**6. Conclusions**

Factors affecting the water sorption of hcps such as w/c, pozzolanic materials, and internal hydrophobation were described in this chapter. The hcps with lower w/c have a less total porosity which results in a less water sorption. The amount of pores filled with water under capillary suction (*εcsuc*) was near to total porosity (*εtot*) for plain hcps (Ref samples). In addition, silica fume as pozzolanic material increases resistance to water transport in hcps due to a reduction in the pore size and the connectivity between the pores, but it is not effective in reducing the total water suction of hcps.

A minor effect on water sorption was observed using alkyl alkoxysilane showing that this agent which is developed for surface treatment is not suitable for internal hydrophobation. However, rapeseed oil as a hydrophobic agent resulted in an obvious reduction in the water suction of hcps. Pore blocking by oil droplets and denser pore structure can be the other possible reasons for less PF values in some samples. However, the effect of a denser pore structure is not comparable to the water repellency effect of the oil. The behavior of hcps under water suction can be different from cement-based composites due to the effect of ITZ in the composite materials and the formation of micro-cracks in hcps during drying.

Due to the lack of clear capillary nick points, for the determination of resistance number and capillary number, an alternative parameter "effective moisture transport (*EMT*)" factor was proposed instead in this chapter. The *EMT* factor can be a more comparative measure for denser or hydrophobed samples, especially when the samples are dried at lower temperatures to reduce the effect of drying on pore structure and composition of the material components.
