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Search Publications by: Nicos Martys (Assoc)

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Displaying 26 - 50 of 184

Research Needs to Advance Concrete Pumping Technology

April 10, 2015
Author(s)
Chiara F. Ferraris, Nicos Martys, Myoungsung Choi, Van Bui, Trey Hamilton, Didier Lootens
With the increasing use of pumping to place concrete, the development and refinement of the industry practice to ensure successful concrete pumping is becoming an important need for the concrete construction industry. To date, research on concrete pumping

Universal scaling law for the flow of non-Newtonian colloidal suspension

October 1, 2014
Author(s)
Nicos Martys, William L. George, Maxime Liard, Pascal Hebraud, Didier Lootens
It has been observed that flow curves (viscosity vs shear-rate) of spherical non-colloidal particles suspended in a non-Newtonian fluid matrix can be rescaled so as to collapse onto the flow curve of the matrix fluid. This result is surprising given the

Corrosion Detection in Concrete Rebars Using a Spectroscopic Technique

January 11, 2014
Author(s)
Edward J. Garboczi, Paul E. Stutzman, Shuangzhen S. Wang, Nicos Martys, Dat Duthinh, Virgil Provenzano, Shin G. Chou, David F. Plusquellic, Jack T. Surek, Sung Kim, Robert D. McMichael, Mark D. Stiles, Ahmed M. Hassan
Detecting the early corrosion of steel in reinforced concrete is a goal that has been much pursued. Since 2010, NIST has been working on a large project to develop an electromagnetic (EM) probe that detects the actual corrosion products via spectroscopic

Measurement and Simulation of Millimeter Wave Scattering Cross-sections from Steel-Reinforced Concrete

January 11, 2014
Author(s)
Ahmed M. Hassan, Edward Garboczi, Robert McMichael, Jack T. Surek, Mark D. Stiles, David F. Plusquellic, Virgil Provenzano, Paul E. Stutzman, Shuangzhen S. Wang, Sung Kim, Michael D. Janezic, Jason Coder, Nicos Martys, David R. Novotny
Some iron oxide corrosion products exhibit antiferromagnetic magnetic resonances (AFMR) at around 100 GHz at normal temperatures. AFMR can be detected in laboratory conditions, which serves as the basis for a new non-destructive spectroscopic method for

Development of Standard Reference Materials for Cement-Based Materials

January 6, 2014
Author(s)
Chiara F. Ferraris, Nicos Martys, William L. George
Rotational rheometers are routinely used for homogeneous materials, but their usage for characterization of a granular fluid like concrete is a relatively new phenomenon. As measurements with rheometers can involve flow in a complex geometry, it is

Development of Standard Reference Materials for Cement-Based Materials

May 13, 2013
Author(s)
Chiara F. Ferraris, Nicos Martys, William L. George
Rheometers are used to determine the rheological properties of materials ranging from mayonnaise to concrete. While rotational rheometers are routinely used for homogeneous materials such as mayonnaise, their usage for characterization of a granular fluid

Modeling of the Influence of Transverse Cracking on Chloride Penetration into Concrete

April 23, 2013
Author(s)
Dale P. Bentz, Edward J. Garboczi, Yang Lu, Nicos Martys, Aaron R. Sakulich, William J. Weiss
Concrete service life models have proliferated in recent years due to increased interest in designing infrastructure elements with at least a 75-year service life, along with greater emphasis on life cycle costing in general. While current models consider

Measurement Science Needs for the Expanded Use of Green Concrete: Workshop Summary Report

February 6, 2013
Author(s)
Kenneth A. Snyder, Dale P. Bentz, Jeffrey W. Bullard, Chiara F. Ferraris, Nicos Martys, Paul E. Stutzman
In July 2012, NIST conducted the Green Concrete Workshop to bring together stakeholders from the concrete construction industry and identify critical needs for the expanded use of industrial by- product materials, such as fly ash and slag, in concrete

Concrete rheometers

May 1, 2012
Author(s)
Chiara F. Ferraris, Nicos Martys
The scope of this chapter is to introduce the current technology for measuring the rheological properties of concrete. The need to evaluate or assess the flow properties of concrete has resulted in the invention or design and standardization of hundreds of

Stress propagation in a colloidal suspension under shear

March 1, 2012
Author(s)
William L. George, Pascal Hebraud, Didier Lootens, Mouhamad Khalil, Nicos Martys
The stress propagation in a concentrated attractive colloidal suspension, under shear, is studied using mumerical simulations. A novel way of describing the intercolloidal stress field is proposed and its spatial correlations are studied. An inertia-like