A waterproof structure for joints between new and old concrete and its construction method

Abstract

This application relates to the field of concrete technology and specifically discloses a waterproof structure for the joint between new and old concrete and a construction method thereof. The structure comprises a new concrete block connected to an old concrete block, wherein the side end of the connection surface of the old concrete block is provided with multiple connection holes, and the inner wall of the connection hole is provided with a strip groove, and the distance between the side wall of the strip groove and the axis of the connection hole gradually decreases from the closed end to the open end. The new concrete block is pre-embedded with dowel bars that can be inserted into the connection holes, and the connection holes are poured with bonding mortar. This application achieves a stable connection, good waterproofing effect, and convenient construction.

Description

Technical Field

[0001] The present application relates to the field of concrete technology, and in particular to a waterproof structure for a joint between new and old concrete and a construction method thereof. Background Art

[0002] Architectural design often involves the renovation of old concrete buildings. Since the newly poured concrete has a different setting and hardening time from the old concrete, two separate bodies are formed after hardening, and the new and old concrete are only bonded together by the wall surface where the new and old concrete are in contact with each other.

[0003] Therefore, the subsequent concrete construction has insufficient fusion performance and poor integrity with the previous concrete construction, which eventually leads to gaps in the connection between the two. Water can easily seep in from the connection between the new and old concrete. After the water seeps in from the gaps, the strength of the connection between the two is further reduced.

[0004] Therefore, it is necessary to propose a waterproof structure that is convenient for connecting the new and old concrete, enhance the waterproof performance of the connection between the two, and improve the overall strength of the two after pouring. Summary of the Invention

[0005] In order to improve the problems of poor waterproof performance and low connection strength at the joints of new and old concrete, the present application provides a waterproof structure at the joints of new and old concrete and a construction method thereof.

[0006] In a first aspect of the present application, the present application provides a construction method for a waterproof structure at a joint between new and old concrete, the construction method comprising the following steps:

[0007] S1. Treatment of old concrete blocks: Drill holes in the connection surfaces of the old concrete blocks and roughen the inner walls of the holes and the connection surfaces.

[0008] S2. Pre-casting of new concrete blocks: Create a new concrete pre-casting area on the side formwork of the connection surface, insert rebar into the holes opened in the old concrete blocks, and secure them;

[0009] S3 grouting: The bonding mortar is injected into the hole opened in step S1, and the concrete prepared using the bonding mortar is poured into the new concrete pre-cast area;

[0010] The concrete is made of bonding mortar, gravel and water in a mass ratio of 1:0.25:0.3.

[0011] S4. Sealing: Curing, forming new concrete blocks, removing the formwork, sealing the gaps between the new concrete blocks and the old concrete blocks, and forming a waterproof structure at the joints of the new and old concrete blocks.

[0012] Optionally, step S1 further includes the following steps:

[0013] S11. Opening holes: Open multiple connection holes on the connection surface of the old concrete block;

[0014] S12 slots: A plurality of strip grooves are opened along the axial direction of the connecting hole, the sidewalls of the strip grooves gradually expanding outward from the opening of the connecting hole to the closed end thereof;

[0015] S13. Chiseling a notch: Chisel a notch in the old concrete block, open a notch at the top and bottom of the old concrete, and roughen the bottom wall of the notch, the connecting surface of the old concrete block, and the inner wall of the connecting hole.

[0016] S2 further comprises the following steps:

[0017] S21. Support the formwork, forming a new concrete pre-cast area next to the support formwork on the connection surface, and fastening the fixed dowel rods corresponding to the connection holes, and inserting the end of the dowel rods into the connection holes;

[0018] S22. A notch is reserved in the formwork in the new concrete precast area and a pre-fixed angle steel is placed at the notch 5. The angle steel is vertically offset from the connection surface.

[0019] S4 further comprises the following steps:

[0020] S41 curing demoulding, curing 28d after the formwork, angle steel corresponding to the removal of the formation of a new concrete block 2;

[0021] S42. Apply waterproof membrane to the sidewalls of the recess and use cement nails to nail the waterstop strips into the new and old concrete blocks.

