[0034] The self-positioning detachable concrete durability test stress loading device of the present invention is composed of a stress loading fixture 1, a positioning fixture 2 and a stress measurement and control fixture 3 to form a detachable structure with a self-positioning function. Below in conjunction with accompanying drawing, the connection mode of each component of the present invention and its function are described as follows:
[0035] see Figure 1A and figure 2 As shown, the stress loading fixture 1 includes two columns 4 , a lower pressure plate 5 , a middle pressure plate 6 , an upper pressure plate 7 , a plurality of rollers 8 and two springs 9 for applying constant stress to the concrete specimen 11 . Among them, the lower end of each column 4 and the two sides of the lower pressure plate 5 are provided with matching threads and screw holes, and the two are connected with screws and fixed with nuts 10; The pressure plate 6, the spring 9 and the upper pressure plate 7 pass through the upper end of the upright column 4 in turn and are sheathed between the two upright columns 4 and can slide up and down. The upper end of the upright column 4 is fixed with a nut 10, and one end extends to the upper edge of the nut 10; the lower pressure plate There are a plurality of circular grooves 17 above and below the middle pressure plate 6 for preliminarily positioning the roller 8 and preventing it from sliding;
[0036] see Figure 1A , Figure 1B and Figure 3A , Figure 3B As shown, the positioning fixture 2 is a concave plate with a groove-shaped cross-section, which is made of stainless steel channel steel (see Figure 3B ), placed longitudinally between the lower pressure plate 5 and the middle pressure plate 6 of the stress loading fixture 1, and the channel steel is installed on the rear side of the stress loading fixture 1 to locate the concrete specimen 11 and the roller 8 to ensure load distribution. The channel steel bottom plate 22 of the positioning fixture 2 is provided with a plurality of ( Figure 3A Display 8) positioning holes 21 corresponding to the number and position of the rollers 8 with a specific spacing, the positioning holes 21 are longitudinal oblong holes, and the positioning holes 21 distributed on the upper and lower ends are half oblong holes and are above the lower pressing plate 5. , The positions and shapes of the plurality of circular grooves 17 provided under the middle pressure plate 6 correspond to the positions and shapes. The channel steel wings 23 are used to locate the concrete specimen 11, and the concrete specimen can slide up and down; the lower pressure plate 5, the roller 8, the positioning fixture 2 and the middle After the pressing plates 6 are positioned relative to each other, the concrete test pieces 11 are inserted and placed in the positioning fixture 2 .
[0037] see Figure 1A and Figure 4As shown, the stress measurement and control fixture 3 includes a round handle 12 , a screw rod 13 , a pressure bearing plate 14 , two sleeves 15 and a sensor 16 . Among them, the upper end of the screw 13 and the circular handle 12 are provided with matching positioning pins and positioning pin holes, and the two are fixedly connected by the nut 10; the middle of the pressure plate 14 has screw holes matching the screw 13, and the two are connected by screws. There is a circular hole on both sides of the pressure-bearing plate 14, and the screw on the upper end of the sleeve 15 passes through the circular hole and is fixedly connected with the nut 10; during the loading process, the lower end of the sleeve 15 is sleeved on the upper end of the column 4 of the stress loading fixture 1 and Connected with a screw thread; the lower end of the screw 13 is provided with a groove, and the sensing head of the sensor 16 is clamped in the groove to contact the screw 13. The sensor 16 is a load sensor, and the external intelligent digital display shows the magnitude of the stress. The bottom of 16 is placed in the groove 18 in the middle of the upper surface of the upper pressing plate 7 of the stress loading fixture.
[0038] After the stress measurement and control fixture 3 and the stress loading fixture 1 are connected with the upright column 4 through the sleeve 15, rotate the circular handle 12 to make the sensor 16 contact the upper pressure plate 7 of the stress loading fixture 1. After the digital display is cleared, the concrete can be tested. Part 11 measures and controls the applied stress. Continue to rotate the circular handle 12 to exert downward force, and transmit the force to the concrete specimen 11 in turn through the screw 13, the sensor 16, the upper pressure plate 7, the spring 9, the middle pressure plate 6 and the roller 8, and the sensor 16 measures and controls the load to achieve accurate stress. load. The loading load is maintained by tightening the nut 10 on the upper end of the column 4 of the stress loading fixture 1 .
