How can you use a potentially polluting algae to build a solid home?

Posted by Derek Mason

20th August 2019

Sargassum is blooming. There’s a large amount of this brown seaweed growing between the coast of Africa and Brazil. While it’s at sea, this algae’s berry-like gas-filled bladders make it buoyant, and it floats on the surface, creating a natural habitat that benefits fish, sea turtles, marine birds and other wildlife.

But once it washes up onto beaches, it dies and produces toxic gases and acid which leaks back into the sea, damaging the marine ecosystem. The gas released – hydrogen sulphide – is also unpleasant for tourists, giving off a rotting egg smell.

And when tourism is a key industry, and your livelihood depends on the presence of pristine white sands and clear blue oceans, this seaweed is a major problem.

It washes up on the shores of Mexico’s beaches in large quantities, and it can be expensive and time-consuming to get rid of. But one entrepreneur in the Quintana Roo region has been thinking laterally about the problem.

Omar Vázquez Sánchez, the owner of an agricultural nursery in Puerto Morelos, near Cancún, has found a way to turn sargassum seaweed into house bricks.

He told a Mexican magazine, “I woke up in the middle of the night one night with this idea to use the overload of seaweed washing up on our beaches to make a brick and build many houses to one day help the people of Quintana Roo.”

After his moment of inspiration, it took him about a week and a half to come up with the right formula for making sargassum bricks. With a ratio of 60% sargassum and 40% adobe and clay, the bricks have similar thermal properties to traditional adobe bricks, but cost around 50% less to make.

Mr Vázquez Sánchez says the bricks are very hard and also hurricane resistant. There is no smell from the bricks as, during production, workers stomp on the sargassum and ensure it dries out completely before the material is incorporated into the bricks.

Once he’d perfected his bricks, Vázquez Sánchez constructed a prototype home, named Angelita after his late mother, which he uses as an office for his nursery business. The house is red in colour, like a traditional adobe home, and this innovative entrepreneur is planning to build ten more, donating them to families in need. The first of these has already been built and gifted to a family who had lost their home in a fire.

Others in the area are embracing this method for re-purposing seaweed, with a hotel in Tulum planning to use the bricks to construct a new eco hotel.

The handmade bricks are completely organic, with no cement or metal rods, and the mixture also goes through a waterproofing process. The bricks do not need to be fired, meaning they are energy efficient to make. The only downside to the bricks is that they are not tremor resistant, but as this is not a seismic region this should not cause any issues.

Another potential issue with bricks made from a living organism is that insects could be attracted to them. This is one of the challenges with straw bale housing in Africa, or adobe homes where the bricks contain straw. However, as these sargassum bricks don’t contain straw, insects should not be a problem.

This creative use of an unwanted organic substance is the kind of innovative development that we’ll need to see more of as the planet’s climate changes and new challenges occur. It will be interesting to see whether the other regions affected by sargassum begin to use it in this way too.

I hope this was of interest, and if you need assistance with the structural elements of an upcoming project, please do get in touch.

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