[0022] S43. Cap the waterproof layer by pouring waterproof mortar into the recess and smoothing it to form a waterproof layer. After curing for 7 days, a waterproof structure is formed at the joint of the new and old concrete.

[0023] By adopting the above construction method, the strip grooves are opened in the connection holes to increase the bonding area of ​​the bonding mortar, making the bonding between the new and old concrete stable; the inserted bars are arranged to be inserted between the new concrete block and the old concrete block, so that the shear resistance of the two is greatly improved after the two are fixed; the entire process is simple to operate and easy to construct.

[0024] Optionally, in step S3, the bonding mortar includes the following components in parts by weight:

[0025] 710-870 parts of dry ingredients,

[0026] 61.2-104 parts of additives,

[0027] 125 parts of active agent,

[0028] 149.5-182 parts of water.

[0029] Optionally, the dry material consists of silicate cement, graded quartz powder, medium sand and fine sand in a weight ratio of (230-280): (50-55): (180-230): (250-300).

[0030] By adopting the above technical solution, the graded quartz powder is naturally weathered, chemically stable, and has an almost zero thermal expansion rate, which makes it have excellent thermal stability. After adding other dry materials, it can make the cement performance more extensive, increase impermeability and compressive strength.

[0031] Optionally, the auxiliary agent is composed of a defoamer, a water reducer, fly ash, and a waterproofing agent in a weight ratio of (0.1-0.5): (0.1-0.5): (60-100): (1-3).

[0032] The defoamer is polyoxyethylene polyoxypropylene pentaerythritol ether, the water reducer is selected from any one of lignin sulfonate and naphthalene sulfonate formaldehyde polymer; the fly ash is ground fly ash with an activity index of more than 65%; and the waterproofing agent is hydroxy silicone oil.

[0033] By employing the above technical solutions, the water-reducing agent improves the workability and viscosity of the bonding mortar; the water-repellent agent increases the mortar's impermeability; and fly ash, which contains a large amount of pozzolanic active substances, reacts chemically when added to the bonding mortar, generating a cementitious substance that increases the mortar's strength. Fly ash, when mixed in the mortar, acts as a tumbling and densifying agent, reducing the mortar's water consumption, enhancing its structural strength after hardening, and improving the mortar's mixing efficiency, thereby improving its crack resistance, impermeability, and later strength.

[0034] Optionally, the active agent is composed of lime paste, starch ether, and metakaolin in a weight ratio of (15-30): (35-60): (50-60).

[0035] The starch ether is selected from any one of potato starch, tapioca starch, corn starch and wheat starch, preferably potato starch.

[0036] By adopting the above technical solution, starch ether can thicken the bonding mortar, increase the anti-sagging, anti-drooping and rheological properties of the bonding mortar. When starch ether is dissolved in water, it will be evenly dispersed in the cement mortar system. Since the starch ether molecules have a network structure and are negatively charged, they will adsorb positively charged cement particles and act as a transition bridge to connect the cement, thereby giving the slurry a larger yield value and improving the anti-sagging or anti-slip effect. After being compounded with lime paste and metakaolin according to the above ratio, it can achieve better water retention and thickening effects, thereby improving the bonding strength.

[0037] Optionally, the invention further comprises an additive, wherein the additive is selected from at least one of red mud and palm fiber.

[0038] Optionally, the additive consists of red mud and palm fiber in a weight ratio of (0.9-1.1):1, preferably 1:1.

[0039] By adopting the above technical solution, palm fiber has the advantages of being low-cost, recyclable, degradable and renewable. Red mud can change the surface affinity of palm fiber. The evenly distributed red mud and palm fiber form a mesh support system in the bonding mortar, effectively reducing the internal stratification, water seepage and cavity generation of the mortar, and also reducing aggregate settlement cracks; forming a "bridging" effect on the various parts of the mortar, which can disperse and offset part of the shrinkage internal stress in the mortar, thereby inhibiting the generation of microcracks.

