scholarly journals Waste Rubber from End-of-Life Tires in ‘Lean’ Asphalt Mixtures—A Laboratory and Field Investigation in the Arid Climate Region

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3802
Author(s):  
Stefano Marini ◽  
Michele Lanotte

Waste rubber from end-of-life tires has been proved to be an excellent source of polymeric material for paving applications. Over the years, however, the rubberized asphalt technology has never been used in ‘lean’ (low bitumen content) asphalt mixtures typically used in arid regions. This study offers an insight on the potential benefits and drawbacks resulting from this technology if applied in such ‘lean’ mixes. Results show that the ‘lean’ nature of those asphalt mixes eliminates the potential benefits given by the modified bitumen for rutting performance. Instead, the aggregates gradation plays a major role in the response of the materials, with gap-graded mixtures often outperforming those with a dense-graded gradation. On the contrary, fatigue cracking resistance is affected by the bitumen properties, and rubberized asphalt perform better than others. The performance-based analysis suggests that the current specifications tend to overachieve the goal of reducing permanent deformation while cracking becomes a major concern which can be solved by using rubberized asphalt. In the field, gap-graded asphalt with rubberized bitumen showed the best response in terms of skid resistance and noise reduction.

2015 ◽  
Vol 73 (4) ◽  
Author(s):  
Ekarizan Shaffie ◽  
Juraidah Ahmad ◽  
Ahmad Kamil Arshad ◽  
Dzraini Kamarun

This paper presents the potential benefits of nanopolyacrylate (NPA) for the asphalt mixtures used on pavement. This research evaluates the resilient modulus performance of dense graded Superpave-designed HMA mix. Two different types of dense graded Superpave HMA mix were developed consists of unmodified bitumen mix (UMB) and nanopolyacrylate modified bitumen mix (NPMB). Nanopolyacrylate polymer modified bitumen was prepared from addition of 6 percent of NPA polymer into asphalt bitumen. Resilient modulus results from Resilient Modulus test were determined to evaluate the performance of these mixtures. Results showed that all the mixes passed the Superpave volumetric properties criteria which indicated that these mixtures were good with respect to durability and flexibility. The Resilient modulus result of NPMB demonstrates better resistance to rutting than those prepared using UMB mix. It was estimated that the average resilient modulus values for both UMB and NPMB mixtures are decreased by 80 percent when the test temperature increased from 25ºC to 40ºC.   In conclusion, the addition of NPA to the binder has certainly improved the bitumen properties significantly and hence increase the resistant to rutting of the asphalt mixture.


2021 ◽  
Vol 13 (6) ◽  
pp. 3315
Author(s):  
Mansour Fakhri ◽  
Danial Arzjani ◽  
Pooyan Ayar ◽  
Maede Mottaghi ◽  
Nima Arzjani

The use of waste materials has been increasingly conceived as a sustainable alternative to conventional materials in the road construction industry, as concerns have arisen from the uncontrolled exploitation of natural resources in recent years. Re-refined acidic sludge (RAS) obtained from a waste material—acidic sludge—is an alternative source for bitumen. This study’s primary purpose is to evaluate the resistance of warm mix asphalt (WMA) mixtures containing RAS and a polymeric additive against moisture damage and rutting. The modified bitumen studied in this research is a mixture of virgin bitumen 60/70, RAS (10, 20, and 30%), and amorphous poly alpha olefin (APAO) polymer. To this end, Marshall test, moisture susceptibility tests (i.e., tensile strength ratio (TSR), residual Marshall, and Texas boiling water), resilient modulus, and rutting assessment tests (i.e., dynamic creep, Marshall quotient, and Kim) were carried out. The results showed superior values for modified mixtures compared to the control mix considering the Marshall test. Moreover, the probability of a reduction in mixes’ moisture damage was proved by moisture sensitivity tests. The results showed that modified mixtures could improve asphalt mixtures’ permanent deformation resistance and its resilience modulus. Asphalt mixtures containing 20% RAS (substitute for bitumen) showed a better performance in all the experiments among the samples tested.


Author(s):  
H. Barry Takallou ◽  
Hussain U. Bahia ◽  
Dario Perdomo ◽  
Robert Schwartz

