@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} } @article{GalanBriendlThumannetal., author = {Galan, Isabel and Briendl, Lukas G. and Thumann, Maria and Steindl, Florian and Roeck, Rudolf and Kusterle, Wolfgang and Mittermayr, Florian}, title = {Filler Effect in Shotcrete}, series = {Materials}, volume = {12}, journal = {Materials}, number = {19}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/ma12193221}, pages = {1 -- 24}, abstract = {The effects of fine limestone powder on the early hydration of cementitious systems accelerated by means of alkali-free aluminum sulfate based products, commonly used for shotcrete applications, were investigated in the course of laboratory and real scale tests. In binary (CEM I + limestone) and ternary (CEM I + limestone + slag) systems the addition of fine limestone led to an enhancement of the hydration degree and strength development at early times (<24 h). The formation of ettringite, aluminate hydrates, and C-S-H is affected by the joint action of the setting accelerator and the fine limestone. Accelerator and limestone, in combination with the cement, can be optimized to enhance ettringite and silicate reaction, in some cases coupled with aluminate reaction inhibition, to produce mixes suitable for sprayed concrete applications. Such optimization can help to reduce the cement content in the mixes without compromising the early strength development of the shotcrete.}, language = {en} }