Christophe Petit

Bio: Christophe Petit is an academic researcher from University of Limoges. The author has contributed to research in topics: Viscoelasticity & Finite element method. The author has an hindex of 19, co-authored 79 publications receiving 1243 citations.

Harvesting the unexplored potential of European waste materials for road construction

Abstract: This paper demonstrates how a considerable amount of waste produced in the urban and peri-urban environment can be recycled in asphalt roads. The example presented is from Europe, however, the barriers and conclusions are universal. It was shown that various waste materials such as glass, asphalt, concrete, wood, plastics etc. have a potential for re-use in asphalt roads. The available quantities of the European target waste materials that would otherwise be incinerated or disposed in landfills were considered. It was shown that there is high potential in Europe for recycling in road construction, in particular, under the hypothetical scenario where 33% of new roads would be made of the target waste materials (excluding RAP which is already recycled), it is estimated that 16% of the available waste quantities could be recycled in roads. Four hypothetical roads were analysed showing a considerable savings in costs, CO2 and energy in comparison to conventional asphalt mixtures using all virgin components.

Mechanical Testing of Interlayer Bonding in Asphalt Pavements

Abstract: Steadily increasing requirements on pavement performance properties, in terms of bearing capacity and durability, as well as new innovative developments regarding pavement materials and construction, are observed worldwide. In this context interlayer bonding at the interfaces of multi-layered bituminous systems is recognized as a key issue for the evaluation of the effects, in terms of stress-strain distribution, produced by traffic loads in road pavements. For this reason a correct assessment of interlayer bonding is of primary importance, and research efforts should be addressed in order to improve the lack of correlation and/or harmonization among test methods. Following this principle RILEM TG 4 organized an interlaboratory test in order to compare the different test procedures to assess the interlayer bonding properties of asphalt pavement. The results of the experimental research are presented with a preliminary overview of basic elements, test methods and experimental investigations on interlayer bonding. Then the RILEM TG 4 experimental activities, based on the construction of three real- scale pavement sections, are presented in detail. Each pavement section was composed of two layers, and three different interface conditions were chosen. The first pavement was laid without interface treatment and the others with two different types of emulsion. Fourteen laboratories from 11 countries participated in this study and carried out shear or torque tests on 1,400 cores. The maximum shear or torque load and the corresponding displacement were measured, and the shear or torque strength was calculated as a function of the following parameters: diameter, test temperature, test speed, stress applied normal to the interface and age of the specimen. The results of this study are presented in terms of precision and correlations regarding the parameters which results in useful information on asphalt pavement interlayer bond tests.

Shear Fatigue Behaviour of Tack Coats in Pavements

Abstract: For many years, pavement engineers use mechanistic design methods that are based on algorithms to compute stresses, strains and displacements in a flexible pavement structure, or in a multi-layered structure in general. Most of these methods assume, to ease the modelling of the structure and the computation process, that the layers are fully bonded or completely unbounded to each other. Moreover, determining the effectiveness of the bonding between two layers is difficult since there is no standard test procedure to assess it. Hence, proper modelling of the interface bonding condition will represent an important finding in understanding the real behaviour of road structures, and will lead to reduce maintenance and rehabilitation costs. Asphalt emulsion is commonly used, as tack coat, to ensure the bond between two pavement layers. This study deals with an experimental characterization of interfaces shear fatigue behaviour through laboratory tests. A testing device for determining the shear fatigu...

Digital image correlation techniques to investigate strain fields and cracking phenomena in asphalt materials

Abstract: This paper is the outcome of a specific task group of the RILEM Technical Committee 241-MCD “Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements”. The group on “Advanced Measurement Techniques” was established in 2011 to investigate DIC applications for non-destructive and non-contact measurements of strain fields during laboratory testing. The paper illustrates different DIC/optical flow applications in measuring strain distribution during laboratory testing. Specific applications of DIC for evaluating crack initiation and crack propagation in asphalt materials are presented.

An energy‐conserving scheme for dynamic crack growth using the eXtended finite element method

Abstract: This paper proposes a generalization of the eXtended finite element method (X-FEM) to model dynamic fracture and time-dependent problems from a more general point of view, and gives a proof of the stability of the numerical scheme in the linear case. First, we study the stability conditions of Newmark-type schemes for problems with evolving discretizations. We prove that the proposed enrichment strategy satisfies these conditions and also ensures energy conservation. Using this approach, as the crack propagates, the enrichment can evolve with no occurrence of instability or uncontrolled energy transfer. Then, we present a technique based on Lagrangian conservation for the estimation of dynamic stress intensity factors for arbitrary 2D cracks. The results presented for several applications are accurate for stationary or moving cracks. Copyright © 2005 John Wiley & Sons, Ltd.

