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30 The system operates on single phase 208/230 V AC power and according to the manufacturer's specifications requires only a modest air-flow of 3 cfm at 60 psi pressure. For the specifi- cation compliance testing, the equipment was operated with 208 V power with air pressure regulated at 75 psi. The ma- chine is capable of completing the sawing and coring opera- tions within the specified time of 15 min. The first step in preparing a test specimen with the Flex- PrepTM is to secure the gyratory specimen in the chuck of the machine. This is done by opening the top door and moving the specimen back-up plate to the open position as shown in Figure 26. The chuck is opened (See Figure 27) by turning the motor in the reverse direction using a socket wrench while the chuck is held stationary by an air actuated pin. The reverse force on the chuck opens the chuck mechanism, which has springs to ensure a minimum contact pressure when closed. Once the chuck is opened, the gyratory specimen is dropped into the chuck as shown in Figure 28. The core barrel is used to center the specimen vertically in the chuck as shown in Fig- ure 29. When the gyratory specimen is centered, the chuck is closed by turning the motor in the forward direction with the socket wrench. The back-up plate is secured as shown in Figure 25. Shedworks, Inc. FlexPrepTM System, serial number 001. the device was delivered in September 2006 and subjected to the specification compliance testing as described below. 4.2.3. Specification Compliance Testing Table 12 summarized the requirements contained in the first article equipment specification. The size, electrical power, air supply, and specimen preparation time were checked through measurements or information contained on compo- nent label plates. A small experimental plan was developed to check the dimension of specimens prepared with the device. This plan was based on 20 gyratory specimens that included the following variables: Aggregate type: limestone and granite. Nominal maximum aggregate size: 9.5 mm and 19.0 mm. Binder grade: PG 58-28 and PG 64-22. Air void content: 4 and 7 percent. Height: 165 and 175 mm. The sections that follow present the findings of the specifi- cation compliance testing. Physical and Operational Requirements The FlexPrepTM is very compact measuring 37 in. wide by Figure 26. Top view of FlexPrepTM chuck with upper 30 in. deep by 44 in. high and weighing approximately 400 lb. door and specimen back-up plate open.

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31 Figure 27. Opening chuck using a socket wrench. Figure 30, then the top and front doors are closed, and the machine is ready to prepare the SPT test specimen. The FlexPrepTM system automatically performs the sawing and coring operations. First, the cutoff blades are advanced to trim the specimen ends. Once the ends are trimmed, the Figure 29. Centering the gyratory specimen vertically cutoff blades retract, and the core barrel advances from the using the core barrel. bottom to core the test specimen. The finished specimen is removed from the core barrel by removing a cap on the bot- tom of the core barrel as shown in Figure 31. The waste ring is removed by opening the chuck mechanism as described above. Figure 32 shows the finished specimen after removal from the core barrel. Figure 28. Inserting gyratory specimen in the FlexPrepTM chuck. Figure 30. Securing the back-up plate.

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32 The operator can adjust the speed of the cutoff blades and the core barrel using controls on the machine. The feed rates should be adjusted to obtain smooth cuts, generally slower for harder aggregates. Additionally the feed rates must be such that the current draw for the motor remains below 10 amps, otherwise the motor circuit breaker will trip. An amp meter is provided to aid in setting the feed rates. The FlexPrepTM circulates the cooling water. The system includes a pump and settling tank under the machine as shown in Figure 33 to capture then circulate the cooling water. Specimen Dimensions One of the objectives of the specification compliance test- ing was to investigate the effect of several specimen variables on the finished dimensions of specimens fabricated with the FlexPrepTM system. The planned experiment included differ- ent binder grades, different nominal maximum aggregate sizes and aggregate hardness, high and low air void content Figure 31. Removing finished test specimen from the specimens, and gyratory specimens compacted to two bottom of the core barrel. heights. Twenty test specimens were fabricated, and the dimensions of the test specimens were measured and com- pared to the tolerances listed in Table 12. Table 14 summa- rizes the measurements. As shown, all of the specimens meet the SPT specification requirements for diameter, height, and end perpendicularity. The top of several specimens fail the flatness requirement. The failing specimens are highlighted in bold. All of these specimens had aggregate torn from the top end near the middle of the specimen as shown in Figure 34. As the cutoff blade moves through the specimen, it tends to lift the waste material from the specimen as it cuts. If the cut- ting speed it too fast or there is an air void near the middle of the specimen, the waste material breaks from the specimen. If it breaks below the plane of the cutting blade, a divot is Figure 32. Finished test specimen. Figure 33. Water circulation system.