[0040] In the second aspect of the present application, the present application provides a waterproof structure for the joint between new and old concrete, which adopts the following technical solution:

[0041] A waterproof structure for a joint between new and old concrete, comprising a new concrete block connected to an old concrete block, a plurality of connection holes being formed on the side end of a connection surface of the old concrete block, strip grooves being formed on the inner walls of the connection holes, and a distance from the side walls of the strip grooves to the axis of the connection holes gradually decreasing from the closed end to the open end;

[0042] The new concrete block is pre-buried with dowel bars that can be inserted into the connection holes. The connection holes are poured with bonding mortar. The new concrete block is made by pouring the bonding mortar and stones.

[0043] By adopting the above technical solution, after the bonding mortar solidifies and is cured into shape, it can be bonded to the side walls of the connection hole and the strip groove, and the inserted reinforcement is wrapped in the connection hole, thereby increasing the strength of the connection between the new and old concrete layers, increasing the connection area, and improving the waterproof performance.

[0044] Optionally, before pouring the new concrete block, a new concrete pre-casting area is reserved on one side of the connection surface of the old concrete block, and the top and bottom of the old concrete block and the new concrete pre-casting area are both provided with notches;

[0045] The bottom wall of the recess is fixed with a waterproof roll, and the waterproof roll is provided with water stop strips at both ends corresponding to the recess, and a waterproof layer is cast on the top wall of the waterproof roll.

[0046] By adopting the above technical solution, when pouring a new concrete layer, the angle steel can seal the gap between the new and old concrete, making it difficult for concrete and mortar to leak from the connection between the two during the pouring process; in addition, the water stop strip and waterproof membrane can cover the connection between the new and old concrete, making it difficult for water to seep in from the connection between the two, thereby enhancing the anti-seepage effect of the connection between the new and old concrete.

[0047] In summary, this application includes at least one of the following beneficial technical effects:

[0048] 1. After the bonding mortar solidifies and cures, it can adhere to the side walls of the connection hole and the strip groove, covering the inserted reinforcement in the connection hole, thereby increasing the strength of the connection between the new and old concrete layers, increasing the connection area, and improving the waterproof performance;

[0049] 2. Starch ether can thicken the bonding mortar, increase the anti-sagging, anti-drooping and rheological properties of the bonding mortar. When compounded with lime paste and metakaolin according to the above ratio, it can achieve good water retention and thickening effects, thereby improving the bonding strength;

[0050] 3. The evenly distributed red mud and palm fiber form a mesh support system in the fresh mortar, effectively reducing the internal stratification, bleeding, and cavity formation of the mortar, as well as the settlement cracks of the aggregate; forming a "bridging" effect on the various parts of the mortar, it can disperse and offset some of the shrinkage internal stress in the mortar, thereby inhibiting the formation of microcracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a construction flow chart of the waterproof structure in Example 1 of the present application.

[0052] Figure 2 It is a front view of the connection surface of the old concrete block in the embodiment of the present application.

[0053] Figure 3 This is a schematic diagram of the position structure of setting up a new concrete pre-cast area and fixing angle steel during the construction process of the embodiment of the present application.

[0054] Figure 4 It is a schematic cross-sectional view of the waterproof structure in an embodiment of the present application.

[0055] Figure numerals: 1. old concrete block; 11. connecting surface; 2. new concrete block; 21. dowel bar; 22. formwork; 23. new concrete pre-cast area; 3. connecting hole; 31. strip groove; 4. bonding mortar; 5. notch; 6. angle steel; 7. waterproof membrane; 71. water stop strip; 72. cement nail; 8. waterproof layer. DETAILED DESCRIPTION

[0056] The following is combined with Figure 1-4 This application is described in further detail.

