UHPC MATERIAL FOR REINFORCING EXISTING STONE MASONRY WALL AND REINFORCING METHOD THEREOF

Abstract

A UHPC material for reinforcing existing stone masonry wall and its reinforcement method are disclosed, which belongs to the technical field of wall reinforcement. The UHPC material for reinforcing existing stone masonry wall includes: 550-600 kg/m.sup.3ofsilicate cement, 180-200 kg/m.sup.3ofwhite silica fume, 510-530 kg/m.sup.3 of limestone powder, 715-735 kg/m.sup.3 of quartz sand, 60-75 kg/m.sup.3 of iron ore tailings particles, 50-60 kg/m.sup.3 of pumice particles, 15-30 kg/m.sup.3 of polycarboxylic acid water reducing agent, 230-255 kg/m.sup.3 of water and 25-35 kg/m.sup.3 of POM fiber; the disclosure uses the combination of improved new UHPC increased cross-section method and steel banding method to strengthen the existing stone masonry wall, which can increase the thickness of the stone masonry wall and it can improve the stability of the wall; significantly improve the seismic performance and durability, and the construction is convenient, so it can be widely used in the seismic reinforcement of the stone masonry wall.

Claims

1. A method for reinforcing an existing stone masonry wall, wherein, the UHPC (ultra high performance concrete) material for reinforcing an existing stone masonry wall as a reinforcing material, comprising following steps of: step (1): carrying out a pretreatment to the existing stone masonry wall to be reinforced, wherein the pretreatment comprises keeping a main spacer between an upper layer of regular rubble and a lower layer of regular rubble and cleaning mortar joints; step (2): tensioning and thereby reinforcing the existing stone masonry wall pretreated in the step (1) horizontally and vertically by a steel bar binding method; step (3): injecting a prepared UHPC material for reinforcing the existing stone masonry wall into the mortar joint by a manual squeezing to form an embedded UHPC layer into bed joints; step (4): spraying prepared UHPC material for reinforcing the existing stone masonry wall onto the existing stone masonry wall that has been treated in the step (3) by a spraying process, so as to form a UHPC reinforcing surface layer; step (5): maintaining; the UHPC material for reinforcing an existing stone masonry wall, comprising, calculated according to an amount per cubic meter, 550-600 kg/m.sup.3 of silicate cement, 180-200 kg/m.sup.3 of white silica fume, 510-530 kg/m.sup.3 of limestone powder, 715-735 kg/m.sup.3 of quartz sand, 60-75 kg/m.sup.3 of iron ore tailing particles, 50-60 kg/m.sup.3 of pumice particles, 15-30 kg/m.sup.3 of polycarboxylic acid water reducing agent, 230-255 kg/m.sup.3 of water and 25-35 kg/m.sup.3 of POM fibers.

2. The method for reinforcing an existing stone masonry wall according to claim 1, comprising, calculated according to the amount per cubic meter, 580 kg/m.sup.3 of silicate cement, 193.3 kg/m.sup.3 of white silica fume, 515.6 kg/m.sup.3 of limestone powder, 725.7 kg/m.sup.3 of quartz sand, 70 kg/m.sup.3 of iron ore tailing particles, 55 kg/m.sup.3 of pumice particles, 20 kg/m.sup.3 of polycarboxylic acid water reducer, 249.9 kg/m.sup.3 of water and 28.2 kg/m.sup.3 of POM fibers.

3. The method for reinforcing an existing stone masonry wall according to claim 1, wherein, an average particle size of the pumice particles and the iron ore tailing particles is 2-8 mm.

4. The method for reinforcing an existing stone masonry wall according to claim 2, wherein, an average particle size of the pumice particles and the iron ore tailing particles is 2-8 mm.

5. The method for reinforcing an existing stone masonry wall according to claim 1, wherein, the POM fibers have a diameter of 0.1 to 0.3 mm.

6. The method for reinforcing an existing stone masonry wall according to claim 2, wherein, the POM fibers have a diameter of 0.1 to 0.3 mm.

7. The method for reinforcing an existing stone masonry wall according to claim 1, wherein, a pretreatment process in the step (1) further comprises: after cleaning mortar joints, coating a layer of cement paste or interface binder on a surface of the existing stone masonry wall to be reinforced.

