Johnny Ching Ming Ho Senior Lecturer School of Civil Engineering Faculty of Engineering, Architecture and Information Technology Migrating to the use of low-carbon-footprint high-performance concrete with multi-sized fillers Abstract: High performance concrete (HPC) has been widely advocated thanks to its superior performance in strength, workability and segregation stability. However, the cement content in HPC is normally very high at about 40%, which increases the carbon footprint, cost of production and impair the dimensional stability of concrete. To this, the speaker proposes to use multi-sized fillers (limestone and superfine sand in this study) coupled with other supplementary cementitious materials SCM (i.e. fly ash and silica fume) to reduce the cement paste, and hence embodied carbon content and production cost of concrete. Some test data on fresh concrete containing two paste volume of 50% and 40%, as well as water binder ratios of 0.5 and 0.4, with and without using fillers will be presented. From the results, it can be observed that up to 25% partial replacement of cement with limestone and/or super-fine sand, the workability performance of concrete in terms of slump flow, passing ability, filling ability and segregation stability is not adversely affected. The results obtained are inspiring as concrete with even lower paste volume could be produced without jeopardizing the workability performance given that more fillers and superplasticiser are provided. This new type of “low-paste concrete” will not only reduce the carbon footprint of the construction, but also improve the dimensional stability by reduces early thermal cracking, long term creep and shrinkage that is capable of prolonging the structural design life and contributing significantly towards a more sustainable built environment. Biography: Dr Johnny Ho is a Senior Lecturer in the School of Civil Engineering, The University of Queensland. Before joining the university in 2013, he has been working as an Assistant Professor in The University of Hong Kong for 6 years. Regarding practical experience, Dr Ho worked in both Hong Kong and Brisbane offices of Arup on some large scale infrastructure projects such as The Stonecutters Bridge in Hong Kong and the Ipswich Motorway Upgrade (Wacol to Darra) in Brisbane. Dr Ho’s research interests are on low-carbon, low-cost high-performance concrete using filler technology and packing theory, as well as its application in the concrete-filled-steel-tube columns with external confinement.