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Evaluation of Concrete Structural Cracking Behavior Induced by Early Drying Shrinkage
Mengxi Zhang1,2, Chuntian Lu3, Qiaolin Min2
1State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China.
Materials (Basel, Switzerland)
|January 25, 2025
Summary
This study calibrated early drying shrinkage coefficients for hydraulic cement mortars using laboratory experiments and mesoscale modeling. Findings guide crack prevention in concrete structures, particularly roller-compacted concrete dams.
Area of Science:
- Materials Science
- Civil Engineering
- Computational Mechanics
Background:
- Early drying shrinkage in concrete can lead to cracking, impacting structural integrity.
- Understanding factors influencing shrinkage is crucial for durable concrete construction.
Purpose of the Study:
- To calibrate early drying shrinkage coefficients for moderate-heat Portland cement (MHPC) and low-heat Portland cement (LHPC) mortars.
- To develop and validate an improved mesoscale model for simulating concrete's early drying shrinkage.
- To investigate the influence of ambient humidity, cement type, and aggregate volume ratio on concrete shrinkage.
Main Methods:
- Laboratory experiments were conducted to calibrate shrinkage coefficients.
- An improved mesoscale modeling approach was developed to simulate concrete at the mortar, aggregate, and ITZ level.
- 3D simulations were validated against experimental data, showing less than 4.99% error after 28 days.
Main Results:
- The early drying shrinkage coefficient for LHPC was found to be approximately 82% of MHPC.
- Ambient humidity influences concrete shrinkage up to a depth of about 15 mm after 28 days.
- Increasing ambient humidity or aggregate volume ratio effectively controls early drying shrinkage and reduces mass-loss rate.
Conclusions:
- The developed mesoscale model accurately predicts concrete early drying shrinkage.
- Findings provide theoretical guidance for crack prevention strategies in concrete structures, especially roller-compacted concrete (RCC) dams.
- Optimizing ambient humidity and aggregate content can mitigate shrinkage-induced cracking in dams.
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01:20Microcracking in Concrete
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01:28Types of Non-structural Cracks in Concrete
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01:27Shrinkage in Concrete
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Shrinkage in concrete is primarily due to water loss from evaporation, hydration of cement, or carbonation, leading to a reduction in volume. The volumetric contraction results in volumetric strain in concrete. However, in practice, shrinkage is measured as linear strain, which is one-third of the volumetric strain.
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01:23Behavior of Concrete Under Compressive Load
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Concrete exhibits specific behaviors under different compressive loads. Understanding this is crucial for understanding its structural integrity. When concrete undergoes uniaxial compression, it tends to develop cracks that run parallel to the direction of the force. These parallel cracks stem from localized tensile stresses that occur perpendicular to the compression direction. Additionally, angled cracks may appear due to the formation of shear planes.
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