# Study on Rheological Properties and Enhancement Mechanisms of Ethylene-Vinyl-Acetate-Copolymer-Modified Cement Grouting Materials

## TL;DR

This study improves cement grouting materials by adding EVA copolymer, enhancing strength and flow properties while explaining the underlying mechanisms.

## Contribution

The study introduces a systematic analysis of EVA-modified cement grouts, linking EVA content to rheology, microstructure, and mechanical performance.

## Key findings

- 12% EVA increased 28-day compressive strength by 68% to 21.03 MPa.
- EVA promotes C–S–H gel formation and reduces microcracks at optimal content.
- The Vipulanandan model better describes the non-Newtonian flow of EVA-modified grouts than the Bingham model.

## Abstract

This study addresses the brittleness, poor bonding, and low crack resistance of ordinary Portland cement (OPC) grouting materials by incorporating an ethylene-vinyl acetate (EVA) copolymer. The enhancement mechanisms and engineering applicability of EVA-modified cement grouts were systematically investigated. Using EVA contents from 0% to 20%, macro-scale tests covering fluidity, rheology, bleeding rate, and compressive strength were conducted, along with microstructural analyses (SEM, XRD, FT-IR). Results indicate that with 12% EVA, the 28-day compressive strength reached 21.03 MPa, reflecting a 68% increase over the unmodified grout. Most favorable amount of EVA promoted the formation of C–S–H gel, filled microcracks, and enhanced structural densification, whereas excessive EVA content led to the formation of a polymer film that hindered hydration and reduced strength. Furthermore, EVA effectively improved the rheological behavior of the grout, with the Vipulanandan model demonstrating superior accuracy over the Bingham model in characterizing its non-Newtonian flow. This study systematically established a quantitative–qualitative correlation between EVA content, nonlinear rheological behavior (characterized by advanced models), microstructure evolution (porosity, C–S–H, polymer film) and final macromechanics and durability.