Testing superabsorbent polymer (SAP) sorption properties prior to implementation in concrete: results of a RILEM Round-Robin Test

Abstract

This article presents the results of a round-robin test performed by 13 international research groups in the framework of the activities of the RILEM Technical Committee 260 RSC "Recommendations for use of superabsorbent polymers in concrete construction". Two commercially available superabsorbent polymers (SAP) with different chemical compositions and gradings were tested in terms of their kinetics of absorption in different media; demineralized water, cement filtrate solution with particular cement distributed to every participant and local cement chosen by the participant. Two absorption test methods were 2 considered; the tea-bag method and the filtration method. The absorption capacity was evaluated as a function of time. The results showed correspondence in behaviour of the SAPs among all participants, but also between the two test methods, even though high scatter was observed at early minutes of testing after immersion. The tea-bag method proved to be more practical in terms of time dependent study, whereby the filtration method showed less variation in the absorption capacity after 24 hours. However, absorption followed by intrinsic, ion-mediated desorption of a respective SAP sample in the course of time was not found by the filtration method. This SAP-specific characteristic was only displayed by the teabag method. This demonstrates the practical applicability of both test methods, each one having their own strengths and weaknesses at distinct testing times.

Autogenous Healing in Strain-Hardening Cementitious Materials With and Without Superabsorbent Polymers: An 8-Year Study

“…An issue which may be important is the possible degradation of a SAP in time, especially in the harsh alkaline environment such as pore solution or the cementitious matrix (Vandenhaute et al, 2017). Also, the exposure to UV light may be detrimental for the use of SAPs in time, as their swelling capacity may decrease over time and may completely dissolve or carbonate (Mechtcherine et al, 2018). With the polymers used in this research, no degradation was found.…”

A Review of Self‐Healing Concrete for Damage Management of Structures

“…Attention should thus be paid when comparing water penetration in specimens with and without SAPs as the microstructure of these samples is different. Moreover, it has to be mentioned that the swelling of SAPs in cementitious materials, as determined mainly by the tea‐bag method (proved to be more practical in terms of time‐dependent study) or the filtration method (less variation in absorption after 24 h, but not detecting polymer‐inherent desorption), is always lower than in plain water . This is due to the interaction of SAP‐ionic groups with the large variety of ionic species that can be found in the cement matrix (as K + , Na + , SO 4 2− , and OH − ) and which are dependent on the type of cement, age of the specimen, and the use of alternative binders and additives.…”

Characterization of Polyacrylamide based Superabsorbent Polymers for potential use in PC Matrices with Supplementary Cementitious Materials

“…Table 1 shows chemical compositions and selected physical characteristics of the supplementary cementitious materials. Filtrate solutions with different proportions of SCMs (Table 2) have been prepared in a water/binder ratio of 5 (Mechtcherine et al 2018). Binders have been immersed and stirred in deionised water for 24 hours.…”

“…Binders have been immersed and stirred in deionised water for 24 hours. After this time the binder slurry was filtrated to obtain the required filtrate solution (Mechtcherine et al 2018;Schröfl et al 2017).…”

“…In an effort to reduce this cracking susceptibility, Superabsorbent polymers (SAPs) have been proved a promising internal curing agent for concrete and mortars (Bentz and Jensen 2004;Jensen andHansen 2001, 2002;Mechtcherine et al 2013;Mechtcherine and Reinhardt 2012;Mignon et al 2017;Snoeck et al 2015). Also, SAPs are able to control water supply in fresh and hardened state, and hence to help extended hydration reactions of SCMs (Almeida and Klemm 2018;Beushausen et al 2014;Klemm and Sikora 2013;Snoeck et al 2014). Moreover, absorption capacities and kinetics of SAPs' ab-desorption have a critical impact on concrete mix design.…”