Parameter Study of Superabsorbent Polymers (SAPs) for Use in Durable Concrete Structures
Laurence De Meyst1, Els Mannekens2, Maria Araújo3,4
1Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Tech Lane Ghent Science Park, Campus A, Technologiepark Zwijnaarde 60, B-9052 Ghent, Belgium. Laurence.DeMeyst@UGent.be.
Materials (Basel, Switzerland)
|May 15, 2019
Summary
Superabsorbent polymers (SAPs) improve concrete durability by providing internal curing and reducing shrinkage cracking. Optimizing SAP cross-linking and particle size is key to enhancing concrete properties without compromising strength.
Area of Science:
- Materials Science
- Civil Engineering
- Polymer Chemistry
Background:
- Superabsorbent polymers (SAPs) offer potential for internal curing of concrete, mitigating early-age shrinkage cracking and enhancing structural durability.
- The effectiveness of SAPs in concrete is influenced by their swelling characteristics, water release kinetics, dosage, and particle size.
Purpose of the Study:
- To investigate the impact of varying cross-linking degrees, particle sizes, and soluble content on SAP properties.
- To evaluate the performance of synthesized SAPs in a mortar matrix, assessing workability, hydration kinetics, and mechanical properties.
- To identify optimal SAP characteristics for specific concrete applications.
Main Methods:
- Synthesis of anionic SAPs with controlled cross-linking (0.15-1 mol%) and particle sizes (10-100 µm).
- Measurement of SAP swelling capacity in demineralised water and cement filtrate.
- Incorporation of SAPs into mortar to assess workability, hydration, and compressive strength development.
- Investigation of the effect of soluble fractions on mortar properties.
Main Results:
- Swelling capacity increased significantly with decreased cross-linking degree (from 66 g/g to 270 g/g for 40 µm particles).
- SAPs showed 3-4 times higher swelling in demineralised water than in cement filtrate.
- Mortar workability was maintained with appropriate water compensation; limited flow reduction observed.
- Lowest swelling capacity SAPs exhibited minimal negative impact on compressive strength (23% reduction at 28 days) and hydration.
- Particle size (10-100 µm) did not significantly affect mortar properties.
- Soluble fractions did not impact mortar properties, except for a ~100% increase in setting time.
Conclusions:
- SAP properties, particularly swelling capacity, can be tuned by adjusting cross-linking degree.
- Optimized SAPs can enhance concrete durability through internal curing without significant detrimental effects on fresh or hardened properties.
- The soluble fraction of SAPs primarily affects setting time and can be managed or removed if necessary.
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