Self-sealing of cracks in concrete using superabsorbent polymers

Lee, H.X.D.; Wong, H.S.; Buenfeld, N.R.

doi:10.1016/j.cemconres.2015.09.008

Cited by 234 publications

(131 citation statements)

References 26 publications

(2 reference statements)

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“…Studies have reported on SAP-induced changes in cement composite properties after Jensen et al proposed SAP as a water-entraining admixture for internal curing in high-performance concrete [1,2]. It has been reported that SAPs can reduce the permeability of water through cracks when cracks occur in cement composites [3,4,5,6]. It also has been reported that SAPs heal cracks by supplying moisture to cement composites [7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Influence of Effective Water-to-Cement Ratios on Internal Damage and Salt Scaling of Concrete with Superabsorbent Polymer

et al. 2019

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Superabsorbent polymer (SAP) is attracting attention as a water-entraining admixture that reduces shrinkage or heals cracks in concrete. Cross-linked sodium polyacrylate SAPs, which are the most widely produced SAPs in the global market, are applicable as concrete admixtures. However, there have been contradictory results on the freeze–thaw resistance of concrete with SAPs. This study aims to clarify these results considering the water absorption behavior of SAPs in hardened concrete when effective water-to-cement ratios are different. Firstly, the absorbencies of one kind of cross-linked sodium polyacrylate SAP (SAP_SP) in pore solution and fresh mortar were measured by a tea bag test and flow test, respectively. Pore size distribution, capillary water absorption, and deformation during freeze–thaw cycles were analyzed for mortar samples with varying SAP_SP dosages. In the main tests, concrete samples with three different SAP_SPs/cement ratios (0.1%, 0.2%, and 0.3%) and a reference sample were prepared, and internal damage and salt scaling were measured under freeze–thaw cycles. Because SAP_SP absorbs water in fresh mixtures, additional water was added to the mixture considering the water absorbency of the SAP_SP. It was found that the used SAP_SPs prematurely release their stored water so the effective water-to-cement ratio was increased when a larger amount of SAP_SP was used. The higher effective water-to-cement ratio caused more internal damage and salt scaling due to the weaker cementitious matrix. In addition, mortar samples with a high SAP_SP content show a larger absorption of capillary water than the reference sample. The result can be interpreted by an observation that SAP_SP in air voids absorbs water and expands to relatively large capillary pores or neighbor air voids during the capillary water absorption process.

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Section: Introductionmentioning

confidence: 99%

Influence of Effective Water-to-Cement Ratios on Internal Damage and Salt Scaling of Concrete with Superabsorbent Polymer

et al. 2019

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“…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"), particularly 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] and self-healing [23], early-age restrained cracking [12,24], creep [25,26], thermal coefficient [27], and freeze-thaw resistance [16,28,29]. The findings were not quite different among the studies: (1) additions Polymers 2017, 9, 600 2 of 14 thermal coefficient [27], and freeze-thaw resistance [16,28,29].…”

Section: Introductionmentioning

confidence: 99%

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

Yun

Kim²,

Choi

et al. 2017

Polymers

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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.

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“…Within this research area, different mechanisms are under development. The most common ones use encapsulated polymers (Dry and McMillan 1996;Thao et al 2009;Van Tittelboom et al 2011), calcium carbonate precipitating bacteria (Wiktor and Jonkers 2011;Van Tittelboom et al 2010;Wang et al 2012), or embedded hydrogels (Dennis Lee et al 2010;Kim and Schlangen 2010;Snoeck et al 2013) as healing/sealing agents. The current paper describes a preliminary study to evaluate whether alkaline activators can be used as healing agents in order to obtain self-healing in special types of concrete such as those containing large amounts of unhydrated fly ash (FA) or blast-furnace slag (BFS) particles.…”

Section: Introductionmentioning

confidence: 99%

Activation of Pozzolanic and Latent-Hydraulic Reactions by Alkalis in Order to Repair Concrete Cracks

Gruyaert

Tittelboom

Rahier

et al. 2015

J. Mater. Civ. Eng.

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Abstract:The low degree of hydration of fly ash (FA) and slag (BFS) particles in high-volume FA and BFS concrete offers the possibility to activate the unreacted particles upon crack formation to close the crack. In this paper, a preliminary study is performed to evaluate the use of alkaline activators to stimulate the formation of reaction products in the crack. First, the reaction rates of crushed pastes mixed with alkaline solutions or water were monitored by calorimetry. These tests showed that alkaline activators stimulate the reactions more than water. Secondly, cracked mortar beams were stored in different alkaline solutions or water and the crack self-closing ratio was calculated after microscopic investigation at different time intervals. The results indicated that reference mixes, containing only ordinary portland cement as binder, heal very well autogenously, while a solution of CaðOHÞ 2 þNa 2 CO 3 seems to be the most suitable activator to stimulate crack closing of BFS concrete. Thirdly, the regain in strength due to healing of the cracks was determined. Compared to other self-healing techniques, strength regain is limited (about 10-40%).

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Self-sealing of cracks in concrete using superabsorbent polymers

Cited by 234 publications

References 26 publications

Influence of Effective Water-to-Cement Ratios on Internal Damage and Salt Scaling of Concrete with Superabsorbent Polymer

Influence of Effective Water-to-Cement Ratios on Internal Damage and Salt Scaling of Concrete with Superabsorbent Polymer

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

Activation of Pozzolanic and Latent-Hydraulic Reactions by Alkalis in Order to Repair Concrete Cracks

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