Mud bricks
Living in a desert environment, our most abundant resources are sand and stone. When people first arrived at the camps, they built their homes using mud bricks and fabric roofs, which were later replaced by tin roofs. Mud bricks are excellent thermal insulators and cost nothing to produce. However, they lack water resistance. While it only rains every few years in this region, the downpours are intense. In 2015, severe flooding destroyed most of the mud-brick homes. Unwilling to rebuild their houses every few years, the community abandoned mud bricks in favor of cement.
For us, this was an unfortunate shift because mud brick is environmentally friendly, highly insulating, and free. In 2019, we began experimenting with modified mud-brick formulas to solve the water resistance issue. Our first trial involved adding 10% cement and 10% gypsum. After the bricks dried, we tested them by smashing them and submerging them in water. Although slightly stronger, they were still susceptible to water damage. We used them anyway to build a small shade structure for a water pump.
We later expanded our experiments by adding three local, drought-resistant materials to our two native soil types: surface soil (which has a slight red color) and soil dug from one meter deep (which has a green color). We chose aloe vera and cactus, hoping their natural gels would seal the mud’s pores and prevent water absorption, and we added clay to improve cohesion. We also tested a control batch using 20% cement (20PC).
We produced various combinations: cement, aloe vera (with and without straw), cactus (with and without straw), and a mix of aloe vera, cactus, and clay. We tested fermented versus unfermented mixtures, as well as compacted versus uncompacted bricks. All bricks measured 10 × 20 × 12.5 cm. They were left outside to dry in temperatures ranging from 30°C to 44°C. They were ready after three days, but we waited five days to ensure they were completely dry. During this time, we noticed termites eating the organic matter inside the bricks, leaving tiny holes.
Once fully dry, we conducted two tests: a water-submersion test for water resistance, and a 4-meter drop test onto a hard surface for hardness.
- Hardness test ranking: (1) 20PC, (2) Compacted bricks, (3) Fermented bricks, (4) Traditional soil and water bricks.
- Water resistance test: The 20PC brick survived two hours submerged in water without damage. All other variations dissolved within nine minutes.
Ideally, a mud brick should consist of 70% sand, 10–15% silt, and 15–20% clay. To determine our soil’s clay content, we conducted a jar test using two glass bottles, both soil types, and a teaspoon of dish soap to separate the layers. The results showed that the red surface soil contained no clay at all—it was 24% silt and 76% sand. The deeper green soil contained 11.24% clay, 77.51% sand, and 11.24% silt.
More about this experimrnt in the future…