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Displaying 26 - 50 of 164

Local elastic moduli of simple random composites computed at different length scales

December 3, 2020

Author(s)

Edward Garboczi, Pietro Lura

Techniques like nanoindentation and atomic force microscopy can estimate the local elastic moduli in a region surrounding the probe tip used. For composites with phase regions much larger than the size of the probe, these procedures can identify the phases

Temperature-induced heteroaggregation in polydisperse portlandite suspensions

August 17, 2020

Author(s)

Edward Garboczi, Gaurav Sant, Iman Mehdipour, Narayanan Neithalath, Mathieu Bauchy, Samanvaya Srivastava, Sharu Bhagavathi Kandy

Temperature is well-known to affect the aggregation behavior of colloidal suspensions. This paper elucidates the temperature dependence of the rheology of portlandite (calcium hydroxide: Ca(OH)2) suspensions that feature a high ionic strength and a pH

Thermochemical principles of the production of lightweight aggregates from waste coal bottom ash

August 12, 2020

Author(s)

Edward Garboczi, Mohammad Balapour, Rathin Rao, Sabrina Spatari, Grace Hsuan, Peter Billen

Manufacturing lightweight aggregate (LWA) (i.e., porous ceramics) by means of a sintering technique requires a delicate balance among three conditions: (i) forming a sufficient amount of molten liquid phase during sintering, (ii) reaching an appropriate

Density Driven Damage Mechanics (D3-M) Model for Concrete II: Fully Coupled Chemo-Mechanical Damage

July 23, 2020

Author(s)

Pavitra Murrua, Zachary Grasley, Christa Torrence, KR Rajagopal, Edward Garboczi

In Part I, a density driven damage mechanics (D3-M) approach and its application to model mechanical damage in concrete are presented. In this study, chemical and chemo-mechanical damage in concrete are modeled using the D3- M approach. It is proposed that

How clay particulates affect shear jamming and the coiling stability of yield stress-matched cementing suspensions

March 25, 2020

Author(s)

Iman Mehdipour, Hakan Atahan, Narayanan Neithalath, Mathieu Bauchy, Edward Garboczi, Gaurav Sant

The remarkable increase in the flow resistance of dense suspensions (jamming) can hinder 3D- printing processes on account of flow cessation and filament fragility/rupture in the extruder. Understanding the nature of rheological changes that occur is

Dispersing nanosized portlandite particulates via electrosteric exclusion at short screening lengths

March 16, 2020

Author(s)

Jason Timmons, Iman Mehdipour, Shang Gao, Hakan Atahan, Narayanan Neithalath, Mathieu Bauchy, Edward Garboczi, Samanvaya Srivastava, Gaurav Sant

In spite of their high surface charge (ζ = + 34 mV), aqueous suspensions of portlandite (calcium hydroxide: Ca(OH)2) exhibit a strong tendency to aggregate, and thereby present unstable suspensions. While a variety of commercial dispersants seek to modify

Dissolution and Initial Hydration Behavior of Tricalcium Aluminate in Low Activity Sulfate Solutions

January 22, 2020

Author(s)

Alexander Brand, Steven B. Feldman, Paul E. Stutzman, Anton V. Ievlev, Matthias Lorenz, Darren C. Pagan, Sriramya Nair, Justin Gorham, Jeffrey W. Bullard

The effects on cubic tricalcium aluminate (C3A) hydration of alkali or alkaline earth sulfate electrolytes were evaluated by in situ dissolution rate measurements, by ex situ near-surface composition measurements with secondary ion mass spectrometry, and

Three-Dimensional Particle Shape Analysis Using X-ray Computed Tomography: Experimental Procedure and Analysis Algorithms for Metal Powder

November 23, 2019

Author(s)

Edward Garboczi, Nikolas Hrabe

Measuring the size distribution of the particles in a powder is a common activity in science and industry. Measuring the shape distribution of the particles is much less common. However, the shape and size of powder particles are not independent quantities

Three-dimensional mortars using real-shaped sand particles and uniform thickness interfacial transition zones: Artifacts seen in 2D slices

November 11, 2019

Author(s)

Edward Garboczi, Yang Lu, Aminul Islam, Stephen Thomas

All scanning electron microscopic (SEM) examination of mortars are based on two-dimensional (2D) slices through the true three-dimensional (3D) microstructure. Even though stereology guarantees that certain quantities are equal in 3D and in 2D slices of

Potential Use of Lightweight Aggregate (LWA) Produced from Bottom Coal Ash for Internal Curing of Concrete Systems

October 1, 2019

Author(s)

Mohammad Balapour, Weijin Zhao, Edward Garboczi, Nay Ye Oo, Sabrina Spatari, Grace Hsuan, Peter Billen, Yaghoob Farnam

This study evaluates the potential use of a novel lightweight aggregate (LWA), spherical porous reactive aggregate (SPoRA), which is produced from waste coal bottom ash, for internal curing of concrete. Engineering properties of SPoRA required for concrete

ADDITIVE MANUFACTURING PROCESSES FOR INFRASTRUCTURE CONSTRUCTION: A REVIEW

July 25, 2019

Author(s)

Abhinav Bhardwaj, Scott Jones, Negar Kalantar, Zhijian Pei, John Vickers, Pablo Zavattieri, Timothy Wangler, Na Zou

Machine Learning Can Predict Setting Behavior and Strength Evolution of Hydrating Cement Systems

July 25, 2019

Author(s)

Tandre Oey, Scott Jones, Jeffrey W. Bullard, Gaurav Sant

Setting and strength development of ordinary portland cement (OPC) binders is a complex process that involves multiple interacting chemical reactions, which result in the formation of a solid microstructure. A long-standing yet elusive goal of the

