Morris De Beer - Academia.edu (original) (raw)
Morris De Beer, Ph.D (Civil Engineering, University of Pretoria, UP). After 43 years research in road/pavement/tyre/pavement contact stress and road building materials research at CSIR (SA), Dr De Beer retired and started his consulting business as Director, ROAD PAVEMENT FORENSIC ENGINEERING (RPFE), (Pty) Ltd, Pretoria, South Africa. Business address:926 Pierneef Street, Villieria, Pretoria, 0186, Republic of South Africa (RSA).Mobile (Cell): 27(0)74 101 7406E-mail: morris@rpfe.co.za and Web: https://www.rpfe.co.za
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Papers by Morris De Beer
Journal of The South African Institution of Civil Engineering, Apr 1, 2012
Eighth International Conference on Asphalt PavementsFederal Highway Administration, 1997
Accelerated load testing (ALT) facilities like the LINTRACK are believed to be an essential tool ... more Accelerated load testing (ALT) facilities like the LINTRACK are believed to be an essential tool in the development of improved performance models for asphalt pavements. It should, however, be realized that even such facilities are only capable of modelling real life conditions in a simple way. For that reason ALT studies undertaken in the Netherlands have the primary goal to improve response and damage models, which in turn can be used for performance predictions. This paper first describes the main features of the ALT studies performed in the Netherlands on a thick (150 mm) and thin (70 mm) asphalt pavement on a sand subgrade. These show that the current Dutch design model is unable to fully describe the behaviour of these pavements. Therefore, three suggested improvements to this design model are described: 1) Mix-wise prediction of fatigue characteristics for practical conditions from simple tests; 2) Calculation of strains and stresses using a linear visco-elastic multi-layer approach; and 3) Modelling of the wheel load, using a rectangular, non-uniform three-dimensional distribution of contact stresses.
Paper presented at the 13th Annual Transportation Convention, University of Pretoria, Pretoria, 1993
XIIIth World meeting of the International Road FederationInternational Road Federation, 1997
Transportation Research Record, 1998
In South Africa there is a great need to upgrade the accessibility of rural areas. With the aid o... more In South Africa there is a great need to upgrade the accessibility of rural areas. With the aid of the heavy-vehicle simulator (HVS), the Gauteng Department of Transport and Public Works and the Council for Scientific and Industrial Research (CSIR) investigated the upgrading of in situ gravel roads to the paved standard through addition of a gravel bonding surface layer only. The HVS program consisted of nine tests in which loading and environmental conditions were varied. The results of this investigation indicated that loading and environmental conditions were the dominant influences on the behavior of superlight pavements. An interim transfer function for the design of superlight pavements based on the results of the investigation is provided, together with recommendations for optimization of the transfer function.
Paper presented at the Annual Transportation Convention, CSIR Conference Centre, Pretoria, 1991
This report is a publication of the National Department of Transport, South Africa, made availabl... more This report is a publication of the National Department of Transport, South Africa, made available by CSIR.
Eighth International Conference on Asphalt PavementsFederal Highway Administration, 1997
The increase of the maximum axle load limit in South Africa sparked renewed interest into methods... more The increase of the maximum axle load limit in South Africa sparked renewed interest into methods of quantifying traffic load associated damage on pavements. Extensive research with the Heavy Vehicle Simulator (HVS) over the past 20 years has led to improved fundamental understanding of pavement performance and has permitted the development of Equivalent Damage Factors (EDFs) for single-axle loads. A major limitation of this approach is that it does not directly facilitate the calculation of EDFs for multiple axle configurations, i.e., tandem or tridem axles. This paper describes a method for extending the existing HVS-based method to the determination of EDFs for multiple axle configurations. This, in principle, facilitates the development of guidelines on permissible axle loads and tyre inflation pressures for different axle configurations. The method assesses the effects of: wheel load, contact stress, single and dual wheels, and single, tandem and tridem axle configurations. The method, therefore, enables determination of EDFs for the accurate estimation of equivalent traffic loading for design purposes and performance analysis enhancing life predictions and management decisions. Initial determinations indicated the advantage to road friendliness of grouping axles together into tandem or tridem configurations. Additionally, the use of dual-wheel instead of single-wheel axles could result in the axle load being increased by up to 30% without any increase in pavement damage.
