Improving Freeze–Thaw Resistance of Concrete Road Infrastructure by Means of Superabsorbent Polymers

Craeye, Bart; Cockaerts, Geert; Kara De Maeijer, Patricia

doi:10.3390/infrastructures3010004

Cited by 15 publications

(6 citation statements)

References 14 publications

(9 reference statements)

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“…Superabsorbent polymers (SAP) [ 8 , 9 ] have gained significant interest as additives in concrete due to their unique properties. These are e.g., the mitigation of autogenous [ 10 ] and plastic shrinkage [ 11 ] or increasing the freeze–thaw resistance [ 12 , 13 ]. The most prominent types of SAP are anionic, crosslinked polyacrylates.…”

Section: Introductionmentioning

confidence: 99%

Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete

2020

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Superabsorbent polymers (SAP) are of major interest as materials to control the cement hydration process. The swelling behavior of the SAPs significantly influences the performance of the resulting concrete by slowly releasing polymer-bound water in order to maintain a consistent w/c value. A round-robin test conducted by the RILEM Technical Committee 260-RSC showed that the same batch of polymer can lead to large deviations in concrete performance and this was assumed to originate in different storage conditions of the SAP. In this contribution the change in the performance of two SAPs, a crosslinked poly(acrylate) and a crosslinked poly(acrylate-co-acrylamide), was assessed after ageing in standard climate, at 50 °C, and under UV irradiation. During storage in standard climate or 50 °C, ageing led to dehydration of the SAP, and this subsequently led to a higher water uptake during swelling. By contrast, UV irradiation reduced the water uptake, most likely as a result of photo-crosslinking. Dynamic water vapor sorption experiments indicated a strong dependence of the water uptake on both the ambient humidity and the temperature. As a result, cement mixtures containing SAP must be calculated on the dry mass of the SAP rather than the actual weight on site. A standard procedure of how to pack and handle SAP to be used in concrete is also provided.

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Section: Introductionmentioning

confidence: 99%

Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete

2020

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“…However, the majority of recent studies about SAP have focused on the effect and theory on the shrinkage, hydration and mechanical performances of cement-based materials due to the variation of SAP content and entrained water-to-cement ratios [24,25,26]. There are relatively few studies devoted to the influence of dosing methods of SAP and the majority of the studies choose to add dry SAP powder to other components of the cement-based materials for mixing [27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Performances of Cement Mortar Incorporating Superabsorbent Polymer (SAP) Using Different Dosing Methods

et al. 2019

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Modified cement mortar was prepared by incorporating a superabsorbent polymer (SAP) with two kinds of dosing state, dry powdery SAP and swelled SAP (where the SAP has been pre-wetted in tap water), respectively. The mechanical properties, drying shrinkage and freeze–thaw resistance of the mortars were compared and analyzed with the variation of SAP content and entrained water-to-cement ratios. Additionally, the effect of SAP on the microstructure of mortar was characterized by scanning electron microscopy (SEM). The results indicate that agglomerative accumulation is formed in the voids of mortar after water desorption from SAP and there are abundant hydration products, most of which are C-S-H gels, around the SAP voids. The incorporation of the powdery SAP increases the 28 d compressive strength of the mortars by about 10% to 50%, while for the incorporation of swelled SAP, the 28 d compressive strength of the mortar can be increased by about −26% to 6%. At a dosage of 0.1% SAP and an entrained water–cement ratio of 0.06, the powdery SAP and the swelled SAP can reduce the mortar shrinkage rate by about 32.2% and 14.5%, respectively. Both the incorporation of powdery and swelled SAP has a positive effect on the freeze–thaw resistance of cement mortar. In particular, for powdery SAP with an entrained water-to-cement ratio of 0.06, the mass loss rate after 300 cycles is still lower than 5%.

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“…Many experimental studies have found that SAP improves the freeze–thaw resistance of concrete [11,12,13,14,15]; however, opposite cases have also been reported [13,14,16]. A possible explanation for these conflicting results could be the complex absorption behavior of SAPs in hardened concrete when the concrete is exposed to water.…”

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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Improving Freeze–Thaw Resistance of Concrete Road Infrastructure by Means of Superabsorbent Polymers

Cited by 15 publications

References 14 publications

Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete

Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete

Performances of Cement Mortar Incorporating Superabsorbent Polymer (SAP) Using Different Dosing Methods

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

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