Experimental study on mechanical properties of steel fiber reinforced 3D printing UHPC
To investigate the mechanical properties and failure modes of 3D printed ultra-high performance concrete(3DP-UHPC),steel fiber reinforced 3DP-UHPC was fabricated in this study and experiments including compression,splitting and bending tests were conducted.The effects of steel fiber content,force direction,and inter-layer interval time on the basic mechanical properties were investigated.The 3DP-UHPC specimens show favorable mechanical properties,and the compressive strength in all three loading directions reaches 160 MPa,with the highest strength exceeding 200 MPa.The compressive strengths in all three directions are enhanced as the content of steel fiber increases.The inter-layer bonding strength decreases by 46.4％ as the printing interval between adjacent layers increases from 0 min to 70 min.When the steel fiber content increases from 0.5％ to 2.0％,the flexural strength at initial cracking increases by 15.0％,and the flexural strength increases by 49.4％.The flexural toughness is also improved.Moreover,the cracking mode changes from single vertical crack to crack deflection,forked cracks at the tip and double major cracks.
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