As late as 1976 Fulton wrote: 'In South Africa the only known cases (of alkali-aggregate reaction damage to concrete) have arisen when glass has been used as an aggregate or in the form of insets in deocrative concrete'. The occurrence of damage as a result of alkali-aggregate reaction has now been Identified in the Western and Eastern Cape and also the Witwatersrand area. Very little is known of how to repair structures that have deteriorated as a result of alkali-aggregate reaction. The paper descriptionbes the effects of alkali-aggregate reaction on exposed reinforced concrete structures and some of the techniquel that have been developed to effect repairs to structures in the Witwatersrand area.
Following some experimental observations in the Crocodile River near Brits, it is shown in this paper that the Colebrook-White equation loses its validity in the extreme rough turbulent zone where Manning's n exceeds about 0,05. Consequently, It is recommended that the Colebrooke-Whlte equation should not be applied in this zone. A number of important research requirements with regard to the Colebrook-White equation, are identified In this paper.
A major problem in the construction Industry today is the adequacy, or otherwise, of information passed from the designer to the end user, particularly in the sphere in which I am directly concemed, that of a reinforcing steel subcontractor. This statement may come as a surprise to many a consulting engineer but there is a reason for that Reinforcing steel is normally handled under subcontract and officially there is no direct contact between a sub-contractor and the designer. The sub-contractor's problems end with the main contractor. The latter has sufficient of his own without having to carry forward the sub-contractor's as well. The purpose of this paper is not to teach how to detail reinforcing steel, but it is rather an attempt to reiterate and remind originators of Information of the basic principles of communication which, it is hoped, will then result in more adequate details being produced by them for any construction purpose, but principally for reinforcing steel. The work study method of asking five basic questions will be used with certain illustrations.
This paper descriptionbed the proposals for a limit-state formulation of a new South African code for the design of steel buildings. During the development of this approach a number of anomalies and potential sources of confusion became apparent in ensuring consistency with the British interpretation of limit-state principles, as embodied in the South African concrete code. A framework was provided for a critical evaluation of the inflexibility in the present practice, and an alternative formulation was identified. The recommended approach to load combinations and conditions of overturning and stress reversal in the proposed code was also discussed.