ERI: Optimizing Interlayer Delay Timing in 3D Concrete Printing Using Rayleigh Waves

Michigan Technological University, Houghton MI

Investigators

Abstract

This Engineering Research Initiation (ERI) award supports research to explore a novel, non-contact, ultrasonic method based on surface-traveling sound waves such as Rayleigh waves to optimize delay timing in three-dimensional (3D) concrete printing. 3D concrete printing is an emerging technology that is increasingly used in the civil engineering industry. However, determining the optimal printing delay time between printed layers remains a major challenge. Stopping and restarting the concrete printing process can cause weak connections between layers, which can lead to layer separation and reduced structural strength. Changes in the surrounding environment, such as temperature and humidity variations, make it difficult to maintain consistency at different construction sites. This research aims to develop a real-time scanning system that monitors the concrete surface without touching it, using Rayleigh waves to track how the material changes over time. By studying how the concrete properties affect the way Rayleigh waves move through it, the project looks to deepen the understanding of how to detect material changes during the printing process. This knowledge has important applications in testing the properties of materials without damaging them, a practice known as non-destructive testing, and improving advanced additive manufacturing. By providing real-time insights into how printed concrete layers bond together, the project aims to make 3D-printed structures safer and more reliable. This research supports the national interest by advancing the science of acoustics and construction materials, contributing to safer infrastructure, and supporting public education. The project will also include a pilot education program in partnership with Michigan Technological University’s Center for Science and Environmental Outreach to raise awareness of non-destructive testing techniques. The primary goals of this research are (1) to elucidate the interaction mechanisms of Rayleigh waves with fresh concrete during the early setting process and (2) to determine how Rayleigh wave characteristics can be used to identify the best time to place the next layer in 3D concrete printing. To achieve these goals, the project seeks to develop a theoretical framework and numerical simulation to predict how the waves respond to changes in surface properties of the concrete, such as plastic viscosity, stiffness, setting time, and the content of the solid particles in the mixture. Laboratory experiments will be conducted to confirm the results of the model and to improve understanding of how the waves respond as the concrete hardens. Experiments will also explore how the characteristics of Rayleigh waves relate to the strength of the connection between printed layers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.