Effect of Polypropylene fibres on the Workability parameters of Extrudable Cementitious Material

Additive manufacturing in construction industry has been introduced as an aspiration for a more sustainable built environment and currently evolving with high demand amongst researches. This study is an investigation of the influence of polypropylene (PP) fibre addition on the workability parameters of a new extrudable concrete mixture. As the quality of final printed structure prominently depends on the fresh state properties of concrete, this investigation mainly focused on the rheological properties such as workability (flow), setting time, extrudability and buildability. These parameters were systematically investigated through a small scale experimental process with time after mixing. The selected control mix with Ground granulated blast furnace slag (GGBS) and Silica Fume (SF) was used in this analysis. The Control cementitious specimens without fibre inclusion and with fibre addition in different volume fraction of binder, ranging from 0.5% to 3% were printed. The results showed that the fibre addition of 0, 0.5 and 1.0% have the better flowability and extrudability compared to 1.5, 2 and 3%. Also, reduction in the print quality was assessed visually with increasing fibre percentage. However, results indicated that the initial setting time is comparatively low for those mixes with higher fibre inclusion which is required for better bond strength between layers. Moreover, higher fibre content caused better buildability and shape retention in the extruded samples.