Introduction to the operation of the penetration tester—quickly save this for future reference!

　　The penetration tester is a new product developed in response to the rapid advancement of nondestructive testing technology. In recent years, nondestructive testing technology has been rapidly evolving in China, and current building codes as well as new construction systems now require the use of penetration testers to assess the early strength of concrete—for instance, the formwork removal strength for large-formwork systems, the concrete strength prior to relaxation of prestressed members, and the critical strength level of concrete during winter construction. Unlike the rebound method, this new instrument evaluates concrete conditions by measuring the surface hardness of the concrete. The penetration tester measures the state of concrete by determining how deeply a probe penetrates into the material; thus, it can accurately reflect the actual stiffness of concrete and effectively address issues that have long plagued the rebound method—such as the early-stage rigidity of concrete, the strength and quality of concrete components in older buildings, and the hardening of concrete elements that have undergone chemical corrosion, fire damage, or freeze-thaw cycles.

　　How does the penetration tester work? Let us introduce it to you: Actually, the ZXL-1000 penetration tester is based on the penetration resistance principle outlined in ASTM C803-82. A steel measuring pin equipped with a compression spring is inserted into the concrete. By measuring the depth to which the pin penetrates, we can determine the thickness of the concrete. The penetration depth of the pin is inversely proportional to the strength of the concrete—specifically, the deeper the pin penetrates, the lower the concrete’s quality; conversely, the shallower the penetration, the higher the concrete’s quality. In the laboratory, numerous cylindrical and cubic specimens with various mix proportions were tested, yielding an extensive dataset. Based on this data, a relationship curve was established between the concrete’s condition and the penetration depth. Practical tests have demonstrated that the testing accuracy of this instrument meets the requirements specified by the standard.

　　What are the operating steps for the penetration tester? Let’s continue introducing them to you below.

　　1. Grind the surface of the joint with a grinding wheel.

　　2. Assemble the penetration tester: Take out the measuring pin from the box and insert it into the hole on the measuring pin holder of the penetration rod, with the measuring pin facing outward. Then, use the tightening wrench to tighten the nut on the measuring pin holder, securely fixing the measuring pin in place. Holding the main body of the penetration tester with one hand, use the other hand to slide the long slot surface of the force-applying rod onto the force-applying slot rod at the rear of the penetration tester, ensuring that the force-applying cross-pin on the force-applying rod aligns precisely with the force-applying slot. Next, grasp the ends of the pressurizing rod with both hands and slowly apply inward pressure with both hands. When you notice the trigger mechanism clicking and switching over, it indicates that the hook of the penetration tester has been properly engaged (during application of force, you can apply force in any direction up to approximately 3600 Newtons, which helps extend the service life). After removing the force-applying rod, the product is ready to proceed to the subsequent testing phase.

　　3. During the test, hold the device horizontally with one hand so that its flat tip can press against the smoothly ground mating surface. Grip the handle (5) firmly to counteract the recoil, then pull the trigger to allow the penetrometer to freely release its energy. This completes one test. Afterward, remove the object and use a hairdryer to clean the measurement hole thoroughly.

　　4. Use a depth gauge to measure the depth of the measurement hole, and read the measured depth value directly from the display screen.