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A procedure is developed by which the likelihood of delamination of bonded concrete overlays on continuously reinforced concrete pavements is reduced. The procedure compares the early age interface stress to the expected interface bond strength for a variety of environmental conditions. When the calculated stress exceeds the expected strength, it is recommended that overlay placement be curtailed until the possibility of debonding is reduced. A finite element method program is used to determine the early age stresses resulting from temperature and shrinkage induced volume changes. Stresses were determined for a variety of environmental and material combinations and overlay thicknesses. Analyses show that a significant reduction in stress results from the use of overlay materials which have a lower modulus and thermal coefficient than those of the existing slab. The stresses for a given combination of materials and environmental conditions are compared to the interface bond strength at early ages. Early age interface shear and tensile strengths are estimated from 7-day strength test results. The estimated strength, together with the variability of the interface strength, are used to calculate the likelihood of delamination for a given type of overlay and time of placement. This likelihood can be reduced through the selection of a different overlay material or time of placement.
An important new report from the RILEM Technical Committee 119. This book presents models and methods to determine thermal stresses and cracking risks in concrete. The possible influences on and causes of thermal cracking of concrete are discussed and cases of practical measures for avoiding cracking are detailed.
Among different approaches that can be considered for concrete rehabilitation, bonded overlays are often the most economical alternative. The primary purpose of overlays is to extend the life of the candidate structures, either by restoring the quality and integrity of the surface and/or the re-establishing or improving the load-carrying capacity. Nevertheless, the durability of bonded overlay systems still draws concerns in the technical community because of bond sustainability problems encountered in a number of cases. At this time, there is still no accepted design approach or methodology that can warrant the practitioner a successful outcome of the repair. This State-of-Art report summarizes the findings with respect to all aspects involved in the overlaying process.
An important new report from the RILEM Technical Committee 119. This book presents models and methods to determine thermal stresses and cracking risks in concrete. The possible influences on and causes of thermal cracking of concrete are discussed and cases of practical measures for avoiding cracking are detailed.
This book presents the latest advances in research to analyze mechanical damage and its detection in multilayer systems. The contents are linked to the Rilem TC241 - MCD scientific activities and the proceedings of the 8th RILEM International Conference on Mechanisms of Cracking and Debonding in Pavements (MCD2016). MCD2016 was hosted by Ifsttar and took place in Nantes, France, on June 7-9, 2016. In their lifetime, pavements undergo degradation due to different mechanisms of which cracking is among the most important ones. The damage and the fracture behavior of all its material layers as well as interfaces must be understood. In that field, the research activities aims to develop a deeper fundamental understanding of the mechanisms responsible for cracking and debonding in asphalt concrete and composite (e.g. asphalt overlays placed on PCC or thin cement concrete overlay placed on asphalt layer) pavement systems.