TiO nanoparticles' effects on properties of concrete using ground granulated blast furnace slag as binder

In the present study,compressive strength,pore structure,thermal behavior and microstructure characteristics of concrete containing ground granulated blast furnace slag and TiO2 nanoparticles as binder were investigated.Portland cement was replaced by different amounts of ground granulated blast furnace slag and the properties of concrete specimens were investigated.Although it negatively impacts the properties of concrete at early ages,ground granulated blast furnace slag up to 45 wt% was found to improve the physical and mechanical properties of concrete at later ages.TiO2 nanoparticles with the average particle size of 15 nm were partially added to concrete with the optimum content of ground granulated blast furnace slag and physical and mechanical properties of the specimens were measured.TiO2 nanoparticle as a partial replacement of cement up to 3 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount at the early age of hydration and hence increase compressive strength of concrete.The increased TiO2 nanoparticles' content of more than 3 wt% may cause reduced compressive strength because of the decreased crystalline Ca(OH)2 content required for C-S-H gel formation and unsuitable dispersed nanoparticles in the concrete matrix.TiO2 nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and less-harm pores.