Portland Cement Paste Modified by TiO₂Nanoparticles: A Microstructure Perspective

Abstract

Nanomodified Portland cement paste with a water/cement ratio of 0.4 was prepared with the addition of TiO2 nanoparticles at 0.1, 0.5, 1.0, and 1.5% by mass of cement. The flexural strengths of the prepared cement-based composites were tested, and the fracture surfaces were observed by scanning electron microscopy (SEM). The flexural strength of the nanomodified TiO2 Portland cement paste reached the highest value with a dosage of 1.0 mass %. The SEM observation shows that admixing of the TiO2 nanoparticles largely decreased the quantity of internal microcracks in the cement paste. A new type of needle-shaped hydration product was observed, and its potential growth mechanism was proposed. Atomic force microscopy was introduced to observe the microstructure of nanomodified Portland cement paste, and the results show that the nanoroughness of the hardened cement pastes with admixed TiO2 nanoparticles was much lower than that without the TiO2 nanoparticle addition. Coupled with X-ray diffraction data, the morphological information obtained at the micrometer and nanometer scales shed light on the role of TiO2 nanoparticles in the cement-based composite.

Self-cleaning engineered cementitious composites

“…The mass loss from room temperature to 400 °C is attributed to the loss of physically adsorbed and chemically bound water on the C-S-H and the ettringite. The weight loss at about 450 °C is associated to the decomposition of Ca(OH) 2[21]. As can be seen, the addition of TiO 2 does not cause any significant change on the types and amount of hydration products, which indicates that TiO 2 should be considered as fillers to the cement matrix.…”

Review on Characterization and Mechanical Performance of Self-cleaning Concrete

“…Al [12] but the TiO 2 nanoparticles and cement were soaked in water and vibrated ultrasonically for 30 min in order to achieve better distribution before mixing process. On the other hand, P. Duan et.…”

Effects of nano-TiO2 on strength, shrinkage and microstructure of alkali activated slag pastes

“…Nano materials are new emerging materials in the field of civil engineering and have been utilized by some researchers to enhance the properties, such as mechanical strength, abrasion resistance, impermeability and so on, of Portland cement concrete [19]. The commonly used nano materials in cement-based materials are nano-TiO 2 [20][21][22][23][24], nano-Al 2 O 3 [19,25], and nano-SiO 2 [26][27][28][29]. Feng et al [22] showed that with the addition of 0.9% nano-TiO 2 , the flexural strength and compressive strength of cement pastes at 28d increases by 16.12% and 14.15%, respectively.…”

“…Feng et al [22] showed that with the addition of 0.9% nano-TiO 2 , the flexural strength and compressive strength of cement pastes at 28d increases by 16.12% and 14.15%, respectively. The investigation into the microstructure by Feng et al [24] demonstrated that the incorporation of TiO 2 decreases the quantity of inner micro cracks in Portland cement paste. Nazari et al [30] investigated the effect of nano-TiO 2 on physical, thermal and mechanical properties of concrete using ground granulated blast furnace slag replacing OPC, showing that TiO 2 accelerates the formation of C-S-H gel and improves the pore structure.…”