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International Concrete Abstracts Portal

Showing 1-5 of 62 Abstracts search results

Document: 

SP179-08

Date: 

June 1, 1998

Author(s):

M. Tamai and T. Matsukawa

Publication:

Symposium Papers

Volume:

179

Abstract:

The void diameter and the internal surface area of porous concrete (PoC), prepared with crushed stone and glass balls of differing diameters as aggregate, were determined by slicing off the central cross section, cutting it into pieces at constant intervals and making an image analysis of those sections to examine the effect of the analytical results on the physical properties of the porous concrete and the growth of plants. The results indicated that the mean void diameter of the porous concrete is approximately 0.22 to 0.24 times the particle diameter of the aggregate packed with 30% binder and that the interconnected void, approximately 3 mm in mean diameter, is appropriate for grass-planting concrete.

DOI:

10.14359/6035


Document: 

SP179-55

Date: 

June 1, 1998

Author(s):

J. Le Marechal, B. Gerard, J. Marchand, J. Ph. Gagnon and 0. Oidry

Publication:

Symposium Papers

Volume:

179

Abstract:

In the past decades, cement-based materials have been increasingly used for the construction of radioactive-waste barriers. The design of durable structures for this specific application requires a precise knowledge of the evolution of the material engineering properties over a 1000-year period. Among the wide range of degradation phenomena to which the structure can be exposed upon its service life, the leaching of calcium appears to be the most critical. Given the intricate nature of the leaching process, a reliable prediction of the long term behavior of the concrete barriers can only be made through numerical modeling. In order to generate more quantitative information on the subject, a new accelerated leaching test has been developed. The operating principle of the test is quite simple. The leaching process is accelerated by applying an external electric field through the material. This paper details the different electrochemical phenomena involved during a LIFT experiment. It also presents several experimental data obtained for various neat paste samples. In this series of tests, the evolution of the hydrated cement paste microstructure was studied using various experimental techniques such as X-ray diffraction, DTA/TG analyses and scanning electronic microscopy. The advantages and limitations of this new procedure are discussed.

DOI:

10.14359/6081


Document: 

SP179-32

Date: 

June 1, 1998

Author(s):

S. Nagataki, T. Kamada and A. Matsumoto

Publication:

Symposium Papers

Volume:

179

Abstract:

In this paper, a method to evaluate the crack size of concrete structures by infrared thermography was investigated. This method is based on the relation between the crack depth or width and thermal distribution in concrete. First, the influence of crack depth and width to thermal distribution was examined. Next, the influence of the distance between cracks and heater to thermal distribution was investigated. The effectiveness of this method was confirmed by the results of the experiment on flexural cracks in reinforced concrete beams. From these results, it was demonstrated that the thermal distribution measured at the surface of concrete by infrared thermography was effective in evaluating the crack size in concrete structures.

DOI:

10.14359/6059


Document: 

SP179-45

Date: 

June 1, 1998

Author(s):

D. Van Gemert and K. U. Leuven

Publication:

Symposium Papers

Volume:

179

Abstract:

Automated production of precast polymer concrete construction components is presented. Both batchwise and continuous production are discussed, and examples of both techniques are shown. Automated on-site application and execution systems allow benefits to be taken of the specific features of polymer-cement concrete. Automated execution of overlays, tunnels, porous polymer-cement concrete pavements and polymer-cement shotcrete are presented as examples.

DOI:

10.14359/6072


Document: 

SP179-35

Date: 

June 1, 1998

Author(s):

A.B. Ammar, J.M. Loche and P. Dumargue

Publication:

Symposium Papers

Volume:

179

Abstract:

Penetration of aggressive ions, such as chlorides, through concrete is one of the factors which causes to the depassivation of reinforcement and therefore may shorten the service life of a reinforced concrete structure. Most research work focusing on natural or accelerated diffusion tests generally rely on the validity of Fick’s laws. In this paper, we present both a new accelerated diffusion cell and an original test operating mode. The theoretical approach is based upon the study of diffusion-migration mechanism within the pore solution. The experimental results presented here have been obtained with tests on samples of saturated mortar.

DOI:

10.14359/6062


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