The effect of different mixing times and mixing temperatures on the performance of asphalt-rubber binder was evaluated. Four different types of asphalt-rubber binders and neat asphalt were characterized using the Strategic Highway Research Program (SHRP) binder method tests. Subsequently, mix designs were carried out using both the SHRP Levels I and II mix design procedures, as well as the traditional Marshall mix design scheme. Additionally, performance testing was carried out on the mixtures using the Superpave repetitive simple shear test at constant height (RSST-CH) to evaluate the resistance to permanent deformation (rutting) of the rubberized asphalt mixtures. Also, six rectangular beams were subjected to repeated bending in the fatigue tester at different microstrain levels to establish rubberized asphalt mixtures’ resistance to fatigue cracking under repeated loadings. The results indicate that the Superpave mix design produced asphalt-rubber contents that are significantly higher than values used successfully in the field. Marshall-used gyratory compaction could not produce the same densification trends. Superpave mixture analysis testing (Level II) was used successfully for rubberized asphalt mixtures. Results clearly indicated that the mixture selected exhibited acceptable rutting and fatigue behavior for typical new construction and for overlay design. Few problems were encountered in running the Superpave models. The results of the RSST-CH indicate that rubber-modified asphalt concrete meets the criteria for a maximum rut depth of 0.5 in.; and more consistent results were measured for fatigue performance analysis using the repeated four-point bending beam testing (Superpave optional torture testing). The cycles to failure were approximately 26,000 at 600 microstrain.


2017 ◽  
Vol 2633 (1) ◽  
pp. 108-116 ◽  
Author(s):  
Max A. Aguirre ◽  
Marwa M. Hassan ◽  
Sharareh Shirzad ◽  
Louay N. Mohammad ◽  
Samuel B. Cooper

The use of recycled asphalt shingles (RAS) in asphalt paving construction represents a sustainable approach to reduce virgin material consumption and negative environmental effects, as well as the cost of asphalt pavement. However, many challenges are yet to be addressed about the use of RAS in paving applications. This study evaluated the effect of the incorporation of postconsumer waste shingles and rejuvenators on the performance of hot-mix asphalt. Four asphalt rejuvenators—one bio-oil and three synthetic oils—were evaluated. A set of laboratory tests was conducted to characterize the performance of asphalt mixtures against permanent deformation and fatigue cracking. The addition of 5% RAS showed an improvement in permanent deformation when compared with a conventional mixture with no RAS. Yet the addition of asphalt rejuvenator products slightly decreased the performance against permanent deformation. On the basis of Hamburg wheel-tracking device test results, the addition of RAS did not adversely affect moisture resistance. Yet semicircular bending test results showed that the asphalt mixtures that contained asphalt rejuvenators had a lower critical strain energy release rate than the minimum threshold value (0.5 kJ/m2), which indicated a greater susceptibility to intermediate-temperature cracking.


2019 ◽  
Vol 9 (13) ◽  
pp. 2697
Author(s):  
Gabriela Ceccon Carlesso ◽  
Glicério Trichês ◽  
João Victor Staub de Melo ◽  
Matheus Felipe Marcon ◽  
Liseane Padilha Thives ◽  
...  

Fatigue cracking and rutting are among the main distresses identified in flexible pavements. To reduce these problems and other distresses, modified asphalt mixtures have been designed and studied. In this regard, this paper presents the results of a study on rheological behavior and resistance to permanent deformation and to fatigue of four different asphalt mixtures: (1) with conventional asphalt binder (CAP 50/70); (2) with binder modified by nanoclay (3% NC); (3) with binder modified by styrene–butadiene–styrene polymer (SBS 60/85); and (4) with binder modified by nanoclay and SBS (3% NC + 2% SBS). For this analysis, the mixtures were evaluated based on complex modulus, permanent deformation tests, and fatigue tests (4PB, in the four-point bending apparatus), with the subsequent application of numerical simulations. The results obtained show a better rheological behavior related to greater resistance to permanent deformation for the mixture 3% NC + 2% SBS, which could represent an alternative for roads where a high resistance to rutting is required. Otherwise, on fatigue tests, higher resistance was observed for the SBS 60/85 mixture, followed by the 3% NC + 2% SBS mixture. Nevertheless, based on the results of the numerical simulations and considering the possibility of cost reduction for the use of the 3% NC + 2% SBS mixture, it is concluded that this modified material has potential to provide improvements to the road sector around the world, especially in Brazil.


Author(s):  
Mohammad Jamal Khattak ◽  
Gilbert Y. Baladi

A large research program sponsored by the Michigan Department of Transportation was designed and completed to evaluate the effect of polymer modification on the various properties of asphalt mixtures. These include the micro- and macrostructural, morphological, chemical, and engineering properties. Some of the engineering properties of the styrene-butadiene-styrene and styrene-etylene-butylene-styrene polymer-modified asphalt mixtures are presented and discussed. The elastic, fatigue, tensile, and permanent deformation properties were investigated at 60, 25, and –5°C. It was found that, for some polymer systems, the fatigue life and the indirect tensile strength increased considerably at 25°C while the elastic properties at -5°C were not affected by the addition of polymer. The implication of this is that the use of some polymer systems in asphalt mixtures enhances their fatigue cracking and rutting resistance without affecting the low temperature cracking potential.


