0000000001018302
AUTHOR
Armando Astolfi
Quality-control procedure for dry-process rubberised asphalt mastics
Crumb Rubber (CR) can be incorporated into asphalt mixes via the dry process by directly adding CR into the mixer together with other asphalt mixture’s components, or with the wet process where the CR is used as a bitumen modifier. While the wet process allows an accurate monitoring of the interaction between CR and bitumen, the lack of control represents a main issue in the dry process. In fact, in the latter the CR particles keep swelling during hauling and possibly also after paving operations, often causing workability issues and premature failures. This study wants to provide a methodology that could help quality control procedures of bitumen/filler/rubber systems during mixing, haulin…
A new and simplified approach to assess the pavement surface micro- and macrotexture
Abstract Road safety depends on pavement skid resistance and surface texture. Skid resistance mainly depends on micro-texture and macrotexture. Skid and texture measurements on samples, in the laboratory, at the preliminary stage of the design, would enhance the design in terms of timing, costs, and reliability. Consequently, this study aims at setting up and validating simple methods for assessing surface texture and skid resistance based on core/sample measurements. Experiments were carried out and predictive relationships were set up to explain and predict results. Under given conditions, miniaturised macro-and microtexture tests (modified EN 13036-1 and modified EN 13036-4, respectively…
In-lab versus on-site measurement of surface performance of flexible pavements
Road safety is one of the major problems which affect our society. Skid resistance mainly depends on a pavement surface microtexture and macrotexture. Macrotexture can be easily measured on site through the Sand Patch method (mean texture depth, MTD, UNI EN 13036-1, ASTM E 965, CNR B.U. 94/83). Carrying out the measurements above on the samples, in the laboratory, at the preliminary stage of the design of the pavement, would enhance the design in terms of timing and costs. In the light of the above, the objective of the study presented in this paper is to set up and validate a method for deriving the sand patch value based on core measurements. A Predictive relationship is proposed in terms…
SURFACE AND MECHANISTIC PROPERTIES OF RECYCLED BITUMINOUS MIXTURES
EXECUTIVE SUMMARY Problem Often, when the characteristics of a bituminous mixture are analised, there are major differences between in-lab and in-situ results. This is due to the fact that the procedures and techniques implemented during the design phase (in lab) may be different from those used on site. Then, is very important to be able to predict the main properties of a mixture particularly when innovative materials are used. For example, when crumb rubber is used, phisical and volumetric properties of mixes may change over time, in particular due to the swelling phenomenon that it alters different properties of the mixture (e.g., viscosity). This study aims to investigate the main aspe…
Impact of Asphalt Mixture Specification Limits: A Theoretical Analysis
AbstractSpecifications limits and tolerances are crucial in the relationships among contractor, road agency, and citizens because they influence profits, acceptance procedures, and pavement durabil...
Issues and Perspectives in the Application of Different Pavement Design Methods to Life Cycle Cost Analysis
Life cycle costs analysis (LCCA) is an economic evaluation tool that can provide valuable guidance to transportation officials in management decision process. The application of LCCA to pavement management is vital because it permits the selection of the best alternative, based on the analysis of agency costs and user costs, taking into account (after selecting pavement type) different maintenance and rehabilitation (M&R) strategies within the same pavement type. Additionally, environmental costs can be considered. Issues arise when comparing the expected life of the pavement derived according to different pavement design tools, such as the Mechanistic-Empirical pavement Design Guide (M…