Mitigating autogenous shrinkage of cement with carbon nanotube sponge

Autogenous shrinkage can be mitigated by the addition of superabsorbent polymer (SAP), however, typically at the cost of a significant strength loss. To overcome such dilemma, hydrophilic carbon nanotube sponge (H-CNTSP) was proposed in this study as a novel internal curing agent. Due to the high porosity and enriched hydrophilic functional groups, H-CNTSP can absorb pore solution at 72 g/g driven by the capillary force, which is 176%–620 % higher than the commercial SAPs. The autogenous shrinkage of cement can be reduced or mitigated with the addition of 0.05–0.2 wt% H-CNTSP due to the continuous water release after final setting. Interestingly, the compressive strength loss resulting from the addition of H-CNTSP can be greatly diminished and even be overcompensated by the formation of CNT/hydrate nanocomposite shell with a higher modulus. This study illustrates the great potential to optimize concrete performance through proper design of assembly structures with chemically functionalized nanomaterials.