Guidance for Increasing the Use of Recycled Concrete Pavement Materials

Recycling concrete pavements has been a common practice in the US for decades, and recently, public agencies have been more closely examining recycling opportunities. Reasons supporting recycling include the diminishing quantity of good natural materials, economics, improved project execution, minimizing traffic disruption, and supporting sustainability goals. Many states, however, have specifications or policies that restrict concrete pavement recycling. The contracting industry may overlook opportunities to use recycled concrete aggregates (RCAs) due to a lack of familiarity with technical requirements or uncertainty of performance. The National Concrete Pavement Technology Center (CP Tech Center) recently completed a comprehensive set of technical resources for the Federal Highway Administration to assist practitioners with sound approaches to project selection, scoping and construction requirements to support increased use of recycled concrete pavement materials. This paper describes the results of a 2016 survey of agency and industry RCA usage, presents an overview of the technical resources prepared as part of this initiative, and presents recommendations for supporting broader application of recycling concrete pavement materials.

Enhancement of sustainable road design towards compatibility between pavement materials

The need for correctly made comparisons of different pavement materials, regarding cost-efficiency to reduce the climate impact, is increasing, especially in connection with new types of climate-neutral materials, so that sub-optimizations and oblique competition do not arise. Both the Swedish and USA's authorities are beginning to demand the Environmental Product Declaration (EPDs) as a certificate of the pavements' environmental performances from the contractors. There are some methodological difficulties to use the EPDs for comparison of the environmental impacts between different asphalt mixes or between the asphalt- and concrete pavements. This paper has analyzed two new standards which propose to extend the declaration to several aspects of sustainability: technical, environmental and economic performance. In this article, we have investigated if these standards can be used to form a framework to create an extended sustainability declaration of road pavements allowed a multidisciplinary comparison of different materials based on technical performance, Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA).

Full-Scale Experimental Evaluation of the Flood Resiliency of Thin Concrete Overlay on Asphalt Pavements

The capacity to resist flooding is one of the critical challenges of pavement resiliency in locations subject to inundation. Flooding increases moisture contents, which weakens most pavement materials. Although the effect of moisture on the mechanical properties of most pavement materials is reversible, the structural damage caused by trafficking applied on the weakened pavement structure is not. The critical time for structural damage is typically after the flood and before “life-line” pavements have dried back when trucks are bringing in relief supplies and hauling out demolition. This fact, together with the increased occurrence of extreme weather events and sea level rise resulting from climate change, emphasizes the need to better understand the impacts of flooding on identified life-line pavements. This paper evaluates the flooding resiliency of thin concrete overlay on asphalt (COA) pavements by studying the effects that water saturation produces on the pavement structure. The research is based on the structural response and distresses measured in five thin COA sections that were instrumented with sensors and tested with a heavy vehicle simulator (HVS) under flooded conditions. The research shows that the flooding did not produce a noticeable change in the structural capacity of the COA, based on the structural response measured under the loading of the HVS wheel and the falling weight deflectometer, but did result in some structural damage to the asphalt base in some of the sections.

Applying Feasibility Investigation of Resin Modifying Agent in Asphalt Pavement Materials

In order to promote the resin modifying agent applied into pavement materials, a type of resin modifying agent was selected as the modifier to prepare modified asphalt. The molecular crystal structure of the modifying material was characterized by using the X-ray diffraction test (XRD). The microstructure and element composition of PA6 was investigated through focused ion beam scanning electron microscopy (FIB-SEM). The thermal property and functional groups of PA6 were studied by thermogravimetric analysis-Fourier infrared spectroscopy (TG-FTIR) test. The physical property and rheological properties of PA modified asphalt were evaluated to confirm the applying feasibility of PA6 in asphalt. The results indicated that PA6 was the semicrystalline polymer and the existence of γ crystal form might improve the toughness of asphalt materials effectively. The thermal decomposition process of PA6 could be divided into three stages roughly: inert weight loss stage, rapid weight loss stage, and stable stage. The amount of PA6 modifier should be appropriately controlled during the application process to ensure the comprehensive effect of PA6 on high-temperature performance and low-temperature performance. The corresponding initial modulus attenuation value of PA modified asphalt was less than 70# asphalt under the same test conditions.

Application of Response Surface Method for Analyzing Pavement Performance

Hot mix asphalt (HMA) is a common material that has been largely used in the road construction industries. The main constituents of HMA are asphalt binder, mineral aggregate, and filler. The asphalt binder bounds aggregate and filler particles together and also waterproofs the mixture. The aggregate acts as a stone skeleton to impart strength and toughness to the structure, while the filler fills pores in the mixture which can improve adhesion and cohesion as well as moisture resistance. The HMA behavior depends on individual component properties and their combined reaction in the mixture. Asphalt binder properties change due to different factors. Over the years, asphalt pavement materials age, causing binder embrittlement which adversely affects pavement service life. Response Surface Method (RSM) is a set of techniques that are used to develop a series of experiment designs, determining relationships between experimental factors and responses, and using these relationships to determine the optimum conditions. Incorporating RSM in pavement technologies can beneficially help researchers to develop a better experimental matrix and give them the opportunity to analyze the changes in pavement performance in a faster, more effective, and reliable way.

Utilization of Reclaimed Asphalt Pavement Material in Wet Mix Macadam (W.M.M)

Reclaimed asphalt pavement (RAP) is one of the innovative and effective technologies in many places in the world. The utilization of RAP is rapidly increasing popularity and becoming an emerging technique in India. As per IRC-120:2015, removing or reprocessing pavement materials containing aggregates that are bitumen coated is termed as RAP. These materials are gained through a process in which the existing surface pavement is reclaimed and reused after processing for reconstruction, resurfacing, or repaving. Well graded and high-quality aggregate are achieved from this process. Proper utilization of RAP with specified properties and specified percentages, not only serve as an alternative useful pavement material but also helps in reducing the usage of natural construction material, that will directly reduce the overall cost of projects. By conducting tests as per MoRTH specifications (5th Revision), the various characteristics of RAP material and fresh aggregates are observed. The main objective of the study is to carry out the performance tests: Modified Proctor test on fresh material as well as on material mixed with reclaimed asphalt pavement i.e. 10%, 20%, and 30% of total mix and to achieve optimum moisture content and maximum dry density by using Modified Proctor Test. Attempts are carried out to design a new pavement using Indian Road Congress (I.R.C-37:2018) guidelines and utilization of RAP material. Economic benefits are calculated in terms of fresh and RAP (10%, 20%, and 30%) mix material pavement.