Mitigating chloride attack in cementitious materials without compromising other properties via the use of viscosity modifying admixture

To mitigate the harmful chemicals ingression into cementitious materials, traditional methods often aim to densify the pore structure, posing challenges for concrete dead-load or crack control. This paper proposes a facile method to mitigate chloride attack via increasing the pore solution viscosity in cementitious material without changing the matrix density or compromising other properties. The results indicate that the addition of viscosity modifying admixtures (VMAs) to the mortar, as an equivalent mass replacement of mixing water, can mitigate chloride ingress. Although it reduces the early age hydration heat, the mechanical strength at full age (3 d-28 d) and the porosity at 28 d remain unchanged when using an effective VMA (PEG1000). In addition, the matrix resistance to leaching is improved as well. These results may be attributed to the enhanced pore solution viscosity and the coexistence of VMA and C-S-H with decreased interlayer distance and shortened mean chain length. After 28 d of exposure, the most effective experimental group (PEG1000) showed approximately a 28 % decrease in chloride diffusion coefficient compared to the control group. This paper may inspire new technology to mitigate ions diffusion and promote its practical application.