International Center for Aggregates Research (ICAR)
The International Center for Aggregates Research is the voice of the aggregates industry in the research community and serves as a facilitator for determining the most effective use of aggregates in design, specification and construction.
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Recent Submissions
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Sensitivity Analysis of Flexible-Pavement Response and the AASHTO Design Guide to Properties of Unbound Layers. Summary
(International Center for Aggregates Research, 2005)"Unbound granular materials generally compose the base and subbase layers in road pavements. The granular materials distribute the load through aggregate contacts to a level sustainable by the subgrade. Pavement design and ... -
LASS Incorporates the Third Dimension in Order to Improve the Accuracy of Rapid-Gradation Technology
(International Center for Aggregates Research, 2004)"Sophisticated asphalt designs, such as the Superpave specification, specify aggregate shape parameters like flatness and elongation ratios as an additional design variable. Conventional sieve analysis has drawbacks such ... -
Structural Characteristics of Unbound Aggregate Bases for Mechanistic Design
(International Center for Aggregates Research, 2001)The next AASHTO Guide for the Design of Pavement Structures will make extensive use of mechanistic-empirical design principles, and may result in pavement designs with different layer thicknesses than are currently common. ... -
Increased Single-Lift Thicknesses For Unbound Aggregate Base Courses
(International Center for Aggregates Research, 1998)"State departments of transportation (DOTs) have used aggregate base courses for many years as an integral structural component of pavements. Specifications prescribe requirements for placement and compaction of aggregate ... -
Implication of Aggregates in the Frictional Performance of Seal Coat Overlays
(International Center for Aggregates Research, 1988)To investigate the effect of aggregate type on pavement friction, researchers used Texas as a test model and constructed 59 seal coat test sections 1,000 feet (304 m) long in the four climatic regions of the state. The ... -
From 12 Months to 3 Months : ICAR Study Yields New Test for Alkali-Silica Reaction that Reduces Time Required
(International Center for Aggregates Research, 2002)ICAR PROJECT 301, "Alkali-Silica Reaction in Portland Cement Concrete," headed by Dr. David W. Fowler at The University of Texas at Austin, succeeded in modifying ASTM C 1293 to yield comparable findings in [three] weeks ... -
Role of Aggregate Characteristics in Resistance to Load in SMA
(International Center for Aggregates Research, 2006)Stone Matrix Asphalt (SMA) mixtures rely on stone-on-stone contacts among particles to resist applied forces, and permanent deformation. Aggregates in SMA should resist degradation (fracture and abrasion) under high stresses ... -
Evaluation of Aggregate Characteristics Affecting Hot Mix Asphalt (HMA) Response
(International Center for Aggregates Research, 2004)Aggregate shape properties are known to influence asphalt pavement performance. Angularity and texture govern the frictional properties and dilation of the aggregate structure. Aggregate texture plays a major role in ... -
Evaluation of Superpave Aggregate Specifications
(International Center for Aggregates Research, 2002)The purpose of this study was to evaluate the restricted zone effect using four different aggregates: crushed granite, crushed limestone, crushed river gravel, and a mixture of crushed river gravel as coarse aggregate with ... -
Measuring Workability of High-Fines Concrete
(International Center for Aggregates Research, 2005)"The workability of fresh concrete has traditionally been evaluated with the slump test, which provides an inadequate indication of this important parameter... The need for a better test method for workability is well ... -
ICAR Project 102 Leads to High-Microfines Concrete
(International Center for Aggregates Research, 2001)"This study is the most comprehensive yet undertaken on microfines in concrete. Excellent cooperation was provided by industry; aggregates were furnished, an autogenous crusher was provided along with operating personnel ... -
Status of By-Product Fines in the United States
(University of Texas at Austin. International Center for Aggregates Research, 1997)"The objectives of the study were to identify the scope and diversity of marketing by-product fines; develop a technically and economically based protocol to identify potential uses; establish an advisory team to assist ... -
Role of Aggregate Characteristics to Load in SMA
(2006-08)Stone matrix asphalt (SMA) mixtures rely on stone-on-stone contacts among particles to resist applied forces and permanent deformation. Aggregates in SMA should resist degradation (fracture and abrasion) under high stresses ... -
Rapid Test to Establish Grading of Unbound Aggregate Products: Automation of Aggregate Characterization Using Laser Profiling and Digital Image Analysis
(2002-06)This final project report describes the development of a laser scanning device for measuring the gradation and other morphological characteristics of unbound construction aggregates. The device is called the LASS, for ... -
Rapid Test to Establish Grading of Unbound Aggregate Products: An Evaluation of Automated Devices to Replace and Augment Manual Sieve Analyses in Determining Aggregation Gradation
(2002-02)Several automated devices are commercially available for measuring the gradation of unbound stone aggregates. These computerized machines, which provide a rapid alternative to manual sieving, capture and process two-dimensional ... -
Rapid Test to Establish Grading of Unbound Aggregate Products: Evaluation of Potential Aggregate Grading Technologies
(2000-02)A research study is underway to develop automated methods for rapidly grading aggregates on the production line in a typical aggregate separation or mixing facility. This interim report serves to document preliminary work ... -
Characterization of Unbound Granular Layers in Flexible Pavements
(2001-12)The mathematical characterization of unbound granular materials should ideally be based on the behavior of the individual constituent elements and their interaction. Until particulate mechanics are developed to a level ... -
Field Validation of the Cross-Anisotropic Behavior of Unbound Aggregate Bases
(2001-03)The ICAR Research Project 502 has focused on determining structural considerations of unbound aggregate pavement layers for a proper representation in the new AASHTO Pavement Design Guide 2002. The research team developed ... -
Structural Characteristics of Unbound Aggregate Bases to Meet AASHTO 2002 Design Requirements: Interim Report
(2001-07)This report gives the results of a study of the properties of unbound aggregate base materials using both laboratory testing data from full scale field tests in Illinois, Georgia, and Texas, and a model of cross-anisotropic ... -
Increased Single-Lift Thicknesses for Unbound Aggregate Base Courses
(1998-10)A study was conducted to evaluate the feasibility of compacting unbound aggregate base courses in thicker lifts than currently permitted by state departments of transportation (DOTs). At present, the majority of states ...