Cracking Mechanism and Life-Cycle Performance Evaluation of Early-Age Concrete Based on Environment-Damage Coupling

Area of Science:

• Civil Engineering
• Materials Science
• Environmental Science

Background:

• Green concrete development faces challenges from environmental factors impacting lifecycle performance.
• Early-age concrete tensile damage effects on thermal conductivity, moisture transport, and their coupling mechanisms are unclear, causing cracking.
• Understanding these coupled effects is crucial for concrete durability and structural integrity.

Purpose of the Study:

• To explore early-age concrete cracking mechanisms under coupled environmental and damage conditions.
• To evaluate concrete performance throughout its lifecycle under various environmental stresses.
• To provide insights into concrete's response to high temperature, humidity variations, and early-age damage.

Main Methods:

• Comparative experiments on concrete performance under high temperature, varying humidity, and early-age damage.
• Monitoring temperature, humidity, and strain variations in concrete specimens.
• Investigating microstructural and compositional evolution, including porosity and hydration degree (Ca/Si ratio).

Main Results:

• Porosity response to ambient humidity differs between restrained (+0.0353%/RH) and unrestrained (-0.0245%/RH) specimens.
• A critical ambient relative humidity of 50% RH was identified, significantly altering the concrete's degree of hydration (Ca/Si ratio).
• Established variation laws for temperature, humidity, and strain, alongside microstructural changes.

Conclusions:

• Environmental conditions and early-age damage significantly influence concrete's lifecycle performance and cracking.
• The identified 50% RH threshold and differential porosity responses offer critical data for predicting concrete behavior.
• Results support enhanced cracking risk assessment and control strategies for concrete structures, particularly thin-walled ones.