Pine Ridge Job Corps “Green Club” students took a field trip in August to the Black Hills and learned the principles of how to mix a combination of clay, sand, Portland cement, and water to use in rammed earth construction and compressed earth blocks (CEB’S) The students used the red clay from near-by Hot Springs, South Dakota to make some simple rammed earth bricks.   Rammed earth construction was one of the first building techniques.  It was utilized in the building of the Great Wall of China.   The material is mixed and tamped either manually or automatically with pneumatic tampers.  The mixture is laid down between forms in thin layers one after another until the forms are full.