Self-Assembling Particle-Siloxane Coatings for Superhydrophobic Concrete

Abstract

We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single-and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156°for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic waterrepellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering.

Anti-Icing Superhydrophobic Surfaces: Controlling Entropic Molecular Interactions to Design Novel Icephobic Concrete

“…The concentration of the PVA surfactant in water was kept constant at 5% for both types of emulsions. The procedure of emulsion preparation was described in detail in our previous study [72][73][74].…”

“…Three sets of samples of 10 different formulations were used in the experiment. The first set was used without any treatment as a reference, and two others were differently modified with hydrophobic "shell type" emulsions, as discussed in our previous study [73].…”

Nano-engineered Superhydrophobic and Overhydrophobic Concrete

“…To prepare the emulsions, de-ionized water was used as a dispersion medium, water-soluble PVA as surfactant and PMHS as the dispersion phase. Micro-particles of silica fume or metakaolin were used to stabilize [ 17 ] and modify the emulsion using two different approaches: "shell" and "core" as described in CFIRE 07-03 [ 18 ] and explained in detail in Flores-Vivian et al [ 3 ]. First, the application of superhydrophobic emulsions was considered as surface treatment.…”

A Self-Assembly and High-Robustness Super-Hydrophobic Coating Based on Waste Marble Powder

“…It also displayed an excellent robustness property after the related tests [8][9][10] . Such coating can be considered to be used in many diverse elds, including self-cleaning coatings for external walls [11][12][13] and micro uidics [14][15][16][17][18] and it was also an effect way to reuse the waste marble powder.…”