This technique offers a means of determining relative strengths of concrete in the same structure or relative strength of different structures. Because of nature of equipments, it can not and should not be expected to yield absolute values of strength. ASTM C-803 gives this standard test method titled “Penetration Resistance of Hardened Concrete”.
Windsor Probe is penetration resistance measurement equipment, which consists of a gun powder actuated driver, hardened alloy of probe, loaded cartridges, a depth gauge and other accessories. In this technique a gunpowder actuated driver is used to fire a hardened alloy probe into the concrete. During testing, it is the exposed length of probe which is measured by a calibration depth gauge. But it is preferable to express the coefficient of variation in terms of depth of penetration as the fundamental relation is between concrete strength and penetration depth.
The probe shown in fig.1 has a diameter of 6.3mm, length of 73mm and conical point at the tip. The rear of the probe is threaded and screwed into a probe-driving head, which is 12.6mm in diameter and fits snugly along with a rubber washer into the bore of the driver. As the probe penetrates into the concrete, test results are actually not affected by local surface conditions such as texture and moisture content. However damage in the form of cracking may be cause to slender members. A minimum edge distance and member thickness of 150mm is required. It is important to leave 50mm distance from the reinforcement present in the member since the presence of reinforcing bars within the zone of influence of penetrating probe affects the penetration depth.
A pin penetration test device (PNR Tester) which requires less energy than the Windsor Probe system is given in fig.2
This technique offers a means of determining relative strengths of concrete in the same structure or relative strength of different structures. Because of nature of equipments, it can not and should not be expected to yield absolute values of strength. ASTM C-803 gives this standard test method titled “Penetration Resistance of Hardened Concrete”.Windsor Probe is penetration resistance measurement equipment, which consists of a gun powder actuated driver, hardened alloy of probe, loaded cartridges, a depth gauge and other accessories. In this technique a gunpowder actuated driver is used to fire a hardened alloy probe into the concrete. During testing, it is the exposed length of probe which is measured by a calibration depth gauge. But it is preferable to express the coefficient of variation in terms of depth of penetration as the fundamental relation is between concrete strength and penetration depth.The probe shown in fig.1 has a diameter of 6.3mm, length of 73mm and conical point at the tip. The rear of the probe is threaded and screwed into a probe-driving head, which is 12.6mm in diameter and fits snugly along with a rubber washer into the bore of the driver. As the probe penetrates into the concrete, test results are actually not affected by local surface conditions such as texture and moisture content. However damage in the form of cracking may be cause to slender members. A minimum edge distance and member thickness of 150mm is required. It is important to leave 50mm distance from the reinforcement present in the member since the presence of reinforcing bars within the zone of influence of penetrating probe affects the penetration depth.A pin penetration test device (PNR Tester) which requires less energy than the Windsor Probe system is given in fig.2
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