Syntactic foam

Microballoons are available in a variety of sizes and materials, including glass microspheres, cenospheres, carbon, and polymers.

Cementitious syntactic foams are reported to achieve compressive strength values greater than 30 MPa (4.4 ksi) while maintaining densities lower than 1.2 g/cm3 (0.69 oz/cu in).

[citation needed] Current applications for syntactic foam include buoyancy modules for marine riser tensioners, remotely operated underwater vehicles (ROVs), autonomous underwater vehicles (AUVs), deep-sea exploration, boat hulls, and helicopter and airplane components.

Cementitious syntactic foams have also been tested for their mechanical performance under high strain rate loading conditions to evaluate their energy dissipation capacity in crash cushions, blast walls, etc.

Ultimately, unlike the polymeric and metallic syntactic foams, they did not emerge as suitable materials for energy dissipation applications.

Generally, the hollow inclusions tend to buoy and segregate in the low shear strength and high-density fresh cement paste.