SPLITTING TENSILE STRENGTH OF CONCRETE USING GROUND GRANULATED BLAST FURNACE SLAG AND SiO2 NANOPARTICLES AS BINDER

Split tensile strength, pore structure, thermal behaviour and microstructure of concrete containing ground granulated blast furnace slag (GGBS) and SiO2 nanoparticles were investigated. Portland cement was replaced by different amounts of GGBS and the properties of concrete specimens were measured. Although it negatively impacted the properties of concrete at early ages, GGBS improved the physical and mechanical properties of concrete up to 45 wt% at later ages. SiO2 nanoparticles with an average particle size of 15 nm were partially added to concrete with the optimum content of GGBS and the physical and mechanical properties of the specimens were studied. Up to 3 wt% SiO2 nanoparticle as a partial replacement of cement 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 split tensile strength of concrete specimens. More than 3 wt% SiO2 nanoparticle content caused a reduction in split tensile strength because of the decreased crystalline Ca(OH)2 content required for C-S-H gel formation. SiO2 nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and less harmful pores.