Effects of Asphalt Foaming on Damage Characteristics of Foamed Warm Mix Asphalt

2021 ◽  
pp. 036119812199782
Author(s):  
Biswajit K. Bairgi ◽  
Md Amanul Hasan ◽  
Rafiqul A. Tarefder
Keyword(s):  
Permanent Deformation ◽  
Warm Mix Asphalt ◽  
Creep Recovery ◽  
Deformation Model ◽  
Contact Method ◽  
Moisture Susceptibility ◽  
Viscoelastic Continuum Damage ◽  
Foamed Asphalt ◽  
Flexural Beam ◽  
Wheel Tracking

In the asphalt foaming process, the foaming water content (FWC) controls the formation and characteristics of water bubbles. These water bubbles are expected to be expelled from the foamed warm mix asphalt (WMA) during mixing and compaction. However, foaming water may not be completely expelled, rather some of the microbubbles may be trapped in the foamed WMA even after compaction. These microbubbles, or undissipated water, can diffuse over time and cause damage to the foamed WMA. To this end, this study has determined the effects of foaming on the fatigue, moisture damage, and permanent deformation characteristics of foamed WMA. Foamed asphalt and mixtures were designed with varying FWCs and they were tested using linear amplitude sweep, multiple stress creep recovery, four-point flexural beam, and Hamburg wheel tracking tests. Primarily, asphalt foaming dynamics were assessed with a laser-based non-contact method. A simplified viscoelastic continuum damage concept and a three-phase permanent deformation model were used for damage evaluation. The study reveals that foaming softens the binder, which results in slightly higher rutting and moisture susceptibility, though an equivalent or slightly improved fatigue characteristic compared with the regular hot mix asphalt.

Effectiveness of Loaded Wheel Tracking Test to Ascertain Moisture Susceptibility of Asphalt Mixtures

2021 ◽  
pp. 036119812110363
Author(s):  
Moses Akentuna ◽  
Louay N. Mohammad ◽  
Sanchit Sachdeva ◽  
Samuel B. Cooper ◽  
Samuel B. Cooper
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Moisture Damage ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Creep Recovery ◽  
Moisture Susceptibility ◽  
Freeze Thaw ◽  
Wheel Tracking ◽  
Mixture Samples

Moisture damage of asphalt mixtures is a major distress affecting the durability of asphalt pavements. The loaded wheel tracking (LWT) test is gaining popularity in determining moisture damage because of its ability to relate laboratory performance to field performance. However, the accuracy of LWT’s “pass/fail” criteria for screening mixtures is limited. The objective of this study was to evaluate the capability of the LWT test to identify moisture susceptibility of asphalt mixtures with different moisture conditioning protocols. Seven 12.5 mm asphalt mixtures with two asphalt binder types (unmodified PG 67-22 and modified PG 70-22), and three aggregate types (limestone, crushed gravel, and a semi-crushed gravel) were utilized. Asphalt binder and mixture samples were subjected to five conditioning levels, namely, a control; single freeze–thaw-; triple freeze–thaw-; MiST 3500 cycles; and MiST 7000 cycles. Frequency sweep at multiple temperatures and frequencies, and multiple stress creep recovery tests were performed to evaluate asphalt binders. LWT test was used to evaluate the asphalt mixture samples. Freeze–thaw and MiST conditioning resulted in an increase in stiffness in the asphalt binders as compared with the control. Further, freeze–thaw and MiST conditioning resulted in an increase in rut depth compared with the control asphalt mixture. The conditioning protocols evaluated were effective in exposing moisture-sensitive mixtures, which initially showed compliance with Louisiana asphalt mixture design specifications.

Analysis of Foaming Properties of Asphalt Binder Through a Laser Based Non-Contact Method

2017 ◽  
Author(s):  
Biswajit Kumar Bairgi ◽  
Rafiqul Tarefder
Keyword(s):  
Volume Expansion ◽  
Asphalt Binder ◽  
The United States ◽  
Warm Mix Asphalt ◽  
Expansion Ratio ◽  
Parameter Analysis ◽  
Foaming Properties ◽  
Contact Method ◽  
Contributing Factors ◽  
Foamed Asphalt

Water injected foamed asphalt application in warm mix asphalt (WMA) accounts for more than 90% of all WMA technologies in past several years in the United States (US). Among different asphalt foaming variables: foaming temperatures, foaming water content (FWC), and air pressure are the major controlling factors of foamed asphalt binder characteristics. Foaming induced binder volume expansion and durability of the expanded volume are two contributing factors of foamed asphalt binder properties and foamed mixtures workability. This study evaluates the effect of FWC on foamed asphalt binder properties through a non-contact method. A laser distance meter has been utilized to record the foaming induced binder volume expansion and subsequent foamed bubbles collapse rate. Recently developed four foaming parameters such as expansion ratio (ER), half-life (HL), foaming index (FI), and stability of semis-table foamed binder bubbles (k-values) have been evaluated to characterize foamed asphalt binder. It is seen that addition of higher FWC results in a higher expansion and durability of overall foamed bubbles. Foaming parameter analysis also shows that semi-stable foamed bubbles durability is fairly constant in higher FWCs. Foamed binder rheology is also found to be correlated with FWCs.

