100% Hot Mix Asphalt Recycling: Challenges and Benefits

Abstract

Dramatically rising asphalt binder cost, dwindling budgets, growing traffic loads, and the desire to find more sustainable paving practices are forcing agencies to seek ways for maximizing the re-use of Reclaimed Asphalt Pavement (RAP). While most of the academic and industrial institutions have been focused on the development of procedures to recycle hot asphalt mixes with up to 40% RAP content, a few industry innovators have refined 100% recycling technologies over the past four decades to a level where routine production of 100% recycled mixes is in clear sight. The main hindrance in the widespread use of 100% recycling is the unproven performance of 100% RAP pavements and lack of a unified and rational system for selection of materials and mix design. The objective of this research was, therefore, to critically investigate the concept of 100% recycling, determine whether such mixtures can perform as well as conventional asphalt mixes and if yes, develop a mixture design method for 100% recycled asphalt. This article presents a summary of the research, demonstrating that with adequate mixture design 100% recycled asphalt mixtures can perform equally to conventional asphalt. The available production technologies are also shortly summarized. Finally an environmental effect and cost calculation is performed demonstrating reduction of emission by 35% while reducing the costs of materials by half.

Study the Effect of Microwave Heating on Physical Properties of Asphalt

“…The amount of power absorbed and the rate of heat generation depend on the dielectric properties of the materials, the intensity and frequency of the applied microwave radiation [9]. The microwave energy is assumed to enter the road way from the normal (z) direction or at an appropriate angle, as transverse electromagnetic wave (for heating of patch compound for pothole repair can be modeled as a one dimensional problem), one can set up a heat balance on a per unit time and unit volume as: TES = microwave energy adsorbed + net heat input by conduction (1) Where: (TES) is the thermal energy stored and can be determined by…”

“…Asphalt is uses in bituminous (flexible pavement) construction. Recently, the need to asphalt recycling is becoming increasingly very important [1]. In the United States, Malaysia and other developed countries, asphalt is used in more than 94% of road surfaces, only 6% are rigid pavements and in many countries, only asphalt roads are in service and there are no rigid pavements in service.…”

Stiffness Modulus and Marshall Parameters of Hot Mix Asphalts: Laboratory Data Modeling by Artificial Neural Networks Characterized by Cross-Validation

“…Road pavements are transport infrastructures built with different types of hot mix asphalt (HMA), namely mixtures made of aggregates and bitumen, mixed at temperatures higher than 150 • C. In order to withstand traffic loads and environmental conditions, such infrastructures have to be properly designed in terms of their thickness and material properties. With respect to the composition and mechanical characteristics of HMAs, experimental methods are currently used to design and optimize such bituminous mixtures [1][2][3][4][5][6]. Particularly, for what concerns the bitumen content identification and the mixtures' performance evaluation, quite onerous laboratory tests are necessary; moreover, such experimental procedures require experienced and skilled technicians.…”

The Evaluation Method of Particle Clustering Phenomena in RAP

“…These improved properties are useful in the construction of the road bases and sub-bases [1,2]. The average RAP content added in the new asphalt mixture has steadily increased in recent years [3]. From an environmental perspective, higher percentages of RAP (e.g., >50%) are being utilized to reduce costs and save natural resources.…”