PSI - Issue 70

R. Mohanraj et al. / Procedia Structural Integrity 70 (2025) 82–88

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under controlled conditions for 28 days to ensure adequate hydration and hardening of the cement mortar. After the curing period, the cubes were subjected to a series of non-destructive tests (NDT) to evaluate the effects of nano-SiO 2 incorporation on the material properties.

Fig.1. (a) SiO 2 (b) Sample Preparation and Curing

3. Experimental Study We start by making the concrete mixture (cement, coarse aggregate, fine aggregate, and water), and then we add SiO 2 with a certain percentage, SiO 2 1% to SiO 2 5%, and we cast the cube mold of SiO 2 1%, SiO 2 2%, SiO 2 3%, SiO 2 4%, and SiO 2 5%. After 7 days, 14 days, and 28 days, all of the cube molds are placed in water tanks to achieve the strength. After 7 days, we test one cube of each percentage, record the test reading, and compare it. The Ultrasonic Pulse Velocity (UPV) test, a non-destructive technique, is essential for evaluating the quality and homogeneity of nano-SiO 2 concrete cubes. The procedure initiates with meticulous surface preparation, ensuring the transducer contact areas are clean, smooth, and free from debris, potentially requiring light grinding. Subsequently, a coupling agent is applied to the transducer faces to eliminate air gaps and facilitate efficient ultrasonic pulse transmission. Prior to testing, the UPV equipment undergoes calibration using a standardized block, adhering to manufacturer guidelines. Test points are then marked on opposing cube faces, ensuring accurate distance measurement between transducers. During the test, transducers are firmly placed on the marked points, maintaining consistent pressure, and ultrasonic pulses are transmitted through the concrete. The transit time is recorded, and the pulse velocity is calculated using the formula V=L/T, where V is velocity, L is distance, and T is time. Multiple readings are taken for accuracy, and data, including transit time, distance, calculated velocity, cube identification, age, mix design, and environmental conditions, are meticulously documented. Data analysis involves calculating the average pulse velocity and interpreting it to assess concrete quality. Higher velocities typically indicate denser, more homogeneous concrete, which is often observed in nano-SiO 2 concrete due to its refined microstructure. When interpreting results, it is vital to acknowledge factors such as moisture content, temperature, reinforcement, and contact conditions, which can influence UPV readings. Nano-SiO2's impact on increasing density and refining pore structure should be considered, as it often leads to higher UPV values compared to standard concrete. By consistently following these procedures, reliable insights into the internal quality of nano-SiO2 concrete cubes can be obtained. 3.1. Ultrasonic Pulse Velocity Test