Inclusion of nano metakaolin as additive in ultra high performance concrete (UHPC)

The utilisation of nano particles to enhance concrete can be seen in its densification and refining. In this study, nano metakaolined UHPC mixes were used as an additive range of 1%, 3%, 5%, 7%, 9% and 10% from cement weight. All UHPC specimens were compared to the plain UHPC and metakaolined UHPC mixes. The effect of nano metakaolined UHPC was evaluated in the forms of workability in fresh state, strength property and the morphology of the microstructure in the UHPC. The determination of the fresh property was conducted by a workability test. Meanwhile, the strength property was conducted by compressive strength in 3, 7 and 28 days. Next, the morphology in the UHPC microstructure was analysed by Scanning Electron Microscope (SEM). The uniqueness and difference morphology formation was analysed and compared to the plain UHPC. It can then be concluded that the nano metakaolined UHPC mix contributed to a low workability effect due to its clay properties and ultrafine size as compared to the OPC and metakaolin. The inclusion of nano metakaolin in UHPC shows similar compressive strength at early age but gradually increased at later ages as compared to the plain UHPC and metakaolined UHPC.