This article presents the results of an interlaboratory experimental study performed by 13 international research groups within the framework of the activities of the RILEM Technical Committee 225-SAP ''Applications of Superabsorbent Polymers in Concrete Construction''. Two commercially available superabsorbent polymers (SAP) were tested in terms of their influence on the freeze-thaw resistance of ordinary concrete. To test the robustness of the method, all participating laboratories used locally produced materials. Furthermore, following this aim, various accelerated methods were used to estimate the resistance of the concrete to freeze-thaw cycles. The effect of adding SAP was from insignificant to

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.

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Nanotechnologies open up broad prospects for the creation of nanocatalysts, which are being more and more used in solving many problems associated with the protection of environment. Their behavior is directly related to the unique physical and chemical properties that are provided by quantum size effects, as well as the large specific surface area.It is known that the presence of photo catalysts in the construction segment of nanomaterials is becoming more prominent. One of the most significant achievements of the last years are photo catalytic active cement composites, including cements and concretes produced with the use of nanoparticles of titanium dioxide TiO 2 sensibilized through a nanotechnology . Currently they are widely used in practice to produce selfcleaning structures and to make clean an air of megacities.Further research in the field of development of new high-performance photo catalysts based on TiO 2 nanoparticles seems to be very relevant, because such R&D could significantly improve the technical characteristics of photo catalytic cements and concrete.In this paper an improved method to produce photo catalysts has been proposed. New synthesized products are based on TiO 2 nanoparticles applied on different inert carriers, including nanosilica. It was showed that these products can be used as a high performance photo catalyst in cement and cement-gypsum composites suitable for the conversion processes of nitric oxide and volatile organic substances, and air purification. It was determined that performance of the cementitious composites containing synthesized samples is 1,5…3,0 times higher than that for the commercial sample of the nanotitanium dioxide.The use of mechanical mixture of nanotitanium dioxide and inert supports is less effective and subjected to the «dilution law», in general.