115A and the results obtained were almost identical. The modified Bohme machine is thus suitable for the Dorry test. 854056 Skid resistance of marginal durability aggregates
Stewart, I E lnt Assoc Engng Geol Bull N29, June 1984, P449-452 (paper to the International Symposium on Aggregates, Nice, 21-23 MaJ~ 19841
Field and laboratory test data for the friction and wear prcperties of various aggregates are analysed. For marginal to poor durability stones. field results can differ significantly from laboratory tests, giving higher or lower values. Three distinct rock textures were found which led to predictable differences between laboratory and field polishing. For one type, field skid resistance is much lower than might be predicted from laboratory testing. As this texture is commonly found amongst skid resistance aggregates, the effect must be taken into account when evaluating new deposits. 854057 Use of the sand blast test to determine rock durability Verhoef, P N W: Kuipers, T J; Verwaal, W Int Assoc Engng Geol Bull N29, June 1984, P457-461 (paper to the International SJ,mposium on Aggregates, Nice, 21-23 May 1984)
Eight hard rock samples were subjected to sand blasting in order to investigate its effectiveness as an indicator of abrasion resistance. There was good discrimination between rock types, and the test was found to be sensitive to rock anisotropy. The decay mechanism was found to be largely fracturing along extant cracks containing minerals. or along grain boundaries. Loosening along discontinuities was an important part of the process. Good correlation was found between the volumetric wear rate and tensile strength of the rock.
854060 Durability of aggregates: the soundness tests (In French)
Aubertin, M; Larochelle, F Int Assoc Engng Geol Bull N29. June 1984. P335-338 (paper to the International Symposium on Aggregates. Nice, 21-23 May 1984)
The sulphate soundness test (ASTM C-88) is evaluated. It is concluded that sulphate soundness is directly related to microstructure and mineralogy and not reliably related to actual performance of aggregates exposed to the elements. It should only be used as a general index of behaviour which. combined with petrographic analysis, may indicate potential weakness. It should not be used as an exclusive criterion for selection. 854061 Effect of the solvent action of saturated sulfate solutions in the ASTM soundness test
0~01, M A Int Assoc Engng Geol Bull N29, June 1984, P415-417 (paper to the International Symposium on Aggregates, Nice? 21-23 May 1984j
The sulphate soundness test (ASTM C88) 1s used to assess damage caused by freezing and thawing. Saturated Na and Mg sulphate solutions may dissolve limestones thus placing a chemical bias on a test to measure physical resistance. The employment of previously used sulphate solution is suggested for work on limestones, but experimental results showed that solutions did not become saturated after 100 hours exposure to limestone. It was concluded that the dissolution effect may be small for dense crystalline materials, but may be important in the case of a biomicrite, where the solvent action could lead to significant weakening. 854062
Time dependent behaviour
Chemical soundness test on Carboniferous Limestone samples from the Bristol area
Al-Jassar, S A; Hawkins, A B Q J Engng Geol V17, N4, 1984, P351-355
Creep processes in landslides
Van Asch, W J Earth Surf Land Process V9. N6, Not-Dee 1984, P573-583 Displacement of landslide blocks after initial slope failure is mostly attributed to sliding along a well-defined slip surface. The contribution of creep in the slow displacement is discussed. A study was carried out in the Bonne Valley in the French Alps with displacements measured over three years. Inclinometer measurements showed a creep zone developed above the slip surface in a zone about Im thick. Soil mechanical analysis of creep movements supported field observations. Back analysis using the field creep model of Ter-Stepanian gave threshold values comparable with threshold values for creep found in the laboratory. It is concluded that during measuring periods up to 15”” of block movement possibly occurred due to these creep movements. 854059 Creep in rock as a stochastic process
Pusch. R Engng Geol V20. N4, Dee 1984, P301-310 A stochastic model allowing for large variations in strength and size of rock mass is outlined. It is shown to account well for typical creep behaviour of rock at moderate stresses and temperatures. providing typical linear behaviour at moderate stresses and temperature.
Soundness tests using sodium sulphate and magnesium sulphate solutions on seven lithologies are presented to determine surfacing aggregate durability. Results indicate that the percentage loss tested in the sodium solution is higher than for aggregate immersed in the magnesium solution, explained by the chemical activity of the elements. It is concluded that the soundness test confirmed the problem of referring simply to limestones, rather than separating the carbonate rocks into the main lithological subdivisions. 854063 Effect of column wetting on soil thermal conductivity
Horton, R; Wierenga, P J Soil Sci V138. N2, Aug 1984, P102-108 Soil thermal conductivity as a function of water content was measured using laboratory packed soil columns brought to uniform water content by the microwave technique. The values were compared with those measured in soil columns packed with premoistened soil and those predicted using the method of ‘de Vries’.
Permeability See also: 854266