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

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 a particular cement distributed to every participant and a local cement chosen by the participant. Two absorption test methods were 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 h. However, absorption followed by intrinsic, ionmediated desorption of a specific SAP sample in the course of time was not detected by the filtration method. This SAP-specific characteristic was only displayed by the tea-bag method. This demonstrates the practical applicability of both test methods, each one having their own strengths and weaknesses at distinct testing times

Recommendations of RILEM TC 260-RSC for using superabsorbent polymers (SAP) for improving freeze–thaw resistance of cement-based materials

This recommendation is focused on application of superabsorbent polymers (SAP) for the improvement of the resistance of cement-based materials to freeze—thaw attack with or without deicing salts. A simple approach to the determination of the amount and properties of SAP as well as methods to verify SAP effectiveness for frost resistance protection are presented

Textile-reinforced concrete to realise ultra high durability concrete (UHDC) in the framework of the EU H2020 project "ReSHEALience"

The EU H2020 project “ReSHEALience” (rethinking coastal defence and green-energy service infrastructures through enhanced-durability high-performance cement-based materials) focuses on a holistic approach to create ultra-high durability concrete (UHDC) encompassing the concept and development of advanced materials and tailored design approaches to provide innovative structural solutions. One kind of cement-based composites to realise UHDC structures is textile-reinforced concrete (TRC), in which multiple layers of carbon multifilament yarns composed to a fabric serve as the reinforcement. TRC exhibits multiple micro-crack formation upon tensile loading with fairly small individual crack opening widths, below about 100 µm under service conditions. This characteristic in conjunction with functional admixtures is expected to reach a pronounced self-healing propensity of the cement-based matrix even under very harsh XS exposure conditions. Subsequent to durability-related laboratory experiments regarding sea water as the aggressive medium, two real-scale demonstration projects will be implemented, specifically a breakwater on the Irish west coast and the restoration of a historic water reservoir tower in Malta. This paper presents the concept of TRC development towards a UHDC, outlines the characteristics of the two demonstrators and some preliminary laboratory result

Characterization data of reference materials used for phase II of the priority program DFG SPP 2005 “Opus Fluidum Futurum – Rheology of reactive, multiscale, multiphase construction materials”

A thorough characterization of base materials is the prerequisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone powder, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and mineralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program