[0039] The nuts 10 used in the present invention are all locking nuts.
[0040] A typical test operation process is as follows:
[0041] The first step is to place the stress loading fixture 1 backward ( Figure 1B The left side is the rear) on the water platform, the positioning fixture 2 is placed between the lower pressure plate 5 and the middle pressure plate 6, and the two rollers 8 are inserted into the circular groove of the lower pressure plate 5 and the lower end of the positioning fixture 2 from the front along the positioning hole 21. , and then place the three concrete specimens (40mm×40mm×160mm or 100mm×100mm×400mm) 11 and the other six rollers 8 in the positioning fixture 2 in turn, and slightly tighten the nut 10 on the upper end of the column 4. A certain stress is applied to the concrete specimen 11 , then the stress loading fixture 1 , the concrete specimen 11 and the positioning fixture 2 are erected, and then the nut 10 is loosened so that the concrete specimen 11 is in a stress-free state.
[0042] In the second step, use the sleeve 15 to fix the stress measurement and control fixture 3 with the column 4 of the stress loading fixture 1, tighten the nut 10 on the upper end of the sleeve 15 to connect the pressure plate 14 and the sleeve 15, and rotate the circular handle 12 to make the sensor 16 Contact with the upper platen 7 to clear the digital display of the sensor 16 to zero.
[0043] The third step is to rotate the circular handle 12, the screw 13 moves downwards to drive the sensor 16 in turn, compresses the spring 9 through the upper pressure plate 7, and transmits the force to the concrete specimen 11 through the middle pressure plate 6 and the roller 8, until the sensor 16 digital display When the instrument value reaches the set stress, tighten the nut 10 on the upper end of the column 4 with a wrench to maintain the pressure until the digital display instrument value of the sensor 16 stops at zero (indicating that the stress measurement and control fixture 3 is no longer exerting force). Loosen the nut 10 on the upper end of the sleeve 15, rotate the sleeve 15 to separate the stress measurement and control fixture 3 from the stress loading fixture 1, and then remove the positioning fixture 2. At this time, the precise stress loading of the concrete specimen 11 is completed.
[0044] The fourth step is to put the stress loading fixture 1 together with the concrete specimen 11 into a simulation environment with multi-factor coupling effects such as erosion solution, dry-wet cycle or freeze-thaw cycle, and keep the components above the medium pressure plate out of the simulation environment. During the test, the tension of the nut 10 at the upper end of the column 4 can be adjusted regularly to keep the stress constant.
[0045] The fifth step, after the ageing period, loosen the nut 10 on the upper end of the column 4, take out the specimen 11 and perform relevant performance tests on it, and study the coupling of multiple factors such as stress, chemical erosion, dry-wet cycle or freeze-thaw cycle of the concrete specimen. The performance degradation law and damage mechanism under the action.
[0046] The above provides a method of using the stress loading device for the concrete durability test of the present invention. It can be seen that in the present invention, the stress loading fixture 1 and the positioning fixture 2 are used to realize the positioning function of the concrete specimen 11, and then used in conjunction with the stress measurement and control fixture 3. Accurate loading is achieved.
[0047] In addition, the stress measurement and control fixture 3 can be disassembled after loading, and the positioning fixture 2 can also be disassembled. Therefore, a set of positioning fixtures 2 and stress measurement and control fixtures 3 can be used with multiple stress loading fixtures 1 . It can be seen that the self-positioning detachable concrete durability test stress loading device can be assembled with a set of positioning fixture 2, stress measurement and control fixture 3 and multiple stress loading fixtures 1, respectively, to load the required stress on the specimens in different stress loading fixtures 1. , after dismantling, the different stress loading fixtures 1 are tested under different conditions, which improves the loading efficiency.
