Mechanical Reinforcement of Cementitious materials with Cellulose Acetate Produced by Electrospinning

Abstract

This master thesis explores the use of cellulose acetate (CA) microfibers as reinforcement for cementitious composites to improve their mechanical properties. The study focused on the production of nanofiber using the electrospinning process and the incorporation of fiber into cement. A systematic review was conducted to identify the steps involved in producing the nanofibers through electrospinning and the techniques for mixing fibers with cement.

The analyses reveal that electrospinning parameters such as applied voltage, flow rate, tip-to-needle distance, and polymer solution significantly impact the fiber morphology and diameter. The electrospinning parameter for this experiment was set at a tip-to-needle distance of 15cm, voltage of 15kv, and flow rate of 5,9 ml/hr to produce a continuous fiber. Two methods for incorporating the fibers into cement were explored. The first method was an improved collector technique, and the second method was the post-treatment of fiber in the ultrasonication process. The incorporating methods showed similar results for mechanical properties. The results showed that CA fibers enhanced the early-stage flexural strength but decreased significantly in long-term performance due to the quality of the fiber and high water-to-cement ratios. The compressive strength results showed minimal variation compared to the fiber-free sample. The CA fibers didn’t lead to a significant improvement in the compressive strength.

Challenges encountered during electrospinning included polymer clogging at the needle tip due to the high volatility of acetone, which also affects fiber morphology, leading to bead formation and increased fiber diameters. CA affected the workability of cement paste, which may reduce the interfacial bonding in the cement matrix. Recommendations for future research include exploring co-solvents or low-volatility solvents, reducing fiber diameter, and optimizing water-to-cement ratios to enhance composite performance.