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In the present work the internal sulfate attack on pastes made from pure clinker phases was studied. Two binders were produced: (a) a binder with 2% C3A and 18% C4AF content; (b) a binder with 10% C3A and C4AF content each. Gypsum was used as the sulfate bearing compound, while calcium carbonate added to differentiate the binders produced. The phases formed were identified by XRD analysis. The results showed that ettringite was the deterioration phase detected in the case of the low C3A content binder. Carbonation occurred in the specimen without calcium carbonate addition, while portlandite was observed in the one containing calcium carbonate. In the case of the high C3A content binder, traces of thaumasite were detected when calcium carbonate was not incorporated in the binder. A solid solution of thaumasite and ettringite was found when calcium carbonate was added. The amount of C3A had not fully reacted with sulfates, since its corresponding peaks were detected., {"references":["P. Brown, and R. D. Hooton, \"Ettringite and thaumasite formation in\nlaboratory concretes prepared using sulfate-resisting cements,\" Cem.\nConcr. Compos., vol. 24, pp. 361–370, 2002.","N. J. Crammond, \"The thaumasite form of sulfate attack in the UK,\"\nCem. Concr. Compos., vol. 25, pp. 809–818, 2003.","D. E. Macphee, and S. J. Barnett, \"Solution properties of solids in the\nettringite – thaumasite solid solution series,\" Cem. Concr. Res., vol. 34,\npp. 1591–1598, 2004.","B. Tian, and M. D. Cohen, \"Does gypsum formation during sulfate\nattack on concrete lead to expansion?,\" Cem. Concr. Res., vol. 30, pp.\n117–123, 2000.","M. Santhanam, M. D. Cohen, and J. Olek, \"Effects of gypsum formation\non the performance of cement mortars during external sulfate attack,\"\nCem. Concr. Res., vol. 33, pp. 325–332, 2003.","J. Bensted, \"Thaumasite – direct, woodfordite and other possible\nformation routes,\" Cem. Concr. Compos., vol. 25, pp. 873–877, 2003.","T. Schmidt, B. Lothenbach, M. Romer, K. Scrivener, D. Rentsch, and R.\nFigi, \"A thermodynamic and experimental study of the conditions of\nthaumasite formation,\" Cem. Concr. Res., vol. 38, pp. 337–349, 2008.","M. T. Blanco-Varela, J. Aguilera, and S. Martínez-Ramírez, \"Effect of\ncement C3A content, temperature and storage medium on thaumasite\nformation in carbonated mortars,\" Cem. Concr. Res., vol. 36, pp. 707–\n715, 2006.","J. Rose, A. Bénard, S. El Mrabet, A. Masion, I. Moulin, V. Briois, L.\nOlivi, and J.-Y. Bottero, \"Evolution of iron speciation during hydration\nof C4AF,\" Waste Manage., vol. 26, pp. 720–724, 2006.\n[10] E. F. Irassar, \"Sulfate attack on cementitious materials containing\nlimestone filler – A review,\" Cem. Concr. Res., vol. 39, pp. 241–254,\n2009.\n[11] T. Liang, and Y. Nanru, \"Hydration products of calcium aluminoferrite\nin the presence of gypsum,\" Cem. Concr. Res., vol. 24, pp. 150–158,\n1994.\n[12] V. Lilkov, O. Petrov, Y. Tzvetanova, and P. Savov, \"Mössbauer, DTA\nand XRD study of Portland cement blended with fly ash and silica\nfume,\" Constr. Build. Mater., vol. 29, pp. 33–41, 2012.\n[13] B. Z. Dilnesa, B. Lothenbach, G. Le Saout, G. Renaudin, A. Mesbah, Y.\nFilinchuk, A. Wichser, and E. Wieland, \"Iron in carbonate containing\nAFm phases,\" Cem. Concr. Res., vol. 41, pp. 311–323, 2011.\n[14] G. Möschner, B. Lothenbach, J. Rose, A. Ulrich, R. Figi, and R.\nKretzschmar, \"Solubility of Fe-ettringite\n(Ca6[Fe(OH)6]2(SO4)3·26H2O),\" Geochim. Cosmochim. Ac., vol. 72, pp.\n1–18, 2008.\n[15] B. Z. Dilnesa, E. Wieland, B. Lothenbach, R. Dähn, and K. L. Scrivener,\n\"Fe-containing phases in hydrated cements,\" Cem. Concr. Res., vol. 58,\npp. 45–55, 2014.\n[16] B. A. Clark, and P. W. Brown, \"Phases formed during hydration of\ntetracalcium aluminoferrite in 1.0M magnesium sulfate solutions,\" Cem.\nConcr. Compos., vol. 24, pp. 331–338, 2002.\n[17] G. Kakali, S. Tsivilis, E. Aggeli, and M. Bati, \"Hydration products of\nC3A, C3S and Portland cement in the presence of CaCO3,\" Cem. Concr.\nRes., vol. 30, pp. 1073–1077, 2000.\n[18] T. Matschei, B. Lothenbach, and F. P. Glasser, \"The role of calcium\ncarbonate in cement hydration,\" Cem. Concr. Res., vol. 37, pp. 551–558,\n2007."]}

