@article{GalanBaldermannKusterleetal., author = {Galan, Isabel and Baldermann, Andre and Kusterle, Wolfgang and Dietzel, Martin and Mittermayr, Florian}, title = {Durability of shotcrete for underground support}, series = {Construction and building materials}, volume = {202}, journal = {Construction and building materials}, number = {March}, publisher = {Elsevier}, doi = {10.1016/j.conbuildmat.2018.12.151}, pages = {465 -- 493}, abstract = {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.}, language = {en} } @article{SakoparnigGalanSteindletal., author = {Sakoparnig, Marlene and Galan, Isabel and Steindl, Florian Roman and Kusterle, Wolfgang and Juhart, Joachim and Grengg, Cyrill and Briendl, Lukas G. and Saxer, Andreas and Thumann, Maria and Mittermayr, Florian}, title = {Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration}, series = {Materials and structures}, volume = {54}, journal = {Materials and structures}, publisher = {Springer Nature}, doi = {10.1617/s11527-021-01644-7}, pages = {1 -- 23}, abstract = {The reduction of clinker use is mandatory to lower the negative environmental impact of concrete. In shotcrete mixes, similarly to the case of conventional concrete, the use of supplementary cementitious materials (SCMs) and proper mix design allow for the substitution of clinker without compromising the mechanical properties. However, the impact of the substitution on the durability of shotcrete needs to be further assessed and understood. The results from the present study, obtained from real-scale sprayed concrete applications, show a reduction of the Ca2+ leaching and sintering potential of clinker-reduced shotcrete mixes due to the presence of SCMs. This positive effect, crucial for low maintenance costs of tunnels, is mainly related to a reduced portlandite content, which on the other hand negatively affects the carbonation resistance of shotcrete. Additionally, the hydration of SCMs positively influences the chloride penetration resistance presumably due to a combination of microstructural changes and changes in the chloride binding capacity. Differences found in the pore size distribution of the various mixes have low impact on the determined durability parameters, in particular compared to the effect of inhomogeneities produced during shotcrete application.}, language = {en} } @article{SteindlGalanBaldermannetal., author = {Steindl, Florian Roman and Galan, Isabel and Baldermann, Andre and Sakoparnig, Marlene and Briendl, Lukas G. and Juhart, Joachim and Thumann, Maria and Dietzel, Martin and R{\"o}ck, Rudolf and Kusterle, Wolfgang and Mittermayr, Florian}, title = {Sulfate durability and leaching behaviour of dry- and wet-mix shotcrete mixes}, series = {Cement and Concrete Research}, volume = {137}, journal = {Cement and Concrete Research}, number = {November}, publisher = {Elsevier}, doi = {10.1016/j.cemconres.2020.106180}, pages = {1 -- 19}, abstract = {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.}, language = {en} }