Investigations on concretes containing fly ash for use in Qatar.

In Qatar it is permissible to use granulated blastfurnace slag meal, fly ash and microsilica as additions in concrete beside Portland cement. Granulated blastfurnace slag meal accounts for the largest proportion of concrete additions used in Qatar. However, it is not always available in the required quantity because, like the other concrete constituents (with the exception of Portland cement and water), it has to be imported. The aim of these investigations was to check the fundamental suitability of a locally available fly ash in concrete under realistic conditions when compared with a granulated blastfurnace slag that is also regionally available. Test mix formulations were designed on the basis of selected reference concretes and of the QCS 2010 series of standards valid in Qatar, the analyses of the constituent materials and the requirements for the fresh and hardened concrete properties. All the mix formulations were produced and tested in Qatar by a concrete test laboratory. It was found that the use of the available fly ash at lower water/ binder ratios and slightly lower superplasticizer contents led to workability properties that were comparable with the properties of the reference concretes. This confirmed that, regardless of the temperature, fly ash can have a positive effect on the workability properties. As expected, the early strengths of concretes containing fly ash are lower. This is also normally associated with lower evolution of heat. The results of the durability investigations that were carried out showed that concretes containing fly ash can be placed in the same respective durability classes defined in QCS 2010 as the reference concretes containing granulated blastfurnace slag meal. [ABSTRACT FROM AUTHOR]