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Results of rock property measurements made on core samples from Yucca Mountain boreholes, Nevada Test Site, Nevada; Part 1, Boreholes UE25A-4, -5, -6, and -7; Part 2, Borehole UE25PNo.1

Description: Laboratory measurements of resistivity, bulk and grain density, porosity, compressional sonic velocity, water permeability, magnetic susceptibility, and remanent magnetization were made on core samples from Yucca Mountain boreholes located in Drill Hole Wash at the Nevada Test Site. The samples are representative of lithologic variations to be found in the Tiva Canyon, Yucca Mountain, Pah Canyon, and the upper Topopah Spring Members of the Paintbrush Tuff. Boreholes penetrated to a depth of approximately 152 meters (500 ft.). The Paintbrush Tuff consists primarily of nonwelded to densely welded rhyolitic ash-flow tuff with relatively thin beds of ash-fall tuff typically separating each Member. Resistivity and bulk density measurements were made on samples containing natural pore waters and repeated following resaturation with local tap water. Density comparisons indicate the samples to be undersaturated in their natural environment as expected in that the boreholes did not intersect the water table.
Date: December 31, 1991
Creator: Anderson, L.A.
Partner: UNT Libraries Government Documents Department

Transparent ultralow-density silica aerogels prepared by a two-step sol-gel process

Description: Conventional silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels <.020 g/cc. We have developed a two-step sol-gel process that circumvents the limitations of the conventional process and allows the formation of ultralow-density gels in a matter of hours. we have found that the gel time is dependent on the catalyst concentration. After supercritical extraction, the aerogels are transparent, uncracked tiles with densities as low as .003 g/cc. 6 figs., 11 refs.
Date: September 1, 1991
Creator: Tillotson, T.M. & Hrubesh, L.W.
Partner: UNT Libraries Government Documents Department

Equation-of-state from SiO sub 2 aerogel Hugoniot data

Description: The significance of the new aerogel data for the equation-of-state of SiO{sub 2} is discussed. On this basis the use of SiO{sub 2} aerogels as a standard witness material for Hugoniot release wave measurements is advocated. We compare the Hugoniot data of Holmes on aerogel samples of density 0.128 gm/cm{sup 3} with a multiphase EOS for quartz developed by F. Ree some 15 years ago. His tabular EOS includes compositional changes arising from both chemical and ionization equilibrium, and is found to be in excellent agreement with the Hugoniot data and its extension to higher pressures. The roles of phase and compositional changes along the aerogel Hugoniot and the close agreement with the measured linear shock velocity relation are discussed. In this connection a useful simple Grueneisen EOS model for quartz with an energy dependent gamma is derived from the linear velocity relation and is supported by the Ree EOS.
Date: May 1, 1991
Creator: Grover, R.; Ree, F. & Holmes, N.
Partner: UNT Libraries Government Documents Department