8. The method for reinforcing an existing stone masonry wall according to claim 1, wherein, a process of tensioning and thereby reinforcing by using a steel bar binding method in the step (2) is as follows: penetrating a mortar joint of a wall with a steel bar, binding the regular rubble, wherein an interval between adjacent vertical binding bands is s; evenly arranging horizontal steel bars at a distance h, and welding and connecting the horizontal steel bars with vertical steel bar binding bands; wherein s is not greater than 400 mm; h is not greater than 500 mm; a diameter of the steel bar is not less than 10 mm.

9. The method for reinforcing an existing stone masonry wall according to claim 1, wherein, an average thickness of the UHPC reinforcing surface layer in step (4) is 25-35 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a diagram showing the thickness of an existing stone masonry wall of the present disclosure;

[0036] FIG. 2 is a schematic view of existing stone masonry wall of the present disclosure (mortar joint fullness is poor);

[0037] FIG. 3 is a diagram of a masonry process of existing stone masonry wall according to the present disclosure;

[0038] FIG. 4 is a schematic view showing the relationship between the upper and lower layers of regular rubbles according to the present disclosure;

[0039] FIG. 5 is a schematic view of the process of steel bar binding according to the present disclosure;

[0040] FIG. 6 is a schematic cross-sectional view of a double-sided reinforcement of an existing stone masonry wall of the present disclosure;

[0041] FIG. 7 is a schematic diagram of a test piece and a test loading device according to the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the objects, technical solutions and advantages of the present disclosure more apparent, the present disclosure is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating embodiments of the disclosure, are given by way of illustration only, not by way of limitation, i.e., the embodiments described are intended as a selection of the best mode contemplated for carrying out the disclosure, not as a full mode.

[0043] Thus, the following detailed description of the embodiments of the present disclosure is not intended to limit the scope of the disclosure as claimed, but is merely representative of selected embodiments of the disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present disclosure without making any creative effort, shall fall within the protection scope of the present disclosure.

Embodiment 1

[0044] The embodiment provides a method for reinforcing an existing stone masonry wall, which comprises the following steps:

[0045] step (1): carrying out a pretreatment to the existing stone masonry wall to be reinforced, comprising: determining the position of the main spacer, protecting the main spacer, removing a plurality of auxiliary stone spacers (keeping auxiliary stone spacers which are difficult to remove) by using a chisel, and digging out partial red clay mortar in the mortar joint; cleaning dust in the mortar joint, and coating a layer of cement paste on the surface of the wall to be reinforced for enhancing the interface bonding performance of the wall and the reinforcing surface layer;

[0046] step (2): tensioning and thereby reinforcing the existing stone masonry wall pretreated in the step (1) horizontally and vertically by a steel bar binding method; the specific process is as follows: performing tightening and reinforcing horizontally and vertically. Penetrating a mortar joint of a wall by using steel bars (the diameter of each steel bar is 15 mm), binding the regular rubble (each 3-4 layers are one bundle, one layer of regular rubble is lapped between the upper bundle and the lower bundle), and an interval between adjacent vertical binding bands is s (s is 400 mm). Evenly arranging horizontal steel bars at a distance h (h is 500 mm), and welding and connecting the horizontal steel bars with a vertical steel bar binding bands (as shown in FIG. 5);

[0047] step (3): preparing UHPC material for an existing stone masonry wall; the specific process is as follows: 580 kg/m.sup.3 of silicate cement (42.5 R), 193.3 kg/m.sup.3 of white silica fume (particularly zirconia silica fume), 515.6 kg/m.sup.3 of limestone powder, 725.7 kg/m.sup.3 of quartz sand, 70 kg/m.sup.3 of iron ore tailing particles (with the average particle size of 5 mm), 55 kg/m.sup.3 of pumice particles (with the average particle size of 5 mm), 20 kg/m.sup.3 of polycarboxylic acid water reducer and 249.9 kg/m.sup.3 of water are added into a forced mixer to be continuously stirred for 15 minutes, and then 28.2 kg/m.sup.3 of POM fiber (with the diameter of 0.2 mm) are added into the forced mixer through multiple times to be continuously stirred for 10 minutes;

[0048] and (4): injecting the prepared UHPC material for reinforcing the existing stone masonry wall into the mortar joint by a manual squeezing to form an embedded UHPC layer into the bed joints;

[0049] and (5): spraying prepared UHPC material for reinforcing the existing stone masonry wall onto the existing stone masonry wall that has been treated in the step (3) by a spraying process, and forming a UHPC reinforcing surface layer with the average thickness of 30 mm;

[0050] and (6): water maintaining for 28 days.