Prediction of Ultimate Compressive Strength for Biopolymer-bound Soil Composites (BSC) Using Sliding Wingtip Crack Analysis

July 24, 2019

Author(s)

Edward Garboczi, Isamar Rosa, Michael Lepech, David Loftus, Henning Roedel, Maria Allende

This paper introduces a damage-based model for determining the compressive strength of Biopolymer- bound Soil Composites (BSC), a novel class of bio-based construction composites that are produced through the mixture and desiccation of biopolymers with

A Digital Holographic Microscopy Study of Beta-Dicalcium Silicate Dissolution Kinetics in Water

March 10, 2019

Author(s)

Alexander S. Brand, Justin Gorham, Jeffrey W. Bullard

The surface normal dissolution flux of beta dicalcium silicate is quantified using in situ digital holographic microscopy. The dissolution flux in flowing solutions depends on the water activity to an empirically determined power of 1.7. The heterogeneous

The effect of rough vs. smooth aggregate surfaces on the characteristics of the interfacial transition zone around a single spherical aggregate

March 6, 2019

Author(s)

Edward Garboczi, Kai Lyu, Wei She, Changwen Miao

Due to its higher porosity, the interfacial transition zone (ITZ) between cement paste and aggregates in cementitious composites is often viewed as a weak link in the microstructure. Sectional plane analysis based on back-scattered electron scanning

Three-dimensional shape characterization of fine sands and the influence of particle shape on the packing and workability of mortars

December 25, 2018

Author(s)

Edward Garboczi, Jeffrey W. Bullard, Pierre Estephane, Olafur Wallevik

TThis paper studies a selection of fine sands, their particle shape and its effect on the plastic properties of mortars via the influence on the workability and packing of cementitious mixtures. Five sands from different sources were sampled, wet sieved

RILEM and the National Institute of Standards and Technology (NIST) over the past 50 years

September 20, 2018

Author(s)

Edward Garboczi

There has been a long partnership in the materials science of building materials between the National Institute of Standards and Technology (NIST) in the United States and RILEM. This paper discusses on the technical contributions NIST has made to RILEM

Numerical study of the initial particle parking structure of cement/geopolymer paste and dissolution of amorphous silica using real-shape particles

July 18, 2018

Author(s)

Edward Garboczi, Guang Ye, Zhiwei Qian, Yibing Zuo

Many particle-based numerical models have been used to simulate the hydration process of cementitious materials. But most of these models employ regular shape particles, like the commonly used spheres, to represent cement, slag or fly ash, which neglects

Improved Mesoscale Segmentation of Concrete from 3D X-ray Images Using Contrast Enhancers

June 28, 2018

Author(s)

Pietro Carrara, Rolands Kruse, Dale P. Bentz, M Lunardelli, Thorsten Leusmann, P Varady, Laura De Lorenzis

Obtaining the mesostructure of concrete from X-ray computed tomography (CT) requires segmentation of the data into distinct phases, a process complicated by the limited contrast between aggregates and mortar matrix. This paper explores the possibility to

Reducing setting time of blended cement paste containing high-SO3 fly ash (HSFA) using chemical/physical accelerators and by fly ash pre-washing

March 20, 2018

Author(s)

Franco Zunino, Dale P. Bentz, Javier Castro

Reducing the carbon footprint of the cement industry has become one of the main concerns of researchers in the field. This study explores different strategies to reduce the setting retardation effect of high-SO3 fly ash (HSFA) on cement paste. The SO3

Freeze-Thaw Crack Determination in Cementitious Materials Using 3D X-ray Computed Tomography and Acoustic Emission

March 8, 2018

Author(s)

Edward Garboczi, Jason Weiss, Yaghoob Farnam, Yasmina Shields

Cracking in concrete due to freeze-thaw cycles is known to damage the structural integrity of materials and provides venues for water and ionic species to penetrate into concrete pores and create additional damage due to corrosion of reinforcement or

Grout-Concrete Interface Bond Performance: Effect of Interface Moisture on the Tensile Bond Strength and Grout Microstructure

March 8, 2018

Author(s)

Igor de la Varga, Jose Munoz, Dale P. Bentz, Paul E. Stutzman, Benjamin Graybeal

Bond between two cementitious materials is crucial in applications such as repairs, overlays, and connections of prefabricated bridge elements (PBEs), to name just a few. It is the latter that has special interest to the authors of this paper. After

Relating the Electrical Resistance of Fresh Concrete to Mixture Proportions

March 5, 2018

Author(s)

K H. Obla, Rongjin Hong, Stuart Sherman, Dale P. Bentz, Scott Jones

Characterization of fresh concrete is critical for assuring the quality of our nation's constructed infrastructure. While fresh concrete arriving at a job site in a ready-mixed concrete truck is typically characterized by measuring temperature, slump, unit

A Multiscale Framework for the Prediction of Concrete Self-Desiccation

March 1, 2018

Author(s)

Madura Pathirage, Dale P. Bentz, Giovanni Di Luzio, Enrico Masoero, Gianluca Cusatis

Cement hydration in concrete and mortar has been studied thoroughly over the past 50 years. To fully understand hydration in concrete and predict the evolution of the hygral, thermal, and mechanical properties at the structural level, one needs to study

Simulation of the Influence of Intrinsic C-S-H Aging on Time-Dependent Relaxation of Hydrating Cement Paste

December 30, 2017

Author(s)

Xiaodan Li, Zachary Grasley, Edward Garboczi, Jeffrey W. Bullard

A numerical model has been developed that combines finite element methods with microstructure development algorithms to quantitatively predict the stress relaxation of cement paste due to intrinsic calcium silicate hydrate (C- S-H) viscoelasticity