Investigating Hydrogel Deposition in 3D Printed Cement Paste Samples for Increased Water Uptake

Abstract

This thesis investigates the effect of in-situ hydrogel deposition on water absorption in additively manufactured cement paste samples. Hydrogels can absorb many times their weight in water and are commonly used in traditional concrete to assist hydration, but become relatively useless after curing. In this project, hydrogel powders were deposited directly onto 3D printed cement paste samples, with the intention of water diffusing through the sample, thus allowing the hydrogels to absorb water after curing is complete. Samples were printed by depositing hydrogels on varying layers, then submerging the cured samples in water. Absorption is measured by changes in mass over time. Results demonstrated that hydrogels consistently increased water uptake, especially within the first hour of submersion, though absorption plateaued after two hours. Samples with higher hydrogel content experienced layer delamination, as well as gels seeping out the sides. While this gave the gels much more room to expand and dramatically increased water uptake, it destroyed the samples. A proposed solution involves modifying print geometry to include internal cavities for hydrogel containment and expansion. These findings support the potential for additively manufactured cement with embedded hydrogels to serve as a passive flood mitigation strategy in urban areas.