Y.N. Peng’s research while affiliated with National Yang Ming Chiao Tung University and other places

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.

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 dtffractrometer (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/steaminjection (DA/57) 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.

This paper discusses the basic concept of steam hydration and presents test data on heat of hydration by exposing cement compounds to pressurized steam. The test samples include cement and its individual compounds; tricalcium silicate (C 3S), dicalcium silicate (C 2S), tricalcium aluminate (C 3A), and tetracalcium aluminoferrite (C 4AF). For a compacted 10 grams C 3S sample, the heat of hydration was determined as 209 cal/g. All samples except C 3A hardened during steaming. Nonetheless, the C 3A 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.

Concrete is used in massive amounts on Earth for the construction of buildings, foundations, roadways, pipes, and specialty uses. Its use on the Moon and Mars has to take into consideration the availability of the natural materials as well as the environment in which it is cast and cured. It has not been considered ideal for planetary surface construction because it requires water, which has been assumed to be in short supply, and because special processes would have to be used in the very low atmospheric pressure environment of the Moon and Mars. However, the authors have conducted a cement/ concrete research program using simulated lunar and martian materials over a period of several years. Funding has come from governmental agencies in the United States, Japan, Indonesia, and Taiwan. NASA has considered various approaches to building outposts on other planets. Concepts that establish habitation for several crew members, power supplies, and processing plants to produce propellant from indigenous sources have been considered. The availability of construction materials from indigenous sources can enable the construction of shelters for habitats and unpressurized storage areas, as well as radiation, meteoroid, and thermal shielding without the importation of large masses of materials from the Earth. Concrete is a versatile material that can be derived entirely from the natural resources of the planet's surfaces.