Concrete Admixtures by SikaSika's latest products include several novelties in the range of concrete admixtures. Sigunit®-L52 AF S and Sigunita®-L53 AF S are ecological alkali-free accelerator shotcrete admixtures, for sprayed concrete and mortars. They are essentially used for the shotcreting of mortars and concrete when high initial resistance is required, such as underground support, stabilization and retaining of rocks, slopes, etc., tunnel and underground constructions, primary waterproofing with the Oberhasli method, and construction of pools and basins, etc.The advantages and effects of Sigunit®-L52 AF S and Sigunit®-L53 AF S as setting accelerators depend on the content, class and age of the cement that is used, the shotcrete temperature and ground nature, the thickness of the applied layer and the shotcreting method. The water/cement ratio of the wet-mix shotcrete and the quantity of water added in the dry-mix method are also important parameters that influence the accelerating effect. The two products react with cement giving the mortar or shotcrete the following advantages: they improve bond between the shotcrete and the rock, thus easing the shotcreting operations on vaults and roofs; they augment the shotcrete impermeability; they reduce the shotcrete rebound; layers of up to 30-40 cm on walls and 15-20 cm on vaults may be sprayed; they produce a rapid setting and high hardening in the first 24 hours, with little incidence on the final resistance. Visit www.sika.com 18/06.