[0051] FIG. 6 shows a cross-sectional view of the double-sided reinforcement of the existing stone masonry wall reinforced by the existing stone masonry wall reinforcing method in this example; in this example, if there is no particular limitation on the raw materials, commercially available products or conventional methods in the art can be directly selected; in this example, if there is no particular limitation to the procedure, the conventional procedures in the art can be used, and the description is not repeated.

Embodiment 2

[0052] This Embodiment provides a method for reinforcing an existing stone masonry wall, which differs from Embodiment 1 only in that: the UHPC material that is used for reinforcing the existing stone masonry wall, according to the amount per cubic meter, includes: 550 kg/m.sup.3 of silicate cement, 200 kg/m.sup.3 of white silica fume, 530 kg/m.sup.3 of limestone powder, 735 kg/m.sup.3 of quartz sand, 75 kg/m.sup.3 of iron ore tailing particles, 60 kg/m.sup.3 of pumice particles, 30 kg/m.sup.3 of polycarboxylic acid water reducing agent, 255 kg/m.sup.3 of water and 25 kg/m.sup.3 of POM fibers; the rest steps and parameters are the same.

Embodiment 3

[0053] This Embodiment provides a method for reinforcing an existing stone masonry wall, which differs from Embodiment 1 only in that: the UHPC material that is used for reinforcing the existing stone masonry wall, according to the amount per cubic meter, includes: 600 kg/m.sup.3 of silicate cement, 180 kg/m.sup.3 of white silica fume, 510 kg/m.sup.3 of limestone powder, 715 kg/m.sup.3 of quartz sand, 60 kg/m.sup.3 of iron ore tailing particles, 50 kg/m.sup.3 of pumice particles, 15 kg/m.sup.3 of polycarboxylic acid water reducing agent, 230 kg/m.sup.3 of water and 35 kg/m.sup.3 of POM fibers; the rest steps and parameters are the same.

Comparative Example 1

[0054] This example provides a method for reinforcing an existing stone masonry wall, which differs from Embodiment 1 only in that: the UHPC material that is used for reinforcing the existing stone masonry wall does not contain pumice particles; the rest steps and parameters are the same.

Comparative Example 2

[0055] This example provides a method for reinforcing an existing stone masonry wall, which differs from example 1 only in that: the UHPC material that is used for reinforcing the existing stone masonry wall does not contain iron ore tailing particles; the rest steps and parameters are the same.

Comparative Example 3

[0056] This example provides a method for reinforcing an existing stone masonry wall, which differs from Embodiment 1 only in that: the preparation process of the used UHPC material for reinforcing the stone masonry wall comprises: 580 kg/m.sup.3 of silicate cement (42.5 R), 193.3 kg/m.sup.3 of white silica fume (specifically, zirconia silica fume), 515.6 kg/m.sup.3 of limestone powder, 725.7 kg/m.sup.3 of quartz sand, 70 kg/m.sup.3 of iron ore tailing particles (with the average particle size of 5 mm), 55 kg/m.sup.3 of pumice particles (with the average particle size of 5 mm), 40 kg/m.sup.3 of polycarboxylic acid water reducer and 249.9 kg/m.sup.3 of water are added into a forced mixer to be continuously stirred for 15 minutes, and then 28.2 kg/m.sup.3 of POM fiber (with the diameter of 0.2 mm) are added into the forced mixer through multiple times to be continuously stirred for 10 minutes; the rest steps and parameters are the same.

