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International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP254-04

Date: 

October 1, 2008

Author(s):

P. Mondal, S.P. Shah, and L.D. Marks

Publication:

Symposium Papers

Volume:

254

Abstract:

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.

DOI:

10.14359/20210


Document: 

SP254-05

Date: 

October 1, 2008

Author(s):

M. Sonebi

Publication:

Symposium Papers

Volume:

254

Abstract:

Nano-technology based on depth-sensing microindentation apparatus was used to evaluate the elastic modulus and micro-hardness of the interfacial transition zone (ITZ) and to estimate the extent of the ITZ around the aggregate-matrix interface for underwater concrete (UWC) and around steel reinforcement for selfconsolidating concrete (SCC) and vibrated concrete. The micromechanical properties of ITZ near to aggregates of concrete cast in water were lower than those of concrete cast in air. The modulus elasticity and the microstrength of concrete cast in water were lower than those of concrete cast in air. It is attributed to the dilution of paste cement and fines particles in water causing reduction of strength and increasing the porosity of concrete. The results of the interfacial properties between selfconsolidating concrete and conventional concrete revealed that the elastic modulus and the micro-strength of the ITZ were lower on the bottom side of a horizontal steel bar than on the top side, particularly for the vibrated reference concrete. The difference of ITZ properties between top and bottom side of the horizontal steel bar appeared to be less pronounced for the SCC mixtures than for the corresponding control mixtures.

DOI:

10.14359/20211


Document: 

SP254-02

Date: 

October 1, 2008

Author(s):

P. Balaguru and K. Chong

Publication:

Symposium Papers

Volume:

254

Abstract:

Nanotechnology is one of the most active research areas that encompasses a number of disciplines including civil engineering and construction materials. The most active fields are electronics, biomechanics, and coatings. Interest in nanotechnology concept for portland-cement composites is steadily growing. Currently, the most active research areas dealing with cement and concrete are: understanding of the hydration of cement particles and the use of nano-size ingredients such as alumina and silica particles. There are also a limited number of investigations dealing with the manufacture of nanocement. If cement with nanosize particles can be manufactured and processed, it will open up a large number of opportunities in the fields of ceramics, high-strength composites ,and electronic applications. This will elevate the status of portland cement to a high-tech material in addition to its current status of the most widely used construction material. Very few inorganic cementing materials can match the capabilities of portland cement in terms of cost and availability. The main objective of this paper is to outline promising research areas. Basic background information on nanotechnology research, state of the art on use of this technology in concrete, opportunities, and challenges are discussed.

DOI:

10.14359/20208


Document: 

SP254-01

Date: 

October 1, 2008

Author(s):

P.J.M. Bartos

Publication:

Symposium Papers

Volume:

254

Abstract:

Compared with other major industrial sectors, the construction industry has lagged behind in awareness of the potential for exploitation of nanotechnology. Both the awareness and actual exploitation in construction are now increasing; however, progress is uneven, especially in the current early stages of its practical exploitation. A roadmap then becomes a useful tool, a template, for predictions of trends and developments connecting nanotechnology and construction. The Roadmap for Nanotechnology in Construction (RoNaC) outlined in this paper is aimed at facilitating identifications of desirable aims/destinations for construction research and technical development (RTD) over a short-to-medium timescale (up to 25 years). The RoNaC was developed as an aid for forecasting research and investment directions. It provides guidance to construction industry, investors, and national/international bodies supporting research and development about the diverse pathways toward current nanotechnology-linked expectations, aims, and targets in this very large and economically significant domain. The complexity of the construction domain is such that a single overall chart would be far too general in a scale so large that it would become incomprehensible. Sectorial or "topical" charts have been developed instead of a single "map", and three examples of such charts have been worked out to illustrate this approach. Requirements for adequate research infrastructures, effects of appropriate drivers, and diverse vehicles for RTD are considered together with an assessment of the "environment" conducive to progress along the pathways and directions indicated in the charts.

DOI:

10.14359/20207


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


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