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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 11 Abstracts search results
Document:
SP254-10
Date:
October 1, 2008
Author(s):
M. Drábik, L. Gáliková, S. Balkovic, and R.C.T. Slade
Publication:
Symposium Papers
Volume:
254
Abstract:
The latest research on the reactivity toward cross-linking of inorganic matrixes formed by cement-based materials, and the associated grafting at the nanoscopic and atomic levels, is highly promising. Macro-defect-free (MDF) materials and technologies were originally comprised of high-alumina cements cross-linked to poly(vinyl alcohol/acetate) or of portland cement with poly(acrylamide). Although the high-alumina system has shown promising results and is the more efficient system, it suffers from economic disadvantages; modern efforts to identify MDF systems focus on portland cement and a variety of polymer additives. We report recent findings regarding the potential and limitations of portland cement-based MDF materials, considering aspects of the associated chemistry (at the nanoscopic and atomic levels), of the mechanism linking polymer to the surface of cement grains, and of technologically relevant attributes such as moisture resistance of the formed MDF material.
DOI:
10.14359/20216
SP254-09
H. Li, H. Xiao, and J. Ou
The electrical properties of nanophase carbon black-filled cement-based composites are sensitive to moisture content. Previous studies indicate that cementbased composites filled with 120 nm carbon black (CB) in the amounts of 15% (A-15) and 25% (A-25) by weight of cement have promising strain self-sensing properties (that is, piezoresistance properties), thus, this study investigated the effects of moisture on the electrical properties of A-15 and A-25. The results indicate that the initial resistance of composites increases with moisture content. Additionally, the resistance of specimens with certain moisture content increases with measurement time. These two phenomena are mainly attributed to a polarization effect. A waterproof measurement (that is, a specimen encapsulated by epoxy) was developed to insulate the composites from ambient moisture for the composites as strain self-sensing materials. The initial resistance of the specimens encapsulated with epoxy and dipped into water stayed constant during measurement time, and their piezoresistance properties were almost the same as those of the specimens exposed to ambient moisture.
10.14359/20215
SP254
Editors: K. Sobolev and S.P. Shah / Sponsored by: ACI Committee 236
This volume consists of ten papers that were presented at a technical session, sponsored by ACI Committee 236, Materials of Science of Concrete, at the ACI Fall 2007 Convention in Denver, CO. Papers include “ Nanotechnology in Construction: A Roadmap for Development”, “ Nanotechnology and Concrete: Research Opportunities”, “Molecular Engineering of the Cohesion in Neat and Hybrid Cement Hydrates”, and “Use of Atomic Force Microscopy and Nanoindentation for Characterization of Cementitious Materials at the Nanoscale”.
10.14359/20092
SP254-04
P. Mondal, S.P. Shah, and L.D. Marks
In this research, sample preparation techniques were developed to image the nano- and microstructure of hardened cement paste and to determine local mechanical properties. An atomic force microscope (AFM) was used to image the nanostructure of hardened cement paste. AFM and a Hysitron Triboindenter equipped with an in-situ scanning probe microscopy were used to determine the Young’s modulus of cement paste at the nanoscale.
10.14359/20210
SP254-03
A. Gmira, J. Minet, A. Franceschini, N. Lequeux, R.J.-M. Pellenq, and H. Van Damme
On the basis of recent molecular simulation or experimental studies, we discuss two possible strategies for improving the mechanical properties of cementitious materials by modifying the bonding scheme in the hydrates at molecular level. We focus on the calcium silicate hydrates (C-S-H). A first strategy would be based on the strengthening of the cohesion forces acting between the individual C-S-H lamellae or between their crystallites. Monte Carlo simulations in the primitive model framework and ab initio atomistic calculations suggest that the cohesion of C-S-H is mainly due to a combination of sub-nano range ionic-covalent forces and meso-range ionic correlation forces. Both types of forces may be modified, at least in theory, by changing the nature of the interstitial ions, their hydration state, or the charge density on the C-S-H lamellae.
10.14359/20209
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