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- Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese
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- Volume 45, Issue 2, 2003
Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese - Volume 45, Issue 2, 2003
Volumes & issues
Volume 45, Issue 2, 2003
Improvement of aggregate interlock equation for new mechanistic concrete pavement design method : technical paperSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 2 –8 (2003)More Less
This paper presents aspects of an investigation into methods for modelling aggregate interlock shear transfer in jointed concrete pavements. The aim was to improve the aggregate interlock load transfer equation used in the software developed for the new South African mechanistic concrete pavement design method. The paper presents the evaluation of the results of the investigation into aggregate interlock load transfer efficiency across joints in concrete slabs subjected to simulated 20 kN dynamic wheel loads and 40 kN control loads. One of the main conclusions reached from the study was that there was no significant deterioration of the crack face during dynamic loading, which indicated that fatigue of the aggregate interlock at the joint face did not play a role. This could be attributed to the high quality of the crushed stone used in South Africa. The equation developed from the laboratory results was used to refine the aggregate interlock load transfer model in the software developed for the new mechanistic design method.
Source: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 9 –19 (2003)More Less
End-use water demand modelling is used to generate water demand projections by modelling various end uses, for example showers, toilets and washing machines. End-use models can be used to estimate water demand changes due to various scenarios, such as price increases, housing densification and conservation programmes. This study reports on the potential application of end-use modelling in South Africa, based on a pilot study that was done for Rand Water. The model includes elasticities of water demand with respect to variations in water price, household income, stand size and pressure. The study highlights many of the difficulties and limitations, as well as the potential applications of end-use modelling as a water demand predictor. A special effort is made to explain the meaning and application of elasticity in end-use modelling. Various data sources were used to determine elasticities for the variables used, and to identify minimum and maximum elasticity values. The implications of the elasticities are illustrated using a sensitivity analysis and case study.
Source: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 20 –25 (2003)More Less
The marine environment provides a severe test of the durability of reinforced concrete structures. Predictions of durability need to consider the complex interactions between environment, materials and structure that affect long-term performance of marine structures. An empirical chloride prediction model has been developed for chloride ingress into marine concretes. The prediction model was formulated from the relationship between early-age chloride conductivity test results and medium- and long-term observations of the performance of concrete in different marine environments. This paper presents some of the practical results of this approach in terms of design limits and mix design recommendations. Design guidance is given such that a matrix of factors may be optimised, including water/binder ratio, binder type, cover depth, environment, and construction practice, in order to produce durable marine concrete structures. Preferred concrete mixes for marine applications are also given, showing the advantage of concrete containing supplementary cementitious materials. However, good material selection and design are not sufficient to ensure durability, and recommendations are made for a system of performance specifications to ensure durable marine structures.
Author G. HeymannSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 26 –31 (2003)More Less
The seismic cone test is an in situ test used to measure body wave velocities in soils. Geotechnical parameters that may be derived from the test include void ratio, small strain stiffness and Poisson's ratio. In addition, results from the seismic cone test allows judgement to be made on the static and dynamic liquefaction potential of soils. The test makes use of a cone containing several geophones that is hydraulically pushed into the soil under investigation. Seismic waves are generated at the surface and the time required for the waves to propagate through the soil to the cone is measured. The information is used to determine the velocities of different wave types in the material. This paper describes the seismic cone test. Field results are presented and parameters that may be derived from the results are discussed.