Loss of mass, structural, and thermodynamic properties of concretes under rainy conditions

Abstract A chemical rationalization of the loss of mass of concretes under rainy conditions, as well as the effects of the rain as water clusters on the structural and thermodynamic quantities of these materials are advanced. Results showed that the chemical equilibrium constants of the hydrations of calcium oxide and aluminum oxide are 1.00 × 10 10 and 0.80, respectively. These values revealed that when the concretes were prepared, the hydration of calcium oxide (mainly due to the components of cement) was majority when compared with the hydration of aluminum oxide. Therefore, the unreacted materials were hydrated only when these concretes were under rainy conditions, which led to these materials to reduce mass. Further, structural and thermodynamic properties revealed that when the concretes are under rainy conditions, their main inorganic compounds are predicted to interact with water clusters via hydrogen bonding. From both structural and thermodynamic perspectives, the calcium hydroxide is predicted to form the most stable hydrogen-bonded complexes when the concretes are under rainy conditions. Finally, the ability of the main components of the concretes to form hydrogen bonding can be ordered as follows: Ca(OH) 2 » Al(OH) 3  ≈ SiO 2 » Fe 2 O 3 . In this sense, the iron oxide can easily lose its hydrogen bonds with clusters of water, which tends to preserve the original properties of concrete when the rain is over. On the other hand, calcium hydroxide is predicted to form strong interactions with water clusters, that can be difficult to be broken when the rainy conditions are over, which can lead to pathological manifestations of the material.