scholarly journals Performance Evaluation of Crumb Rubber Asphalt Modified with Silicone-Based Warm Mix Additives

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Nonde Lushinga ◽  
Liping Cao ◽  
Zejiao Dong ◽  
Chen Yang ◽  
Cyriaque O. Assogba
Keyword(s):  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Crumb Rubber ◽  
Warm Mix Asphalt ◽  
Asphalt Binders ◽  
Water Repellent ◽  
Creep Recovery ◽  
Viscoelastic Continuum Damage ◽  
Warm Mix Additives ◽  
Different Temperatures

This research was conducted to elucidate better understanding of the performance of crumb rubber asphalt modified with silicone-based warm mix additives. Two different silicone-based warm mix asphalt (WMA) additives (herein Tego XP and Addibit) were used to prepare crumb rubber modified (CRM) warm mix asphalt binders. The viscosity of these CRM binders was measured at different temperatures and shearing rates. Furthermore, softening point and penetration tests, Multiple Stress Creep Recovery (MSCR), Time Sweep (TS), Atomic Force Microscopy (AFM), Frequency sweep (FS), and Fourier Transform Infrared (FTIR) tests were also conducted on prepared samples. Based on these robust and rigorous laboratory experiments, it was established that viscosity of CRM binders was reduced by addition of Tego XP and Addibit WMA additives. However, WMA additives had different influence on rheological properties of the binder. CRM binder with Tego XP improved resistance to rutting of the binders but would degrade the fatigue performance. On the contrary, viscoelastic continuum damage (VECD) model results and those of phase angle approach revealed that the binder with Addibit improved resistance to fatigue cracking of the binders but had no adverse effects on high temperature rutting performance. FTIR test results established a presence of polydimethylsiloxane (PDMS) in CRM binders with Tego XP and Addibit. PDMS is a well-known hydrophobic organic and inorganic polymer that is water repellent; therefore, binders containing these silicone-based warm mix additives could be beneficial in resisting moisture damage in asphalt binders and mixtures. Morphology of CRM binders with and without WMA revealed good distribution of the rubber particles in asphalt binder matrix. Further addition of WMA increased surface roughness of the binder, which can be correlated to changes in microstructure properties of the binder. Therefore, the study concluded that addition of Tego XP and Addibit reduces viscosity and improves mechanical properties of the asphalt binder.

scholarly journals Performance of High Rap Half-Warm Mix Asphalt

2020 ◽  
Vol 12 (24) ◽  
pp. 10240
Author(s):  
Ana R. Pasandín ◽  
Ignacio Pérez ◽  
Breixo Gómez-Meijide
Keyword(s):  
Resilient Modulus ◽  
Mixing Time ◽  
Permanent Deformation ◽  
Tensile Tests ◽  
Warm Mix Asphalt ◽  
Fatigue Tests ◽  
Reclaimed Asphalt ◽  
Compaction Energy ◽  
Indirect Tensile ◽  
Wheel Tracking

The current global situation regarding climate change makes it necessary to promote the circular economy and the use of more environmentally friendly technologies in the construction sector. To that end, it is of interest to deepen our understanding of the performance of half-warm mix asphalt (HWMA) manufactured with high proportions of reclaimed asphalt pavement (RAP). Thus, in the present study, a laboratory analysis was carried out in which the behavior of HWMA manufactured with 100% RAP and without rejuvenators was compared with that of a control mix, i.e., an HWMA manufactured with 0% RAP. In particular, we analyzed the compaction energy with a gyratory compactor, mixing time and temperature, volumetric properties, moisture damage resistance through indirect tensile tests after immersion (ITS), stiffness based on the resilient modulus, resistance to permanent deformation using wheel tracking tests, and fatigue resistance through indirect tensile fatigue tests (ITFT). Both mixtures displayed adequate volumetric and mechanical properties, but the performance of the high-RAP HWMA was better than that of the control mixture in terms of resistance to permanent deformation in hot areas. In addition, the high-RAP HWMA without rejuvenators could provide energy and material savings, thus promoting sustainable development.

