Recommendation of RILEM TC237-SIB on cohesion test of recycled asphalt

This recommendation describes how to evaluate the presence of potentially active bitumen in recycled asphalt (RA) materials through the cohesion test. The experimental protocol is designed according to the research performed by the RILEM Technical Committee 237-SIB ‘‘Testing and characterization of sustainable innovative bituminous materials and systems’’ with the purpose, to develop a new, simple and fast method for the characterization of RA while limiting the need for conventional rheological tests. The guidelines in this recommendation focus on the testing procedure including specimen preparation, data analysis and provide information on the preparation of a tests report

Synthesis of Specimen Preparation and Curing Processes for Cold Recycled Asphalt Mixes

The process of cold recycling (CR) is becoming method of choice for pavement rehabilitation due to significantly added environmental and economic benefits. Understanding and standardization of specimen preparation and curing processes are critical to replicate field conditions in lab. This paper presents an extensive synthesis of various specimen preparation and curing processes for cold recycled asphalt mixes. Topics synthesized include RAP, emulsion/bitumen and aggregate preparation, mixing processes, pre- and post- compaction curing, compaction and mechanical testing. This paper was developed through efforts of cold recycling task group (TG6) of RILEM Technical Committee on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems (TC-SIB)

Fracture toughness evaluation of bituminous binders at low temperatures

When asphalt roads turn brittle at low temperatures, they are no longer able to relax completely from traffic induced stresses and may also suffer damage through crack initiation and propagation. In order to avoid early structural damages, the bituminous binders must be selected very carefully. However, conventional test methods for assessing performance of bituminous binders at low temperatures are often unsatisfactory reliable, in particular in case of polymer modified bituminous binders. In this study, an alternative experimental method based on fracture mechanical principles was performed on pre-notched specimens in the brittle state inside a cooling media. This fracture toughness test was evaluated in terms of its suitability for distinguishing different types of polymer modified and unmodified bituminous binders. In addition, the feasibility to evaluate different ageing states was also analysed by testing samples after artificial short-term and long-term ageing procedures. The repeatability obtained from the experimental results showed that the fracture toughness test is a suitable candidate for being introduced in a standardization framework

La teoría de la relevancia y la estrategia humorística de la incongruencia-resolución

En la teoría de la Relevancia Sperber y Wilson proponen un modelo cognitivo de la interpretación humana basado en el interés del receptor por adquirir, en cada estadio de la conversación, la información más relevante Esta elección está influida, en última instancia, por un equilibrio entre interés y esfuerzo. En el presente artículo se propone una posible aplicación de esta teoría a la estrategia humorística de la "disonancia cognitiva", concretamente la estrategia de incongruencia-resolución, de tal modo que podemos encontrar una explicación de cómo el emisor consigue el efecto humorístico deseado.In Relevance theory Sperber and Wilson propose a cognitive model of human interpretation based on the addressee's willingness to grasp, in every step of the conversation the most relevant information. This choice is influenced, eventually, by a balance of interest and effort. In the present article we propose an application of this theory to the humorous strategy of "cognitive dissonance", specifically the strategy of incongruence-resolution, in such a way that we can find an explanation of how the addresser manages to get the desired humorous effect

A rheological study on rejuvenated binder containing very high content of aged bitumen

Hot recycling of reclaimed asphalt pavement (RAP) coming from flexible pavement rehabilitation is a technique able to ensure real economic and environmental benefits related to the reduction of virgin bitumen and aggregate supply and to the reuse of a recycled aggregate. Otherwise, adequate performance of recycled materials with high amount of RAP must be guaranteed since the recycling involves the presence of old and stiffened aged binders within the mixture. In this perspective, the present experimental study was aimed at verifying in the laboratory the performance at mid and high-service temperatures of bituminous blends composed by 40% of virgin binder and 60% of old rejuvenated bitumen (simulating aged bitumen coming from RAP). Rheological properties of materials were studied through the dynamic shear rheometer, testing unaged, short-term aged and long-term aged samples. Viscosity, stiffness and permanent deformation resistance of recycled blends seemed to guarantee comparable behavior with those of original bitumens, regardless the aging condition of the materials. These findings seemed to demonstrate the effectiveness of the hot recycling procedure using rejuvenators to obtain suitable bituminous binder containing high amount of aged bitumen

Cold Recycling of Reclaimed Asphalt Pavements

Pavement engineers have in front of them multiple challenges linked to addressing issues related to social development and society’s expanding needs. One of the most substantial of these issues is perhaps how to effectively rehabilitate and/or maintain the existing road network while preserving and sustaining limited natural resources. The re-usage of existing pavement materials to reconstruct/rehabilitate our future pavements is the solution that is now more and more selected by the different road administrations around the world. However, upon closer inspection, one can find many areas and details, not negligible issues, that are simply extensions of HMA technology (i.e. mix design process in cold recycling) or empirical arrangements; in particular RAP still does not have an internationally recognized classification. So SIB – TG6 decided to develop a classification protocol of RAP, depending on its intended application. The objective has been followed by considering the procedures generally utilized to classify the natural aggregates: tests able to identify the main components (i.e. the geometrical and mechanical properties of aggregates and the characterization of recovered bitumen for RAP) and provide information on their behaviour under specific conditions, near to real life usage (e.g. the Los Angeles test for aggregates gives an idea of the potential behaviour of aggregates under the action of a roller compactor). The following sections illustrate and explain the actions of the TG in order to achieve the goals outlined above: the review of current standards, the protocol designed to classify RAP and the round robin tests carried out to validate the protocol

Recommendation of RILEM TC237-SIB on fragmentation test for recycled asphalt

This recommendation describes how to characterize the reclaimed asphalt through the fragmentation test. The guidelines given hereafter are based on the results of a round robin test organized by the RILEM Technical Committee 237-SIB \u2018\u2018Testing and characterization of sustainable innovative bituminous materials and systems\u2019\u2019 and provide information on the testing procedure, data analysis and indications for the preparation of a test report