# Effect of Vibration Timing on Mechanical and Durability Properties of Early-Strength Cement-Based Composites for Bridge Wet Joints

## TL;DR

This study shows that vibrating cement composites at the wrong time weakens their strength and durability, which is important for building strong bridges.

## Contribution

The study reveals how vibration timing during cement setting affects microstructure and durability, offering new insights for bridge construction.

## Key findings

- Vibration between initial and final setting phases reduces compressive, flexural, and bond strengths due to micro-cracks and pore connectivity.
- Vibration increases chloride diffusion, especially in high water-to-binder mixtures, raising durability concerns.
- Optimizing mix proportions and vibration timing is crucial for mechanical performance and service life of cement composites.

## Abstract

This study explores the influence of vibration timing on the performance of high early-strength cement-based composites used in bridge wet joints. A series of experimental techniques, including SEM, MIP, and RCM tests, were employed to evaluate microstructural evolution, mechanical properties, and durability. The results indicate that vibration applied between the initial and final setting phases has a critical impact, significantly reducing early-age compressive, flexural, and bond strengths. This deterioration is mainly attributed to micro-crack formation and enhanced pore connectivity, as confirmed by SEM and MIP analyses. Moreover, vibration markedly increases the chloride diffusion coefficient, particularly in mixtures with higher water-to-binder ratios, thereby raising long-term durability concerns. These findings underscore the necessity of optimizing mix proportions and strictly controlling vibration timing to ensure both the mechanical performance and service life of high early-strength cement composites in bridge construction. The study provides practical insights for the design and application of durable, resilient bridge wet joints.