What I understand is that a material is introduced into the soil matrix which will increase or decrease the maximum dry density of the soil mass, and the optimum moisture content. I am trying to make sense of this statement. If a material is introduced in the soil matrix that can fit within the voids, density can be increase and the moisture will be displaced. The net effect is that the maximum dry density will increase, but optimum moisture (moisture at which maximum density is achieved for the given energy level imparted) will be decrease. The converse may also be true depending on the nature of the material being introduced into the soil matrix.
