TY - CHAP A1 - Sakoparnig, Marlene A1 - Galan, Isabel A1 - Balderman, Andre A1 - Steindl, Florian A1 - Dietzel, Martin A1 - Thumann, Maria A1 - Saxer, Andreas A1 - Kusterle, Wolfgang A1 - Mittermayr, Florian T1 - Experimental Ca leaching of shotcrete & secondary precipitation T2 - ICCC 2019: 15th International Congress on the Chemistry of Cement, ICCC 2019, 16.-20.09.2019, Prague, Czech Republik Y1 - 2019 UR - https://iccc-online.org/fileadmin/gruppen/iccc/proceedings/ICCC15_2019.pdf SP - 3488 EP - 3495 ER - TY - JOUR A1 - Galan, Isabel A1 - Baldermann, Andre A1 - Kusterle, Wolfgang A1 - Dietzel, Martin A1 - Mittermayr, Florian T1 - Durability of shotcrete for underground support BT - Review and update JF - Construction and building materials N2 - Shotcrete is often used for the construction and stabilization of tunnels and other underground structures, where it is susceptible to different forms of physical and chemical attacks affecting its durability. An advanced understanding of the factors that limit the durability of shotcrete is crucial to develop tailored strategies for enhancing its service life. The main focus of this contribution is to shed light on the durability of shotcrete by revising the literature, highlighting what is missing and needs to be addressed, assessing how the knowledge about concrete durability can be transferred to shotcrete, and providing recommendations for durable shotcrete structures. (C) 2018 Elsevier Ltd. All rights reserved. KW - CEMENT-BASED MATERIALS KW - CHEMOMECHANICAL COUPLING BEHAVIOR KW - Corrosion KW - Durability KW - FREEZE-THAW RESISTANCE KW - INDUCED CONCRETE CORROSION KW - Leaching KW - LEACHING BEHAVIOR KW - POLYPROPYLENE FIBERS KW - PORTLAND-CEMENT KW - POTENTIAL ALKALI-REACTIVITY KW - Shotcrete KW - Sintering KW - Sprayed concrete KW - Sulfate attack KW - THAUMASITE SULFATE ATTACK KW - Tunnel KW - Underground Y1 - 2019 U6 - https://doi.org/10.1016/j.conbuildmat.2018.12.151 VL - 202 IS - March SP - 465 EP - 493 PB - Elsevier ER - TY - CHAP A1 - Steindl, Florian A1 - Galan, Isabel A1 - Baldermann, Andre A1 - Sakoparnig, Marlene A1 - Dietzel, Martin A1 - Röck, Rudolf A1 - Kusterle, Wolfgang A1 - Mittermayr, Florian T1 - Dauerhaftigkeitsuntersuchungen an Trocken- und Nassspritzbetonen mit mineralischen Zusatzstoffen - Investigations on the durability of dry- and wet-mix sprayed concrete with mineral additions T2 - Spitzbeton-Tagung 2021, 21. + 22. Jänner 2021, Alpbach Tirol N2 - Die Dauerhaftigkeit von Spritzbeton kann, insbesondere in seiner Verwendung als Stütz-und Ausbaumaterial im Tunnelbau, durch chemische Angriffe deutlich herabgesetzt werden. Im Forschungsprojekt "Entwicklung neuer dauerhafter und nachhaltiger Spritzbetone (ASSpC)" wurden Prüfkörper von Trocken-und Nassspritzbetonen in Großspritzversuchen hergestellt. Der Sulfatwiderstand und das Lösungsverhalten der Betone in sulfathaltigen wässrigen Lösungen wurden mit drei Testverfahren bestimmt und die Ergebnisse miteinander verglichen: Ein Pulvertestverfahren zeigt die Auflösung von Zementhydratphasen zugunsten der Neubildung von Calcit und Ettringit. Das Ausmaß der Sulfatdehnung an Bohrkernen, ermittelt im zweiten Testverfahren, korrespondiert mit dem chemischen Verhalten des gemahlenen Materials, insbesondere bezüglich der Reaktivität von calcium-und aluminium-haltigen Hydratphasen. Der Thaumasitwiderstand, ermittelt über Masseverlust von Prüf-körpern, zeigte eine weitgehende Übereinstimmung mit den zuvor genannten Tests. Die Verwendung von hochreinen Metakaolinen (7-10 M-% des Bindemittels) oder Feinstcalcit (5-10 M-% des Bindemittels) allein führte insgesamt zu deutlich geringerer Sulfatbeständigkeit. Hingegen konnten hohe Gehalte an Hüttensand oder Silikastaub auch in Kombination mit Metakaolin und Feinstcalcit den Sulfatwiderstand von Spritzbeton erhöhen. The durability of shotcrete can be degraded by chemical attacks, especially if used as ground support in tunnel construction. In the course of the research project "Advanced and Sustainable Sprayed Concrete (ASSpC)" test specimens of dry-mix and wet-mix shotcrete were sprayed in large-scale tests. The sulfate resistance and the leaching behaviour of these shotcretes were assessed in sulfate-bearing solutions. A test procedure based on the use of shotcrete