Browsing by Author "Lin, WM"

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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.
Low leakage reliability characterization methodology for advanced CMOS with gate oxide in the 1nm range
(2004)
Chung, SS
;
Feng, HJ
;
Hsieh, YS
;
Liu, A
;
Lin, WM
A low leakage characterization technique for the lateral profiling of interface and oxide traps in a 12Angstrom-16Angstrom range gate oxide CMOS devices has been demonstrated. The approach being taken includes an incremental frequency Charge-Pumping(IFCP) measurement and a neutralization procedure such that interface and oxide traps can be separated. The most critical steps are the elimination of leakage current during measurement and a neutralization procedure, which enables accurate detennination of interface and oxide traps. This method has been demonstrated successfully for an advanced sub-100nm CMOS devices. As an important merit for its application, evaluations of HC reliability and NBTI effect have also been demonstrated. Evaluations of gate oxide qualities with plasma nitridation in both n- and p-MOSFET reliabilities have been properly described based on the current analysis technique.
Microstructures of fire-damaged concrete
(1996-05-01)
Lin, WM
;
Lin, TD
;
PowersCouche, LJ
;
土木工程學系
;
Department of Civil Engineering
This paper presents results of scanning electron microscopy (SEM) and stereo microscopy investigations of fire-damaged concrete. Samples were either taken from concrete that was subjected to heating and cooling of controlled temperatures in the laboratory or removed from concrete and masonry units exposed to fires in the field. By compiling SEM photographs, a clear chronological pattern of a failure mechanism can be visualized. For instance, the morphologies of hydrates from room temperature up to 900 C and reformation of calcium hydroxides (CH) during cooling all have distinguished morphological appearances of their own. Such visual information that would otherwise be impossible to see with the naked eye will help scientists and engineers understand concrete behaviors in fire. This study has focused on microstructures of cement pastes/aggregates, microvoids/cracks, and separation of the cement paste from aggregates in heated concrete samples. An application of lincrete, a type of polyester-polymer concrete developed at National Chiao Tung University, is included to demonstrate the use of a cement-based polymer mortar in the rehabilitation process of fire-damaged concrete.
Microstructures of fire-damaged concrete
(1996-05-01)
Lin, WM
;
Lin, TD
;
PowersCouche, LJ
;
土木工程學系
;
Department of Civil Engineering
This paper presents results of scanning electron microscopy (SEM) and stereo microscopy investigations of fire-damaged concrete. Samples were either taken from concrete that was subjected to heating and cooling of controlled temperatures in the laboratory or removed from concrete and masonry units exposed to fires in the field. By compiling SEM photographs, a clear chronological pattern of a failure mechanism can be visualized. For instance, the morphologies of hydrates from room temperature up to 900 C and reformation of calcium hydroxides (CH) during cooling all have distinguished morphological appearances of their own. Such visual information that would otherwise be impossible to see with the naked eye will help scientists and engineers understand concrete behaviors in fire. This study has focused on microstructures of cement pastes/aggregates, microvoids/cracks, and separation of the cement paste from aggregates in heated concrete samples. An application of lincrete, a type of polyester-polymer concrete developed at National Chiao Tung University, is included to demonstrate the use of a cement-based polymer mortar in the rehabilitation process of fire-damaged concrete.