Hygral Behavior of Superabsorbent Polymers with Various Particle Sizes and Cross-Linking Densities.

Kyong-Ku Yun,Wonchang Choi,Kwan-Kyu Kim,Jung Yeon

doi:10.3390/polym9110600

Kyong-Ku Yun, Wonchang Choi + Show 2 more

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https://doi.org/10.3390/polym9110600

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Journal: Polymers	Publication Date: Nov 10, 2017
Citations: 20	License type: CC BY 4.0

Affiliation: Kangwon National University, Gachon University

Abstract

This study focuses on investigating the effects of particle size and cross-linking density on the hygral behavior of superabsorbent polymers (SAPs), which are increasingly used as an internal curing material for high-performance concrete. Four SAPs with different mean particle diameters and cross-linking densities were tested under controlled wetting and drying conditions to measure free absorption and desorption kinetics. Absorption capacities of SAPs under actual mixing conditions were additionally measured and verified by means of mortar flow and semi-adiabatic hydration heat measurements. In addition, the effects of SAP type and dosage (i.e., 0.2, 0.4, and 0.6% by mass of cement) on the mechanical properties of hardened mortar were assessed. The results indicated that: (1) the absorption capacity increased with decreased cross-linking density and increased particle size under both load-free and mixing conditions; and (2) the greater the cross-linking density and the lower the particle size, the shorter the desorption time. It was also confirmed that while the early-age mechanical properties were more related with the gel strength of swollen SAP, the later-age mechanical properties were more affected by the water retention capacity and spatial distribution of SAP in the matrix.

Highlights

Superabsorbent polymers (SAPs) are lightly cross-linked polymeric materials that are capable of quickly absorbing a substantial amount of water or aqueous solutions by osmotic pressure [1]
The absorption responses of superabsorbent polymers (SAPs) exposed to distilled water and cement filtrate are presented in
The initial absorption ratealkaline was greatest for SAP Bofinthe both distilled water and filtrate due osmotic pressure that drives fluid uptake of

Summary

Introduction

Superabsorbent polymers (SAPs) are lightly cross-linked polymeric materials that are capable of quickly absorbing a substantial amount of water or aqueous solutions by osmotic pressure [1]. It is well recognized that 1 g of SAP could absorb up to 500 g of aqueous solutions within a few minutes [1,2] Taking advantage of such super-absorptive characteristics, SAPs have been popularly used in the hygiene, agriculture, forestry, and medical industry since the 1970s [3,4]. Most of the latest studies focused on tackling autogenous shrinkage occurring in high-performance cement-based materials with a low water-to-binder ratio as SAPs can serve as internal reservoirs to supply extra curing water to drying areas (so called “internal curing”), caused by self-desiccation [1,7,8,9,10,11]. Other works performed include the effects of SAP additions on mechanical properties [8,12,13,14,15], rheological properties [16,17,18], self-sealing [19,20,21,22]

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