Mechanical properties of chalk with emphasis on chalk-fluid interactions and micromechanical aspects

The paper addresses the problem of water weakening effects in chalk. Using miscible fluids, capillary forces can be eliminated. Experience with water and methanol has revealed that methanol saturated chalk is considerably str onger than water saturated chalk. A study of water-methanol mixtures has sh own that the transition is a gradual one, only dependent on the composition of the fluid. The changes in mechanical properties can be accounted for by repulsive forces at the grain contacts. The strong interaction between the highly polar water molecules and the chalk surface may give rise to charge d or polarized layers which will develop repulsive forces when two surfaces are in close contact like in the grain contact region.