Browsing by Author "Hwang, CL"

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A design consideration for durability of high-performance concrete
(2001-08-01)
Chang, PK
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Peng, YN
;
Hwang, CL
;
交大名義發表
;
National Chiao Tung University
Environmental factors, especially the climate, have significant influence on concrete structure. This paper aims to investigate the harmful effects of maritime climate on the durability of concrete structures built in coastal areas. Singly reinforced beam specimens of traditional design and those of densified mixture design algorithm (DMDA) were employed to study the potential problems of concrete structure. Results indicate that cracks on the concrete structure, if go unnoticed, may cause failures. Thus, it is important to know the methodology of achieving high strength and durable concrete in order to avoid formation of cracks in the structural member. (C) 2001 Elsevier Science Ltd. All rights reserved.
Characteristics of microhydrates formed under steam conditions
(2000-05-01)
Lin, WM
;
Hwang, CL
;
Peng, YN
;
土木工程學系
;
Department of Civil Engineering
This paper presents the physical properties and chemical composition of hydrates formed under steam conditions. The test specimens were made with cement as well as individual compounds. A comprehensive study on the characteristics of hardened hydrates in a microscopic scale was carried out. An improved polymerization of silicate anions resulting in an increased CaO/SiO2 ratio at an elevated temperature was verified by the nuclear magnetic resonance spectroscopy (NMR) analysis. Dense microstructures of hydrates and low content of Ca(OH)(2) crystals were observed by the scanning electron microscope (SEM), energy dispersive spectromer (EDS), environmental scanning electron microscope (ESEM), thermogravimetric analyzer (TGA), and x-ray diffractometer (XRD) tests. Mercury intrusion porosimetry (MIP) had been used to examine the pore structures of hydrates. It revealed that the hardened paste made with the dry-mixture/steam-injection (DMSI) method developed microstructures with low porosity, small pore radius, and larger surface areas. These observations agree with the NMR/TGA test results. This paper also discusses the effects of sample fineness and compaction on the hydrate's microstructures formed under steam environment. The test results verify the validity of the DMSI concept.
Fundamental study on hydration of cement and cement minerals with steam
(1998-01-01)
Lin, WM
;
Lin, TD
;
Hwang, CL
;
Peng, YN
;
土木工程學系
This paper-discusses the basic concept of steam hydration and presents test data oil heat of hydration by exposing cement compounds to pressurized steam. The lest samples include cement and its individual compounds; tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C(3)A), and tetracalcium aluminoferrite (C(4)AF). For a compacted 10 grams C3S sample, the heat of hydration was determined as 209 cal/g. All samples except C;A hardened during steaming. Nonetheless, rite C(3)A samples reacted very rapidly with steam and registered a 91 C temperature rise during the test. This paper also discusses effects of sample's fineness and degree of compaction on heat evolution and hydrate morphology during exposure to steam. The test results verify the validity of the dry-mix/steam-injection (DMSI) concept.
Localized lateral growth of single-walled carbon nanotubes for field-effect transistors by a cobalt-mix-TEOS method
(2005)
Chen, BH
;
Lo, PY
;
Wei, JH
;
Tsai, MJ
;
Hwang, CL
Lateral-growth carbon nanotubes (CNTs) were fabricated in a pre-assigned area using an integrated circuit compatible method. In order to synthesize single wall carbon nanotubes (SWNT) for the fabrication of a field-effect transistor (FET), the cobalt-mix-tetraethoxysilane (TEOS) (CMT) solution is proposed. The CMT solution has the unique property of dispersing the cobalt (Co) catalyst well and uniformly embedding it in a predetermined location after the CMT solution has solidified. The lateral growth of bundle-SWNT could be formed in atmospheric chemical vapor deposition (APCVD) with ethanol. (c) 2005 The Electrochemical Society.
Low temperature growth of carbon nanotubes on printing electrodes by MPCVD
(2006-03-01)
Chen, KC
;
Chen, CF
;
Chiang, JS
;
Hwang, CL
;
Chang, YY
In this work, combination of screen-printing process and microwave plasma enhanced chemical vapor deposition system (MPCVD) was applied to fabricate patterned carbon nanotubes (CNTs) on the cathode electrodes on glass substrates. Solution based Ni catalyst was well-mixed with Ag powders and organic binder materials to forin screen printed paste. CNTs were then grown under the atmosphere Of CH4/H-2 gas mixture below 550 degrees C. In the field emission measurement, the tum-on field was 3.2 V/mu m and uniform electron emission image was also observed. (c) 2005 Elsevier B.V. All rights reserved.