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Displaying 151 - 175 of 176

Advancing the materials science of concrete with supercomputers

January 24, 2011

Author(s)

Jeffrey W. Bullard, Edward Garboczi, William L. George, Nicos Martys, Steven G. Satterfield, Judith E. Terrill

Supercomputers are renowned for being used on grand challenge problems like global weather patterns, nuclear device virtual testing, galaxy formation, unraveling molecular structure - and now concrete! Why do the mysteries of concrete form this kind of a

Evaluation of Sustainable High-Volume Fly Ash Concretes

January 1, 2011

Author(s)

Alejandro Duran-Herrera, Cesar Juarez, P Valdez, Dale P. Bentz

This article presents results of an experimental research work oriented to develop practical tools for the regional concrete industry, as well as to illustrate the potential benefits of the synergistic effect of an ASTM C 618 Class F fly ash (FA) produced

Spherical harmonic-based random fields based on real particle 3-D data: Improved numerical algorithm and quantitative comparison to real particles

October 23, 2010

Author(s)

Edward Garboczi, Sinan T. Erdogan, Yang Lu, Xuefeng Liu, Mircea Grigoriu

The shape of particles often plays an important role in how they are used and in the properties of composite systems in which they are incorporated. When building models of systems that include real particles, it is often of interest to generate new

Three Dimensional Shape Analysis of JSC-1A Simulated Lunar Regolith Particles

October 23, 2010

Author(s)

Edward Garboczi

The three dimensional (3-D) shape of a fairly broad size range of the particles of the lunar regolith simulant JSC-1A was characterized. After wet screening with water, the size classes that were kept and investigated were: those retained on a 300

A Dual Concentric Ring Test for Evaluating Residual Stress Development Due of Restrained Volume Change

September 1, 2010

Author(s)

John Schlitter, Andrew Senter, Dale P. Bentz, Tommy Nantung, Jason Weiss

The standard restrained ring test (ASTM 1581-04) is a simple, economical method to evaluate a concrete mixture s susceptibility of shrinkage cracking. Unfortunately, the test only provides restraint against samples that shrink and can not be used to

LWA Absorption and Desorption: The Influence on the Microstructure and Transport Properties of Internally Cured Mortars

September 1, 2010

Author(s)

Javier Castro, Ryan Henkensiefken, Tommy Nantung, Dale P. Bentz, Jason Weiss

The increased propensity for shrinkage cracking in low water-to-cement ratio (w/c) concrete has resulted in the development of new methods that can reduce the risk of early-age cracking, including internal curing. Internal curing can use water-filled

CT Measurements of SAP Voids in Concrete

August 15, 2010

Author(s)

Sara Laustsen, Dale P. Bentz, Marianne Hasholt, Ole M. Jensen

This paper describes how X-ray computed tomography (CT) scanning can be used to determine the void distribution in hardened concrete. Three different approaches are used to analyse a binary data set created from CT measurement. One approach classifies a

Planar Image-Based Reconstruction of Pervious Concrete Pore Structure and Permeability Prediction

July 1, 2010

Author(s)

Milani S. Sumanasooriya, Dale P. Bentz, Narayanan Neithalath

Transport properties of porous materials such as pervious concretes are inherently dependent on a variety of pore structure features. Empirical equations are typically used to relate the pore structure of a porous material to its permeability. In this

Shape comparison between 0.4 ym to 2.0 ym and 20 ym to 60 ym cement particles

June 15, 2010

Author(s)

L Holzer, R Flatt, S.T. Erodgan, Jeffrey W. Bullard, Edward Garboczi

Portland cement powder has a wide particle size distribution, from approximately 0.1 υm to 60 υm. This wide powder size distribution arises via the grinding of much larger clinker particles in fact, several percent of the world s energy expenditures are

ADVANCES IN PORE STRUCTURE CHARACTERIZATION AND PERFORMANCE PREDICTION OF PERVIOUS CONCRETES

May 3, 2010

Author(s)

Narayanan Neithalath, Dale P. Bentz, Milani S. Sumanasooriya

Pervious concrete is receiving renewed interest as a sustainable construction material for parking lots, sidewalks, and low-traffic-volume roads. A key characteristic of this material is its coarse porosity, achieved by omitting the fine aggregates from a

Evaluation of Precision and Bias of Computerized Optical Sizing and Roundness Determination of Glass Beads Utilized in Traffic Markings

March 24, 2010

Author(s)

Edward Garboczi

The mechanical ASTM sieve analysis and roundness measurement methods are traditionally used for characterization of the glass beads utilized in traffic markings. In recent years, computerized optical testing of the glass beads has been increasingly used as

The Influence of Shrinkage-Reducing Admixtures (SRAs) on Moisture Absorption in Cementitious Materials at Early Ages

March 1, 2010

Author(s)

G Sant, A Eberhardt, Dale P. Bentz, W Weiss

The water absorption behavior of cement pastes (w/c = 0.30) containing varying concentrations (i.e., 0 %, 0.2 % and 5 %) of a shrinkage reducing admixture (SRA) was measured. Moisture ingress was monitored using x-ray absorption. A decrease in both the

