BAWEJA, D, ROPER, H & SIRIVIVATNANON, V 1993, 'RELATIONSHIPS BETWEEN ANODIC POLARIZATION AND CORROSION OF STEEL IN CONCRETE', CEMENT AND CONCRETE RESEARCH, vol. 23, no. 6, pp. 1418-1430.
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BOLAN, NS, HEDLEY, MJ & LOGANATHAN, P 1993, 'PREPARATION, FORMS AND PROPERTIES OF CONTROLLED-RELEASE PHOSPHATE FERTILIZERS', FERTILIZER RESEARCH, vol. 35, no. 1-2, pp. 13-24.
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Controlled-release phosphate fertilizers include phosphate rocks (PRs) for direct application, partially acidulated phosphate rocks (PAPRs) and thermal phosphates. Phosphate rocks contain apatite as the main P containing mineral, the composition and the chemical nature of which vary between PRs. Based on the solubility in chemical extractants PRs are broadly grouped into 'reactive' and 'unreactive'. The 'reactivity' of PRs is influenced strongly by the extent of carbonate substitution for phosphate in the apatite minerals. Under certain soil and climatic conditions reactive PRs (RPRs) can be used as a source of P for direct application. Partially acidulated phosphate rocks (PAPRs) are produced either by direct partial acidulation of PRs with mineral acids or by mixing PRs with fully acidulated superphosphate reaction mixtures. Partial acidulation of PRs with H3PO4 generally results in higher water soluble P contents than those acidulated with H2SO4. Mixing of RPRs with superphosphate reaction mixtures sometimes results in the preferential consumption of free acid and thereby increases the amounts of residual unreacted PRs. Thermal phosphates are produced by either heating PRs below melting point both in the presence and the absence of silica (calcined phosphates) or heating PRs with silica above melting point (fused phosphate). These phosphates are alkaline in nature and hence suitable for acidic soils. © 1993 Kluwer Academic Publishers.
Briscoe, BJ, Thomas, PS & Williams, DR 1993, 'The Strain Rate Dependence of the Interface Shear Strength of Poly(methyl methacrylate) Films', Tribology Series, vol. 25, no. C, pp. 453-460.
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The frictional response for a range of thin poly(methyl methacrylate) (PMMA) films has been assessed in terms of the interface shear strength, τ. The dependence of τ on the shear strain rate, the morphology and the molecular structure of the polymer have been experimentally determined. These dependencies are interpreted using a molecular topographical model of the interface shear process. This type of model allows the accommodation of microscopic shear stresses through molecular deformation in the polymer film. In order to identify the molecular nature of these processes, a theoretical stress activated model of molecular flow is employed. The structural properties of the polymer films, and, in particular, the conformation of the pendant ester group, are characterised by FTER. The current study proposes that the interface rheology of PMMA films is related to the conformation of the pendant ester groups attached to the carbon backbone chain of PMMA. © 1993, Elsevier Inc. All rights reserved.
Cao, HT, Bucea, L & Sirivivatnanon, V 1993, 'Corrosion rates of steel embedded in cement pastes', Cement and Concrete Research, vol. 23, no. 6, pp. 1273-1282.
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Dynamic polarization techniques were used to estimate the corrosion rates of steel embedded in cement paste made with different binder systems. A corrosion model is proposed. The corrosion rates were determined by employing the Evans diagrams constructed from cathodic polarization curve of steel embedded in chloride free cement paste and anodic polarization curve of steel embedded in cement pastes containing chloride. Within the limitations of the adopted experimental conditions and sample configuration, the preliminary results indicate that corrosion rates of steel embedded in blended cement pastes generally fall within the range shown by steel embedded in portland cement pastes. © 1993.
Indraratna, B 1993, 'Effect of bolts on failure modes near tunnel openings in soft rock', Géotechnique, vol. 43, no. 3, pp. 433-442.
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The Paper elucidates the potential failure modes around a circular tunnel opening subjected to a hydrostatic stress field. Physical models have been tested in the laboratory using a large cubical triaxial apparatus to investigate the effect of grouted bolts on failure mechanisms. Depending on the bolt density, the observed failure of a bolted tunnel can deviate significantly from the theoretical rupture surfaces (log spiral) anticipated for an unsupported circular opening. The influence of discontinuities on the rupture process near the tunnel wall is also explored. It is shown that by use of a high bolt density, the propagation of slip lines and the risk of failure close to the tunnel boundary can be minimized. The failure zone (delineating wedges) around the tunnel wall becomes smaller with increasing degree of reinforcement. L'article s'intéresse aux modes possibles de fractu-ration autour de l'ouverture circulaire d'un tunnel dans un champ de contraintes hydrostatique. Des modèles physiques ont été expérimentés en laboratoire, à l'aide d'un appareillage triaxial pour des échantillons cubiques de gros volume, afin d'étudier l'influence des boulons jointifs sur less mécanismes de fracturation. Selon la densité de boulons, la fracturation observée dans un tunnel boulonné peut s'éloigner significativement des surfaces de rupture théoriques (en spirale logarithmique) prévues pour une ouverture circulaire non soutenue. L'influence des discontinuités sur le mécanisme de rupture à proximité de la paroi du tunnel a également été étudiée. Il apparaît que, en utilisant une forte densité de boulons, l'on peut minimiser la propagation des lignes de glissement et le risque de fracturation à proximité des limites du tunnel. La zone de fracturation autour des parois du tunnel devient moins étendue si l'on augmente le degré de renforcement.
