Freeze-Thaw Behavior and Degradation Modeling of Shale-Based Lightweight Structural Concrete

Area of Science:

• Materials Science
• Civil Engineering
• Structural Engineering

Background:

• Freeze-thaw cycles cause significant damage and strength loss in concrete, exceeding the capabilities of traditional empirical models.
• Shale-based lightweight structural concrete (LSC) offers potential for improved durability in cold environments.
• Accurate modeling of concrete degradation under freeze-thaw conditions is crucial for structural integrity in cold regions.

Purpose of the Study:

• To investigate the mechanical performance and freeze-thaw resistance of shale-based lightweight structural concrete (LSC).
• To develop a stochastic degradation model for predicting the compressive strength of LSC under freeze-thaw cycles.
• To provide a scientific basis for the structural design of concrete in cold regions.

Main Methods:

• Experimental testing of LSC specimens (LSC20-LSC50) under various freeze-thaw cycles.
• Analysis of mass loss, relative dynamic elastic modulus, and compressive strength degradation.
• Development and validation of a Gamma process-based stochastic degradation model for compressive strength.

Main Results:

• Compressive strength degradation of LSC increases with freeze-thaw cycles but eventually stabilizes.
• Low-strength LSC deteriorates faster than high-strength LSC.
• LSC30 and LSC50 exhibited significantly lower strength degradation (32.66% and 29.79% respectively) compared to ordinary concrete after 200 cycles.
• The Gamma process model demonstrated high accuracy (R² > 0.96) in predicting LSC strength degradation.

Conclusions:

• Shale-based lightweight concrete demonstrates superior freeze-thaw resistance compared to ordinary concrete.
• The developed Gamma process model accurately predicts the stochastic degradation of LSC compressive strength.
• The findings support the use of LSC in structural applications in cold regions, enhancing durability and safety.