Test apparatus for the dynamic measurement of moisture transport and storage properties of porous materials

1 . A test apparatus for the dynamic measurement of moisture transport and storage properties of porous materials, the test apparatus comprising:

a housing with an interior which forms a watertight main measuring chamber for housing a sample bar having a constant section and having faces sealed in a watertight manner, with all its faces being sealed except for one of its end faces,

a framework structure supporting the housing, a sample holder arranged in the main chamber,

an air-conditioning system for obtaining regulated relative humidity and temperature conditions for the air inside the main chamber comprising:

a humidifying system for humidifying the air inside the main chamber so as to obtain humidified air inside the main chamber,

a thermal regulation system for establishing predetermined working temperatures of the humidified air inside the main chamber so as to obtain thermally conditioned humidified air,

a humidified air recirculation system for providing a recirculation of thermally conditioned humidified air inside the main chamber, and

a control system which controls the humidifying, thermal regulation, and air recirculation systems so as to establish a plurality of combinations of the regulated relative humidity and temperature conditions,

wherein the sample holder comprises first lower support elements for supporting a first end part of the sample bar and second lower support elements for supporting a second end part of the sample bar corresponding to the unsealed end face of the sample bar; and

a first suspension arm and a second suspension arm each hinged at its lower end to one of the lower support elements, the first suspension arm being hinged to an upper part of the framework structure, and the second suspension arm being hinged such that it is connected to a force gauge arranged in the main chamber, the lower support elements being suspended on the suspension arms such that they keep the sample bar axially suspended in a horizontal plane without causing axial stresses in the bar.

2 . The test apparatus according to claim 1 , wherein

the first suspension arm is hinged, by means of a first upper hinge, to an upper part of the framework structure, and by means of a first lower hinge to the lower support element; and

the second suspension arm is hinged, by means of a second upper hinge, to a force gauge arranged in an upper part of the main chamber, the second suspension arm being attached to the second lower support element by means of a second lower hinge.

3 . The test apparatus according to claim 1 , wherein the force gauge is immobilised on a side extension of a frame fixed to the bottom of the framework structure.

4 . The test apparatus according to claim 3 , wherein the suspension arms, the hinges, and the support elements form an adjustable trapezium geometric system to adapt to the dimensions of the sample.

5 . The test apparatus according to claim 1 , wherein at least one of the support elements is in the form of a bracket with a support base for the sample bar.

6 . The test apparatus according to claim 1 , wherein the support elements are symmetrical.

7 . The test apparatus according to claim 1 , wherein the thermal regulation system comprises:

a thermoresistor probe with a negative temperature coefficient for measuring the temperature in the main chamber and for transmitting signals identifying the measured temperature to the control system; and

a Peltier effect thermoelectric system for regulating the temperature in the main chamber so as to establish the predetermined working temperatures of the humidified air inside the main chamber in response to temperatures measured in the main chamber.

8 . The test apparatus according to claim 1 , wherein the humidifying system comprises:

a humidity probe for the humidified air inside the main chamber and for transmitting signals identifying the measured humidity to the control system; and

a first humidity balancing chamber comprising a tray containing a first hydrated salt solution and a second humidity balancing chamber comprising a tray containing a second hydrated salt solution, each balancing chamber having at least one air inlet-communicating with the main chamber and an air outlet communicating with the main chamber;

wherein the first hydrated salt solution is capable of releasing humidity into the air in the first balancing chamber up to or from a temperature at or from which the second hydrated salt solution is capable of releasing humidity into the air in the second balancing chamber.

9 . The test apparatus according to claim 8 , wherein

the humidified air recirculation system comprises a first axial fan for causing the air originating from the main chamber to pass from the air inlet through the first balancing chamber and discharging the air into the main chamber through the air outlet, and a second axial fan for causing the air originating from the main chamber to pass from the air inlet through the second balancing chamber and discharging the air into the main chamber through the air outlet;

and in that the control system regulates the flow rate of the air caused by each fan to pass through each of the balancing chambers based on the air humidity measured by the humidity probe by controlling the speed of each fan.

10 . The test apparatus according to claim 1 , wherein the control system is programmed in a computer operating on the basis of PID (proportional, integral, and derivative)-based software.