Effects of blades inside a nozzle on the fiber orientation and distribution in fiber-reinforced cement-based materials

Abstract

This study developed a nozzle with blades inside called the B-nozzle to improve the fiber orientation and distribution in fiber-reinforced cement-based materials. Numerical simulations were conducted to determine the shape parameters of the B-nozzle while considering the physical interactions between the flow of the cementitious material, the boundaries of the nozzle, and the movement and rotation of the fiber. Based on the shape parameters of the B-nozzle designed from the numerical simulations, experiments were conducted for two sizes of B-nozzles with diameters of 80 and 100 mm to evaluate the influence of the blades on the fiber orientation and distribution. Pouring equipment was also fabricated to maintain the flow direction and initial pressure condition during the tests. The dimensions of the specimen are defined as 130 mm × 130 mm × 260 mm in consideration of the sizes of the fiber and nozzle. A specimen was cut into six pieces to measure the fiber orientation and distribution on the cutting surfaces using image acquisition and processing techniques. Compared to conventional circular nozzles, the B-nozzles increased the mean fiber orientation coefficients by approximately 31–39% and the fiber distribution coefficients by 3–23%.