Influence of carbon nanofiber clustering in cement pastes exposed to sulfate attack

The effects of CNFs and CNF clustering on the microstructural evolution and mechanical response of cement pastes subjected to sulfate attack were studied. Portland cement pastes with and without 0.5% CNFs were exposed to sodium sulfate for a total duration of 550 days. The presence of CNFs and CNF clusters led to pore refinement, limited sulfate-induced microstructural changes, and provided a reinforcing network that delayed the onset of cracking and spalling and increased the cement paste expansion capacity. At all stages of exposure, the cement paste with CNFs experienced less sulfate-induced changes in flexural strength than the reference cement paste.