Had an interesting visit this morning to a building site here in Niamey, Niger. Our FM team here is building a worship/ministry centre that fits into the local architecture and building methods with 21st century applications. These bricks are 'rammed earth' technology, a method used for hundreds of years here in the sahel region of West Africa.
Red laterite soil (think adobe bricks) mixed with 5% cement and just enough water to make the mix clump in your hand. Then placed in a compressor where the mix is 'rammed' in a mold, one brick at a time. Bricks are dried under plastic for a week (retains humidity) then dried in the sun for two weeks. The bricks (10"x12") have a notch design so no mortar is required when laid.
Costs are less than conventional blocks and don't retain heat -- today the temp is over 40C! The Nigerien architect was very happy to work with us in applying this method to our project. 20,000 blocks required for this 2 story building.