Flexural Response Comparison of Nylon-Based 3D-Printed Glass Fiber Composites and Epoxy-Based Conventional Glass Fiber Composites in Cementitious and Polymer Concretes

Abstract

With 3D printing technology, fiber-reinforced polymer composites can be printed with radical shapes and properties, resulting in varied mechanical performances. Their high strength, light weight, and corrosion resistance are already advantages that make them viable for physical civil infrastructure. It is important to understand these composites' behavior when used in concrete, as their association can impact debonding failures and overall structural performance. In this study, the flexural behavior of two designs for 3D-printed glass fiber composites is investigated in both Portland cement concrete and polymer concrete and compared to conventional fiber-reinforced polymer composites manufactured using a wet layup method. Thermogravimetric analysis, volume fraction calculations, and tensile tests were performed to characterize the properties of the fiber-reinforced polymer composites. Flexural testing was conducted by a three-point bending setup, and post-failure analysis was performed using microscopic images. Compared to concretes with no FRP reinforcement, the incorporation of 3D-printed glass-fiber-reinforced polymer composites in cementitious concrete showed a 16.8% increase in load-carrying capacity, and incorporation in polymer concrete showed a 90% increase in flexural capacity. In addition, this study also provides key insights into the capabilities of polymer concrete to penetrate layers of at least 90 microns in 3D-printed composites, providing fiber bridging capabilities and better engagement resulting in improved bond strength that is reflected in mechanical performance. The polymer material has a much lower viscosity of 8 cps compared to the 40 cps viscosity of the cement slurry. This lower viscosity results in improved penetration, increasing contact surface area, with the reinforcement consequently improving bond strength. Overall, this work demonstrates that 3D-printed fiber-reinforced polymer composites are suitable for construction and may lead to the development of advanced concrete-based reinforced composites that can be 3D-printed with tailored mechanical properties and performance.

Keywords: 3D printed; fiber-reinforced polymer; flexure; glass fiber; methyl methacrylate; polymer concrete.

Figure 1

(a) Schematic showing 3D printer components. (b) Microscopic image taken to show precision of printed fiber angle.

Figure 2

Eiger image and schematic of internal fiber orientations in (a,b) unidirectional 3D-printed GFRP composite and (c,d) multidirectional 3D-printed GFRP composite.

Figure 3

Schematic of three-point bending setup with LVDT placement.

Figure 4

Thermogravimetric analysis of fiberglass filament used for 3D-printed GFRP composite.

Figure 5

(a) Tension test setup; (b) conventional unidirectional GFRP composite installed in the setup; (c) specimen after failure.

Figure 6

Comparison of the same concrete type for the two different reinforcement types. Flexural response of conventional and 3D-printed GFRP composites in (a) Portland cement concrete and (b) polymer concrete. Comparison of the same reinforcement type for the two different concretes for three specimens each of Portland cement concrete and polymer concrete with (c) conventional GFRP composite and (d) 3D-printed GFRP composite.

Figure 7

Load–deflection response of (a) Portland cement concrete showing up to 0.5 mm deflection in (a1) and (b) polymer concrete showing up to 6 mm deflection in (b1).

Figure 8

Comparison of load-carrying capacities.

Figure 9

Comparison of maximum deflections measured using LVDT.

Figure 10

Comparison of crack patterns for (a) Portland cement concrete with conventional GFRP composite, (b) Portland cement concrete with 3D-printed GFRP composite, (c) polymer concrete with conventional GFRP composite, and (d) polymer concrete with 3D-printed GFRP composite.

Figure 11

Microscopic image of (a) Portland cement concrete and (b) polymer concrete demonstrating polymer concrete’s ability to penetrate gaps ranging from 94 micrometers to 440 micrometers.

Figure 12

The role of a fiber/matrix interface in the load transfer mechanics and consequently in fracture propagation.