InfiRing of Pore Spaces in Mortar Using Electrically-Driven Solution Transport Systems

摘要

It has been widely established that all types of conventional concrete can be strengthened by reducing the porosity of the concrete matrix. Attempts to infill the pores by converting reactive phases such as calcium hydroxide into calcium carbonate have been partly successful, but the success of this approach has been limited by the amount of Ca(OH)_2 produced in the hydration of the concrete and by the positions of the new crystalline phases that are formed. These limitations can be overcome by using a combination of electrophoresis to move particles into concrete pores and the use of ion transport to move new dissolved reactants into the concrete mass. Bench scale experiments have demonstrated that significant density and strength increases can be obtained by electrophoretically moving seed crystals of selected mineral phases such as calcite, aragonite, or vaterite into the larger pores in concrete and then using a low-voltage DC current to migrate in calcium and carbonate ions to grow the selected crystalline phases in masses sufficient to fill up both large and small pores. This can be done in such a way as to leave even the reactive phases such as Ca(OH)_2 unaltered. The bulk pH of the concrete is not reduced in the mineralization process as it would be in simple carbonation. Pore in-filling using electrophoretic and electro-transport systems can potentially be of use in creating very high-density concrete for concrete pipes, and panels with lower porosity than can be obtained using carbonation or pressure infiltration.