Browsing by Author "Sabine, TM"
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- ItemThe 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, LPSmall 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.
- ItemModelling the microstructure of cement(Australian and New Zealand Institutes of Physics, 1994-02-10) Bertram, WK; Sabine, TM; Aldridge, LPTo 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.
- ItemNeutron beam research in the Pacific Rim region - an Australian perspective(The Institution of Engineers Australia, 1994-05-01) Sabine, TM; Howard, CJA 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.
- ItemA neutron diffraction determination of the magnetic form factor for Ni2+ in NiO(Australian Atomic Energy Commission, 1959-06) Sabine, TMRecently 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.