Study on Anisotropic Mechanical Properties of 3D Printed Concrete with Full Recycled Coarse Aggregate
Nature coarse aggregate(NCA)and recycled coarse aggregate(RCA)concrete were prepared using coarse aggregates with particle sizes ranged from 4.75mm-10 mm,and their printability as a 3D printing ink was comparatively evaluated.The effects of different curing conditions on the anisotropic mechanical properties of 3D printed concrete after hardening were also explored.The experimental results show that compared with NCA,the full replacement of RCA can accelerate the loss of workability of the printing ink.Through the scientific regulation of the mix ratio,the printable ink can still maintain printability after 10 min of resting,which can be increased to 20 min under continuous printing.Compared to standard curing,the 7d strength loss of natural and recycled specimens under natural curing is 19.84%and 20.13%,respectively.The relationship between the anisotropic compressive strengths was X-axis(print direction)>Z-axis(stacking direction)>Y-axis(drive shaft direction,vertical X-axis).The Y-axis compressive strengths of the natural and recycled printed specimens were 83.41%and 84.27%of the X-axis,showed significant anisotropy at 28d of standard curing.Finally,the formation mechanism of anisotropy by aggregate type and 3D printing interlayer properties was elucidated from the micro viewpoint.
3D printingfull recycled coarse aggregatesprintabilityanisotropicmaintenance conditions
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