As a civil engineer, i can say TITLE itself is wrong, because compression is a type of mechanical stabilization so title should specify what type of stabilization. Stabilization can be either mechanical, Chemical. Mechanical stabilization is mainly performed using compactors, rollers, Vibrators etc. Chemical stabilization is done using cement, lime etc. These chemical stabilizers react with clay particles present in earth brick thus hydrating it and reducing its plasticity index (PI).
Now earth bricks can be stabilized without chemical stabilizers by obtaining its maximum dry density and optimum moisture content. But the strength will always be less than chemical stabilized bricks. Also once it is compressed, one must properly burn it to make it hard which increases its compressive strength. Now a days research is focused on stabilized blocks because of its known usefulness.