Self-levelling cement mortar containing grounded slate from quarrying waste

The aim of this research is to obtain a low density self-levelling cement mortar containing grounded slate from quarrying waste that could be used as a substrate levelling layer for flooring purposes. An experimental research was carried out on the design and development of a self-levelling cement mortar substituting up to 75% of the cement by grounded slate from quarrying wastes. In a first stage, the formation of stable reactive binding products of slate–cement pastes was confirmed, using Vicat needle test and Scanning Electron Microscopy and Energy Dispersive Spectroscopy analysis (SEM/EDAX). In addition, mortar mixtures with different amounts of grounded slate have been studied. Fresh state consistency, shrinkage measurements in wet and dry conditions and physical and mechanical properties in the hardened state of these mortars have been assessed. Finally, mortar shrinkage was controlled according to the selected application, including admixtures and glass fibers in the mortar composition, to achieve the flowability and strength required, without segregation.Grounded slate acts as binder, jointly with the cement, confirming that the inclusion of the slate wastes implies a waste valorisation and not a waste disposal. The use of admixtures and short fibers allows to develop a self-levelling mortar.