Four different clay materials that occur in the Western Cape were selected for evaluation as artificial pozzolans. It was found that the degree of pozzolanic activity that could be developed in these materials depends primarily on the proportion of kaolinite (clay substance) present and that the calcining temperature has relatively little influence. Clay materials from this region with high kaolinite contents and calcined at relatively low temperatures should be excellent pozzolans, with the potential to alleviate the deleterious expansion due to alkali-aggregate reaction in concrete.
A basisfor defining partial load factors and expressions for load combinations is presented that could apply comprehensively to the limit-states design of buildings for all structural materials. This formulation has been developed by a working group of the Structural Division of the Institution and it is proposed that enabling clauses be Included in the next revision of the loading code SABS 0160:1980'. Methods are also recommended whereby the committees responsible for individual design codes for different structural materials may calibrate the expressions for the limit states of resistance in a consistent manner to achieve more uniform margins of structural safety.
This paper descriptionbed an investigation into the shape and particle size distribution of two cement products, one sample of fly ash and one of slag. The determination of these parameters is difficult and use was made of scanning electron microscope and Coulter Counter techniques in addition to conventional sieve and hydrometer tests. Results of the tests were presented and discussed.