Abstract
As a long-term durability evaluation of a concrete building, a study about dissolution behavior of hardened cement in the concrete has been carried out. On the other hand, a calculation by a model has been carried out to evaluate the alteration behavior of hardened cement of an extremely long period. In such a model calculation, it is necessary that the dissolution behavior of each hydrate is clarified.
In the present research, representative cement hydrates were synthesized and leaching test on each hydrates were conducted by changing the ratio of mass of leaching water to mass of hydrates. In addition, the equilibrium composition of the water which contacted with hydrates was calculated by a geochemistry calculation cord PHREEQC and RAIDEN3. The propriety of the conditions to calculate chemical equilibrium was examined by comparing a calculation result with an experiment result. From a result of liquid and solid phase analysis, a crystal phase of the AFm varied with the dissolution, but other hydrates did not have the change. It was recognized that second mineral setting was necessary in the calculation of dissolution of AFm. As the calculation result accorded with an experiment result of liquid composition, it was recognized little difference in result between geochemistry calculation cords which we have used. And it was recognized that the appropriate choice of the thermodynamic equilibrium constant was important.
