Investigating the properties and microstructure of high-performance cement composites with nano-silica, silica fume, and ultra-fine TiO2

Nanomaterials find widespread use in industries, including construction, due to their superior mechanical, thermal, and electrical characteristics. Addressing cement composites' weaknesses like low tensile strength and brittleness, researchers increasingly use supplementary cementitious materials and nanoparticles. This study investigates the effects of varied proportions of silica fume (SF), nano-silica (nS), and ultra-fine TiO2 (UFTiO2) in both mixed and separate phases on cement composites. SF represents the pozzolanic family, while nS and UFTiO2 stand for nanomaterials. Tests measured compressive, flexural, and impact strengths, abrasion resistance, and electrical resistivity. Scanning electron microscopy examined microstructure-property relationships. SF and nS enhanced the mechanical strength of the composites, with SF proving superior in durability. The addition of UFTiO2 increased the compressive strength slightly for SF samples (4-7%) and more for nS samples (8-14%). SF samples with UFTiO2 showed 16-25% more flexural strength than nS samples with UFTiO2. The addition of UFTiO2 also raised the electrical resistance by 24-30% for nS samples and 14.5-31.5% for SF samples after 14 days. UFTiO2 affected the abrasion resistance significantly, exhibiting diverse roles in nS and SF specimens. The first crack strength and failure strength for the mixtures containing SF were in the range of 33-36 blows and 39-43 blows, respectively. Meanwhile, for the mixtures containing nS, this impact range was reduced to a maximum of 57%. The impact test results followed the two-parameter Weibull distribution well, with an R-2 value exceeding 0.891 across concrete mixes. The study demonstrates the potential of nanomaterials to improve the performance of cement composites for various applications.