Un-stabilized CEBs are made only with natural earthen material (clay, sand, aggregate, silt). These blocks are not water resistant on their own, so once built into a wall, they will need to be covered with a porch roof or some kind of coating, such as lime, stucco, or paint.
Stabilized CEBs are made with about 92% natural earthen material and about 8% cement, lime, or fly ash. These blocks have the advantage over un-stabilized blocks that they are completely water resistant.
A comparison of un-stabilized CEBs vs. stabilized CEBs is shown in the table below.