Concrete nanoscience and nanotechnology: Definitions and applications

February 10, 2010

Author(s)

Edward Garboczi

There are many improvements needed in concrete, especially for use in renewal and expansion of the world's infrastructure, e.g. increased durability, decreased brittleness and increased tensile strength, and use of non-traditional materials like fly ash

Plastic Shrinkage Cracking in Internally Cured Mixtures Made with Pre-wetted Lightweight Aggregate

February 1, 2010

Author(s)

Ryan Henkensiefken, Peter Briatka, Dale P. Bentz, Tommy Nantung, Jason Weiss

The incorporation of pre-wetted lightweight aggregates (LWA) has been used to reduce the shrinkage cracking associated with self-desiccation in the hardened state. Little research however exists which shows the influence of internal curing on the formation

Quantifying Particle Shape in 3-D: Experimental and Mathematical Considerations

December 23, 2009

Author(s)

Edward Garboczi

Quantifying the shape of particles in 3-D is a general problem and is important in many physical situations in particle technology. In the field of concrete, the 3-D shape of particles like sand, gravel, and cement is of great interest for various

Water Absorption in Internally Cured Mortar Made with Water-Filled Lightweight Aggregate

October 1, 2009

Author(s)

Ryan Henkensiefken, Javier Castro, Dale P. Bentz, Tommy Nantung, Jason Weiss

The increased propensity for shrinkage cracking in low w/c concrete has spawned the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses saturated lightweight aggregate to

Internal Curing Improves Concrete Performance throughout its Life

September 1, 2009

Author(s)

Ryan Henkensiefken, Javier Castro, Haejin Kim, Dale P. Bentz, Jason Weiss

Internal curing (IC) provides a set of water reservoirs within the concrete to prevent self-desiccation and promote hydration. While early research in this area focused on reductions in early-age deformation and cracking, recent efforts have demonstrated

Volume Change and Cracking in Internally Cured Mixtures Made with Saturated Lightweight Aggregate under Sealed and Drying Conditions

August 3, 2009

Author(s)

Ryan Henkensiefken, Dale P. Bentz, Tommy Nantung, Jason Weiss

Increased occurrences of early-age shrinkage cracking in low water to cement ratio (w/c) concrete have spawned innovative developments in mixture design that reduce the risk of cracking. One such development is internal curing, which utilizes the inclusion

Comprehensive Evaluation of AIMS Texture, Angularity, and Dimension Measurements

July 3, 2009

Author(s)

Enad M. Mahmoud, Leslie L. Gates, Eyad A. Masad, Sinan T. Erdogan, Edward Garboczi

Aggregates are the most widely used construction materials in the world in structures built from both asphaltic and portland cement concrete composites. The performance of these composites is affected by aggregate shape characteristics (e.g., angularity

Predicting the Permeability of Pervious Concretes from Planar Images

May 1, 2009

Author(s)

Milani S. Sumanasooriya, Dale P. Bentz, Narayanan Neithalath

This paper discusses the reconstruction of three-dimensional material structures of pervious concretes using two-dimensional digital images obtained from actual specimens, and computational permeability predictions using these reconstructed three

Relationship Between Engineering Properties, Mineralogy, and Microstructure in Cement-Based Hydroceramic Materials Cured at 200 C to 350 C

March 1, 2009

Author(s)

Konstantinos Kyritsis, Christopher Hall, Dale P. Bentz, Nicola Meller, Moira A. Wilson

Cement-based materials used to seal geothermal or deep oil wells are exposed to severe conditions. Optimizing engineering properties such as strength and permeability is therefore very important. We have synthesized hydroceramic materials for such

Stress chains formation under shear of concentrated suspension

July 7, 2008

Author(s)

Didier Lootens, Nicos Martys, William L. George, Steven G. Satterfield, Pascal Hebraud

Results comparing experiments on a model system of mono-disperse silica-particles with the numerical simulation of highly concentrated suspension of spherical particles subject to a constant rate of strain are presented. Giant fluctuations of the shear

Characterization and Modeling of Pores and Surfaces in Cement Paste: Correlations to Processing and Properties

February 15, 2008

Author(s)

Hamlin M. Jennings, Jeffrey W. Bullard, J Thomas, J Andrade, J. Chen, George W. Scherer

Prediction of Elastic Properties of Concrete Using the Virtual Cement and Concrete Testing Laboratory

November 30, 2007

Author(s)

Sinan Erdogan, Edward Garboczi, Jeffrey W. Bullard

Feasibility on Using a Concrete Mixing Truck as a Rheometer

June 14, 2006

Author(s)

S Amziane, Chiara C. Ferraris, E Koehler

Fresh concrete properties are crucial for the performance of the concrete in its hardened state. The measurement of workability is usually done using a simple slump test. This test, although widely used for almost 100 years, does not provide a full picture