Chemical and frost resistance of hardened cement paste

Hardened cement paste may be attacked either by a process of dissolution or by chemical transformation or by both at the same time. The intensity of the attack depends on the specific properties of the aggressive agent, its concentration, the presence of other ions in the solution, etc. Ambient conditions such as temperature and pressure, as well as the length of time and the nature of the contact (i.e. continuous or periodic) between the paste and the aggressive agent, also affect the intensity of the attack. Also, regardless of the specific nature of the agent, the intensity of the attack is determined to a considerable extent by the porosity of the paste. In a dense paste the attack is essentially limited to the surface proceeding with time to the inside. A porous paste, on the other hand, allows the aggressive solutions to penetrate it, and the attack takes place throughout the mass. Such an attack is, therefore, more intensive.