Page 144 - Handbook of Surface Improvement and Modification

9.1 Methods and mechanisms of hydrophobization 139

Figure 9.3. The concept of superhydrophobization. [Adapted, by permission, from Muzenski, S; Flores-Vivian, I;
Sobolev, K, Construction Build. Mater., 81, 291-7, 2015.]

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concrete mix restricts water in entering the capillary voids and porous space. The super-
hydrophobic engineered cementitious composites, SECC, are designed with hydrophobic
or superhydrophobic air voids evenly distributed throughout the cementitious matrix, pro-
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viding effective protection against water infiltration (Figure 9.3). They also incorporate
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fiber reinforcement to reduce the crack opening. The improved durability of fiber rein-
forced cementitious materials by creating a 3-dimensional hydrophobization to reduce the
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water absorption and permeability improves the freeze-thaw performance. The absorp-
tion, rate of absorption, and chloride permeability are improved with the addition of supe-
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rhydrophobic admixtures. The hydrophobic nature of the air voids does not allow water
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to saturate the pore space.
Complex hydrophobization modifiers permit production of high-mobility concrete
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mixtures and reduction of their water separation value by 15-20%. The complex hydro-
phobization modifiers may reduce the water absorption and the capillary infiltration effect
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in concrete by 3-3.5 times.
The moisture properties of historic building material with hydrophobization treat-
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ment have been studied. Moisture present in the building facade may lead to frost dam-
age, mold growth, condensation, and decrease of thermal resistance, which reduce the