Browsing by Author "Sabine, TM"

Now showing 1 - 6 of 6
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    The micro pore structure of concrete determined by small angle neutron scattering
    (Australian and New Zealand Institutes of Physics, 1994-02-10) Sabine, TM; Bertram, WK; Aldridge, LP
    Small angle neutron scattering (SANS) is a complementary technique to electron microscopy for the elucidation of the shape and size of inhomogenities in the nanometric size range. SANS has the advantage that a large volume ( - 0.5 cm3 ) of the specimen is illuminated by the beam, and experiments can be earned out at atmospheric pressure on water saturated samples. It has the disadvantage mat, except for very simple systems, interpretation of the experimental data is not unambiguous. We have collected SANS data on a range of samples of concrete containing different water/cement ratios. The data was collected on the LOQ instrument at the ISIS spallation neutron source. We discuss interpretation of the data in terms of microscopic inhomogenities in the structure of concrete.
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    Modelling the microstructure of cement
    (Australian and New Zealand Institutes of Physics, 1994-02-10) Bertram, WK; Sabine, TM; Aldridge, LP
    To gain a better understanding of the factors that influence the strength and durability of concrete the microporosity of hydrated cement paste has been investigated, by small angle neutron scattering (SANS). The great advantage that SANS has over the more conventional methods of microporosity analysis such as mercury or gas intrusion, is that for SANS measurements it is not necessary to dehydrate the samples and the process is non-intrusive. However the results from SANS are often open to several different interpretations and it is necessary to obtain additional information where possible .One method of obtaining such additional information is through computer modelling of the process of cement hydration. In this poster we present the results of a 3- dimensional computer model that simulates the growth of a layer of calcium-silicate-hydrate (CSH) on a surface. The model used is similar to that for random aggregates (TA Witten and LM. Sanders, Phys. Rev. Lett. 19,1400 (1981)). The model calculates the porosity and the pore size distributions, which can men be compared with those obtained from SANS measurements.
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    Neutron beam research in the Pacific Rim region - an Australian perspective
    (The Institution of Engineers Australia, 1994-05-01) Sabine, TM; Howard, CJ
    A program of research in neutron scattering was established in Australia in the early 1960's, shortly after the reactor HIFAR commenced full power operation. The program has included elements of regional cooperation from the very early days. A report is given on the present status of Australian neutron scattering research, and the activities (including several major new developments) in other Pacific Rim countries are briefly reviewed. Given the increasing sophistication of neutron scattering facilities and techniques, the case for regional cooperation is strongly advocated.
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    A neutron diffraction determination of the magnetic form factor for Ni2+ in NiO
    (Australian Atomic Energy Commission, 1959-06) Sabine, TM
    Recently Roth has shown that the intensities of the magnetic reflections from NiO decrease more slowly with scattering angle than those from MnO. The present investigation in which a larger crystal was used extends the Ni2+ form factor curve.
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    Neutron diffraction on HIFAR
    (Melbourne University Press on behalf of The Australian Atomic Energy Commission, 1958-06-02) Sabine, TM
    A brief account of the use of neutron diffraction as a complementary technique to X-ray diffraction in crystallographic analysis is given. The spectrometers to be installed on HIFAR are described and the experimental limitations of the technique discussed.
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    Powder diffraction using imaging plates at the Australian National Beamline Facility at the Photon Factory
    (American Institute of Physics, 1994-07-18) Garrett, RF; Cookson, DJ; Foran, GJ; Sabine, TM; Kennedy, BJ; Wilkins, SW
    A novel x‐ray diffractometer was installed at the Australian National Beamline Facility at the Photon Factory, Japan, in October 1993. One of the major capabilities of the instrument is high speed high resolution powder diffraction using imaging plate detectors. The diffractometer combines a two circle goniometer and a large cassette in which imaging plates can be loaded covering 320° of 2θ. The diffractometer is enclosed in a large vacuum chamber and can be operated in air, vacuum, or helium. Recently, powder data has been obtained from rutile (TiO2) and NBS Si 640b at wavelengths from 0.62 to 1.9 Å using imaging plates, and has been used to characterize the performance of the instrument. The data has been refined using the Rietveld method and R values of under 2% obtained. The resolution of the system varies from a minimum of about 0.04° to around 0.25° at 2θ angles around 160°, which is the equal of most synchrotron based powder diffractometers, and only slightly worse than that obtained using an analyzer crystal and scintillation detector. Using the imaging plates, 160° of data is simultaneously acquired in an exposure of about 10 min, compared to conventional counter diffractometer scans which routinely exceed 10 hours. © 1995 American Institute of Physics.