Instructions for using a drop ball on-site CBR value testing instrument

Falling ball style on-siteCBRUsage of Value Testing Instruments
keyword:Falling ball style on-siteCBRUsage of Value Testing Instruments
Falling ball style on-siteCBRUsage of Value Testing Instruments
1Falling ball style on-siteCBRThe test of the value tester should be systematic, requiring the surface of the soil foundation to be scraped flat and immediately measured after the soil foundation measurement layer and compaction are completed. The method is to place the base of the ball dropper at the measuring point on the surface of the roadbed soil that has been leveled. At this time, the upper marking on the guide rod should be aligned with the zero marking on the ruler, and the guide rod can be raised to600mmWhen the position of the standard drop height is reached, the notch is stuck. At this time, the bottom marking line of the drop ball instrument is just aligned with the zero of the lower marking line of the ruler. When the notch release switch is pressed, the drop ball falls freely to the on-site roadbed. From the ruler window, the diameter of the drop ball indentation is read（cm）And for depth useDLift the guide rod above the ground, move it along with the base, and then measure the diameter of the ball drop mark with a caliper or steel rulerDThe accurate value of the value.
2When measuring on a test tube for compacted soil samples indoors, the following methods can be used:100mmand150mmTest tube, the instrument is equipped with a board that can be used in both positive and negative directions100mmagainst150mmThe remaining operations are the same as above.
3When the ball marks on the coarse sandy soil subgrade are unclear, recording paper, carbon paper, and plastic paper can be sequentially laid on the surface of the leveled soil subgrade. The sphere falls onto the surface recording paper, and the diameter of the imprint can be measured from the paperDValue and verify with the scale reading.
4Parallel measurements on both sides of each measuring pointDTake the average of the values,