Method and apparatus for controlling the relative humidity in concrete and masonry structures

A method for expulsion or control of humidity in a concrete or masonry structure, having a current source and one or more electrodes comprising at least one anode and cathode being provided in the concrete or masonry structure, the electrodes being a non-corrosive material, and connected in series or parallel with the current source, wherein an earth electrode is provided adjacent to or on the concrete or masonry structure, so that the electrode or electrodes comprise the anode and the earth electrode comprises the cathode in an electric circuit when they are connected with outputs of the current source, wherein the anode and cathode are provided with a pulse voltage supplied by the current source, and wherein the pulse voltage is delivered sequentially as pulse sequences of a given pattern, comprising the steps of feeding the anode with a pulse sequence generated with a first negative pulse of a duration, followed by a neutral interval or a zero voltage interval of a changing duration being from greater than 0 to 2 times that of the duration of said first negative pulse, followed by a positive pulse, having a duration which is about six times that of the duration of the negative pulse, and simultaneously feeding the cathode with a corresponding pulse sequence, but of inverted polarity;

• whereby the humidity in the structure is controlled.

Apparatus for reducing relative humidity in a concrete or masonry structure comprising a controlled power supply, pulse voltage lines, control voltage lines and a neutral conductor, a pulse width modulator, at least one pulse generator, a complimentary push/pull amplifier stage, and first and second output electrodes, wherein said power supply is connected to said pulse width modulator, which in turn are connected to said at least one pulse generator, and thereafter to said amplifier stage, said amplifier stage being bridged for synchronous feeding said electrodes with a pulse sequence to said first electrode and corresponding pulse of inverted polarity to said second electrode, so that a potential between said electrodes is twice that of each electrodes ground potential.