ABOUT THE 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.

International Concrete Abstracts Portal

Showing 1-5 of 33 Abstracts search results

Document: 

SP229-15

Date: 

September 1, 2005

Author(s):

S.M.M. Pinheiro, M.R. Silva, and F.L. dos Santos Souza

Publication:

Symposium Papers

Volume:

229

Abstract:

In order to satisfy the needs of concrete durability, it is important to know the deterioration mechanisms to which the material could be submitted. Among the different mechanisms of concrete deterioration, biodeterioration is one of the most recently observed in structures. Its study is complex and demands a multidisciplinary research which involves different disciplines. This paper addresses biodeterioration concepts, the mechanisms involved, and the impact on concrete phases (cement paste and aggregate). An example of aesthetic and microstructural impacts on the mortar phase of a normal concrete when it is colonised by the Cladosporium sphaerospermum fungus is presented.

DOI:

10.14359/14739


Document: 

SP229-28

Date: 

September 1, 2005

Author(s):

M.A.M. Coelho, M.G. da Silva, F.L. dos Santos Souza, R. Sarmento, R.P. de Moraes Frasson, S.M. de Moraes Pinheiro, E. Zandonade and T. Morimoto

Publication:

Symposium Papers

Volume:

229

Abstract:

This paper reports the results of an investigation on concrete containing alkali-activated slag (AAS). The activators used were liquid sodium silicate (3%, 4% or 5% Na2O, mass of binder) + lime (5%, mass of binder); clinker (10%, mass of binder) + lime (10%, mass of binder); lime (2%, mass of binder) + gypsum (6%, mass of binder) and clinker (16%, mass of binder). The activator of liquid sodium silicate (4% Na2O, mass of binder) + lime (5%, mass of binder) showed better compressive strength when compared to normal portland cement concrete. Other properties were studied such as elastic modulus, flexural strength, absorption of water by capillary forces, drying shrinkage and sulfate attack and the results are discussed in this paper.

DOI:

10.14359/14752


Document: 

SP229-30

Date: 

September 1, 2005

Author(s):

L. Bertolini, M. Carsana, D. Cassago, M. Collepardi, and A.Q. Curzio

Publication:

Symposium Papers

Volume:

229

Abstract:

The paper describes the results of research on the properties of concrete with the replacement of part of portland cement with bottom ash from municipal solid waste incinerators (MSWI). Results showed that MSWI bottom ash is potentially attractive as mineral addition for the production of concrete, provided that the risk of entrapment of hydrogen bubbles produced by corrosion of aluminium metallic particles in the fresh concrete is prevented. This could be achieved by wet grinding the bottom ash so that reactions leading to gas development could start within the slurry. A great variability was observed in the time required to exhaust the hydrogen gas production; a key factor for this variability was found in the pH of the slurry. A modest amount of cement added in slurry could increase the pH, reduce the time required to exhaust hydrogen evolution and allow manufacturing of quality concrete suitable for aggressive chloride bearing environments.

DOI:

10.14359/14754


Document: 

SP229-09

Date: 

September 1, 2005

Author(s):

O. Cascudo, H. Carasek, M.-P. Yssorche-Cubaynes, A.N. Lopes, and J.-P. Ollivier

Publication:

Symposium Papers

Volume:

229

Abstract:

The concrete cover has different characteristics when compared to the concrete confined within the structural elements. Such differences come from the absorption produced by the formwork, from the water evaporation typically pronounced in outer concrete layers, from the wall effect, etc. On account of these factors, it is expected that the concrete cover has worse characteristics in comparison to those of the inner concrete and that this aspect influences the durability as well as the performance of concrete structures. Therefore, the present work aims to evaluate the differences existing between the concrete cover and the inner concrete, taking account the analysis of chloride effective diffusion coefficients (Def) measured in two layers of a beam prototype of reinforced concrete. The study comprises two different concretes cast with W/C 0.40 and 0.55, without curing. Def of two year old specimens were experimentally obtained by means of a migration test, by determining the coefficients in two different depths: in the concrete cover, with a test specimen of 2.0 cm thick, and in a region deeper than 6.0 cm. Contrarily to the expected, the main results showed that Def values in the concrete cover were about 10% of those measured in the inner concrete. The partial carbonation of the concrete cover was the major cause to explain the reduction in chloride movement within the cover layer, since it reduces the paste total porosity.

DOI:

10.14359/14733


Document: 

SP229-16

Date: 

September 1, 2005

Author(s):

T. Yamaji, K.-I. Komure, and H. Hamada

Publication:

Symposium Papers

Volume:

229

Abstract:

The south part of Japan is located in the subtropics. Therefore, steel corrosion in concrete in this region easily tends to initiate and progress due to chloride ion ingress into concrete from the seawater. Under this environment, in order to enhance the durability of reinforced concrete structures in which sufficient concrete cover depth can not be secured due to some restrictions, it is very effective to apply adequate surface coating materials on the concrete surface at early age of exposure. To study the durability of concrete with various surface coating materials under marine environment in the subtropics, exposure test was carried out in the south part of Japan. Various tests such as bond strength of surface coating materials, chloride ion content in concrete and corrosion evaluation of steel bar in concrete were carried out after 15 years of exposure. These results indicate that these surface coating materials are very effective in enhancing the durability of concrete under marine environment. This protection against chloride attack was well maintained for 15 years of exposure to a marine environment.

DOI:

10.14359/14740


12345...>>

Results Per Page 




Please enter this 5 digit unlock code on the web page.