Liu, M.; (2009) Wider application of additions in self-compacting concrete. Doctoral thesis , UCL (University College London).

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Abstract

Compared to normally vibrated concrete (NVC), self-compacting concrete (SCC) possesses enhanced qualities and improves productivity and working conditions due to the elimination of compaction. SCC generally has a higher powder content than NVC and thus it is necessary to replace some of the cement by additions to achieve an economical and durable concrete. The established benefits of using low volumes of fly ash in SCC, high volumes of fly ash in NVC and the search for uses of waste glass led to the research on the possibilities of use higher fly ash contents than hitherto and ground glass as an addition in SCC whilst maintaining satisfactory properties. Mix design methods, tests, target properties and constituent materials were selected. This was followed by investigating the influence of fly ash and ground glass on the mortar fraction of the SCC and then using these results to produce concrete mixes with the target fresh properties. Hardened concrete of these mixes were measured and the relationships between these investigated. The results show that for constant filling ability of the SCC, replacement of cement with fly ash or ground glass requires an increase in water/powder ratio and a reduction in superplasticiser dosage. Both additions degraded the passing ability, consistence retention and hardened properties but not to a prohibitive extent. SCC with up 80% cement replaced by fly ash or glass volume ratio of 6.4% is possible and the material properties of SCC are similar to those of NVC. Also the UCL method of mix design was extended to higher coarse aggregate contents and different additions. The project can lead to the use of higher volume fly ash and ground glass in SCC, thus widening the types of additions available for SCC, saving landfill and reduce CO2 emissions by the use of less cement.

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