Improved Crack Resistance and Pore Structure of Cement-Based Materials by Adding EVA Powder

The improved properties of ethylene-vinyl acetate (EVA)-modified cement-based materials have not been fully clarified, especially crack resistance and pore structure. The purpose of this research was to investigate the influence of EVA copolymer on the mechanical performances and microstructural properties of cement paste. Strengths, autogenous and drying shrinkage, and water absorption expansion were investigated to evaluate the mechanical properties and volume stability. The ring restrained shrinkage and chloride permeability tests revealed the crack resistance and enhancement of impermeability. The microstructures of EVA-modified cement-based materials were characterized by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) techniques. The experimental results indicated that mixing EVA into cement-based materials increased the flexural strength, reduced the crack propagation and chloride ion penetration, and reduced the negative capillary pressure by improving the water retention. The addition of EVA resulted the remarkable reduction of harmful pores. The optimal mass fraction of EVA powder was approximately 4%.