nano sio2

The primary goal of the engineering design of building is to reduce the weight of the structure and its resistance to fires and earthquakes because fires are inevitable. Hence, the direction of this study was to use lightweight concrete because of its unique advantages in weight loss and fire resistance due to its thermal insulation property. It was also intended to enhance the strength and behavior of this concrete at high temperatures. For this purpose, four mixing designs samples without fibers and nano-SiO2, samples with different proportions of nano-SiO2, samples with different proportions of fibers, and samples with both fibers and nano- SiO2 together were prepared. The results showed damage to samples free of nano-SiO2 and fibers, changing their color, reducing their resistance and reducing their weight. But adding nano-SiO2 fibers or using them together leads to improving the properties of concrete at all temperatures. Due to nano- SiO2, its pozzolanic interactions improve the microstructure, and the fibers prevent cracks in concrete. This study also dealt with the effect of changing the size of the samples on the compressive strength, and the results showed an increase in the resistance of the samples with small sizes, and resulted factors for converting the resistance of non-standard samples into a standard.

The effect of nano KCC-1/Ag and nano SiO2 in concrete have been investigated in this study. Nano KCC-1/Ag and nano SiO2 are synthesized and their characterization was investigated by FTIR, SEM, and TEM analysis. After that, these materials use as cement replacement in 1, 2, and 3 percent amounts. SEM images illustrate the denser structure of KCC-1/Ag nanoparticles. Furthermore, in the FTIR  spectra 3640 cm-1 is related to C-S-H, which is sharper and more severe in samples with nano KCC-1/Ag and nano SiO2. The results revealed that nano SiO2 and nano KCC-1/Ag both improved the microstructure of cement paste and increased the concrete compressive and splitting tensile strength. For comparison the performance of nano KCC-1/Ag and nano SiO2, the results indicated that nano KCC-1/Ag improved the microstructure of concrete better than nano SiO2. Hence, it has a better performance in enhancing the strength of concrete. The study showed that the optimal percentage of using nano KCC-1/Ag was 2%.

Lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 piezoceramics with nano SiO2 additive were prepared by conventional solid oxide sintering method. The samples were fabricated by means of cold isostatic pressing and sintering was performed at 1350 °C for 4 h in the air. The phase structure and microstructure were studied via X-ray diffraction technique and field emission scanning electron microscopy. The room-temperature dielectric properties and the variations in the temperature ranging from 23 to 160 °C were measured using a high-precision LCR meter. The mechanical properties such as Vickers hardness and compressive strength were investigated. The obtained results showed that nano SiO2 addition produced dense and uniform microstructures with larger grains than pure BCZT. The Curie temperature of undoped BCZT increased to about 25 °C through the incorporation of 0.75 mol% SiO2 and then, the mechanical properties considerably improved. Accordingly, BCZT piezoceramic with nano SiO2 additive enjoys viable properties, which makes it widely applicable.