On Developing a Hydrophobic Rubberized Cement Paste

Area of Science:

• Materials Science
• Civil Engineering
• Surface Chemistry

Background:

• Cement matrix materials are typically hydrophilic, making them susceptible to water-induced damage.
• This hydrophilicity poses a significant challenge for the durability of structural materials.
• Developing hydrophobic cementitious materials is crucial for enhancing structural integrity and longevity.

Purpose of the Study:

• To create a hydrophobic rubberized cement paste using pretreated crumb rubber.
• To investigate the surface chemistry and microstructure of the modified cement paste.
• To evaluate the hydrophobicity and mechanical properties of the developed material.

Main Methods:

• Crumb rubber was pretreated via partial oxidation.
• Fourier-transform infrared spectrometry (FT-IR), nuclear magnetic resonance (NMR), and atomic force microscopy (AFM) were used for material characterization.
• X-ray diffraction (XRD), scanning electron microscopy (SEM), and static contact angle measurements assessed microstructure and hydrophobicity.

Main Results:

• Partial oxidation introduced functional groups on crumb rubber, enhancing its interaction with cement.
• The hydrophobic rubberized cement paste exhibited excellent static contact angles, indicating superior water repellency.
• Compressive strength was only insignificantly reduced, demonstrating the material's structural viability.

Conclusions:

• Partially oxidized crumb rubber effectively imparts hydrophobicity to cement paste.
• The developed hydrophobic rubberized cement paste offers a promising alternative for durable construction applications.
• This approach addresses the detrimental effects of water absorption in cementitious materials.