Who would’ve thought snail shells could help build stronger cars, greener concrete and safer brake pads?

Nature already did the engineering – we’re just catching up

When it comes to snail farming, the focus is understandably on the snails themselves. The primary aspect of this type of farming focuses on producing high-quality “meat” for human consumption. Very often, the rest of the wonders of the snail are forgotten, like the potential their slime or shells have. Once the snail is removed from its shell, the shells are typically treated as waste. However, scientific research suggests that these shells deserve a second look!

Snail shells are extremely rich in calcium carbonate, which has the potential to be used as sustainable fillers and reinforcements across various engineering applications. If the shells can be used in these applications, they will promote environmental benefits.

According to studies snail shells can be used as cement replacement materials.

Snail shells can substitute cement, reducing CO2 emissions from the cement industry.

• Snail shell ash contains all essential cement constituents, similar to OPC.

• Replacing 5% of OPC with shell ash increases compressive strength by 4.43% (7 days) and 7.5% (28 days).

• Higher replacements above 5% decrease strength; 20% replacement maintains similar strength to 0%.

• Shell ash is mainly composed of calcium oxide, with silica oxide, aluminium oxide, and sulfur trioxide within standards.

• Shell ash acts as a viable pozzolan, comparable to recognised pozzolans.

  

Snail Shells as Fillers in Plastic Composites

Snail shells enhance the mechanical properties of plastics like polypropylene, polyethylene, epoxy, and rubber.

• Particle size reduction improves tensile, flexural, impact strength, and hardness.

• 15% filler content in polypropylene yields maximum strength; higher content decreases properties.

• Filling LDPE and HDPE with shell powder increases strength but reduces elongation.

• Smaller particle sizes improve wear resistance and thermal properties.

• Snail shell powder addition up to 15 wt% enhances epoxy’s tensile, flexural, impact strength.

• Reinforcing silicone rubber with 75 μm shell particles improves insulation and hardness.

• Natural rubber filled with snail shells shows decreased mechanical properties; carbon black performs better.

• Combining snail shells with other fillers like coconut shells can improve polyester resin properties.

Reinforcing Metal Matrix Composites with Snail Shells

Snail shells serve as reinforcement in aluminium and hybrid metal matrix composites.

• Recycled aluminium with 16-48% shell particles shows good wettability and bonding.

• Max hardness and tensile strength observed at 48% shell content with 600 μm particles.

• Shell powder withstands high temperatures (~1400°C), suitable for automotive/aerospace.

• Shells can improve erosion and corrosion resistance in hybrid composites.

  
  

Snail Shells in Grinding Plate and Coating Applications

Snail shell powder enhances wear resistance and mechanical strength.

• Replacing ferrochrome with shell powder in grey cast iron increases tensile strength and hardness.

• Wear rate decreases, achieving 96.7% efficiency.

• Shell particles in zinc coatings increase hardness by 60% and reduce wear by 94.4%.

• Shell-filled polyester coatings improve hardness and corrosion resistance for steel pipes.

  
  

Snail Shells as Eco-Friendly Brake Pad Material

Snail shells can replace asbestos in brake pads, eliminating health hazards.

• Shell powder at 125 μm particle size effectively replaces asbestos.

• Lower wear rate and better thermal resilience compared to asbestos.

• Suitable for environmentally safe brake pad manufacturing.

  
  

Calcium Carbonate Extraction and Characterisation from Snail Shells

Snail shells are rich in CaCO3 (~98%), suitable for industrial use.

• Shells dried, crushed, and sieved to particle sizes from 63 μm to 1000 μm.

• Chemical analysis confirms high CaCO3 content, comparable to commercial calcium carbonate.

• Shells contain minor elements like Na, K, Mg, Fe, Zn.

• NanoCaCO3 synthesised from shells shows high purity and potential for reinforcement in polymers.

• Shell ash analysed via X-ray fluorescence shows similar constituents to cement.

  
  

Snail Shells in Agricultural and Biomedical Applications

Shells neutralise acidic soils and serve as bone substitute materials.

• Crushed shells increase soil pH from 5.5 to 7.5 within 48 hours.

• Hydroxyapatite synthesised from shells exhibits bioactivity superior to conventional forms.

• Shell calcium carbonate aids in soil pH regulation and reduces aluminium toxicity.

• Shell-derived hydroxyapatite is effective for bone and dental implants.

  
  

Snail shells, as abundant and eco-friendly waste materials rich in calcium carbonate, demonstrate versatile applications in construction, plastics, metals, coatings, biomedical fields, and agriculture, offering sustainable alternatives and environmental benefits.