Selection of Reinforcing Fiber for High-strength Lightweight Concrete for 3D-Printing

Abstract

Abstract The knowledge of cement concretes and the availability of raw materials allows them to be used for 3D-printing technology in construction. One of the ways to increase the strength and reduce the shrinkage of the extruded layers is the introduction of reinforcing fibers into the mixture. An important task is the selection of effective types and concentrations of fiber. In this work, research on the selection of such fibers for compositions of high-strength lightweight concrete on hollow microspheres has been carried out. The optimal content of fiber which provides an acceptable decrease in mobility and the greatest strength of concrete is 1.25…1.5 % of the mass of Portland cement. It was found that the studied concretes on hollow microspheres have a reliable connection at the «steel-concrete» interface. The adhesion strength to metal reinforcement with a diameter of 8…12 mm is 6.1… 10.1 MPa with a relative deformation of 0.097…0.025 mm/mm. High-strength lightweight fiber-reinforced concrete has low air permeability parameters, corresponding to the high water permeability grade W20. Such concrete with an average density of 1400 kg/m3 has high frost resistance F1800.