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Crack-Resistant Cements under Drying: Results from Ring Shrinkage Tests and Multi-Physical Modeling
Vít Šmilauer1, Pavel Reiterman2, Rostislav Šulc3
1Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic.
Materials (Basel, Switzerland)
|June 24, 2022
Summary
Cementitious materials prone to drying shrinkage cracks can be made more resistant by using cements with slower strength gain, lower fineness, and higher slag content. Custom-formulated cements significantly improve crack resistance compared to commercial options.
Area of Science:
- Materials Science
- Civil Engineering
- Construction Materials
Background:
- Cementitious materials are susceptible to drying shrinkage, leading to cracking under restraint.
- Cements with slower strength gain generally exhibit enhanced resistance to cracking during external drying.
Purpose of the Study:
- To evaluate the cracking tendency of various cements using the ring shrinkage test.
- To investigate the influence of cement properties (fineness, slag substitution) on crack resistance.
- To propose criteria for crack-resistant cements.
Main Methods:
- Conducted ring shrinkage tests on 25 mortar specimens.
- Utilized 10 commercial cements and 15 custom-formulated cements (including Portland and blended cements with up to 30% slag).
- Employed a hygro-mechanical model to simulate strain evolution and crack formation.
Main Results:
- Restrained ring cracking time increased with lower Blaine fineness and higher slag substitution.
- Proposed upper limits for crack-resistant Portland cements: 2-day compressive strength of 27.7 MPa and Blaine fineness of 290 m²/kg.
- Hygro-mechanical model accurately predicted strain evolution, crack formation, and failure.
Conclusions:
- Custom-formulated cements demonstrated superior crack resistance compared to commercial cements.
- Only 20% of commercial cements met crack-resistant criteria, while 67% of custom cements did.
- Cement properties like fineness and slag content are critical for mitigating drying shrinkage cracking.
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