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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 33 Abstracts search results
Document:
SP154-14
Date:
May 1, 1995
Author(s):
P. Stroeven, D. H. Dalhuisen, N. T. Quy, D. D. Bui, and A. V. Dong
Publication:
Symposium Papers
Volume:
154
Abstract:
Economic solutions for production of high-strength concrete in Vietnam require use of locally available indigenous resources. Proportioning of gap graded mixtures in Northern Vietnam is therefore based on broken rock and very fine Red River sand. Additionally, normal portland cement blended with fine-grained rice husk ash (RHA) is employed in combination with a superplasticizer. This paper discusses results obtained in a Dutch-Vietnamese research cooperation program. RHA was incinerated in a specially constructed oven under temperatures up to 750 C, yielding amorphous silica with a relatively high carbon content (23 percent). Ash was ground for 18 hours in a laboratory ball mill in combination with or without use of a naphthalene type of superplasticizer. Dutch sand and gravel were used, simulating as closely as possible the Vietnamese aggregate. Particularly promising data was obtained for 19 percent sand content in the aggregate and a paste content of 500 kgf/m 3, in which the RHA content amounted to 100 and 200 kg/m 3 with a corresponding water to paste ratio of 0.3 and 0.35, respectively. RHA ground with the superplasticizer was used in such cases (yielding 75 percent of particles to be smaller that 5 micro-m). Compressive strength was found to exceed 50 MPa at seven days and 70 MPa at 28 days.
DOI:
10.14359/958
SP154-15
Y. Tsukinaga, M. Shoya, R. Sugawara, and H. Nonome
In this study, the use of a new permeable sheet was evaluated in making the surface layer of concrete denser, thus improving the performance and durability of the concrete. The application of permeable sheet was confirmed effective in the lowering of water-cement ratio corresponding to the decrease of pore volume; this resulted in the increase of pull-off of tensile strength, rebound number, pulse velocity, and pin penetration resistance in the surface layer. It was also observed that the air bubbles were likely to move from the internal portion to the surface with the expelled flow of water, remarkably reducing bugholes on the concrete surface. The use of new type of permeable sheet improved resistance to freezing and thawing cycling and reduced the depth of carbonation and the ingress of chloride ions. Furthermore, the water tightness was also improved.
10.14359/959
SP154-12
S. Nishibayashi, T. Kuroda, and Y. Okawa
Reports the results of an investigation of the effect of using ground granulated blast furnace slag to prevent alkali-aggregate reaction damage to concrete. The authors discuss the effectiveness of the blast furnace slag on the dilution, stabilization, and fixation of alkali. The relationship between the replacement ratio of blast furnace slag and prevention of the expansion due to the alkali-aggregate reaction in concrete is reported.
10.14359/956
SP154-13
Z. Rusin
Disintegration of many concrete pavements (D-cracking, popouts, etc.) exposed to freezing and thawing is often connected with poor physical quality of aggregates used in the concrete. Inability to differentiate between good and poor quality aggregates is due to the lack of appropriate laboratory techniques for aggregate evaluation. A growing shortage of easily available sources of good quality aggregates highlights the need for aggregate classification. A new rapid laboratory test, called RAO-Method, as well as a new pore size distribution index based on the mercury intrusion porosimetry (MIP) analysis, has been proposed to meet engineers' expectations in the field of aggregate classification. An analysis of some research data of the RAO and MIP tests is presented in this paper to illustrate practical usefulness of the techniques. Results of long-term observations of concrete blocks subjected to outdoor conditions and the results of the new laboratory tests of the aggregates previously used in the blocks were compared. The new tests seem to provide means for more successful evaluation of coarse aggregates for purposes of diagnostics, design, and prediction of service life of concrete.
10.14359/957
SP154
Editor: V.M. Malhotra
SP-154 In 1995, The Canadian Centre for Mineral and Energy Technology (CANMET), in association with the American Concrete Institute and other organizations sponsored a second conference on Advances in Concrete Technology. The objectives of this conference was to bring together representatives from industry, universities, and government agencies to present the latest information and explore new areas of needed research and development. Thirty two papers from 20 countries were reviewed and accepted for inclusion in this new publication based on the symposium subject, advances in concrete technology. The range of subjects is varied due to the wide range of experts involved in this project.
10.14359/14194
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