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.
Vier verskillende kleimateriale wat in die Wes-Kaap voorkom, is uitgesoek vir evaluasie as kunsmatige possolane. Die ondersoek het getoon dat die graad van possolaniese aktiwiteit wat in hierdie materiale ontwikkel kan word hoofsaaklik afhanklik is van die verhouding van kaoliniet (kleibestanddeel) teenwoordig en dat die temperatuur van kalsinering van minder belang is. Kleimateriale van hierdie gebied met 'n hoë kaolinietinhoud en wat by 'n betreklike lae temperatuur gekalsineer is, sal uitstekende possolane uitmaak, met die potensiaal om die afbrekende uitsetting as gevolg van die alkali-aggregaatreaksie in beton te bekamp.
A basis for 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.