Self-cleaning superhydrophobic fly ash geopolymer

Area of Science:

• Materials Science
• Surface Chemistry
• Sustainable Construction

Background:

• Hydrophobic surfaces enhance building material durability by preventing moisture absorption, crucial for protecting reinforcing steel in concrete.
• Geopolymers, a cement-free alternative, are susceptible to moisture intake, limiting their service life.
• Developing protective surfaces for geopolymers is essential for sustainable construction practices.

Purpose of the Study:

• To fabricate a superhydrophobic and self-cleaning surface on fly ash geopolymer materials.
• To evaluate the effectiveness of polydimethylsiloxane (PDMS) coatings with polytetrafluoroethylene (PTFE) or calcium stearate (CS) microparticles.
• To investigate the impact of incorporating fly ash into the coating for enhanced surface properties and cost reduction.

Main Methods:

• Fabrication of geopolymer surfaces using dip-coating with PDMS solutions containing PTFE or CS microparticles.
• Incorporation of fly ash with microparticles to increase surface roughness.
• Measurement of water contact angles and sliding angles to assess hydrophobicity and self-cleaning properties.

Main Results:

• CS microparticle coatings achieved a hydrophobic surface with a 140° contact angle.
• PTFE microparticle coatings resulted in a superhydrophobic surface with a 159° contact angle.
• PTFE/fly ash coatings exhibited a 153° contact angle and an 8.7° sliding angle, demonstrating enhanced roughness and self-cleaning capabilities.

Conclusions:

• The developed coatings provide effective superhydrophobic and self-cleaning properties for fly ash geopolymers.
• Incorporating fly ash enhances surface roughness, leading to improved water repellency and self-cleaning.
• These findings offer a pathway to improve the sustainability and service life of building materials in construction.