Evaluation of Mechanical and Durability Properties of RCC Containing Nano-Silica Through Non-Destructive Ultrasonic Pulse Velocity Method

Abstract

This research examined how the mechanical properties and longevity of roller compacted concrete are impacted by the particle size and dosage of nano-silica. The study involved substituting cement with NS at three different levels (1%, 3%, and 5%) using varying particle sizes of 8nm, 15nm, and 30nm. The study investigated the compressive and splitting tensile strengths of RCC incorporating NS after 7 and 28 days, as well as water absorption. Subsequently, freeze-thaw tests were conducted on RCC samples, with assessments of mass change, ultrasonic pulse velocity, and dynamic modulus of elasticity. Additionally, the microstructure of RCC specimens was analyzed through a scanning electron microscope. Findings revealed a decrease in compressive strength by 4.3% to 8.7% when increasing the particle size of 3% NS from 8nm to 15nm and 30nm. Moreover, an increase in NS dosage from 1% to 3% enhanced the splitting tensile strength of RCC from 2.88 MPa to 3.55 MPa for an 8nm NS particle size. Results indicated that incorporating up to 3% NS in RCC mixtures improved freeze-thaw resistance significantly. Analysis showed that NS dosage had a greater impact than particle size across all experiments. An artificial neural network model was developed to predict RCC's compressive strength under F-T cycles using parameters such as the number of F-T cycles, ultrasonic pulse velocity, and sample mass as inputs, demonstrating high predictive capability. Furthermore, Shapley additive explanations analysis was used to assess the impact of input parameters on prediction accuracy, alongside discussions on sample imbalance's effect on prediction performance.