ASTM E2835-11(R2020) pdf free download

ASTM E2835-11(R2020) pdf free download.Standard Test Method for Measuring Deflections Using a Portable Impulse Plate Load Test Device
4. Significance and Use
4.1 This test method covers the determination of plate deflection resulting from the application of an impulse load. The deflection is measured at the center of the top of the load plate (see Note 1). N OTE 1—If the load plate is in “perfectly uniform” contact with the unbound material under the plate, then deflection of the load plate should be equal to the deflection ofthe surface ofthe unbound material under test. However, with typical unbound materials a 100 % uniform contact can seldom be achieved. Accordingly, the test surface shall be as clean and smooth as possible with loose granules and protruding material removed. For gravel surfaces, it is recommended that a thin layer of fine sand be placed over the test point. For fine-grained materials, this will help in obtaining a reasonably uniform contact between the load plate and the surface. See 5.1 in Test Method D1195/D1195M. 4.2 Deflections may be either correlated directly to pave- ment performance or used to determine in-situ material char- acteristics of the pavement foundation layers. Some uses ofthe data include quality control and quality assurance of com- pacted layers, and for structural evaluation of load carrying capacity (see Note 2 and Guide D4695). N OTE 2—The volume of the pavement foundation materials affected by the applied load is a function of the magnitude of the load, plate size and rigidity, loading rate, buffer stiffness, and the stiffness and shear strength ofthe pavement foundation materials. Therefore, care must be taken when analyzing the results because the data obtained by the Portable Impulse Plate Load Test may be obtained under substantially different conditions than when a heavy moving wheel load passes over the pavement surface after construction is complete.
5. Apparatus
5.1 Instrumentation System, conforming to the following general requirements. 5.2 Instruments Exposed to the Elements, operable in the temperature range from 0 °C to 50 °C (32 °F to 120 °F) and tolerant to relatively high humidity, rain and spray, and other adverse conditions such as dust, shock, and vibrations normally encountered. 5.3 Force-Generating Device (falling mass), capable of being raised, using a guide system, to a preset fixed height and dropped onto a steel-spring subassembly. Designed to operate with negligible friction or resistance. 5.4 Force Pulse, a half-sine or haversine shaped load pulse, with a loading time between 10 and 30 msec, and reproducible within the requirements of 7.5. 5.5 Load Plate, shall be rigid and capable oftransferring the impulse force to the surface. The stress distribution under the load plate depends on both load plate rigidity and material type, and therefore can be parabolic, inverse parabolic, or uniform (1). 3 5.6 Deflection Sensor(s), capable of measuring the maxi- mum vertical plate movement. The deflection sensor or sensors shall be mounted so that the angular rotation is minimized with respect to its measuring plane at the maximum expected deflection. The number and spacing of the sensors is optional and will depend upon the purpose of the test and the material characteristics. Sensors may be of several types such as velocity transducers or accelerometers. The instrument shall be constructed to measure the vertical plate deflection at the center of the point of impact. 5.7 Data Processing and Storage System, displays and optionally records the deflection data. 5.8 Portable Impulse Plate Load Test Device, shall be small enough to be considered portable. Does not require a vehicle or trailer for transport.
6. Reagents and Materials
6.1 Adhere to the precision and bias requirements of this standard. 6.2 Display and store deflection measurements with a reso- lution of 620 µm (60.8 mils) or less. 6.3 Store deflection measurements for a period of 50 msec or greater to ensure that the peak deflection(s) are recorded.