Journal of The South African Institution of Civil Engineering, Apr 1, 2012
Eighth International Conference on Asphalt PavementsFederal Highway Administration, 1997
Accelerated load testing (ALT) facilities like the LINTRACK are believed to be an essential tool ... more Accelerated load testing (ALT) facilities like the LINTRACK are believed to be an essential tool in the development of improved performance models for asphalt pavements. It should, however, be realized that even such facilities are only capable of modelling real life conditions in a simple way. For that reason ALT studies undertaken in the Netherlands have the primary goal to improve response and damage models, which in turn can be used for performance predictions. This paper first describes the main features of the ALT studies performed in the Netherlands on a thick (150 mm) and thin (70 mm) asphalt pavement on a sand subgrade. These show that the current Dutch design model is unable to fully describe the behaviour of these pavements. Therefore, three suggested improvements to this design model are described: 1) Mix-wise prediction of fatigue characteristics for practical conditions from simple tests; 2) Calculation of strains and stresses using a linear visco-elastic multi-layer approach; and 3) Modelling of the wheel load, using a rectangular, non-uniform three-dimensional distribution of contact stresses.
Paper presented at the 13th Annual Transportation Convention, University of Pretoria, Pretoria, 1993
XIIIth World meeting of the International Road FederationInternational Road Federation, 1997
Transportation Research Record, 1998
In South Africa there is a great need to upgrade the accessibility of rural areas. With the aid o... more In South Africa there is a great need to upgrade the accessibility of rural areas. With the aid of the heavy-vehicle simulator (HVS), the Gauteng Department of Transport and Public Works and the Council for Scientific and Industrial Research (CSIR) investigated the upgrading of in situ gravel roads to the paved standard through addition of a gravel bonding surface layer only. The HVS program consisted of nine tests in which loading and environmental conditions were varied. The results of this investigation indicated that loading and environmental conditions were the dominant influences on the behavior of superlight pavements. An interim transfer function for the design of superlight pavements based on the results of the investigation is provided, together with recommendations for optimization of the transfer function.
Paper presented at the Annual Transportation Convention, CSIR Conference Centre, Pretoria, 1991
This report is a publication of the National Department of Transport, South Africa, made availabl... more This report is a publication of the National Department of Transport, South Africa, made available by CSIR.
Eighth International Conference on Asphalt PavementsFederal Highway Administration, 1997
The increase of the maximum axle load limit in South Africa sparked renewed interest into methods... more The increase of the maximum axle load limit in South Africa sparked renewed interest into methods of quantifying traffic load associated damage on pavements. Extensive research with the Heavy Vehicle Simulator (HVS) over the past 20 years has led to improved fundamental understanding of pavement performance and has permitted the development of Equivalent Damage Factors (EDFs) for single-axle loads. A major limitation of this approach is that it does not directly facilitate the calculation of EDFs for multiple axle configurations, i.e., tandem or tridem axles. This paper describes a method for extending the existing HVS-based method to the determination of EDFs for multiple axle configurations. This, in principle, facilitates the development of guidelines on permissible axle loads and tyre inflation pressures for different axle configurations. The method assesses the effects of: wheel load, contact stress, single and dual wheels, and single, tandem and tridem axle configurations. The method, therefore, enables determination of EDFs for the accurate estimation of equivalent traffic loading for design purposes and performance analysis enhancing life predictions and management decisions. Initial determinations indicated the advantage to road friendliness of grouping axles together into tandem or tridem configurations. Additionally, the use of dual-wheel instead of single-wheel axles could result in the axle load being increased by up to 30% without any increase in pavement damage.