Search results for "Crumb rubber"
showing 10 items of 20 documents
The effect of prolonged storage time on asphalt rubber binder properties
2019
Abstract This study wants to provide fundamental understanding of prolonged storage time on asphalt rubber binder properties by performing an investigation on the variation of conventional properties, rheology and morphology of four asphalt rubbers maintained at 180 °C in low shear for different digestion/storage times up to 48 h. The analysed asphalt rubbers were manufactured by combining two different asphalt binder grades, pen 35/50 and pen 50/70, with both cryogenic and ambient crumb rubber. Results have shown that keeping asphalt rubber agitated at the above mentioned processing conditions, up to 48 h, is significantly detrimental when an ambient crumb rubber is used, while it seems no…
Fatigue and Healing Properties of Low Environmental Impact Rubberized Bitumen for Asphalt Pavement
2017
The addition of recycled tyre rubber as a modifier to enhance the mechanical properties of bitumen has proven to provide asphalt mixtures with better mechanical performance. However the rubberised bitumen presents the limitation of requiring higher manufacturing and compaction temperatures. This could be solved by subjecting the tyre rubber to sort of pre-treatments such as: Adding warm-mix additives and/or using partial devulcanisation. These solutions have the potential of lowering the overall environmental impact of the asphalt pavement, however it is still not clear whether these can be detrimental for the rubberized asphalt binder mechanical properties. This paper investigates the effe…
Rutting analysis of different rubberised stone mastic asphalt mixtures: from binders to mixtures
2021
Stone Mastic Asphalt (SMA) has been broadly used on heavily trafficked roads and motorways in the UK due to its known stability and durability. In this study, several sets of SMA mixtures were produced using different rubberised bitumens, including a Fischer–Tropsch wax pre-treated rubberised bitumen. Properties associated with rutting were evaluated using both linear and nonlinear viscoelastic analyses, using different test methods such as the Strategic Highway Research Programme (SHRP), Shenoy rutting parameter, zero shear viscosity (ZSV) and multiple stress creep recovery (MSCR) tests. The rutting resistance of the resulting SMA mixtures was assessed using the Repeated Load Axial Test (R…
Quality control of manufacturing and hot storage of crumb rubber modified binders
2020
The ultimate performance of crumb rubber modified (CRM) binders is linked to the accurate control of the properties during manufacturing and hot storage. However, due to their complexity, asphalt technologists find the characterisation of these materials still challenging. In this study, the adoption of a Dual Helical Ribbon (DHR), a novel mixing/measuring device for rotational viscometers, is proposed for the real-time monitoring of CRM binders during manufacturing and hot storage. According to the laboratory results, manufacturing periods of 45-60 min at 195 degrees, as well as storage temperatures not exceeding 150 degrees C, are recommended for this type of modified binders. (C) 2019 El…
Can crumb rubber modifier effectively replace the use of polymer- modified bitumen in asphalt mixture?
2021
Laboratory scale mechanical performances on six plant produced mixtures; three semi-dense surface courses and three dense binder courses modified with engineered crumb rubber (ECR) using the dry process are presented. The two types of mixtures produced and investigated fulfilled for the most part, the requirements of the Swiss and/or US standards regarding volumetric properties, water sensitivity and rutting. In advanced testing where no requirements exist, the dense ECR mixtures performed similar to the reference polymer modified mixtures and slightly worse for semi-dense mixtures in high temperature tests, where the binder becomes viscous in the rubber-binder composite and its ability to …
CHARACTERIZATION OF RUBBERIZED ASPHALT FOR RAILWAYS
2018
Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-track section. The recycled rubber has become an enhancer of the modified bituminous mixtures. In this work, it has been shown as a sustainable improvement option in HMA mixes due to the elastic behavior exposed by the rubber particles. The impact of thermal susceptibility on the mechanical properties of the railway bituminous sub-ballast layer has served to the advanced measurement of the thermal cycles inside the rail track. Different simulations following the Kentrack and Kenpave software were employed to be effective with the best mix-design for railways. According to weather situation, reviewe…
Rubberised bitumen manufacturing assisted by rheological measurements
2015
This paper investigates the effect of processing temperature and time on the rheological proper- ties of recycled tyre rubber-modified bitumens (RTR-MBs) produced using two different base binders and an ambient ground crumb rubber modifier (CRM). The production of the RTR- MBs was accomplished by means of a standard Brookfield rotational viscometer together with a modified impeller, dual helical impeller, to allow mixing as well as real-time viscosity measurements of the produced RTR-MBs. The rheological properties of the final RTR-MBs were determined by means of standard dynamic mechanical analysis oscillatory and multiple stress creep recovery testing using a dynamic shear rheometer. The …
Towards storage-stable high-content recycled tyre rubber modified bitumen
2018
The addition of crumb rubber particles as bitumen modifier can be currently considered as a well-established alternative to conventional polymers for bitumen modification. However, Recycle Tyre Rubber (RTR) modified binders still present drawbacks such as poor mix workability and hot storage stability. Within this study the authors try unlocking the full potential of devulcanised tyre rubber-heavy oils blend, named Liquid Rubber (LR), by exploring the possibility of tailoring recycled polymer modified bitumen with unconventional high-content of RTR and designed to overcome the above mentioned technological problems of RTR modified bitumen while keeping its advantages. Results show that LR-b…
Comparison between various bituminous binders modified with crumb tyre rubber
2009
The aim of this paper is to show how the rheology, the performance and the storage stability of different bituminous binders, obtained from two bitumens with different asphaltenes content, change their properties when they are modified with recycled tyre crumb rubber. Physical, chemical and performance characterisation followed by rheological and storage stability analyses have been undertaken as the basis for the comparison. The results of the investigation indicate that bitumen with lower asphaltenes content is more influenced by the modification with the rubber. However, the modification of the bitumen with the higher asphaltenes content gives a binder with better performance and storage…
Quality-control procedure for dry-process rubberised asphalt mastics
2019
Crumb Rubber (CR) can be incorporated into asphalt mixes via the dry process by directly adding CR into the mixer together with other asphalt mixture’s components, or with the wet process where the CR is used as a bitumen modifier. While the wet process allows an accurate monitoring of the interaction between CR and bitumen, the lack of control represents a main issue in the dry process. In fact, in the latter the CR particles keep swelling during hauling and possibly also after paving operations, often causing workability issues and premature failures. This study wants to provide a methodology that could help quality control procedures of bitumen/filler/rubber systems during mixing, haulin…