In this paper a simple, but effective methodology to simulate opening mode fracture in high performance fibre reinforced concrete is presented. To obtain the specific fracture energy of the material, load-deflection curves from three point bending (TPB) experiments are extrapolated. The proposed extrapolation technique is an adaptation of an approach originally developed for plain concrete. The experimental part of the paper includes a size effect study on TPB specimens. The post crack behaviour of the material is modelled using a cohesive softening function with crack tip singularity. Numerical simulation of the experiments is performed by means of an embedded discontinuity method. The simulation provides satisfactory predictions of the fracture behaviour of the material and the size-effect observed in the experiments.

A computer program known as CalME has been developed for analysis and design of new flexible pavements and rehabilitation of existing pavements. The paper describes the overlay design procedure and the calibration of the models for reflection cracking and permanent deformation through heavy vehicle simulator (HVS) tests. To simplify the input process, the program includes databases for traffic loading, climatic conditions, and standard materials. A companion program was developed for backcalculation of layer moduli, and the results may be automatically imported into the CalME database. The program incorporates the existing, empirical California Department of Transportation design methods as well as an incremental–recursive analysis procedure based on the mechanistic–empirical method. The effects of different pavement preservation and rehabilitation strategies on pavement damage may be studied with several options for triggering timing of placement. The influence of within-project variability on the propagation of damage can be evaluated using Monte Carlo simulation. The program also permits importation of the results of HVS or track tests into the database and simulation of the experiments on the computer. This feature is useful for the calibration of the mechanistic–empirical models but may also be used for in-depth interpretation of accelerated pavement testing results. An HVS experiment that was used for calibration of the reflection cracking and the permanent deformation models is described.

A research study was conducted with the goal of determining the expected performance life of thin bonded concrete overlay of asphalt (BCOA) in California. Eleven thin BCOA sections were built and tested with the Heavy Vehicle Simulators (HVS) in Davis, California. The performance of the sections in the HVS testing provided insight into the mechanics of the thin BCOA structures and the effects the different rapid-strength concrete materials, traffic, jointing, and base factors on their performance, including testing in both very wet and very dry conditions. Overall, the performance of the thin BCOA sections in the HVS testing was excellent. The eleven sections resisted the predefined HVS loading without cracking. In five of the sections, that loading was equivalent to 6 million single-axle loads and included load levels more than twice the legal limit in California, channelized traffic at the shoulder edge of the slabs, and a continuous water supply that simulated flooded conditions. The main conclusion from this research study is that a well-designed, well-built thin bonded concrete overlay with half-lane width slabs placed on top of an asphalt base that is in fair to good condition can provide 20 years of good serviceability on most of California’s non-interstate roadways.

Full-depth reclamation (FDR) with foamed asphalt has been successfully used as a rehabilitation strategy in California since 2001. Long-term field monitoring on several projects and a comprehensive laboratory study resulted in the preparation of guidelines and specification language in 2008. However, the design criteria were essentially empirical, in line with California design procedures for this level of rehabilitation project. Recently, there has been growing interest in the use of cement, engineered emulsion, and no-stabilizer full-depth reclamation strategies in addition to foamed asphalt and in the use of mechanistic design in rehabilitation projects. Consequently, the research initiative was extended to a second phase to include accelerated load testing on an instrumented test track constructed with these four FDR strategies to gather data for the development of performance models that can be included in mechanistic–empirical rehabilitation design procedures. This paper summarizes the results of the first two tests in this accelerated loading study, which compared no stabilizer and foamed asphalt–cement strategies. The foamed asphalt section outperformed the unstabilized section in all measured aspects. The most notable observation was in rutting performance: the unstabilized section reached a terminal rut depth of 13 mm after approximately 490,000 equivalent standard-axle loads had been applied, compared with the foamed asphalt and cement section, which had a rut depth of only 4.3 mm after more than 17.7 million equivalent standard-axle loads. No cracking was observed on either section. The advantages of using foamed asphalt with cement over unstabilized pulverized material are clearly evident from the results.

Fully permeable (or porous or pervious) pavements are pavements whose layers are all intended to be permeable. They are used to minimize the adverse effects of stormwater runoff generated from impervious surfaces. They may also be an effective solution for cool pavement strategies for improving outdoor thermal environments and mitigating heat island effects in hot climates. Most current applications of permeable pavements in North America are used for roads with a low traffic volume, basic access streets, parking lots, and recreation and landscaped areas, all of which carry light, slow-moving traffic. Structural design methods have been empirical in nature. Mechanistic–empirical approaches for fully permeable pavement designs have not been developed, but when available, would probably speed up the implementation of fully permeable pavements and potentially extend their use to pavements with a higher volume of traffic where appropriate. This paper summarizes the development of a mechanistic–empirical design method and design tool for permeable interlocking concrete pavements, which uses mechanistic analysis and partial validation with accelerated pavement testing results. A new example design table, based on the number of days with standing water in the subbase (0, 10, 30, 50, 90, and 120), was developed with an Excel spreadsheet-based design tool. The format of the table is similar to that of the current guideline for permeable interlocking concrete pavements of the Interlocking Concrete Pavement Institute. Designs for a specific set of project circumstances can be developed with the same Excel spreadsheet-based design tool used to develop the tables along with the hydrological design procedures provided in the Interlocking Concrete Pavement Institute guide.