Silica fume-hydrated lime blended cements: contribution of pre-blending to strength development in mortars

ABSTRACT This paper presents an experimental study on the mechanical properties at 28 days of mortars comprising Condensed Silica Fume (CSF), Hydrated Lime (CH) or both, at various substitution rates and water-to-binder ratios (w/b). An evaluation of the mechanical properties has been carried out using Ultrasonic Pulse Velocity (UPV) tests and compressive/tensile strength tests, to assess CSF, CH and CSF-CH addition and substitution rate effect on strength development. A marked increase in the mechanical properties of the CSF, CSF-CH mortars is noted, with the best results obtained after CSF-CH pre-mixing, reaching 35.71% improvement vs control, highlighting the occurrence of considerable pozzolanic reactions. UPV tests have shown increased velocities for CSF and CSF-CH mixes, transcribing a densification of the matrix. The results of the study seem to indicate that CSF and CSF-CH addition could represent a suitable solution to significantly increase both the mechanical and durability properties of mortars.