[0035] The process, principles, and effects of the present invention will be further described in detail below in conjunction with specific embodiments, drawings and specific experiments.
[0036] When this method is implemented, it includes the following steps: a. Remove the sample from the structure to be repaired (when testing the bonding performance between the repair material and the steel, the substrate is selected as steel), and prepare the substrate of the test piece. The center of the base has a hole in the shape of a truncated cone, and the inclination angle of the cone is θ The range of change is 0°~30° (including 0° and 30°); b. Pouring the repair material into the hole in the test piece matrix to form a truncated cone shape and curing is completed. There is room for at least one end of the hole during pouring. The thickness of the new pouring material is preferably 1/5~1/2 of the hole height; c. Observe the bonding interface of the repair material with a microscope and collect the crack width value to obtain the apparent quality; d. The hole in the specimen matrix Fill the end with room with water to test the relationship between the height of the water drop and the time to obtain the water seepage performance quality; e. Dry the test piece after the water seepage test at 50℃ (this temperature can effectively dry the test piece, To avoid the influence of excessively high temperature on subsequent tests), and then use pressure equipment, use a flat indenter to press the pouring repair material vertically from the small diameter end of the truncated cone-shaped hole, and measure when the repair material and the substrate fall off Pressure value P , Calculate the interface bond strength according to formula (1),
[0037] (Formula 1)
[0038] among them: τ θ —— Tensile-shear bond strength when the inclination angle of the bonding surface is θ, unit: MPa;
[0039] S —— The bonding area between the newly poured material and the base, unit: mm 2;
[0040] D —— The diameter of the upper surface of the newly poured material, in mm;
[0041] P —— Failure load, unit N;
[0042] H —— Pouring thickness, unit: mm;
[0043] θ —— The inclination angle of the bonding surface to the vertical direction;
[0044] π -- PI.
[0045] When this method is implemented, the specimen matrix in this method can be used as figure 1 or figure 2 The shown regular geometric bodies such as cubes or cylinders can facilitate the subsequent bonding strength test steps, but the geometric bodies used as other structures in specific implementation should also be regarded as the protection scope of this technical solution. A truncated cone-shaped through hole opened in the middle of the base; the shape of the base and the diameter of the hole on the upper surface of the truncated cone D 1 (Unit mm) and bottom diameter D 2 There is no limit to the size value (unit mm), so as to facilitate subsequent operations; the inclination angle of the cone surface of the truncated cone hole is θ, θ The value can preferably be in the range of 0°~30° (including 0° and 30°), and it is not conducive to the bond strength test when it is greater than 30°, the best θ The value can be determined by experiment; when the tilt angle θ Is 0° D 1 = D 2 , The shape of the truncated cone hole becomes a round hole of equal diameter. During implementation, when pouring repair materials, new pouring materials can be poured on the upper, middle and lower parts of the truncated cone hole. The new material can be poured in three different positions: the upper, middle and lower parts; the height of the new material is H (Unit mm), the diameter of the upper surface of the new material pouring is D (Unit mm), H with D There is no specific size value, only limited by the hole size.
[0046] In order to further verify the effect of the new test piece matrix used in the present invention on the test results, the applicant used the method and the old flexural test piece to conduct a comparative experiment. In this experiment, the base shape of the new constrained specimen is a cylinder with a diameter of 150mm and a height of 30mm. Large-hole specimens are selected ( D 1 =70mm, θ =5°, D 2 =75mm) and small hole test piece ( D 1 =50mm, θ =5°, D 2 =55mm) two types, the upper part of the repair position is selected ( D = D 1 ),height H =10mm, the difference between the two is that the volume of the new material pouring is different. The base shape of the old flexural test piece is selected as length×width×height=60mm×40mm×40mm; the repair length is 100mm and 50mm. The difference between the two is that the volume of the new material is different. The matrix in the experiment is crushed stone concrete with a compressive strength of 50MPa, and the newly poured materials are phosphate cement mortar, ordinary portland cement mortar and sulphoaluminate cement mortar, as shown in Table 1 and Table 2. . Proportion of phosphate cement mortar (HN 4 H 2 PO 4 :MgO: Sodium tetraborate: Medium sand: Water = 1:4:0.6:5:1) The MgO particle size is 200 mesh re-burned magnesium oxide, and the rest are commercially available industrial-grade raw materials. Ordinary salt cement mortar ratio (cement: medium sand: water reducing agent: water=1:1:0.03:0.25), of which cement grade P·O42.5, polycarboxylic acid water reducing agent. The ratio of sulphoaluminate cement mortar (cement: medium sand: water=1:1:0.33), where cement is R.SAC42.5. The phosphoric acid cement mortar prepared in this experiment showed expansibility, while ordinary Portland cement mortar and sulphoaluminate cement mortar showed shrinkage.