Comparative Example 4

[0057] This example provides a method for reinforcing an existing stone masonry wall, which differs from Embodiment 1 only in that: the preparation process of the used UHPC material for reinforcing the stone masonry wall comprises: 580 kg/m.sup.3 of silicate cement (42.5 R), 193.3 kg/m.sup.3 of white silica fume (specifically, zirconia silica fume), 515.6 kg/m.sup.3 of slag ash, 725.7 kg/m.sup.3 of quartz sand, 70 kg/m.sup.3 of iron ore tailing particles (with the average particle size of 5 mm), 55 kg/m.sup.3 of pumice particles (with the average particle size of 5 mm), 40 kg/m.sup.3 of polycarboxylic acid water reducer and 249.9 kg/m.sup.3 of water are added into a forced mixer to be continuously stirred for 15 minutes, and then 28.2 kg/m.sup.3 of POM fiber (with the diameter of 0.2 mm) are added into the forced mixer through multiple times to be continuously stirred for 10 minutes; the rest steps and parameters are the same.

Experimental Examples

[0058] This example uses a mixed force-displacement controlled loading method for the horizontal low circumference repeated tests of the stone masonry wall after reinforcement of Examples 1-3 and Comparative example 1-4 (the wall size is 2160×1200×210 mm (length×height×thickness), each test piece is composed of a reinforced concrete ground beam, a reinforced regular rubble masonry wall, and a steel bar-concrete top beam, and the schematic view of the test loading device is shown in FIG. 7), and the test results are shown in table 1.

TABLE-US-00001 TABLE 1 Load of Displacement Ultimate Ultimate Coefficient Number cracking of cracking load displacement of ductility Embodiment 1 175 KN 0.51 mm 421 KN 8.21 mm 22.34 Embodiment 2 170 KN 0.57 mm 405 KN 7.94 mm 21.58 Embodiment 3 172 KN 0.50 mm 411 KN 8.01 mm 21.03 Comparative 103 KN 0.33 mm 305 KN 8.06 mm 15.13 example 1 Comparative 97 KN 0.29 mm 287 KN 7.67 mm 15.78 example 2 Comparative 100 KN 0.31 mm 293 KN 8.11 mm 14.63 example 3 Comparative 95 KN 0.25 mm 280 KN 7.93 mm 14.39 example 4

[0059] As can be seen from table 1, the disclosure provides a method for reinforcing an existing stone masonry wall, the used UHPC material can be better suitable for reinforcing the existing stone masonry wall, compared with the conventional UHPC material, the method is optimized, and iron ore tailing particles and pumice stone particles are added on the basis of selecting white silica fume, limestone powder and quartz sand as fine aggregates; the mechanical property of the UHPC material is equivalent to that of an un-weathered stone (the compressive strength is usually over 80 MPa), the surface of the regular rubble is rough (the surface unevenness is within +/−15 mm, and the relation between the upper layer and the lower layer of the regular rubble is shown in a FIG. 4), the UHPC material can better cooperate with the regular rubble, and high-degree material combination fusion is realized; the UHPC material has good fluidity and can fully contact with the surfaces of the upper and lower layer regular rubble so that the stress and the force transmission are reliable, and the UHPC material and the stone material have excellent interface bonding performance and can be more suitable for reinforcing the existing stone masonry wall. When the UHPC material is not added with iron ore tailing particles (comparative example 2), pumice particles (comparative example 1), the dosage ratio of the pumice particles and the polycarboxylic acid water reducer is changed (comparative example 3) and the used fine aggregate component is changed (comparative example 4), the applicability of the prepared UHPC material to the existing stone masonry wall and the cooperativity of the UHPC material and the existing stone masonry wall are influenced, so that the reinforcing effect is reduced.

[0060] In conclusion, the disclosure adopts the combination of the improved novel UHPC (ultra high performance concrete) section enlarging method and the steel bar binding method to reinforce the existing stone masonry wall, thereby increasing the thickness of the rubble wall and improving the stability of the rubble wall; the anti-seismic performance and durability are obviously improved, the construction is convenient, and the method can be widely applied to anti-seismic reinforcement of the stone masonry wall.

[0061] The foregoing is illustrative and explanatory of the present disclosure, and any modification or addition to the specific embodiment described or substitution in a similar manner by a person skilled in the art without creative labor is still fall into the scope of protection of the present disclosure.