Effect of Addition of Dry Crumb Rubber on the Performance of Terminal Blend Crumb Rubber Modified Asphalt Mixtures

Author(s):  
Salih Kocak ◽  
M. Emin Kutay

Three major methods are used to produce crumb rubber modified asphalt pavement: the dry process (CRDry), the terminal blend process (CRTB), and the wet process (CRWet). Although the CRDry process replaces the portion of fine aggregate in the asphalt mixture with crumb rubber (CR) particles, the CRWet process incorporates CR particles into hot liquid asphalt before it is mixed with aggregates. CRTB is known as a special type of CRWet process in which the CR is blended with asphalt binder at the asphalt terminal. In general, the CRWet process can integrate 15% to 22% CR by weight of the binder. This amount ranges from 10% to 12% in the CRTB process as a result of the limitations associated with transportation and pumping. This study investigated the feasibility of increasing the CR content of CRTB modified asphalt mixtures. The addition to the mixture of about 0.5% CR (by weight of the mix) through the CRDry process doubled the amount of rubber to be found in a conventional CRTB mix. The relative performances of the CRTB and the CRTB+CRDry processes [i.e., crumb rubber hybrid (CRHY)] were investigated with respect to their linear viscoelastic properties, rutting susceptibility, moisture damage, resistance to fatigue, and low temperature cracking. It was shown that it was possible to increase the amount of CR in the mixture through the use of the CRHY method proposed here, without adverse effect on the performance of the mixture.

Author(s):  
Ibrahim A. Abdalfattah ◽  
Walaa S. Mogawer ◽  
Kevin D. Stuart

This study addresses the effects of recycled polyethylene (RPE) on the performances of both asphalt binders and asphalt mixtures. Whether using RPE in an asphalt mixture might leach harmful chemicals into rainwater or melted snow was also determined. Two processes, wet and dry, were used to formulate the RPE modified asphalt binders and mixtures. In the wet process, RPE was added to asphalt binder. In the dry process, it was added to heated aggregates. RPE from two sources and PG 64-22 virgin asphalt binders from two sources were used in this study. In conclusion, RPE improved the rutting resistance of the asphalt binders and asphalt mixtures. However, it had adverse effects on their resistance to intermediate-temperature and non-load associated cracking. The dry process could produce a mixture with a higher RPE dosage compared with the wet process using one virgin asphalt binder but not the other; thus, the virgin asphalt binder source was a significant factor for the dry process. Based on an embryotoxicity test, it was found that RPE can be used by the asphalt paving industry without creating any significant environmental risks.


2021 ◽  
Author(s):  
Ovidijus Šernas ◽  
Audrius Vaitkus ◽  
Deimantė Kilaitė

The use of crumb rubber made from end of life tyres for asphalt mixtures modification in order to improve their properties or just utilize waste products may be considered as potential solution. Crumb rubber can be used as a bitumen modifier (wet process) or supplementary component of the asphalt mixture (dry process). Dry modification process has more potential due relatively unsophisticated technology and higher possible to use amount of crumb rubber comparing to the wet process. The performance of asphalt mixtures modified by dry process mainly depends on several factors as crumb rubber type, content and size. However, limited number of publications reported the results of dry method crumb rubber modified asphalt mixtures performance. This paper summarizes the latest findings from literature review on the modification technologies and specifications related to dry modification process, the effect of crumb rubber type and amount on modified asphalt mixture performance in terms of stiffness, rutting resistance, water sensitivity, resistance to fatigue and low temperature cracking. The algorithm of crumb rubber modified asphalt mix design was introduced.


2021 ◽  
Vol 13 (12) ◽  
pp. 6634
Author(s):  
Hayder Al Hawesah ◽  
Monower Sadique ◽  
Clare Harris ◽  
Hassan Al Nageim ◽  
Karl Stopp ◽  
...  

