The Influence Of Basalt Fiber On The Printable And Mechanical Properties Of 3D Printed Concrete

Basalt fiber is a fiber material with good mechanical properties,excellent chemical stability,natural silicate compatibility and high cost performance.Basalt fiber is mixed into 3D printed concrete to solve problems such as weak interlayer bonding,difficult steel structure measures,insufficient ductility,and plastic cracking.The addition of fibers will not only affect the mechanical properties of 3D printed concrete,but also affect the rheological properties.It has an impact on the extrudability and buildability of3 D printed concrete.Research on the influence of basalt fiber properties on the rheological properties,printability and mechanical properties of 3D printed concrete is of great significance for guiding the practical application of 3D printed concrete structures.Basalt fiber content,length,diameter and other characteristics are considered as research objects.Experimental devices such as HC1009 concrete printer,concrete rheometer,and press were used to carry out 3D printing concrete rheological properties,printability and mechanical properties tests.A combination of theoretical analysis,experimental research and finite element simulation is adopted.The influence of basalt fiber properties on the rheological properties,printability and mechanical properties of 3D printed concrete was studied.The following main research results have been achieved:(1)The influence of basalt fiber on the working performance of 3D printed concrete is clarified.The increase of the basalt fiber content or the decrease of the diameter will cause the increase of the static yield stress and dynamic yield stress of the3 D printed concrete and the decrease of the fluidity.As the length increases,the static yield stress and dynamic yield stress first decrease and then increase.Orthogonal experiments show that the amount of fiber has the largest influence weight on the fluidity,dynamic yield stress and static yield stress of 3D printed concrete,and the smallest influence weight on length.(2)The influence of basalt fiber on the extrudability and constructability of 3D printed concrete has been clarified.The dynamic yield stress is negatively correlated with the amount of extrusion per unit time.When the dynamic yield stress of 3D printed concrete is 280 Pa and the extrusion volume per unit time is 1850 g,the printed strips are continuous and uniform,and the strip width meets the design requirements.3D printed concrete has good extrudability.The static yield stress is positively correlated with the inclination angle of the printed specimen.When the static yield stress of 3D printed concrete is above 900 Pa,and it has a moderate dynamic yield stress(about 280Pa),the printed components have good buildability.(3)The influence of basalt fiber properties on the compressive strength and flexural strength of 3D printed concrete is clarified.Through a single variable test,it is found that basalt fibers of different dosages.Orthogonal experimental test results show that the three factors of length,diameter,and dosage have great differences in the impact weights of the compressive strength and flexural strength of 3D printed concrete for 7 days and 28 days,respectively,dosage>length>diameter.(4)Clarified the influence of basalt fiber on the mechanical anisotropy of 3D printed concrete.The average compressive strength in the X direction is relatively high.For the flexural strength test,the flexural strength of the Z-direction and the Y-direction have increased compared with the cast specimens,and both are greater than the X-direction flexural strength.For the split tensile strength anisotropy test,the split tensile strength of the cast specimen is the highest,the split tensile strength in the Z direction is the highest,and the split tensile strength in the Y and X directions is relatively low.The compressive strength,flexural strength and splitting tensile strength of the printed specimens show obvious anisotropy.(5)The influence of interface bonding properties on the mechanical anisotropy of3 D printed concrete and the failure mode of 3D printed concrete specimens are clarified.Under uniaxial loading,the interface will slide laterally.The damage mainly occurs at the contact interface of the printed specimen perpendicular to the Z direction.The interface damage is mainly shear damage.This paper consists of 32 figures,13 tables and 75 references.