Indraratna, B & Balasubramaniam, AS 1993, 'Closure to “ Performance of Test Embankment Constructed to Failure on Soft Marine Clay ” by B. Indraratna, A. S. Balasubramaniam, and S. Balachandran (January, 1992, Vol. 118, No. 1)', Journal of Geotechnical Engineering, vol. 119, no. 8, pp. 1326-1329.
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Indraratna, B, Wijewardena, LSS & Balasubramaniam, AS 1993, 'Large-scale triaxial testing of grey wacke rockfill', Géotechnique, vol. 43, no. 1, pp. 37-51.
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This Paper describes the results of a series of large-scale triaxial tests conducted on greywacke rockfill, used in dam construction in Southern Thailand. The tests are conducted at low to moderate confining stresses to relate their findings to the stability of rockfill dams. Considering the current test results in conjunction with previous laboratory data, revised failure criteria for rockfill are proposed in non-dimensional form. For both low and high confining stresses, lower and upper bounds of strength envelopes have been established, based on a wide array of granular materials. The influence of the confining stress on the shear strength of rockfill is studied in depth, and the implications of a non-linear envelope at low normal stress levels on the stability of rockfill dams are discussed. Although two parallel rockfill gradations for specimens compacted to similar porosities are considered, the exact role of particle size effect on shear strength is not examined in detail, as the difference in maximum particle sizes tested in this study is not sufficiently large. Cet article décrit les résultats d'une suite d'essais au triaxial à grande échelle réalisés sur du remblai rocheux (greywacke) utilisé pour la construction de barrages dans le sud de la Thaïlande. Ces essais sont exécutés à des pressions de cellule faibles à modérées pour rapprocher les résultats de la stabilité de barrages à enrochement. En considérant les résultats existant d'essais, en conjonction avec les données de laboratoire précédentes, des critères de rupture de l'enrochement sont proposés dans une forme sans dimensions. Pour des pressions de cellule faibles et élevées, les enveloppes basses et hautes de résistance ont été établies, basées sur un vaste ensemble de matériaux granuleux. L'influence de la pression de cellule sur la résistance au cisaillement est étudiée en profondeur et les conséquences d'une enveloppe de rupture non linéaire à containtes...
LOGANATHAN, P & HEDLEY, MJ 1993, 'SINGLE SUPERPHOSPHATE - REACTIVE PHOSPHATE ROCK MIXTURES .3. THE USE OF CONCENTRATION RATIOS OF ELEMENTS TO IDENTIFY THE NATURE AND AMOUNTS OF UNACIDULATED ROCK RESIDUES IN THE MIXTURES', FERTILIZER RESEARCH, vol. 36, no. 3, pp. 203-210.
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Water insoluble residues (WIR) of unreactive phosphate rocks in single superphosphate-reactive phosphate rock (SSP-RPR) mixtures are considered to reduce the agronomic value of these mixtures. A technique using concentration ratios of elements to identify the quantities of WIR of ground North Carolina (NC), ground Nauru and as received NC phosphate rocks in a SSP-RPR was developed. Of 22 elements tested P/Sr ratios were found to be the only element ratios that could be used to distinguish between WIR's derived from Nauru and NC. P/Sr ratios in Nauru and NC were markedly different and provided a useful index for differentiating between the two rocks. During acidulation the P/Sr concentration ratio remained essentially constant in the WIR's from both rocks. Using the element ratio technique the percentage of total P in the SSP-RPR sample was determined to be 60-61% water soluble, 5% water insoluble Nauru, 2% water insoluble ground NC and 32-33% water insoluble as received NC. The element ratio technique developed in this study can be applied to partially acidulated P fertilizers made with rocks other than NC and Nauru provided elements which satisfy the same conditions as Sr in this study can be found. © 1993 Kluwer Academic Publishers.
Sheng, D & Knutsson, S 1993, 'Sensitivity analysis of frost heave - a theoretical study', Frost in geotechnical engineering. Proc. 2nd symposium, Anchorage, 1993, pp. 3-16.
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A frost heave model based on quasi-steady state heat and water flow is presented. The model is verified against experimental results. The sensivity of computed frost heave is analyzed, which shows that, 1) the important factors affecting frost heave include overburden pressure, temperature gradient, unfrozen water content in frozen soil, and permeability of the soil; 2) increasing over-burden pressure prevents frost heave by elongating frozen fringe and increasing the space between lenses, and the effect of overburden pressure is not significant for clays; 3) decreasing temperature gradient prevents frost heave by increasing the thickness of frozen fringe and reducing ice lens thickness; 4) as the unfrozen water content increases, the computed heave first increases rapidly and then approaches a constant value at moderate and high unfrozen water content. -from Authors
Sheng, D, Axelsson, KB & Knutsson, S 1993, 'Finite element analysis for convective heat diffusion with phase change', Computer Methods in Applied Mechanics and Engineering, vol. 104, no. 1, pp. 19-30.
