Conclusion

UHPC surfaces have particular topographical characteristics, such as a homogeneous, very smooth appearance, due to the formulation of this type of concrete (spaced stacking, superplasticizers, many fine particles, low water/cement ratio). In addition, molding conditions (type of mold, release agents), storage conditions (duration, relative humidity) and possible post-molding treatments (gumming, sandblasting, cleaning) can have a greater or lesser impact on surface chemical composition, open surface microporosity and roughness, as well as on the appearance of calcium carbonate efflorescence.

In some cases, new hydrophobic features may be added to protect the surface from aqueous stains. Nevertheless, it appears that under most molding/storage conditions, UHPC can be sensitive to staining (by dyes, dust, algae, etc.) due to its open microporosity. Only certain conditions...