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International Concrete Abstracts Portal

Showing 1-5 of 30 Abstracts search results

Document: 

SP202-29

Date: 

August 1, 2001

Author(s):

S. Al-Otaibi, C. J. Lynsdale, and J. H. Sharp

Publication:

Symposium Papers

Volume:

202

Abstract:

Environmental about the high energy consumption and huge emissions of CO2 associated with the production of portland cement are leading to the search for more environmentally viable alternatives to portland cement. One of these alternative materials isalkali-activated slag (AAS) in which ground, granulated blast furnace slag is used not as a partial replacement to cement but as a binder in itself in the production of concrete. This paper presents results of tests carried out to study the performance of alkali-activated slag concrete using sodium silicate (water-glass) as an activator in NazO dosages of 4 and 6%. The fresh concrete properties (setting time, workability and air content) were examined in addition to the engineering properties (compressive strength, splitting tensile strength, drying shrinkage, dynamic modulus of elasticity and ultrasonic pulse velocity). Hydration products were identified using XRD.

DOI:

10.14359/10800


Document: 

SP202-11

Date: 

August 1, 2001

Author(s):

V. Corinaldesi, F. Tittarelli, L. Coppola, and G. Moriconi

Publication:

Symposium Papers

Volume:

202

Abstract:

A judicious use of resources. achieved by the use of by-products and waste materials. and a lower environmental impact. achieved through reduced carbon dioxide emission and reduced natural aggregate extraction from quarries, represent two main actions that meet sustainable building development. Recycled-aggregate concrete containing fly ash is an example of a construction material which is in harmony with this concept, whereby sustainable building development is feasible with satisfactory performance in terms of both safety and serviceability of structures. The structural properties of recycled-aggregate concrete containing fly ash were evaluated by means of compression tests, splitting tension tests and pull-out bond tests on concrete specimens, whereas structure serviceability was checked by means of drying shrinkage. Moreover, corrosion measurements with galvanized steel embedded in natural-aggregate concrete containing fly ash were analyzed in order to expect the use of galvanized steel reinforcement in fly-ash recycled-aggregate concrete.

DOI:

10.14359/10780


Document: 

SP202-28

Date: 

August 1, 2001

Author(s):

R. Cabrillac, J. 1. Gallias, M. Courtial, and G. Pierson

Publication:

Symposium Papers

Volume:

202

Abstract:

The aim of this study is the valorization of magnesium slags in order to recycle them in construction block form. Two kinds of slag with hydraulic properties are obtained according to a l/3-2/3 ratio: powdered slag similar to cement, and granulated slag similar to sand. A previous laboratory study was curried out in order to obtain sufficient mechanical strength for construction blocks and setting kinetics compatible with an industrial process. The present paper deals with the consecutive implementation of life size tests on an industrial scale. Two pre-industrial tests were carried out in extremely different temperature conditions 7°C for the first test and 22°C for the second one. Furthermore, the second test benefited from the new casting conditions resulting from updating of the manufacturing unit. The first test showed that the laboratory study permitted to adjust the set kinetics to a level adequate for industrial casting, whereas the mechanical strength obtained was lower than expected when the powdered slag was used as a substitute for cement. The second test enabled us to obtain enough mechanical strength for mixtures entirely composed of magnesium slags and proved the possibility of total and simultaneous enhancing value of magnesium slags as construction blocks. More generally, these industrial tests show how difficult the transfer to the industrial scale is.

DOI:

10.14359/10799


Document: 

SP202-18

Date: 

August 1, 2001

Author(s):

K. Kawai, E. Tazawa, S. Tanaka, and S. Yokoyama

Publication:

Symposium Papers

Volume:

202

Abstract:

Cement manufactured from incinerator ash has been developed in Japan. This cement contains 1520% of CjA and 0.02~0.1% of chlorine. Since the chlorine content of this ccmcnt is higher than that of normal portland ccmcnt in Japan, thcrc is a concern whether steel bars embedded in concrete using this cement would become rapidly corroded. In this study, the behavior of chlorine in cement hydrates is investigated in terms of the contents of chlorine accommodated by Friedel’s salt. The compositions of pore solution in cement hydrates at early ages and the water-soluble and acid-soluble compositions of cement hydrates are analyzed. As a result, it is found that the concentration of chloride ion in pore solution of cement hydrates using cement manufactured from municipal wastes is not too high. It means that many chloride ions could be accommodated by Friedel’s salt because of high CJA content.

DOI:

10.14359/10789


Document: 

SP202-13

Date: 

August 1, 2001

Author(s):

T. Yen, K. H. Chen, and Y. W. Liu

Publication:

Symposium Papers

Volume:

202

Abstract:

As a result of the Chi-Chi earthquake, which occurred in middle Taiwan on September 2 1, 1999, numerous buildings and bridges were seriously damaged. How to reuse a huge amount of building debris collected from the damaged structures became an important issue. After being crushed and screened, this debris could be served as recycled aggregate in concrete. Such recycled concrete is recommended to be used for sub-structures or other applications. Therefore, the production of fish reefs became one of the possibilities. In the study, treatment and measurement of the basic properties of the recycled aggregates were firstly studied. Then manufacture fish reef with the recycled concrete were undertaken. Test results show that the properties of recycled aggregate can meet the requirements of natural aggregate. The fish reefs produced by using the recycled concrete were satisfactory and conformed to the demands of the Fisheries Administration in Taiwan.

DOI:

10.14359/10782


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