A laboratory study on CO2emission from asphalt binder and its reduction with the use of warm mix asphalt

Warm mix asphalt (WMA) technology can bring certain environmental and technical benefits through reducing the temperature of production, paving, and compaction of mixture asphalt. Recent studies have shown that some WMA additives are able to reduce the temperature by increasing the lubricating properties of asphalt binder.-based on the tribological theory, this paper studied the mechanism of adsorbing and lubricating film of base asphalt and WMA on the surface of stone by molecular dynamics (MD) simulation method, and the effect of surfactant WMA additive on the lubrication performance of the shear friction system of “stone–asphalt–stone”. The model of base asphalt lubricating film, including saturates, aromatics, resin and asphaltene, as well as the model of warm mix asphalt lubricating film containing imidazoline-type surfactant WMA (IMDL WMA) additive molecule, were established. The shear friction system of “stone–asphalt–stone” of base asphalt and warm mix asphalt was built on the basis of an asphalt lubrication film model and representative calcite model. The results show that the addition of IMDL WMA additive can effectively improve the lubricity of asphalt, reduce the shear stress of asphalt lubricating film, and increase the stability of asphalt film. The temperature in the WMA lubricating film rises, while the adsorption energy on the stone surface decreases with the increase of shear rate, indicating that the higher the shear rate is, the more unfavorable it is for the WMA lubricating film to wrap on the stone surface. In addition, the shear stress of the WMA lubricating film decreased with increasing temperature, while the shear stress of the base asphalt lubricating film increased first and then decreased, demonstrating that the compactability of the asphalt mixture did not improve linearly with the increase of temperature.

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Evaluating the Surface Free Energy and Moisture Sensitivity of Warm Mix Asphalt Binders Using Dynamic Contact Angle

Advances in Civil Engineering ◽

10.1155/2019/9153603 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15 ◽

Cited By ~ 6

Author(s):

Muhammad Rafiq Kakar ◽

Meor Othman Hamzah ◽

Mohammad Nishat Akhtar ◽

Junita Mohamad Saleh

Keyword(s):

Contact Angle ◽

Free Energy ◽

Hot Mix Asphalt ◽

Asphalt Binder ◽

Moisture Damage ◽

Warm Mix Asphalt ◽

Work Of Adhesion ◽

Moisture Sensitivity ◽

Modified Binders ◽

Production Temperature

From the environmental conservation perspective, warm mix asphalt is more preferable compared to hot mix asphalt. This is because warm mix asphalt can be produced and paved in the temperature range 20–40°C lower than its equivalent hot mix asphalt. In terms of cost-effectiveness, warm mix asphalt can significantly improve the mixture workability at a lower temperature and thus reduce greenhouse gas emissions, to be environment friendly. However, the concern, which is challenging to warm mix asphalt, is its susceptibility to moisture damage due to its reduced production temperature. This may cause adhesive failure, which could eventually result in stripping of the asphalt binder from the aggregates. This research highlights the significance of Cecabase warm mix additive to lower the production temperature of warm mix asphalt and improvise the asphalt binder adhesion properties with aggregate. The binders used in the preparation of the test specimen were PG-64 and PG-76. The contact angle values were measured by using the dynamic Wilhelmy plate device. The surface free energy of Cecabase-modified binders was then computed by developing a dedicated algorithm using the C++ program. The analytical measurements such as the spreadability coefficient, work of adhesion, and compatibility ratio were used to analyze the results. The results inferred that the Cecabase improved the spreadability of the asphalt binder over limestone compared to the granite aggregate substrate. Nevertheless, the Cecabase-modified binders improved the work of adhesion. In terms of moisture sensitivity, it is also evident from the compatibility ratio indicator that, unlike granite aggregates, the limestone aggregates were less susceptible to moisture damage.

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

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2017-71228 ◽

2017 ◽

Cited By ~ 3

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.

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

Advances in Civil Engineering ◽

10.1155/2020/4840825 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17 ◽

Cited By ~ 1

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.

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Characteristics of a Surfactant Produced Warm Mix Asphalt Binder and Workability of the Mixture

Journal of Testing and Evaluation ◽

10.1520/jte20140447 ◽

2015 ◽

Vol 44 (6) ◽

pp. 20140447 ◽

Cited By ~ 2

Author(s):

Xiaoyan Li ◽

Hainian Wang ◽

Chen Zhang ◽

Aboelkasim Diab ◽

Zhanping You

Keyword(s):

Asphalt Binder ◽

Warm Mix Asphalt

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The Effect of Asphalt Binder Aging on Fatigue Performance of Evotherm WMA

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.1686 ◽

2012 ◽

Vol 535-537 ◽

pp. 1686-1692

Author(s):

Yong Chun Qin ◽

Sui Yuan Wang ◽

Wei Zeng ◽

Xiao Pei Shi ◽

Jian Xu ◽

...

Keyword(s):

Fatigue Life ◽

Asphalt Binder ◽

Asphalt Mixture ◽

Warm Mix Asphalt ◽

Fatigue Tests ◽

Fatigue Performance ◽

Asphalt Binders ◽

Different Temperatures ◽

Binder Aging ◽

Lower Production

One of the main benefits advertised with the use of warm mix asphalt (WMA) is the decreasing aging of the asphalt binder resulting from the lower production temperature compared to conventional hot mix asphalt (HMA). Some tests were performed to determine the asphalt binder aging properties from WMA and HMA. Asphalt binders were recovered by extraction and distillation from asphalt mixtures premixed at different temperatures (140°C, 160°C, 180°C for HMA, 100°C and 120°C for WMA) in the mixing plant. Penetration@25°C, softening point (R&B) and rotational Brookfield viscosity tests were carried out. Results show that the aging of asphalt binder increases as the mixing temperature is elevated, and remarkably accelerates at the temperatures higher than 150°C. Warm mix asphalt (for example, mixing temperature at 100°Cor 120°C) can greatly reduce the aging of asphalt. Aging of the asphalt binder is one of the factors that would affect the mixture’s fatigue life. Four-point beam fatigue test samples were mixed and compacted at 140°C for HMA and 120°C for WMA, and fatigue tests with a frequency of 10 Hz and three constant strain levels (150 micro-strain, 300 micro-strain, 450 micro-strain, respectively) were performed. Results show that WMA’s fatigue life was higher than the control HMA, which indicates that it may reduce aging of asphalt binder and improve fatigue performance of asphalt mixture at lower production temperatures.

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