Study on Toughening and Temperature Sensitivity of Polyurethane Cement (PUC)

Area of Science:

• Materials Science
• Civil Engineering
• Structural Engineering

Background:

• Polyurethane cement (PUC) is widely used for reinforcing aging bridges.
• PUC exhibits limitations including poor toughness, temperature-dependent properties, and brittle failure, risking structural integrity.
• These issues can compromise reinforcement effectiveness and lead to bridge collapse.

Purpose of the Study:

• To enhance the toughness and improve the mechanical properties of PUC.
• To investigate the flexural strength of fiber-reinforced PUC under varying temperatures (-40°C to +40°C).
• To develop a predictive model for PUC flexural strength based on fiber content and temperature.

Main Methods:

• Incorporation of polyvinyl alcohol (PVA) fiber, carbon fiber, and steel fiber into PUC.
• Conducting flexural tests and scanning electron microscopy (SEM) analyses.
• Developing a two-factor (fiber content, temperature) Backpropagation (BP) neural network model.

Main Results:

• Optimal fiber volume ratios identified: 0.3% for PVA, 0.04% for carbon, and 1% for steel.
• Flexural strength initially increased with fiber content, then decreased, with excessive amounts negatively impacting properties.
• Flexural strength decreased as temperature increased for both fiber-reinforced and control samples.
• The BP neural network model accurately predicted flexural strength, showing good agreement with experimental data.

Conclusions:

• Fiber reinforcement significantly improves PUC toughness and mechanical performance within optimal ratios.
• Temperature negatively affects the flexural strength of PUC, necessitating consideration in structural design.
• The developed BP neural network model provides an effective tool for predicting PUC flexural strength, aiding in structural analysis and design.