1. Two test procedures sholl be published as drafts" of RILEM Recommendations: CIF-test and modified Slab test. The CIF test extends the existing RILEM Recommendation CDF test [1] which was' developed for measuring the scaling under the attack of frost and de-icing agents. The modified Slab test relies' on the Swedish Standard SS137244. 2. The tests are presented to give a basis for gaining experience. 3. The descriptions' shall be based on proposals already distributed to the Committee. 4. Responsible authors' are for CIF-Test M.J. Setzer and for Slab-Test Per-Erik Petersson and Luping Tang. 5. Two inter-laboratory-tests have been performed by RILEM TC 176-IDC in 2000 -one for CIF and one for modified Slab test, each comprising three concretes. The results have been evaluated strictly basing on ISO 5725 by Dr. Auberg and Mrs. Kasparek for CIF and by Dr. Luping Tang for modified Slab test. The results have been cross-checked by the two groups'. RILEM TC 176-IDC decided to use these precision data for the drafts,. 6. The deadline for any comments to the drafts ended Apri130, 2002. 7. The final recommendation shall be published (Helsinki 2002). 8. The internal damage is' a yes~no decision. For the internal damage found by ultrasonic trans# time in CIF test it has' been agreed upon that a damage criterion of R~=0.8 (80%) can be given where a damaged concrete can be distinguis'hed from an undamaged (R,,,, = 1.0) with sufficient statistical precision (3 *se). The test result is assessed by the number of cycles which are passed until damage criterion. II. Comments by the Chairman: 1. It must be taken into account that the results and especially the level of damage is different in both tests CIF test and modified slab test. Therefore, it is not appropriate to compare the simple number even if similar physical parameters or naming are used such as transit time, dynamic elastic modulus and relative length change. 2. Based on the inter-laboratory-test, the measured damage can be up to a factor of 3 higher in CIF than in modified Slab test. 3. The damage levels" criterion as defined herein (CIF) by the transgression below the relative dynamic modulus of O.8 marks' the value where a damaged concrete can be distinguished with su~cient statistical certain&Jkom an undamaged Therefore, it has to be distinguished from the acceptance criterion. 4. The acceptance criterion is" the number of cycles a concrete must survive before the damage criterion is passed 5. RILEM TC 176-1DC is, not prepared at this" time to propose acceptance criteria. Acceptance criteria are in the responsibility of contractors' of committees or standardization. For this, adN'tional data which link the test results with performance under practical conditions are necessary (such conditions can vary considerably based on local and regional climatic conditions).

The CIF test extends the existing RILEM Recommendation CDF test 1 which was developed for measuring the scaling under the attack of fiost and deicing agents. The modified Slab test relies on the Swedish Standard SS 1.37244. 2. The tests are presented to give a basis for gaining experience. 3. The descriptions shall be based on proposals already distributed to the Committee. 4. Responsible authors are for CIF-Test M.J. Setzer and for Slab-Test Per-Erik Petersson and Luping Tang. 5. Two inter-laboratory-tests have been pe~rmed by RILEM TC I76-IDC in 2000 -one for CIF and one for modified Slab test, each comprising three concretes. The results have been evaluated strictly basing on ISO 5725 by Dr. Auberg and Mrs. Kasparek for CIF and by Dr. Luping Tang for modified Slab test. The results have been cross-checked by the two groups. The RILEM TC 176-IDC decided to use these precision data for the drafts. II. Comments by the Chairman: i. It must be taken into account that the results and especially the level of damage is different in both tests. Therefore, it is not appropriate to compare the simple number even if similar physical parameters are used such as transit time, dynamic elastic modulus and relative length change. Based on the interlaboratory test, the measured damage can be up to a factor of 3 higher in CIF than in modified Slab test. 2. The damage levels given in the precision tables are not to be mistaken as acceptance criteria. The RILEM TC I76-IDC is not prepared at this time to propose acceptance criteria. Acceptance criteria are in the responsibility of contractors committees of standardization. For this, additional data which link the test results with performance under practical conditions are necessary (such conditions can vary considerably based on local and regional climatic conditions).

BerichteNaturzugkühltürme sind als Teil moderner Kraftwerke von großer Bedeutung für eine sichere und zuverlässige Energieversorgung. Aufgrund einer sehr komplexen Einwirkung aus Betrieb und Umgebung auf die Kühlturmschale, insbesondere der Innenseite, ist ein zusätzlicher Betonschutz in Form spezieller, kunstharzgebundener Oberflächenschutzsysteme erforderlich. Parallel zur Entwicklung der Kraftwerkstechnologie werden auch die Beschichtungssysteme ständig verbessert, um einen dauerhaften und zuverlässigen Schutz zu erzielen. Aufgrund umfangreicher positiver Langzeiterfahrungen kann so für Kraftwerksbetreiber ein sehr hohes Maß an Sicherheit erreicht werden.

R SUMEHardened cement paste (hcp) is a porous heterogeneous material consisting of dispersed particles like Calcium Silicate Hydrates (C-S-H). These are of micron to nanometer size forming pores on a nanometer scale. Thus, hcp can be regarded as a colloidal system. Surface forces play a dominant role. Adsorbed water molecules interact with the surface. Capillary condensation occurs in the pores below bulk conditions acting in form of capillary and disjoining forces. All these forces are able to alter the structure and properties of the hardened cement paste depending on the moisture content. Pore size distributions were measured with mercury intrusion porosimetry on hcp specimens, which had been prestored over the entire range of relative humidity. Swelling and shrinkage of hcp tubes were also determined. The pore size distribution is corrected for each humidity step regarding the particular porosity, contact angle and volume change. The pore size distribution as a function of relative humidity is nonlinear and characterized by an extreme value in the medium range of humidity.

Naturzugkühltürme sind in jeder Hinsicht außergewöhnliche Bauwerke. Aufgrund der enormen Oberfläche in Verbindung mit vielfältigen Einwirkungen aus Umgebung und Betrieb ist ein besonderer Schutz der Kühlturminnenschalen notwendig. Dieser wird durch die Applikation spezieller kunstharzgebundener Beschichtungssysteme erreicht, so dass eine hohe Dauerhaftigkeit der Stahlbetonstruktur und damit eine entsprechende Wirtschaftlichkeit über die Lebensdauer erreicht wird. Um den Erfolg der Beschichtungsmaßnahme hinsichtlich Materialeigenschaften und Applikation zu gewährleisten, sind umfangreiche Qualitätssicherungsmaßnahmen etabliert worden, wozu vor allem die Prüfung der erreichten Trockenschichtdicke und der Haftung des Systems gehören.Trotzdem gibt es gewisse Unsicherheiten hinsichtlich der Gewinnung der Daten am Objekt, die von einer sehr großen Anzahl unterschiedlicher Parameter abhängt. Dies führt besonders bei so exponierten Bauwerken wie Naturzugkühltürmen häufig zu Diskussionen und unterschiedlichen Auslegungen der erzielten Ergebnisse.