Colloid Electrochemistry of Saturated Cement Paste and Some Properties of Cement Based Materials

In a cement hydration product-electrolyte system the hydration products are micron-sized charged particles. The principles of colloid electrochemistry predict that in such a system each solid particle is surrounded by a layer of concentrated solution of its counter-ion. The actual concentration of this layer depends on the surface charge and the concentration of the solution away from the particle, i.e., bulk solution. Divalent counter-ions preferentially concentrate around the solid particles. The principles also predict that the intrinsic diffusivity of an ion is proportional to the square root of its concentration in a solution. The literature on the expressed pore solution, ionic diffusivity through cement based materials, the formation factor, alkali-silica reaction, etc., has been examined from the point of view of colloid electrochemistry. Many of the reported but unexplained phenomena could be explained from the principles of colloid electrochemistry.