Effect of aggregate gradation on permanent deformation behavior of a warm mix asphalt

2016 ◽  
Vol 58 (7-8) ◽  
pp. 678-688 ◽  
Author(s):  
Ebrahim Sangsefidi ◽  
Ali Mansourkhaki ◽  
Hasan Ziari
Keyword(s):  
Deformation Behavior ◽  
Permanent Deformation ◽  
Warm Mix Asphalt ◽  
Aggregate Gradation

scholarly journals Rutting and moisture-induced damage potential of foamed warm mix asphalt (WMA) containing RAP

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Mohammad Ashiqur Rahman ◽  
Rouzbeh Ghabchi ◽  
Musharraf Zaman ◽  
Syed Ashik Ali
Keyword(s):  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Chemical Additives ◽  
Flow Number ◽  
Damage Potential ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Wheel Tracking

AbstractDespite significant economic and environmental benefits, performance of warm mix asphalt (WMA) containing reclaimed asphalt pavement (RAP) remains a matter of concern. Among the current WMA technologies, the plant foaming technique (called “foamed WMA” in this study) has gained the most attention, since it eliminates the need for chemical additives. In the present study, the laboratory performance, namely rutting and moisture-induced damage potential of foamed WMA containing RAP were evaluated and compared with those of similar hot mix asphalt (HMA) containing identical amount of RAP. Dynamic modulus, Hamburg wheel tracking (HWT) and flow number tests were performed to assess the rutting resistance of the mixes. Also, stripping inflection point from HWT tests and tensile strength ratio after AASHTO T 283 and moisture induced sensitivity test (MIST) conditioning were used to evaluate the moisture-induced damage of asphalt mixes. It was found that MIST conditioning effectively simulates the moisture-induced damage and can capture the propensity of asphalt mixes to moisture damage more distinctly compared to AASHTO T 283 method due to application of cyclic loadings. The foamed WMA was found to exhibit higher rutting and moisture-induced damage potential due to lower mixing and compaction temperatures compared to HMA. However, the increase in RAP content was found to reduce rutting and moisture-induced damage potential for WMA. Therefore, the lower stiffness of foamed WMA may be compensated with the addition of stiffer binder from RAP.

Performance of Asphalt Mixture Used for Asphalt Treated Base of Perpetual Pavements

2011 ◽  
Vol 415-417 ◽  
pp. 1531-1536
Author(s):  
Fu Ming Liu ◽  
Duan Yi Wang
Keyword(s):  
Tensile Strain ◽  
Performance Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Asphalt Pavements ◽  
Moisture Susceptibility ◽  
Scale Test ◽  
And Performance ◽  
Wheel Tracking ◽  
Fatigue Endurance

This paper presents the results of laboratory and performance tests for an asphalt treated base (ATB) and mixes developed in this study for perpetual asphalt pavements. Laboratory tests for the mixes included moisture susceptibility, wheel tracking and fatigue tests. The results of performance test indicated that the resistances of the high content binder ATB against moisture and fatigue damage were better than those of the lower one. It was also found from the full scale test sections that the tensile strain values at the bottom of the asphalt layer for the ATB sections were low when the asphalt layer thicknesses of the ATB sections were not thicker than those of the conventional sections. All the tensile strain values measured from the ATB sections were within the fatigue endurance limit of 70 microstrain which is the fatigue criterion of a perpetual asphalt pavement.

Performance Characterization of Stone Mastic Asphalt using Steel Fiber

2021 ◽  
Vol 02 (02) ◽  
Author(s):  
Ekarizan Shaffie ◽  
◽  
H.A. Rashid ◽  
Fiona Shiong ◽  
Ahmad Kamil Arshad ◽  
...  
Keyword(s):  
Steel Fiber ◽  
Mechanical Performance ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Moisture Susceptibility ◽  
Mastic Asphalt ◽  
Bitumen Content ◽  
Stone Mastic Asphalt ◽  
The Stability ◽  
Marshall Stability

Stone Mastic Asphalt (SMA) is a gap-graded hot mixture designed to provide higher resistance towards permanent deformation and rutting potential by 30% to 40% more than dense-graded asphalt, due to its stable aggregate skeleton structure. However, compared to other types of hot mix asphalt, SMA unfortunately has some shortcomings in term of its susceptibility towards moisture-induced damage due to its structure and excessive bitumen content in the composition. This research aims to assess the performance of a SMA mixture with steel fiber by enhancing overall stability, abrasion resistance, and, most importantly, moisture susceptibility. This study involved the incorporation of various steel fiber proportions of 0%, 0.3%, 0.5% and 0.7% by the total weight of mixture. The steel fiber modified SMA was made up of 6.0% PEN 60/70 bitumen content. The performance of SMA were evaluated through Marshall stability and flow test, Cantabro loss test and indirect tensile strength test. The results obtained from the testing showed that the incorporation of steel fiber is significantly effective to enhance the resistance towards moisture damage, while increasing the stability and reducing the abrasion loss of SMA mixture, compared to conventional mixture. Overall, it can be concluded that the addition of steel fiber in asphalt mixture specifically SMA, has improved the mechanical performance in the application of asphalt pavement with the optimum steel fiber proportion of 0.3% by the weight of mixture. The developed models between the independent variables and responses demonstrated high levels of correlation. The study found that Response Surface Methodology (RSM) is an effective statistical method for providing an appropriate empirical model for relating parameters and predicting the optimum performance of an asphaltic mixture to reduce flexible pavement failure.

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