Hot mix asphalt has various benefits such as good workability and durability. It is one of the most general materials used as asphalt mixtures in road pavements. Asphalt mixtures and binders can be improved by modifying them with various additives. Gilsonite is a natural asphalt hydrocarbon which may be used as an additive to hot mix asphalt. It is used as an asphalt binder modifier (wet process) and an asphalt mixture modifier (dry process) to improve the properties of the mix. It provides the option of improved rheological properties, stability, strength rutting resistance and moisture sensitivity. This paper examines the current research relating to the use of gilsonite to improve the asphalt properties (binder and mixture). The rheological properties of the modified asphalt binders and mechanical properties of the modified asphalt mixtures will be reviewed. The influence of adding gilsonite individually or combined with other additives will be discussed. Furthermore, assessment of the environmental and economic perspectives of the studied asphalt along with some suggestions to improve the asphalt binders and mixtures will be explored.


2021 ◽  
Vol 8 ◽  
Author(s):  
Hasanain Radhi Radeef ◽  
Norhidayah Abdul Hassan ◽  
Ahmad Razin Zainal Abidin ◽  
Mohd Zul Hanif Mahmud ◽  
Nur Izzi Md. Yusoffa ◽  
...  

In recent years, the proliferation of plastic waste has become a global problem. A potential solution to this problem is the dry process, which incorporates plastic waste into asphalt mixtures. However, the dry process often has inconsistent performance due to poor interaction with binder and improper distribution of plastic waste particles in the mixture skeleton. This inconsistency may be caused by inaccurate mixing method, shredding size, mixing temperature and ingredient priorities. Thus, this study aims to improve the consistency of the dry process by comparing the control asphalt mixture and two plastic waste-modified asphalt mixtures prepared using the dry process. This study used crushed granite aggregate with the nominal maximum aggregate size of 14 mm whereas the shredded plastic bag is in the range of 5–10 mm. Quantitative sieving analysis and performance tests were carried out to examine the effects of plastic waste added into the asphalt mixture. The volumetric and performance properties combined with image analysis of the modified mixtures were obtained and compared with the control mixture. In addition, the moisture damage, resilient modulus, creep deformation and rutting were evaluated. This study also highlighted in detail the distribution of plastic particles in the final skeleton of the asphalt mixture. Based on the analysis, an enhanced dry process of mixing procedure was proposed and evaluated. Results showed that the addition of plastic particles using the conventional dry process leads to the deviation in the aggregate structure as high plastic content is added. Furthermore, the enhanced dry process developed in this study presents substantial enhancement in the asphalt performance, particularly with plastic waste that accounts for 20% of the weight of the asphalt binder.


2021 ◽  
Vol 54 (5) ◽  
Author(s):  
M. Bueno ◽  
R. Haag ◽  
N. Heeb ◽  
P. Mikhailenko ◽  
L. Boesiger ◽  
...  

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.


Asphalt pavement is typically susceptible to moisture damage. However, it could be improved with the incorporation of additives or modifiers through binder modifications. The objective of the study is to assess the effect of adhesion promoters, namely PBL and M5000, onto the Hot Mix Asphalt (HMA). The performance of asphalt mixture has been assessed in terms of the service characteristics, the bonding properties, and mechanical performances. The service characteristics were assessed through the Workability Index (WI) and Compaction Energy Index (CEI) to evaluate the ease of asphalt mixture during the mixing and compaction stage. The bonding properties of the modified asphalt mixtures were determined using the boiling water test and static water immersion test to signify the degree of coating after undergoing specific conditioning period and temperature. The mechanical performances of the modified asphalt mixture were evaluated via Marshall stability, semi-circular bending, and modified Lottman tests. All specimens were prepared by incorporating adhesion promoters at the dosage rates of 0.5% and 1.0% by weight of asphalt binder. From the investigation, the bonding properties significantly improved for the modified asphalt mixture compared to the control mixture. The WI of the modified asphalt mixture increased while the CEI decreased in comparison to the control specimen. This implies the workability of modified asphalt mixture is better and requires less energy to be compacted. Modified asphalt mixture generally had better mechanical performance. Therefore, it can be deduced that the asphalt mixture with adhesion promoters have better overall performance than the control mixture.