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Stewart, MG 1993, 'Modeling Human Performance in Reinforced Concrete Beam Construction', Journal of Construction Engineering and Management, vol. 119, no. 1, pp. 6-22.
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A significant portion of performance failures are due to human error in the construction stage of a structural engineering project. Statistical studies indicate that the construction of in-situ reinforced concrete elements is most prone to error, and that most errors are committed by contractors (either site staff or workmen). Results are reported herein of a survey investigating the error rate and error magnitude of contractor construction errors, and the frequency of engineering inspections and their influence on construction errors. The survey recipients were practicing structural engineers. Probabilistic models have been proposed for the distribution of error rates and error magnitudes, and include within them the influence of inspections. It was found that engineering inspections reduced the initial on-site construction error content by approximately two orders of magnitude. The models provide construction task performance information that can be incorporated into a probabilistic risk analysis of reinforced-concrete construction. © ASCE.
Stewart, MG 1993, 'Structural reliability and error control in reinforced concrete design and construction', Structural Safety, vol. 12, no. 4, pp. 277-292.
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Available statistical data suggest that human error in design and construction causes a significant proportion of performance failures; namely, structural failure, cost overruns and delays. A Human Reliability Analysis (HRA) model has been developed to simulate the effect of human error on the design and construction of a reinforced concrete beam. The proposed HRA model incorporates the effect of designer checking, independent design checking, engineering inspections of construction works, and interaction between the designer and contractor. Human performance models are described for all design and construction microtasks. It was found that human error leads to a significant loss of structural safety, but that error control measures (particularly design checking) significantly reduce this loss. It was also shown that construction errors are more detrimental to structural safety and are more difficult to detect and correct. © 1993.
Zhou, JL & Banks, CJ 1993, 'Mechanism of humic acid colour removal from natural waters by fungal biomass biosorption', Chemosphere, vol. 27, no. 4, pp. 607-620.
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BALL, JE 1970, 'MODELLING OF UNSTEADY FLOW THROUGH MANHOLES', PROCEEDINGS OF THE SIXTH INTERNATIONAL CONFERENCE ON URBAN STORM DRAINAGE, VOLS 1 AND 2, 6th International Conference on Urban Storm Drainage, SEAPOINT PUBLISHING, NIAGARA FALLS, CANADA, pp. 116-121.
BALL, JE, BARMA, D & AUSTR, IE 1970, 'MODELING FLOOD WAVE MOVEMENT WITH A MODIFIED STRELKOFF SCHEME', HYDROLOGY AND WATER RESOURCES SYMPOSIUM - TOWARDS THE 21ST CENTURY, Engineering for Hydrology and Water Resources Conference 1993: Looking Towards the 21st-Century, INST ENGINEERS AUSTRALIA, NEWCASTLE, AUSTRALIA, pp. 179-184.
BALL, JE, WHITE, MJ, INNES, GD, CHEN, L & AUSTR, IE 1970, 'APPLICATION OF HSPF ON THE UPPER NEPEAN CATCHMENT', HYDROLOGY AND WATER RESOURCES SYMPOSIUM - TOWARDS THE 21ST CENTURY, Engineering for Hydrology and Water Resources Conference 1993: Looking Towards the 21st-Century, INST ENGINEERS AUSTRALIA, NEWCASTLE, AUSTRALIA, pp. 343-348.
BAWEJA, D, ROPER, H, GUIRGUIS, S & SIRIVIVATNANON, V 1970, 'MEASUREMENT OF CORROSION OF STEEL REINFORCEMENT UNDER HIGH CHLORIDE CONDITIONS', FLY ASH, SILICA FUME, SLAG, AND NATURAL POZZOLANS IN CONCRETE, VOLS 1 AND 2, 4TH INTERNATIONAL CONF ON FLY ASH, SILICA FUME, SLAG, AND NATURAL POZZOLANS IN CONCRETE, AMER CONCRETE INST, ISTANBUL, TURKEY, pp. 1543-1563.
BRISCOE, BJ, STUART, BH & THOMAS, PS 1970, 'SOLVENT-INDUCED MORPHOLOGICAL-CHANGES TO POLYCARBONATE', POLYMER/INORGANIC INTERFACES, Materials Research Society, San Francisco, pp. 185-190.
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THOMAS, PS & WILLIAMS, DR 1970, 'THE CHARACTERISATION OF COATED POLYMERIC FIBRES BY INVERSE GAS CHROMATOGRAPHY', ADHESION SOCIETY PROCEEDINGS OF THE SIXTEENTH ANNUAL MEETING AND THE INTERNATIONAL SYMPOSIUM ON THE INTERPHASE, 16th Annual Meeting of the Adhesion-Society/International Symposium on the Interphase, ADHESION SOCIETY, WILLIAMSBURG, VA, pp. 120-122.