[0047] Table 1 The repair size parameters of the new constrained specimens and the types of casting materials
[0048] M1 P1 S1 M2 P2 S2 Repair material Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar Repair size parameters ( D X H ) Ф70mm×10mm Ф70mm×10mm Ф70mm×10mm Ф50mm×10mm Ф50mm×10mm Ф50mm×10mm
[0049] Table 2 Repair size parameters and types of pouring materials of old anti-folding specimens
[0050] M1 P1 S1 M2 P2 S2 Repair material Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar Repair size parameters (length × width × height) 100mm×40mm×40mm 100mm×40mm×40mm 100mm×40mm×40mm 50mm×40mm×40mm 50mm×40mm×40mm 50mm×40mm×40mm
[0051] Stir and place at room temperature, place temperature at 20±1℃, relative humidity at 50%±4, environmental curing for 7 days, using three indexes of apparent quality, water permeability, and interfacial bonding strength to compare the new constrained specimen with the old flexural type The evaluation effect of the test piece on the interface bonding quality of the three repair materials shows the effectiveness and advancement of the new constrained test piece.
[0052] (1) Apparent quality
[0053] The specimens cured for 7 days were used to observe the bonding interface with a microscope with a resolution of 5 μm and the crack width values were collected for comparison.
[0054] Old flexural test piece: There are no obvious cracks in the bonding interface of the three repair materials, and the macroscopic quality of the bonding surface is very small; it does not effectively reflect the effect of the shrinkage of the repair material.
[0055] New constrained specimens: ①The bonding interface of phosphate cement mortar Ф70mm group and Ф50mm group is tightly bonded. ②There are cracks in the Ф70mm group and Ф50mm bonding interface of ordinary cement mortar, and the crack size is 150μm and 70μm respectively. ③There are cracks in the bonding interface of sulphoaluminate cement mortar Ф70mm and Ф50mm, and the crack size is 125μm and 100μm respectively.
[0056] The interface of repair materials with different expansion and contraction properties will show different apparent quality under constraints. When the repair material has shrinkage, cracks will appear in the bonding interface, and the larger the repair size, the wider the crack. The old flexural bonding method cannot reflect the difference in apparent quality, while the new restraint specimen of the present invention can reflect this difference.
[0057] (2) Water seepage test
[0058] The new constrained specimens with apparent quality collected in (1) are filled with water in the reserved round holes to test the relationship between the height of water drop and time, as shown in Table 3.
[0059]
[0060] Table 3 The relationship between the water surface drop height and time of the new constrained specimen
[0061] M1 P1 S1 M2 P2 S2 20min 0 3.7mm 13.3mm 0 2.5mm 4.9mm 60min 0 4.5mm 17.3mm 0 2.9mm 5.3mm
[0062] Phosphate cement mortar: Two different repaired areas of Ф70mm group and Ф50mm group have no water seepage and good adhesion. Ordinary Portland cement mortar: both the Ф70mm group and the Ф50mm group have water seepage, and the Ф70mm group has significantly higher water permeability than the Ф50mm group. Sulphoaluminate cement mortar: both the Ф70mm group and the Ф50mm group have water seepage, and the Ф70mm group has significantly higher water permeability than the Ф50mm group.
[0063] Comparison among the three: the phosphate cement mortar group has no water seepage, the sulphoaluminate cement mortar group has the largest water permeability, and the ordinary cement mortar group takes the second place. Water seepage experiments show that the new constrained specimens can effectively reflect the differences between different repair materials.
[0064] (3) Interface bonding strength
[0065] The new constrained test piece after the water seepage test in (2) is placed in an oven at 50°C for drying, and then the interface bonding strength is tested according to the method of the present invention. The flexural bond strength test refers to the "Cement Mortar Strength Test Method (ISO Method)" GB/T17671-1999. Table 4 shows the interfacial bond strength obtained by the old flexural method, and Table .5 shows the interfacial bond strength obtained by the new restraint specimen.
[0066] Table 4 The interface bond strength of the old flexural specimen
[0067] Unit MPa Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar L=100mm group 10.9 5.6 2.2 L=50mm group 8.5 4.6 2.4
[0068] Table 5 The interface bond strength of the new constrained specimen
[0069] Unit MPa Phosphate cement mortar Ordinary Portland Cement Mortar Sulphoaluminate cement mortar D=70mm group 9.8 0.5 0.2 D=50mm group 5.0 0.7 0.2
[0070] Under constraints, the expansion of the repair material will help improve the interface bond strength, and the increase in repair size will increase the interface bond strength; while the shrinkage of the repair material will not be conducive to the interface bond strength, and the increase in repair size will increase the interface bond strength. Will decrease. In this experiment, the phosphate cement mortar exhibiting swelling properties showed that the larger the size, the better the bonding effect in both the old anti-folding type and the new restraining type. On the other hand, ordinary cement mortar and sulphoaluminate cement mortar exhibiting shrinkage are just the opposite in the old flexural and new constrained types; in the old flexural specimens, the large size is not lower than the small size. In the new constrained specimen, the strength of the large size is lower than that of the small size; it means that the old flexural specimen cannot reflect the influence of material shrinkage on the interface bonding quality, while the new constrained specimen can reflect this effect.
[0071] It can be known from the above experimental results that the method of the present invention can actually and effectively evaluate the bonding quality of the old and new interface.
