Real-time performance analysis of nano-enhanced concrete for high-strength and crack-resistant infrastructure applications

ABSTRACT This study investigates the improvement of mechanical properties and durability of Crushed Recycled Concrete (CRC) and Reprocessed Material Concrete (RMC) by dual nano-strengthening immersion treatment with Nano-SiO2 and Nano-Al2O3 nanoparticles. The main goal is to enhance the structural quality and applicability of recycled concrete for high-strength; crack-resistant infrastructure use by attacking the Phase Transition Layer (PTL) between recycled aggregates and cement paste. The research uses a two-step immersion procedure in which samples are immersed for 48 hours in a 5% Nano-SiO2 sol solution and 48 hours in a 2% Nano-Al2O3 slurry, allowing for even nano-material absorption at room temperature. Extensive experimental testing was undertaken, comprising compressive and flexural strength tests, bond strength evaluation through pull-out tests, Mercury Intrusion Porosimetry (MIP) for porosity examination, and micro-hardness tests to assess the densification of the PTL. Results show remarkable enhancements in treated samples as opposed to untreated controls: compressive strength enhanced from 21.5–23.0 MPa to 29.5–31.0 MPa in CRC, and from 19.9–20.8 MPa to 27.8–29.1 MPa in RMC. Flexural strength exhibited improvements of up to 17% for RMC and 13% for CRC, while bonding strength for steel reinforcement was improved appreciatively. Microstructure analysis verified the decreased porosity and densification of the PTL as the main factors for the overall improved mechanical properties. Simulation results were in good agreement with experimental data, verifying the efficiency of the nano-strengthening treatment. This research illustrates the promise of incorporating nano-materials into recycled concrete as a viable step towards sustainable high-performance materials for key infrastructure.