Performance of Repaired Concrete under Cyclic Flexural Loading

Area of Science:

• Materials Science
• Civil Engineering
• Structural Health Monitoring

Background:

• Cyclic loading tests on cement-based repair materials are crucial but time-consuming.
• Limited research exists on accelerated fatigue testing methodologies for these materials.

Purpose of the Study:

• To develop and validate a novel, accelerated cyclic loading regime for evaluating cement-based repair materials.
• To assess the fatigue life and bond strength of different repair mixes using this new method.
• To confirm the applicability of the Palmgren-Minder rule for fatigue life estimation in accelerated testing.

Main Methods:

• Implementation of a novel loading regime with increasing stress amplitude to expedite testing.
• Application of the Palmgren-Minder rule for estimating fatigue life of repaired specimens.
• Comparative analysis of fatigue performance, slant, and splitting bond strength across different repair mixes (Mix M, Mix S).

Main Results:

• Specimens repaired with Mix M exhibited the longest fatigue life (95,991 cycles) and highest fatigue endurance limit (77.4%).
• Mix M also demonstrated superior slant and splitting bond strength compared to other mixes.
• The estimated fatigue endurance limit for Mix S (70.8%) closely matched literature values (71%) obtained via traditional methods.
• The novel loading regime produced comparable results to traditional methods, significantly reducing test duration.

Conclusions:

• The novel accelerated cyclic loading regime is effective in shortening test processes for cement-based repair materials while yielding reliable results.
• The Palmgren-Minder rule is a useful tool for estimating fatigue life under accelerated testing conditions.
• Mix M shows significant promise as a high-performance repair material due to its superior fatigue life and bond strength.
• Future research should refine failure criteria for improved prediction accuracy, especially for specimens with high endurance.