
Mônica Regina Garcez ◽  
Gracieli Bordin Colpo ◽  
...  
Keyword(s):  
Service Life ◽  
Asphalt Concrete ◽  
Concrete Pavements ◽  
Crack Healing ◽  
Waste Particles

scholarly journals Modeling the Influence of Surface Free Energy on Moisture Damage of Recycled Asphalt Concrete

2020 ◽  
Vol 2 (2) ◽  
pp. 168-183
Author(s):  
Saad Issa Sarsam ◽  
Rana Khalid Hamdan
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Sessile Drop ◽  
Permanent Deformation ◽  
Rest Period ◽  
Moisture Damage ◽  
Crumb Rubber ◽  
Shear Stresses ◽  
Recycled Asphalt ◽  
Before And After

Recycling is a sustainable process for restoration of the pavement quality. In this investigation, aged binder was recycled by digestion with (0.5, 1.0, and 1.5) % of polyethylene and crumb rubber. The recycled binder was implemented in the preparation of Marshal specimens. The surface free energy of the control and recycled binder was determined using the Sessile drop method. Specimens were tested under repeated indirect tensile and double punching shear stresses with the aid of pneumatic repeated load system (PRLS). Another group of specimens was tested for moisture damage, then subjected to the same loading sequence. Specimens were subjected to 1200 load repetitions under stress level of 0.138 MPa at 25 °C. The load was sustained for 0.1 second followed by 0.9 seconds of rest period. The permanent deformation was measured before and after moisture damage process for each testing technique. Regression analysis is used to develop a model for the influence of surface free energy on the deformation and the moisture damage using the SPSS Software. It was concluded that the obtained model can explain 82 % of the variation in moisture damage due to the influence of surface free energy.

Permanent Deformation Behavior of Composite Structure Asphalt Concrete

2010 ◽  
Vol 34-35 ◽  
pp. 1477-1482
Author(s):  
Pei Long Li ◽  
Zheng Qi Zhang ◽  
Bing Gang Wang
Keyword(s):  
High Temperature ◽  
Asphalt Concrete ◽  
Composite Structure ◽  
Deformation Behavior ◽  
Composite Structures ◽  
Permanent Deformation ◽  
Maximum Shear Stress ◽  
Shear Stresses ◽  
Element Analysis ◽  
Temperature Performance

In order to study the high-temperature performance of composite structure asphalt concrete specimens, cylindrical and plate double-layer specimens with two asphalt mixtures are prepared to conduct uniaxial repeated load permanent deformation test and wheel tracking test. The deformation behavior and mechanical characteristics are analyzed and the relationship between rut deformation and mechanical parameters are also discussed. In addition, according to finite element analysis, the deformation mechanism of composite structures under the same loads was discussed. The results and analysis indicate that the deformation behaviors of the specimens with different structures are different significantly despite the same total thickness. Among those specimens, S（4/6）has the smallest deformation and corresponding mechanical parameter εp/Fn is also the smallest under the same load. The maximum shear stresses and their occurrence in different positions for different composite structures have discrepancies. The maximum shear stress of S（4/6）is smaller than other structures, which appears in the upper layer having better high temperature performance. This is the reason that the resistance to permanent deformation of S（4/6） is best among the three composite structures.

scholarly journals Assessing the Flexibility of Recycled Asphalt Concrete Pavement

2019 ◽  
Vol 8 (4) ◽  
pp. 168-174
Author(s):  
Saad Issa Sarsam ◽  
Mohammed Chaloob Saleem
Keyword(s):  
Asphalt Concrete ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Applied Loading ◽  
Compressive Stresses ◽  
Asphalt Concrete Pavement

Utilizing reclaimed asphalt pavement (RAP) in new asphalt mixtures has increased in recent years because of its economic and environmental benefits. The flexibility of the recycled asphalt concrete (with cutback and emulsion) in terms of resilient modulus (Mr), rutting resistance, and permanent microstrain have been investigated in this work. Cylindrical specimens of 102 mm in diameter and 102 mm in height have been prepared from the recycled mixture after the short-term aging process. Specimens were subjected to 1200 repeated compressive stresses at (25) ºC. The vertical permanent microstrain was monitored through video capture. It was concluded that RAP mixture can hold the applied loading with minimal permanent deformation as compared to the recycled mixtures. The resilient modulus is lower by (24 and 39) % for mixes recycled with cutback and emulsion respectively as compared to that of RAP. The rate of strain (slope) increases by 11 % and 4 % when cutback and emulsion were implemented as recycling agent respectively as compared to that for RAP mixture.

scholarly journals Influence of Liquid Asphalt on Resilient Modules and Permanent Deformation of Recycled Asphalt Concrete

2019 ◽  
Vol 25 (9) ◽  
pp. 76-91
Author(s):  
Mohammed Chaloob Saleem AL-Shujairy ◽  
Saad Isaa Sarsam
Keyword(s):  
Asphalt Concrete ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Water Bath ◽  
Repeated Loading ◽  
Recycled Asphalt ◽  
Average Value ◽  
Weight Content ◽  
Three Samples ◽  
Indirect Tensile

Tests were performed on Marshall samples and were implemented for permanent deformation and resilient modulus (Mr) under indirect tensile repeated loading (ITRL), with constant stress level. Two types of liquid asphalt (cutback and emulsion) were tried as recycling agents, aged materials that were reclaimed from field (100% RAP), samples were prepared from the aged mixture, and two types of liquid asphalt (cutback and emulsion) with a weight content of 0.5% were utilized to prepare a recycled mixture. A group of twelve samples was prepared for each mixture; six samples were tested directly for ITRL test (three samples at 25˚C and three samples at 40˚C), an average value for ITRL for every three samples was calculated (ITRL for unconditioned samples). The other six samples were placed in volumetric flask 4000-ml heavy- wall glass filled with water at 25˚C under a vacuum pressure of (3.74 kPa) for 5 to 10 minutes. Then the samples were put in deep freeze for 16 hours at -18˚C. The samples were frozen then were transported to a water bath at 60ºC for 24 hours. Then they were soaked in a water bath for 1 hour at 25ºC and tested for the ITRL test (three samples at 25˚C and three samples at 40˚C), the average value of ITRL for every three samples was calculated (ITRL for conditioned samples). It was concluded that the reduction in (Mr) at the Conditioned test as compared to the Unconditioned test was (29.5%, 22.27% and 9.09%) at 25˚C, while at 40˚C, the reduction was (21.28%, 15.53%, and 17.89%) for aged and recycled mixtures with (cutback), and (emulsion) respectively. The change in permanent deformation at the Conditioned test as compared to Unconditioned one was (76.19%, 75.61% and 53.22%) at 25˚C, while at 40˚C it was (56.48%, 35.19%, and 78.33%) for aged and recycled mixtures with (cutback), and (emulsion) respectively.  

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