Solutions and Integrated Strategies for the Control and Mitigation of Plastic and Microplastic Pollution

Abstract: Plastic pollution is generated by the unsustainable use and disposal of plastic products in modern society, threatening economies, ecosystems, and human health. Current clean-up strategies have attempted to mitigate the negative effects of plastic pollution but are unable to compete with increasing quantities of plastic entering the environment. Thus, reducing inputs of plastic to the environment must be prioritized through a global multidisciplinary approach. Mismanaged waste is a major land-based source of plastic pollution that can be reduced through improvements in the life-cycle of plastics, especially in production, consumption, and disposal, through an Integrated Waste Management System. In this review paper, we discuss current practices to improve life cycle and waste management of plastics that can be implemented to reduce health and environmental impacts of plastics and reduce plastics pollution. Ten recommendations for stakeholders to reduce plastic pollution include (1) regulation of production and consumption; (2) eco-design; (3) increasing the demand for recycled plastics; (4) reducing the use of plastics; (5) use of renewable energy for recycling; (6) extended producer responsibility over waste; (7) improvements in waste collection systems; (8) prioritization of recycling; (9) use of bio-based and biodegradable plastics; and (10) improvement in recyclability of e-waste.

A critical review on recycling of end-of-life carbon fibre/glass fibre reinforced composites waste using pyrolysis towards a circular economy

Abstract: The rapid utilization of carbon fibre reinforced composite (CFRC) and glass fibre reinforced composite (GFRC) in main sectors, such as automobile, aerospace, wind turbines, boats and sport parts, has gained much attention because of its high strength, light weight and impressive mechanical properties. Currently, the increasing amount and handling of composite waste at their end-of-life (EoL) has a negative impact on resources conservation and the environment. Pyrolysis, a two-step process, appeared as most viable process to recover not only valuable materials but also produce fuel and chemicals. However, the testing facilities and optimized operation of composite waste in pyrolysis processes to produce materials with low energy consumption and acceptable mechanical properties are still under development and discussion before commercialization. The aim of this article is to review the studies on CFRC/GFRC recycling via pyrolysis processes and highlight their technical challenges and re-use possibilities in high performance composites. The forthcoming commercialization challenges and respective market potential to recyclates using the pyrolysis process will be addressed. This study will also introduce the strong connection between recycling and re-usability of fibres which would help to explain the concept of circular economy and cradle-to-cradle approach. Finally, based on updated studies and critical analysis, research gaps in the recycling treatments of fibrous composite waste using pyrolysis processes are discussed with recommendations.

Nonlinearity, Heating, Fatigue and Thixotropy during Cyclic Loading of Asphalt Mixtures

Abstract: This paper describes investigation into the change in complex modulus (norm and phase angle) during cyclic tests on bituminous mixtures. The change can be explained by four phenomena: nonlinearity, heating, thixotropy and fatigue. An experimental campaign has been performed at ENTPE laboratory in order to identify and quantify the first three phenomena. The analysis of the results reveals that the two reversible effects (heating and thixotropy) are very important and can not be ignored when interpreting fatigue tests. Nonlinearity, for the rather small strain level amplitudes considered in our experimental campaign (up to 122 μm/m), is also shown to be reversible. Heating is due to the viscous dissipated energy that heats the specimen. At the beginning of the test, temperature increase in the sample is shown to be proportional with the total dissipated energy. Thixotropy effect is quantified. In addition, it is shown that thixotropy effect can be modeled using an equivalent temperature increase.

Science Mapping Approach to Assisting the Review of Construction and Demolition Waste Management Research Published between 2009 and 2018

Abstract: Sustainable treatments of construction and demolition (C&D) wastes have become an increasingly urgent social, environmental, and economic issue worldwide. Based on a filter of 370 articles related to C&D waste management, this review-based study adopted a science mapping approach to evaluating the recent decade’s C&D waste management research. Through a three-step workflow consisting of bibliometric literature search, scientometric analysis, and qualitative discussion, this study identified the most influential journals, scholars, articles, and countries that have been active and influential in the C&D waste management research since 2009. Keyword analysis revealed the emerging research topics, such as BIM, prefabricated construction, Big Data, and Circular Economy. The follow-up discussion summarized the mainstream research areas (e.g., qualification of waste generation), discussed research gaps (e.g., integration of BIM and Big Data into C&D waste management), and proposed the framework for near-future research, such as a comprehensive evaluation of the performance of C&D waste diversion, human factors, and design and planning for waste diversion. By providing the big picture of the latest research in C&D waste management since 2009, the paper serves as a multi-disciplinary guide for practitioners and researchers to link current research areas into future trends.