Synergistic effects of carbon nanotubes and polyvinyl alcohol on enhancing mechanical strength and carbonation resistance of concrete

Abstract

<p>Concrete infrastructure faces significant durability challenges from carbonation-induced degradation, driving the need for advanced enhancement strategies. This study investigates the synergistic potential of carbon nanotubes (CNTs) and polyvinyl alcohol (PVA) to enhance mechanical properties and carbonation resistance in concrete. Accelerated and natural carbonation experiments were conducted to evaluate carbonation depth, strength, and water absorption of concrete. Microstructural analysis via scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) elucidated the underlying mechanisms. Results showed that an optimal CNTs/PVA dosage increased flexural and compressive strength of concrete and reduced the carbonation depth by 26.9 % versus the control group. After carbonation, modified concrete exhibited higher strength and lower water absorption. SEM revealed that CNTs and PVA form a robust 3D interpenetrating network, effectively restricting crack propagation, while MIP confirmed pore refinement—reducing average pore diameter from 46.54 nm to 37.86 nm and increasing sub-100 nm pores from 46.0 % to 54.6 %. These microstructural modifications collectively enhance durability and mechanical performance, supporting CNT/PVA composites as a dual-functional solution for sustainable infrastructure.<br></p>