Retarding Crack Reflection Using Bitumen-Rubber Seals and Overlays – Historic Overview of Csir Research (original) (raw)
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Asphalt Rubber Interlayer Benefits on Reflective Crack Retardation of Flexible Pavement Overlays
This paper provides an overview of the asphalt rubber interlayer benefits on reflective crack retardation in flexible pavement preservation and rehabilitation strategies. These interlayers are known in California as asphalt rubber absorbing membrane interlayers (SAMI-R) or as asphalt rubber aggregate membrane interlayers (ARAM-I) chip seals. These interlayers have been used successfully as part of cape seals and as part of an overlay system. The paper focuses on the performance in terms of field project reviews, laboratory performance tests and finite element analysis. The paper concluded that SAMI-R are effective in minimizing reflective cracking distress and in extending pavement life.
Evaluating Alternative Solutions to Reflective Cracking Through Asphalt Overlays
Transportation Research Record, 1989
The problem of reflection cracking through asphalt overlays can be approached from the design perspective of the factors or mechanisms involved, the alternative treatments available, and the analyses and testing required to evaluate the treatments. Then, a selection of the best alternative, provided it satisfies economic criteria, can be made and implemented. This paper concentrates on evaluation and first illustrates how an analytical method, based on a wide-crack band theory in finite element formulation, can effectively be used for the first step of the process. Then, it illustrates how the most promising alternative treatments can be experimentally evaluated. Test procedures and example results are used for this purpose, and relationships between induced stress, or strain energy, and cycles to failure are presented. Selection, installation, and follow-up considerations are briefly discussed. It is pointed out that even with the most technically and economically feasible alternat...
Rapid assessment of the tracking resistance of bituminous crack sealants
Canadian Journal of Civil Engineering, 2007
The bituminous sealants used in the preventive maintenance of pavements sometimes deform (track) under the action of passing vehicles. In summer, this is the prevalent mode of sealant failure. To assess the propensity of a sealant to deform in summer, a standard flow test is used, but the imprecision in the results has prevented any correlation with field performance. Two methods were evaluated in an attempt to find an alternative means of assessing deformation. The first method relied on the use of the French rut tester, and the second method relied on the use of a Taber abraser. The first method was found to be inappropriate to test sealants because of its severity, but the second method proved promising. The Taber abraser allowed for the measurement of sealant displacement at various temperatures and for distinguishing the deformation propensity of sealants.Key words: pavements, roadways, maintenance, sealants, sealing, specification, testing, performance.
International Journal of Pavement Engineering, 2019
Reflective cracking is a frequent type of distress in asphalt concrete (AC) pavements that decreases pavement service life in a newly constructed AC overlay. In this study, natural zeolite and hydrated lime were added to crumb rubber modified (CRM) asphalt binder in order to assess their effects on reducing propagation of reflective cracks in composite pavements. CRM asphalt binder containing these additives was used in both AC overlay and sand asphalt interlayer to investigate crack propagation in the composite specimen under dynamic cyclic loading. The results show that asphalt interlayer modification is more effective than AC overlay modification (using CRM binders containing additives) in controlling reflective cracks. In other words, sand asphalt interlayer modification is more capable of absorbing the energy of crack propagation and, consequently, delaying the crack propagation. The results also indicated that simultaneous modification of both the interlayer and overlay significantly decreases reflective cracking potential. With respect to the significant role of additive type in crack propagation delaying, the results show that CRM binders containing natural zeolite are more efficient in crack mitigation compared to CRM binders containing hydrated lime.
The traffic and temperature effect on the reflective cracking
2008
This paper presents a study on the influence of the effects of temperature variations, in comparison to the traffic effects, on the reflective cracking behavior. It intends to contribute to the improvement of the pavement overlay design methods which consider reflective cracking as one among distress criteria. The development of this study was based on the numerical simulation of the overlay behavior, through the implementation of numerical thermal and mechanical models based on the finite element, considering the simultaneous action of traffic and temperature variations and their influence on reflective cracking. For overlay design purposes, it is important to consider temperature variations in the evaluation of the overlay behavior produced by the reflective cracking. The expected performance of an asphalt rubber hot mix, produced by the wet process with 20% crumb rubber was compared to a conventional asphalt taking into account the performance of these mixes.
Influence of bitumen type on cracking resistance of asphalt mixtures used in pavement overlays
Cracking is one of the predominant distresses occurring in flexible pavements, especially in old pavements that were rehabilitated with an asphalt overlay. In such cases asphalt mixtures should be designed to ensure high resistance to reflective cracking because new asphalt layers are exposed to existing cracks of the old pavement. The nature of these cracks can be various (transverse, longitudinal as well as crazy cracking). One factor that minimizes this type of distress is the proper mix design process, which should involve selection of specific bitumen binder and mineral mix gradation. However, still there is no universally adopted laboratory test method that would allow to clearly assess resistance of asphalt mixtures to reflective cracking. This paper describes the usage of one of the devices developed to test asphalt mixtures in terms of such distress – Texas Overlay Tester. For this test, samples prepared in laboratory conditions (i.e. compacted with the use of Superpave Gyratory Compactor) as well as obtained in the field (by core drilling) can be used. The results are obtained not only quickly and easily, but also with sufficient repeatability. The described method characterizes both crack initiation and crack propagation properties of asphalt mixtures. In this work one type of mineral mixture was tested with 4 different types of bitumen (one neat bitumen, two ordinary polymer-modified and one polymer-modified with high polymer content). For selected cases extra additives (rubber and loose fibres) were also tested. In total, six asphalt mixtures were tested. A ranking of the used binders was created on the basis of the results in order to conclude which bitumen would ensure the best performance characteristics in terms of reflective cracking. The results have clearly shown that deliberate choice of the binder used in the asphalt mixture for the overlay will significantly improve its reflective cracking resistance or even fatigue resistance.
Reflective Cracking Included into Routine Design of New Asphaltic Pavements
2016
During the past decades, it has been experienced that reflective cracking is a very complex phenomenon. Not only which one of the possible mechanisms behind the reappearance of cracks in new pavement surfaces (traffic, temperature variations in time or uneven settlements) is dominant, depends on the typical circumstances of a specific project, but also a variety of maintenance solutions often seems to be applicable. Examples are: (combinations of) thick overlays, use of modified asphaltic mixtures, application of stress-relieving systems or the incorporation of reinforcement. At motorway and airfield (maintenance and rehabilitation) projects there usually is time, budget and information. At those large projects it pays tribute to include reflective cracking into the routine design, because a cement treated base or concrete slabs are quite often present. From these specific pavement layers, cracks or joints propagating into and through the asphaltic overlay is the dominant mechanism....