powders shows that hydrated cement phases dissolve in favour of calcite and ettringite neo-formation. The sulfate expansion measured on drill cores in the second procedure corresponds to the behaviour of the powders, especially regarding the reactivity of calcium-and aluminium-bearing hydrated phases. The resistance against thaumasite attack, assessed by measuring the mass loss of prisms, coincides with the former test results. The exclusive use of high-purity metakaolin (7-10 wt-% of binder) or fine calcium carbonate (5-10 wt-% of binder) leads to a decrease in the sulfate durability. However, high amounts of blast furnace slag or silica fume can increase the sulfate resistance of shotcrete even when used in combination with metakaolin or fine calcium carbonate. Y1 - 2021 UR - https://www.spritzbeton-tagung.com/downloads/vortraege/2021/17_Steindl.pdf SP - 94 EP - 111 ER - TY - JOUR A1 - Steindl, Florian R. A1 - Mittermayr, Florian A1 - Sakoparnig, Marlene A1 - Juhart, Joachim A1 - Briendl, Lukas G. A1 - Lindlar, Benedikt A1 - Ukrainczyk, Neven A1 - Dietzel, Martin A1 - Kusterle, Wolfgang A1 - Galan, Isabel T1 - On the porosity of low-clinker shotcrete and accelerated pastes JF - Construction and Building Materials N2 - Although the number and size of interconnected pores have been identified as the most important aspects of concrete microstructure, comprehensive datasets on shotcrete porosity and pore size distributions are still scarce and their key controls are poorly investigated. In this study we investigate the effects of the spraying process, setting accelerator addition and mix design on the microstructure of real-scale dry- and wet-mix shotcrete and hand-mixed and sprayed accelerated pastes. A newly proposed deconvolution analysis of the pore size distributions, measured by mercury intrusion porosimetry, offers increased precision in determining the critical and median pore diameter parameters. In total >50 samples were analysed. Results show that the dry-mix shotcrete exhibits a shift towards coarser pore sizes (∼100–1 μm) than wet-mix shotcrete. Combinations of different supplementary cementitious materials are favourable for producing wet-mix shotcretes with refined pore structures. The addition of setting accelerators, up to 10 wt-% of binder mass, and the spraying process cause systematic variations in the pore volume and pore structure of (sprayed) paste and shotcrete. KW - Porosity KW - Shotcrete KW - Mercury Intrusion KW - Durability KW - SCMs Y1 - 2023 U6 - https://doi.org/10.1016/j.conbuildmat.2023.130461 SN - 0950-0618 VL - 368 PB - Elsevier CY - 14 ER - TY - JOUR A1 - Steindl, Florian Roman A1 - Galan, Isabel A1 - Baldermann, Andre A1 - Sakoparnig, Marlene A1 - Briendl, Lukas G. A1 - Juhart, Joachim A1 - Thumann, Maria A1 - Dietzel, Martin A1 - Röck, Rudolf A1 - Kusterle, Wolfgang A1 - Mittermayr, Florian T1 - Sulfate durability and leaching behaviour of dry- and wet-mix shotcrete mixes JF - Cement and Concrete Research N2 - Shotcrete is a material frequently used in underground constructions such as tunnels, where Ca leaching and sulfate attack are important durability issues. In this study, two test methods were employed to investigate the sulfate resistance and leaching behaviour of dry- and wet-mix shotcretes in sulfate solutions on a time-resolved basis. Tests on powdered samples showed the dissolution of AFm, portlandite and C-A-S-H, subsequently followed by the precipitation of calcite and ettringite. The extent of sulfate expansion of drill cores corresponded to the chemical response of the powder materials, particularly on the reactivity of Ca- and Al-containing hydrated cement phases. The use of high-purity metakaolin (7-10 wt%) in the shotcrete binder significantly decreased the sulfate durability, while high amounts of other SCMs such as blast-furnace slag and silica fume (> 20 wt%) had a positive effect on the durability of shotcrete. KW - ADMIXTURES KW - ALKALI-FREE KW - ATTACK KW - BLAST-FURNACE SLAG KW - concrete KW - Durability KW - Leaching KW - MECHANISM KW - METAKAOLIN KW - RESISTANCE KW - SCMs KW - Shotcrete KW - Sulfate attack KW - TEMPERATURE KW - THAUMASITE FORM Y1 - 2020 U6 - https://doi.org/10.1016/j.cemconres.2020.106180 VL - 137 IS - November SP - 1 EP - 19 PB - Elsevier ER -