Sustainable bridge strengthening techniques with UHPC overlay systems for jointless structures

Area of Science:

• Materials Science
• Civil Engineering
• Structural Engineering

Background:

• Jointless bridge structures offer advantages but require robust overlay systems.
• Ultra-high-performance concrete (UHPC) is a promising material for structural enhancement.
• Evaluating UHPC overlay performance is crucial for bridge durability and longevity.

Purpose of the Study:

• To assess the mechanical properties, durability, field behavior, and numerical response of UHPC overlay systems for jointless bridges.
• To compare a standard UHPC mix with a fly ash-modified UHPC mix.
• To determine the effectiveness of UHPC overlays in improving structural performance and sustainability.

Main Methods:

• Laboratory testing of UHPC mixtures (standard and fly ash-modified).
• Pilot-scale field applications on jointless bridge sections.
• Finite element analysis to model structural response.

Main Results:

• Standard UHPC achieved 162 MPa compressive strength and 23.0 MPa flexural strength; fly ash-UHPC achieved 156 MPa and 21.5 MPa, respectively.
• Both UHPC mixes demonstrated bond strengths 125% above specification requirements, ensuring strong substrate adhesion.
• UHPC overlays improved load distribution, reduced cracking, and enhanced resistance to thermal and environmental factors in bridge sections.

Conclusions:

• UHPC overlay systems significantly enhance the structural response and durability of jointless bridge sections.
• Fly ash-modified UHPC provides a viable, sustainable alternative, reducing cement content without compromising key mechanical properties.
• The study validates UHPC overlays as an effective solution for improving bridge infrastructure performance and extending service life.