Aggregate gradation impacts on fresh properties of 3D concrete printing mixtures

3D printed concrete (3DPC) offers potential benefits in construction efficiency, labor reduction, and material optimization, but its widespread adoption is limited by reliance on cement-rich mortar mixes and the lack of standardized mixture design frameworks. Existing literature on 3DPC identifies qualities of printable mixtures, such as a range in fluidity/rheology where the mixture’s pumpability, extrudability, and buildability requirements are met. However, no comprehensive framework exists to optimize aggregate gradation and paste volume, thereby reducing cement content, to meet targeted fresh property requirements for printability. This research study employed an experimental central composite design to quantify the effects of sand fineness and sand content on rheology, extrusion pressure, and forced bleed stability in 3DPC mixtures containing Type IL Portland cement, a three aggregate blend (coarse and two sand), and water. Test results show that concrete yield stress is predictable using the Chateau-Ovarlez-Trung model, which depends on aggregate void content, and the proposed excess paste film thickness model, which incorporates aggregate specific surface area. An increase in the sand content resulted in higher (shear and extrusion) yield stress while reducing the sand fineness reduced the bleed rate, improving mixture stability for pumping. The combined aggregate gradations evaluated had minimal effect on the predicted pipe-flow pressures in pumping because the lubrication layer rheology is largely determined by the makeup of the cement paste, which was held constant. The proposed framework offers a practical starting point for designing 3DPC mixtures (i.e., selecting constituents and proportions) with lower cement and higher coarse aggregate contents without sacrificing print performance.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Manaugh, Benjamin

Contributors dc:contributor

• Roesler, Jeffery R

• 3D-printing
• concrete
• rheology
• gradation

Statement dc:rights

• Copyright 2025 Benjamin Manaugh

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132693

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132693