2021 ◽  
Vol 6 (4) ◽  
pp. 58
Author(s):  
Ana Dias ◽  
Hugo Silva ◽  
Carlos Palha ◽  
Joel Oliveira

When temperatures drop to significantly low levels, road pavements are subjected to thermally-induced stresses, resulting in the appearance of thermal cracking, among other distresses. In these situations, polymers can be used as asphalt binder modifiers to improve certain asphalt binder properties, such as elastic recovery, cohesion, and ductility. Polymers also minimize some of the problems of asphalt mixtures, such as thermal and fatigue cracking and permanent deformation. This work’s objective was to study the behavior of asphalt mixtures at low temperatures, mainly when using modified binders. Thus, three binders were selected and tested: a standard 50/70 penetration grade bitumen and two polymer-modified binders (PMB), obtained by adding, respectively, 2.5% and 5.0% of styrene–butadiene–styrene (SBS) in the 50/70 pen grade bitumen. Then, the PMBs were incorporated into stone mastic asphalt mixtures (namely SMA 11), which were subjected to low-temperature mechanical tests based on the most recent European Standards. The asphalt binders and mixtures evaluated in this work were tested for thermal cracking resistance, creep, elastic recovery, cohesive strength, and ductility strength. Overall, it is concluded that the studied asphalt mixtures with PMB, with just 2.5% SBS, performed adequately at low temperatures down to −20 °C.


2019 ◽  
Vol 11 (0) ◽  
pp. 1-6
Author(s):  
Lina Šneideraitienė ◽  
Daiva Žilionienė

The European building sector is facing a pressing issue of natural resources. Importing road building materials for the asphalt surfacing increases the cost of the asphalt mixture. The asphalt surfacing mixtures shall consist of a mixture of graded aggregates accounting for 80−90% of the total volume of the asphalt mixture, or 90−96% of the total weight of the asphalt mixture and binder: road bitumen or polymer modified bitumen. In the Republic of Lithuania, asphalt mixes are designed in accordance to the Design Regulations for Road Pavement Standardized Pavement Structures KP SDK 19 and accordance to the normative documents and their requirements for graded aggregates and binders. Road builders import graded aggregates to asphalt mixes from other countries, and this increases the cost of asphalt mixes. According to the scientific researches in the Lithuanian quarry Petrašiūnai II, using unique production technology is produced class I dolomite crushed stone, which mechanical, physical properties and designed asphalt mixtures can replace imported graded aggregates. The economic question remains as to the economic effect of the most commonly used asphalt mixtures in Lithuania AC 11 VS (asphalt mixture of asphalt pavement wearing course) and SMA 11 S (crushed and mastic asphalt) made from indigenous minerals compared to imported minerals. The aim of the paper is to perform the calculation and evaluation of the economic effect of asphalt mixtures AC 11 VS, SMA 11 S with different minerals and micro-aggregate. The paper identifies and analyses the properties of asphalt test mixtures, and identifies the locations of mineral suppliers in Lithuania. According to the economic impact assessment scheme, the economic effect of asphalt mixtures AC 11 VS, SMA 11 S with different minerals and micro-aggregate was calculated. According to the calculations made, the economic effect of producing asphalt mixtures AC 11 VS, SMA 11 S with class I dolomite chips is 13−14%.


2021 ◽  
Author(s):  
Ciprian Rares Tarta ◽  
Nicolae Ciont ◽  
Mihai Iliescu ◽  
Gavril Hoda

Asphalt mixtures are composite building materials consisting of a mineral skeleton mixed with a bituminous binder, following a recipe which may also include fibres and/or polymers. The natural aggregates sustain the mixture structure, but adequate bitumen behaviour under various temperature and mechanically-induced stresses is also essential for the structural durability. Much research effort was directed towards improving the asphalt mixtures’ resistance to permanent deformation, implying an increase in mixture stiffness. At the same time, the mixture must exhibit enough low temperature cracking resistance. Six reference asphalt mixture samples were prepared and tested: mixtures M1 and M2 for base and binder courses respectively, as well as four mixtures for wearing courses (two asphalt concrete - AC1 and AC2, a stabilised mixture SMA containing fibres, and a porous mixture - PM). A 50/70 penetration grade bitumen was used to prepare all mixtures. In some cases, the obtained results did not meet the standard requirements. Bitumen or mixture modification is commonly performed by adding thermoplastic or elastomeric polymers, to improve the asphalt mixture behaviour. In this study, the effects of four thermoplastic polymers on the stiffness modulus, dynamic creep and fatigue resistance were studied. All tested polymers were introduced as grains during mixture preparation. Polymer addition led to a 31 % to 104 % increase in mixture stiffness modulus. A 220 % average increase in fatigue resistance was observed for mixtures M1 and M2. For the wearing course mixtures, creep resistance is expressed through a 99 % reduction in deformation speed and a 50 % to 80 % reduction in rut depth. The obtained results met the standard requirements. Using grain polymers is currently an effective alternative to polymer-modified bitumen, because of several technological and economical advantages. Polymer quality is essential to obtain adequate mixture characteristics.


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