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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 10 Abstracts search results
Document:
SP267-08
Date:
October 1, 2009
Author(s):
J. Belkowitz and D.L. Armentrout
Publication:
Symposium Papers
Volume:
267
Abstract:
With the advent of nano technology, materials have been developed that can be applied to high performance concrete mix designs. Nano silica reacts with calcium hydroxide to develop more of the strength carrying structure of cement paste, calcium silica hydrate. In this paper, predictive relationships have been developed to distinguish the strength benefits when using different sizes of nano silica in cement paste. An extensive regime of experimental analysis was carried out to determine the effect of nano silica in the cement paste. Through these experiments the heat of hydration of multiple cement mix designs were measured. After that, the concentration of calcium hydroxide was recorded through X-ray diffraction. Then, the crystallographic structures were examined through scanning electron microscopy. Finally, the compressive strength was determined for each cement paste mixture. Through these experiments it was found that as the silica particles decreases in size and incorporate a wider gradation of sizes, the calcium silicate hydrates became more rigid; this increased the compressive strength.
DOI:
10.14359/51663285
SP267-05
J. Schoepfer and A. Maji
The development of nanotechnology has led to the ability to produce silicon dioxide in nano-sized particles of predictable size ranges. In this study, concrete mixtures were developed using silicon dioxide of various sizes. Compressive strength testing showed significant increase in strength with decrease in particle size of the silicon dioxide down to 12 nm (4.7 × 10–7 in.). However, the mixture under 12 nm (4.7 × 10–7 in.) had a slightly lower increase in strength. High vacuum SEM analysis was performed on the samples. High-resolution images at magnifications of 5000× to 60,000× were achieved. The photographs suggest that only the surface of silicon dioxide particles is involved in chemical reactions. The particles then appear to become nucleation sites for the development of CSH crystals. Fine silicon dioxide particles provide numerous and small nucleation sites. Silicon dioxide particles smaller than 12 nm (4.7 × 10–7 in.) do not appear to generate additional nucleation sites for CSH. SEM photos of the 7 nm (2.8 x 10–7 in.) mixture reveal a structure similar to that of the 150 nm (59.1 × 10–7 in.) mixture.
10.14359/51663282
SP267
Editors: Konstantin Sobolev and Mahmoud Reda Taha / Sponsored by: ACI Committee 236
This CD-ROM consist of 9 papers sponsored by ACI Committee 236, at the Fall 2009 Convention in New Orleans, LA, in November 2009. The papers included cover a broad range of subjects related to the nanotechnology and material science of concrete with focus on nanostructure characterization, synthesis, design, and modeling of cement based materials, as well as application of nano-materials in concrete technology. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-267
10.14359/51663354
SP267-09
D.A. Koleva, K. van Breugel, G. Ye, J. Zhou, G. Chamululu, and E.A.B. Koenders
This work presents results from an on-going investigation on the microstructural properties of cement-based materials in the presence of very low concentration of polymeric nano-aggregates. The hereby discussed properties are mainly porosity and permeability of mortar specimens, containing 0.5 g/L (0.03 lb/ft3 ) (mixing water) Poly(ethylene oxide)-block-Polystyrene (PEO113-b-PS218) stabilized micelles. The coefficient of water permeability, K, for the samples cast with nano-aggregates was found to be significantly lower, 3.65 e–14 m/s, compared to the control specimen, 3.7 e–8 m/s. Apparently, even a very low concentration of PEO113-b-PS218 micelles is able to significantly reduce water permeability at early ages. The phenomena are most likely denoted to re-distribution and transformation of hydration products in the matrix, the micelles contributing to restructuring of the pore space and altering the cement hydration mechanisms due to their specific amphiphilic properties.
10.14359/51663286
SP267-07
A.M. Said and M.S. Zeidan
The authors aim to investigate the effect of using colloidal nano-silica on the properties of concrete especially for the case of fly ash concrete. The study includes a laboratory study on six concrete mixtures in which three have 30% of the cement content replaced with fly ash, while the others were normal cement concrete mixtures. Two ratios of colloidal nano-silica were added to concrete with and without fly ash to examine its effect. Testing was conducted to assess the reactivity and the durability of the studied mixtures, including adiabatic temperature test, compressive strength test, splitting tensile strength test, and rapid chloride penetration test. Results show the addition of nano-silica can enhance the reactivity and early age strength of fly ash concrete mixtures to match normal concrete mixtures. Furthermore, the use of nano-silica improved the mechanical properties and reduced the permeability of concrete.
10.14359/51663284
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