Effect of CNT addition and dispersive agents on the transport properties and microstructure of cement mortars

[Display omitted] •Mortars present a refinement of pores as a function of curing time and CNT content.•Refinement is due to CNTs dispersion and deflocculating of cement by dispersants.•Small amounts of CNTs (up to 0.4 wt%) are beneficial for the transport properties.•Dispersive agents’ role is crucial in controlling transport of nanomodified mortars. The current study investigates the dependence of transport properties of carbon nanotube (CNT)-modified mortars on tube content, type of dispersive agent and microstructure. CNT addition was found to result in up to 50% reduction of sorptivity, due to the refinement of pores in the mortars. No relation was found between water absorption at equilibrium, chloride diffusion and gas permeability coefficient with CNT content, dispersive agent type and microstructural parameters. The behavior was linked with the presence of high amount of dispersive agents which, not only control the level of compaction, but also chemically interact with water or methanol altering transport.