2012 ◽  
Vol 193-194 ◽  
pp. 452-457 ◽  
Author(s):  
Meng Yun Huang ◽  
Jing Hui Liu ◽  
Xi Zhang ◽  
Dan Ni Li

Using the waste crumb rubber modified asphalt to pave the road surface could reduce cost and save energy. However,in order to obtain adequate workability, the mixing temperature and compaction temperature of rubberized asphalt binder and its mixture is much higher than those of conventional asphalt mixtures. Warm Mix Asphalt (WMA) is the name given to certain technologies that reduce the production and placement temperatures of asphalt mixes. One of the main benefits advertised is the increased workability at conventional and lower compaction temperatures with the WMA addition. This paper evaluates whether there are any synergy effects of using warm mix technologies and Asphalt Rubber(AR) hot mixes. This paper summarizes a lab research to evaluate the workability of Asphalt Rubber hot mixes containing warm mix technologies. Both asphalt binder and asphalt mixture were evaluated and compared. The research suggests that combining WMA technology with Asphalt Rubber mixtures is a win-win.


2010 ◽  
Vol 168-170 ◽  
pp. 1145-1148 ◽  
Author(s):  
Xin Qiu ◽  
Lan Yun Chen ◽  
Liang Xue

The paper investigates the effects of different concentrations of crumb rubber (CR) on the pavement performance of the conventional penetration-grade 80/100 bitumen and the dense-graded wearing course asphalt mixture (AC16). A wet process and 0.6mm size CR were used and the control variables included three types of CR of concentrations 5%,10% and 15% by total weight of binder. The evaluations were twofold. Firstly, a comparison of the basic and rheological properties of those modified and unmodified binders was conducted. Secondly, a comparison of the resistance to moisture damage, low temperature cracking and permanent deformation of the AC16 and CR modified AC16 was performed. The results show that all the CR modified binders and mixtures are found to have improved performance as evaluated by a series of laboratory tests. In addition, among three CR concentrations, AC16 modified with 10%CR by total weight of binder exhibits the most satisfactory performance properties with respect to the resistance to moisture damage, permanent deformation and low temperature cracking.


Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5051
Author(s):  
Fei Zhang ◽  
Lan Wang ◽  
Chao Li ◽  
Yongming Xing

To identify the most accurate approach for constructing of the dynamic modulus master curves for warm mix crumb rubber modified asphalt mixtures and assess the feasibility of predicting the phase angle master curves from the dynamic modulus ones. The SM (Sigmoidal model) and GSM (generalized sigmoidal model) were utilized to construct the dynamic modulus master curve, respectively. Subsequently, the master curve of phase angle could be predicted from the master curve of dynamic modulus in term of the K-K (Kramers–Kronig) relations. The results show that both SM and GSM can predict the dynamic modulus very well, except that the GSM shows a slightly higher correlation coefficient than SM. Therefore, it is recommended to construct the dynamic modulus master curve using GSM and obtain the corresponding phase angle master curve in term of the K-K relations. The Black space diagram and Wicket diagram were utilized to verify the predictions were consistent with the LVE (linear viscoelastic) theory. Then the master curve of storage modulus and loss modulus were also obtained. Finally, the creep compliance and relaxation modulus can be used to represent the creep and relaxation properties of warm-mix crumb rubber-modified asphalt mixtures.


Since 1960 Using crumb rubber modifier (CRM) in hot asphalt mixtures has become a frequent practice in road construction. Using the CRM by the dry process method is not commonly used, although it has great advantages such as it is less fuel consuming and it does not require storage container like the wet process method. This research evaluates the mechanical properties of dense graded asphalt rubber mixtures manufactured using the dry process. The results obtained from this mixture compared with similar asphalt mixture without CRM. The mechanical properties of all mixtures evaluated using a set of tests such Marshall Stability and flow test, moisture susceptibility test, indirect tensile strength test, dynamic modulus and flow number test. The research results showed that using CRM with 0.75% of aggregate’s weight increased the mixture’s stability, flow and enhanced its cracking and permanent deformation resistance.


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