Abstract
Photocatalytic cementitious materials are used in the exterior of the buildings and infrastructure for self-cleaning and air-purifying purposes. These materials are exposed to the aggressive exposure conditions like acid rain, runoff water and are subjected to the deterioration due to the leaching of calcium. The knowledge of leaching attack upon photocatalytic cementitious materials after the addition of nano-materials is necessary. In the current study, the influence of nano-silica addition on the leaching attack upon photocatalytic cement mortars was thoroughly investigated. For this purpose, photocatalytic mortars were made by adding 3% TiO2 and variable amount (0–2%) of nano-silica. Accelerated leaching environment was created by immersing mortars in 6 M ammonium nitrate (NH4NO3) solution. The progressive development of the leaching depth in mortars was measured. The loss of hardened properties was monitored by evaluating the compressive strength, flexural strength, porosity, and dynamic modulus of elasticity. X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy tests were conducted to know the microstructural deteriorations. Results indicated that the leaching attack induced mechanical and microstructural damages in the mortars, but the addition of nano-silica decreased mechanical and microstructural damages in the photocatalytic mortars and increased the resistance of photocatalytic mortars to leaching attack.
Highlights
Titanium dioxide (TiO2) is added in concrete to make self-cleaning, anti-bacterial, and air-purifying concrete (Li et al 2018; Staub de Melo et al 2018; Binas et al 2018; Guo and Poon 2018; Seo and Yun 2017; Han et al 2017)
This study focuses on the decalcification of hydration products after the addition of nano-silica in photocatalytic cement mortars
4 Conclusion This study focused on the decalcification attack upon photocatalytic cement mortars after incorporating 0%, 0.5%, 1.0%, 1.5%, and 2.0% nano-silica
Summary
Titanium dioxide (TiO2) is added in concrete to make self-cleaning, anti-bacterial, and air-purifying concrete (Li et al 2018; Staub de Melo et al 2018; Binas et al 2018; Guo and Poon 2018; Seo and Yun 2017; Han et al 2017). Nano-silica changes the fresh, hardened, and microstructure properties of photocatalytic mortars (Sikora et al 2017; Mendoza et al 2015; Senff et al 2012; Eom et al 2019) It effects the durability properties like carbonation and chloride penetration (Mohseni et al 2015). Addition of nano-silica increases the strength in photocatalytic cement-based materials and it does not reduce the photocatalytic performance (Wang et al 2018; Mendoza et al 2015). It can have effects on the leaching attack upon photocatalytic mortars, but it has not been yet explored. X-ray diffraction (XRD), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) analysis were conducted to evaluate the microstructural damages
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