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International Concrete Abstracts Portal

Showing 1-5 of 53 Abstracts search results

Document: 

SP172-46

Date: 

December 1, 1999

Author(s):

Byung-Hwan Oh, WonKi Chung, Seun-Yup Chang and Kyu-Jung Lee

Publication:

Symposium Papers

Volume:

172

Abstract:

The present study was to develop high-durability concrete(HDC) and to apply it to actual structures. For the improvement of durability of concrete structures, the appropriate mixture proportions with mineral admixtures or slag (fly ash, silica fume, blast-furnace slag) have been selected and applied to various experimental studies. Two ievels of strength such as high and normal strength concretes have have been considered. Various durability tests including resistance to freezing and thawing, resistance to steel corrosion, resistance to sulfate attack, and permeability were performed and the durability characteristics for each mixture proportion have been analyzed to develop high-durability concrete. In addition, several in-situ applications of HDC, i.e., tetrapod at Tangjin power plant, a reinforced concrete slab bridge at Euwang, and sewage treatment structure at Gayang, were executed and investigated. Then, the results of field applications were discussed with those of laboratory tests.

DOI:

10.14359/6168


Document: 

SP172-11

Date: 

December 1, 1999

Author(s):

Salil K. Roy, Poh Kong Beng and Derek 0. Northwood

Publication:

Symposium Papers

Volume:

172

Abstract:

Concrete prisms (40 x 40 x 160 mm) were made with crushed aggregate, non-reactive sand, portland cement with added alkali (NaOH) content (2.5%’ by mass), and water in proportion (by mass) of 1: 1: 1:0.5. The prisms were demolded after 24 hours, cured in water at room temperature for another 24 hours, then boiled under water at a constant pressure (0.15 Mpa) and temperature of 111°C in an autoclave for 2 hours, cooled to room temperature and examined for presence of cracks and changes (before and after boiling) in ultrasonic pulse velocity as well as dynamic Young’s modulus. Conditions for a suspect aggregate to be innocuous could be established from measurements made on aggregates collected from twelve quarries in Singapore, and on a sample of one of these aggregates mixed with an opal from Indonesia. Results obtained by this method are found to agree with those obtained by each of the three ASTM methods (Petrographic Examination (C 229-85) Chemical Method (C 295- 85) and Mortar Bar Expansion Test (C 227-81).

DOI:

10.14359/6133


Document: 

SP172-32

Date: 

December 1, 1999

Author(s):

Oan Chul Choi, Young Soo Shin, Gi Suop Hong, Young Kyun Hong, Byung Guk Kim and Long Choi

Publication:

Symposium Papers

Volume:

172

Abstract:

A series of 16 reinforced concrete beams was tested to evaluate the flexural performance of RC beams strengthened by epoxy bonded plates after repair. The key parameters for this study were the repair materials, polymer, cementitious materials and strengthening materials, steel plates and carbon fiber sheets. The repaired specimens failed by a typical flexural mode with minor interfacial bond failure. The results show that the flexural performance of the strengthened beams is varied depending on the repaired material. Specimens with epoxy polyester resins and latex modified cementitious mortars are effective for repairing the concrete beams, compared to specimens repaired with cement mortar. The flexural capacity of specimen strengthened by epoxy bonded steel plates or carbon fiber sheets after repair are less than those of strengthened specimens without repair. The interfacial behavior between was the repair material and strengthening material observed as the major influencing factor for the composite structures.

DOI:

10.14359/6154


Document: 

SP172-16

Date: 

December 1, 1999

Author(s):

Sun Wei, Pan Ganghua and Ding Dajun

Publication:

Symposium Papers

Volume:

172

Abstract:

In this paper, a technic of both adding ultra-fine fly ash(UFFA) and silica fume(SF) for preparing high performance concrete(HPC) of C150~200 is presented. Under the condition of replacing 15% cement with UFFA or SF or their composite respectively, the strength characters of HPC with the same proportion of both UFFA and SF were systematically studied by comparing adding-both UFFA and SF sample(HPFASFC--- high performance’ fly ash and silica fume concrete) with adding only UFFA sample(HPFAC---high performence fly ash concrete) and adding only SF sample(HPSFC---high performence silica fume concrete). The experimental results showed that the strength of HPFASFC may be higher than that of HPSFC or HPFAC because of existence of effects of promoting and making up each other in strengthening of mineral admixture. The results of micro tests and analysis for the mechanism of composite effects proved the conclusion. It follows that there is a possibility for preparing high performance concrete with UFFA.

DOI:

10.14359/6138


Document: 

SP172-40

Date: 

December 1, 1999

Author(s):

Somnuk Tangtermsirikul and Yukio Aoyagi

Publication:

Symposium Papers

Volume:

172

Abstract:

This paper explains the development of a roller-compacted concrete for constructing or renovating concrete pavement (RCCP), using lignite fly ash in Thailand. A method for proportioning the lignite fly ash RCCP based on the ratio, y, between paste volume and void content of total aggregate is proposed. It was found from the tests conducted by varying fly ash replacement ratio, water to total binder ratio, and paste content that the range of value of y which gives rise to optimum strength and density of the RCCP were in between 1.02 and 1.05 for the tested materials. The design curves for compressive strength were derived based on test results with varied fly ash replacement ratio and water to total binder ratio of the RCCP with y being equal to 1.02. Some selected RCCP mixtures were compared with conventional concrete for constructing pavement in terms of flexural strength, drying shrinkage and abrasion resistance. The tested RCCP specimens were found to have higher flexural strength than the ACI-proposed formula for conventional concrete. Drying shrinkage of RCCP was smaller than that of the conventional concrete and was even smaller when lignite fly ash replacement ratios were larger. Similar to the conventional concrete, the abrasion resistance of the RCCP was found to have a good correlation with compressive strength.

DOI:

10.14359/6162


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