Overview

The mortar permeability tester is easy to use and simple to operate, making it suitable for use by departments involved in production, construction, design, research, and education for conducting permeability tests on mortar.

Technical Performance

Specimen Molding

Before molding, wipe the inner walls of the molding molds with a cloth (do not use any oily substances). Prepare a batch of mortar suitable for two test specimens by weighing out 200 grams of cement and 600 grams of sand, then place them simultaneously into the mixing bowl and manually stir for 1 minute. Next, add water according to the standard consistency requirements and mix wet for 3 minutes. Once mixing is complete, immediately pour the mortar into two separate molding molds, using a small knife moistened with water to gently tamp down the mixture 15 times. At the end of tamping, ensure that the mortar extends about 1 centimeter above the mold edges. Then place the molds on a vibrating table and vibrate them 30 times, pressing down on the molding molds with your hand during vibration to prevent displacement. After vibration, cure the molding molds along with the test specimens in air for approximately 30 minutes. Use a small knife dampened with water to scrape off any excess mortar, bringing the mortar level with the top surface of the molds. Number the specimens and immediately place them in a curing chamber for further curing.

2. Curing and Demolding of Test Specimens

After the test specimens are molded, they shall be cured in a humid environment for 24 ± 2 hours, then demolded and placed in a curing chamber for an additional 2 days of curing. The temperature in the curing chamber should be maintained at 20 ± 3°C, and the relative humidity should be kept above 90%.

3. Seal the test specimens with wax.

After being molded and cured in a humid environment for 3 days and nights, the test specimens shall undergo a permeability test. However, one hour prior to the test, the specimens should be removed from the curing chamber. The wax used for sealing should be heated until completely melted, then the specimens should be rolled once in the molten wax. Afterwards, they should be placed into the test molds (note that the two end faces of the specimens must not come into contact with the wax).

4. Permeability Test

(1) Water filling: Unscrew the nut on the water inlet nozzle, fill the water storage tank with water, and ensure that the inside of the mold base is also completely filled with water (this serves to expel air from the piping system).

(2) Install the test mold and mount the mold containing the encapsulated test specimens onto the instrument.

(3) Turn on the power switch to start the instrument.

(4) When pressurizing the pump, first open the pressure-reducing valve until the water flow becomes a steady stream (the purpose is to remove any air). Then open valves 1–6 and close the pressure-reducing valve.

(5) Apply pressure for 2 hours; if no water leakage is observed in the specimen, continue increasing the pressure until water begins to seep through the specimen, then record the water permeability pressure and the corresponding time.

Methods for Handling Pump No Pressure Boost

1. Check whether the water tank inside the reservoir is fully filled with water.

2. During the pressurization process, if water is lost midway, air may enter, resulting in a failure to pressurize. You must fully release the pressure and then restart the instrument.

3. If the instrument is left unused for an extended period, the steel balls inside the inlet (and outlet) valves may become stuck and immobile, preventing water from flowing through and resulting in no pressure testing. To resolve this, gently tap the inlet (and outlet) valves with a metal rod to loosen the steel balls; once water starts flowing out of the outlet valve (the upper valve), you can proceed with pressure testing.

4. If the instrument is used frequently but the pressure fails to rise, it’s because there is foreign matter inside the inlet valve (lower valve), which needs to be removed and cleaned. If the pressure rises but remains unstable, it’s because there is foreign matter inside the outlet valve (upper valve) or grease on the surface of the steel ball; in this case, the outlet valve must be removed and cleaned.

Operation of the Digital Display Controller

1. Settings

After powering on, press the Set key for 3 seconds—the digital display will flash, entering the setting mode. Press the Adjust key to modify the values, then press the Save key to save the settings once you’ve made the desired adjustments.

2. Work

After the set value is stored, the motor switch is activated and the device begins operation. If the (Time Reset) button is pressed for 3 seconds, the time can be reset to 0 hours, with the lower pressure limit automatically increasing by 0.1 MPa every hour—until the lower limit, upper limit, and pressure display all match. After one hour of operation, an alarm sounds to indicate that the experiment has concluded. In the event of a power outage during operation, the instrument can retain its original operating data. If pressurization exceeds 10 minutes without any increase in pressure, the instrument will cease operation and sound an alarm, indicating low water levels or a malfunction in the pressurizing pump. While in measurement mode, if the system shows no pressure but the displayed value is not zero and is less than 0.3 MPa, you can press the (Zero Adjustment Key) to reset the pressure to zero. Pressing the (Time Review) key will switch the pressure display to minutes; releasing the key will return the display to pressure readings.

Maintenance and upkeep

1. Grease should be added to the gearbox on a regular basis.

2. After each experiment, the water in the instrument should be completely drained, the mold assembly should be wiped clean and coated with anti‑rust grease, and all exposed surfaces of the instrument should be thoroughly cleaned to prevent rusting. Then, cover the instrument with its outer housing.

Precautions

1. In winter, the water in the instrument’s storage tank must be completely drained to prevent freezing and cracking.

2. The instrument must be reliably grounded, and the power should be turned off when not in use.

3. If water is leaking from the drain hole at the bottom of the pump, it indicates that water is being carried by the piston; simply tighten the gland nut.