The acid attack on cement mortars modified with rubber aggregates and EVA polymer binder was studied. Mortar specimens were prepared using a type CEM I 42.5 Portland cement and siliceous sand, as well as by substituting 25% of sand with shredded used automobile tires, and by adding EVA polymer in two percentages (5% and 10% of cement mass). Some specimens were only air cured, at laboratory conditions, and their compressive strength and water absorption were determined. The rest specimens were stored in acid solutions (HCl, H2SO4, HNO3) after 28 days of initial curing, and stored at laboratory temperature. Compressive strength tests, mass measurements and visual inspection took place for 28 days. Compressive strength and water absorption of the air-cured specimens were significantly decreased when rubber aggregates are used. The addition of EVA polymer further reduced water absorption, while had no important impact on strength. Compressive strength values were affected in a greater extent by hydrochloric acid solution, followed by sulfate and nitric acid solutions. The addition of EVA polymer decreased compressive strength loss for the specimens with rubber aggregates stored in hydrochloric and nitric acid solutions. The specimens without polymer binder showed similar mass loss, which was higher in sulfate acid solution followed by hydrochloric and nitric acid solutions. The use of EVA polymer delayed mass loss, while its content did not affect it significantly., {"references":["L. A. Alamo-Nole, O. Perales-Perez, and F. R. Roman-Velazquez, \"Sorption study of toluene and xylene in aqueous solutions by recycled tires crumb rubber,\" J. Hazard. Mater., vol. 185, pp. 107–111, 2011.","A. Benazzouk, O. Douzane, T. Langlet, K. Mezreb, J. M. Roucoult and M. Quéneudek, \"Physico-mechanical properties and water absorption of cement composite containing shredded rubber wastes,\" Cem. Concr. Compos., vol. 29, pp. 732–740, 2007.","F. Pelisser, A. Barcelos, D. Santos, M. Peterson and A. M. Bernardin, \"Lightweight concrete production with low Portland cement consumption,\" J. Clean. Prod., vol. 23, pp. 68–74, 2012.","H. A. Toutanji, \"The use of rubber tire particles in concrete to replace mineral aggregates,\" Cem. Concr. Compos., vol. 18, pp. 135–139, 1996.","A. R. Khaloo, M. Dehestani, and P. Rahmatabadi, \"Mechanical properties of concrete containing a high volume of tire-rubber particles,\" Waste Manage., vol. 28, pp. 2472–2482, 2008.","F. Pelisser, N. Zavarise, T. A. Longo and A. M. Bernardin, \"Concrete made with recycled tire rubber: Effect of alkaline activation and silica fume addition,\" J. Clean. Prod., vol. 19, pp. 757–763, July 2011.","C. Albano, N. Camacho, J. Reyes, J. L. Feliu and M. Hernández, \"Influence of scrap rubber addition to Portland I concrete composites: Destructive and non-destructive testing,\" Compos. Struct., vol. 71, pp. 439–446, 2005.","Y. Ohama, \"Polymer-based admixtures,\" Cem. Concr. Compos., vol. 20, pp. 189–212, 1998.","J. A. Rossignolo, and M. V. C. Agnesini, \"Mechanical properties of polymer-modified lightweight aggregate concrete,\" Cem. Concr. Res., vol. 32, pp. 329–334, 2002.\n[10]\tD. W. Fowler, \"Polymers is concrete: A vision for the 21st century,\" Cem. Concr. Compos., vol. 21, pp. 449–452, 1999.\n[11]\tA. M. Betioli, P. J. P. Gleize, V. M. John, and R. G. Pileggi, \"Effect of EVA on the fresh properties of cement paste,\" Cem. Concr. Compos., vol. 34, pp. 255–260, 2012.\n[12]\tR. E. Beddoe, and H. W. Domer, \"Modelling acid attack on concrete: Part I: The essential mechanisms,\" Cem. Concr. Res., vol. 35, pp. 2333–2339, 2005."]}

258 σ., Σκυρόδεμα, Ασβεστολιθικά τσιμέντα, Ανθεκτικότητα, Θειικά ιόντα, Χλωριόντα, Διάχυση χλωριόντων, Διάβρωση οπλισμού, Concrete, Limestone cements, Durability, Sulfates, Chlorides, Chloride diffusion, Reinforcement corrosion, Κωσταντίνος Χ. Σωτηριάδης