About: Asphalt concrete is a(n) research topic. Over the lifetime, 9587 publication(s) have been published within this topic receiving 93844 citation(s). The topic is also known as: blacktop & asphalt.
01 Jan 2004-Waste Management
TL;DR: An overview of some of the research published regarding the use of scrap-tires in portland cement concrete and the benefits of using magnesium oxychloride cement as a binder for rubberized concrete mixtures are presented.
Abstract: Solid waste management is one of the major environmental concerns in the United States. Over 5 billion tons of non-hazardous solid waste materials are generated in USA each year. Of these, more than 270 million scrap-tires (approximately 3.6 million tons) are generated each year. In addition to this, about 300 million scrap-tires have been stockpiled. Several studies have been carried out to reuse scrap-tires in a variety of rubber and plastic products, incineration for production of electricity, or as fuel for cement kilns, as well as in asphalt concrete. Studies show that workable rubberized concrete mixtures can be made with scrap-tire rubber. This paper presents an overview of some of the research published regarding the use of scrap-tires in portland cement concrete. The benefits of using magnesium oxychloride cement as a binder for rubberized concrete mixtures are also presented. The paper details the likely uses of rubberized concrete.
01 Oct 1993-
Abstract: A result of the Strategic Highway Research Program's asphalt research is the development of performance-based specifications for asphalt binders and mixtures to control 3 distress modes: rutting; fatigue cracking; and thermal cracking. The SHRP A-005 project developed detailed pavement performance models to support these binder and mixture specifications and performance-based mixture designs. This report documents the findings of this extensive research effort and provides supporting data for the performance-based specifications and mixture design procedure called SUPERPAVE. The A-005 contract developed and used a sophisticated, mechanistic-based pavement performance model to define the relationships between asphalt binder and mixture properties and pavement distress. A comprehensive pavement performance model was developed that predicts the amount of fatigue cracking, thermal cracking and rutting in asphalt concrete pavements with time, using results from the accelerated laboratory tests. The pavement performance models for each distress were also used to confirm the relevant binder and mixture properties established by other SHRP contractors. The model has 3 parts: a mixture evaluation model; a pavement response model; and a pavement distress model.
01 Apr 1999-Journal of Computing in Civil Engineering
Abstract: The performance of asphalt concrete (AC) mixtures is influenced by the arrangement of aggregates and their associated air voids. Parameters to measure aggregate orientation, aggregate gradation, and air void distribution in AC mixes are proposed. Computer automated image analysis procedures were used to measure these parameters. The air void distribution was characterized using X-ray tomography images. The new parameters were used to study the evolution of the internal structure of AC mixes during laboratory compaction by the Superpave Gyratory Compactor and in the field. The preferred orientation of the aggregate structure in the laboratory was found to increase with compaction up to a certain compaction effort. Thereafter, the aggregate structure tended to have more random orientation. Percent voids measured on X-ray tomography images compared well with percent voids measured in the laboratory. The void distribution in the specimens was found to be nonuniform. More internal voids were concentrated at the top and the bottom portions of the gyratory compacted specimen. The gyratory compacted specimens reached the initial aggregate orientation of the field cores at a higher number of gyrations whereas they reached the percent air voids in cores at a lower number of gyrations. Coarse aggregate gradation of gyratory compacted specimens was well captured using the image analysis techniques. There was no change in gradation with compaction.
01 Jan 1971-Highway Research Record
Abstract: THE PURPOSE IS TO DEFINE BETTER THOSE PROPERTIES OF GRANULAR BASE MATERIALS THAT CONTRIBUTE TO THE RESILIENT RESPONSE OF PAVEMENT STRUCTURES. A STUDY IS INCLUDED OF THE INFLUENCE OF AGGREGATE DENSITY, AGGREGATE GRADATION (PERCENT PASSING NO. 200 SIEVE), AND DEGREE OF SATURATION ON THE RESILIENT RESPONSE OF TWO AGGREGATES REPRESENTATIVE OF THOSE USED IN THE CONSTRUCTION OF ASPHALT CONCRETE PAVEMENTS. TESTS CARRIED OUT IN TRIAXIAL COMPRESSION, CONSISTED OF APPLYING REPEATED AXIAL STRESSES WITH REALISTIC STRESS HISTORIES AT A FIXED FREQUENCY AND AT A LOAD DURATION REPRESENTATIVE OF THAT EXPECTED IN THE FIELD. FOR BOTH GRANULAR MATERIALS, THE RESILIENT MODULUS INCREASED CONSIDERABLY WITH AN INCREASE IN CONFINING PRESSURE AND ONLY SLIGHTLY WITH AN INCREASE IN AXIAL STRESS. POISSON'S RATIO INCREASED WITH A DECREASE IN CONFINING PRESSURE AND AN INCREASE IN REPEATED STRESS. THE RESILIENT MODULUS AND POISSON'S RATIO WERE ALSO AFFECTED TO LESSER DEGREES BY DENSITY, PERCENT PASSING THE NO. 200 SIEVE, AND DEGREE OF SATURATION. AN ANALYSIS OF A CONVENTIONAL ASPHALT CONCRETE PAVEMENT OVER A SANDY CLAY SUBGRADE INDICATED THAT REASONABLE CHANGES IN THE MODULUS OR POISSON'S RATIO OF THE GRANULAR BASE LAYER CAN RESULT IN CONSIDERABLE CHANGES IN THE RESPONSE OF THE PAVEMENT STRUCTURE TO LOAD. /AUTHOR/
01 Jan 2003-
Abstract: The purpose of this paper is to present a new, rational and effective model for estimating the modulus of asphalt concrete using binder modulus and volumetric composition. The model is based upon an existing version of the law of mixtures, called the Hirsch model, which combines series and parallel elements of phases. In applying the Hirsch model to asphalt concrete, the relative proportion of material in parallel arrangement, called the contact volume, is not constant but varies with time and temperature. Several versions of the Hirsch model were evaluated, including ones using mastic as the binder, and one in which the effect of film thickness on asphalt binder modulus was incorporated into the equation. The most effective model was the simplest, in which the modulus of the asphalt concrete is directly estimated from binder modulus, voids in mineral aggregate, and voids filled with asphalt binder. Models are presented for both dynamic complex shear modulus and dynamic complex extensional modulus. Semi-empirical equations are also presented for estimating phase angle in shear loading and in extensional loading. The proposed model was verified by comparing predicted modulus and phase angles to values reported in the literature for a range of mixtures.