[0057] Example 1

[0058] Reference Figure 1 The construction method of the waterproof structure at the joint of new and old concrete in the embodiment of the present application includes the following steps:

[0059] S1. Treatment of old concrete blocks 1: Openings in the connection surface 11 of the old concrete block 1, chiseling the inner wall of the opening and the side wall of the connection surface 11;

[0060] S2 new concrete block 2 pre-casting process: the connecting surface 11 side support formwork 22, forming a new concrete pre-cast area 23, the old concrete block 1 is inserted into the hole opened by the dowel 21 and fixed;

[0061] S3 grouting: The bonding mortar 4 is injected into the hole opened in step S1, and the concrete prepared using the bonding mortar 4 is poured into the new concrete pre-cast area 23;

[0062] S4. Sealing: Curing, forming a new concrete block 2, removing the formwork 22, sealing the gap between the new concrete block 2 and the old concrete block 1, and forming a waterproof structure at the joint of the new and old concrete.

[0063] Specifically, S1 further includes the following steps:

[0064] S11 opening: open multiple connection holes 3 in the connection surface 11 of the old concrete block 1;

[0065] S12 slots: A plurality of strip grooves 31 are opened along the axial direction of the connecting hole 3, and the sidewalls of the strip grooves 31 are gradually expanded from the opening of the connecting hole 3 to the closed end thereof;

[0066] S13. Chisel out the notches 5: open notches 5 at the top and bottom of the old concrete, and roughen the bottom wall of the notch 5, the connecting surface 11 of the old concrete block 1, and the inner wall of the connecting hole 3.

[0067] S2 further comprises the following steps:

[0068] S21 support formwork 22: the connection surface 11 next to the support formwork 22 to form a new pre-cast concrete area 23, corresponding to the connection hole 3 tied fixed dowel 21: the dowel end 21 is inserted into the connection hole 3;

[0069] S22 template 22 reserved notch 5: in the new concrete precast area 23 through the template 22 reserved notch 5 and pre-fixed angle steel 6 at the notch 5, the angle steel 6 and the connecting surface 11 vertically dislocated;

[0070] S4 further comprises the following steps:

[0071] S41 curing demolding: After curing 28d, the template 22, the angle steel 6 corresponding to the removal of the formation of a new concrete block 2;

[0072] S42. Blocking the recess 5: Use waterproof membrane 7 attached to the side wall of the recess 5, use cement nails 72 to nail the water stop strip 71 into the new concrete block 2 and the old concrete block 1;

[0073] S43. Capping the waterproof layer 8: Pour waterproof mortar into the recess 5 and smooth it to form a waterproof layer 8. After curing for 7 days, a waterproof structure is formed at the joint of the new and old concrete.

[0074] The implementation principle of the construction method of the waterproof structure at the joint of the new and old concrete in Example 1 is as follows: the strip grooves are opened in the connection holes to increase the bonding area of ​​the bonding mortar, so that the bonding between the new and old concrete is stable after forming, and the pull-out and tensile strengths are improved; the inserted bars are arranged to be inserted between the new concrete block and the old concrete block, so that the shear resistance of the two is greatly improved after the two are fixed; the entire process is simple to operate and easy to construct.

[0075] Example 2

[0076] Example 2 of the present application discloses a waterproof structure for the joint between new and old concrete. Figure 2 and Figure 3 A waterproof structure at the joint of new and old concrete includes a new concrete block 2 connected to the old concrete block 1, a plurality of connection holes 3 are opened on the side end of the connection surface 11 of the old concrete block 1, and a strip groove 31 is opened on the inner wall of the connection hole 3. The distance from the side wall of the strip groove 31 to the axis of the connection hole 3 gradually decreases from its closed end to its open end.

[0077] The new concrete block 2 is pre-buried with a dowel bar 21 that can be inserted into the connection hole 3. The connection hole 3 is poured with bonding mortar 4. The new concrete block 2 is made by pouring the bonding mortar 4 and stones.

[0078] Reference Figure 3 and Figure 4 Recesses 5 are provided on the top and bottom walls of the old concrete block 1 and the new concrete block 2. Before pouring new concrete, a template 22 is used to fix and divide the new concrete pre-cast area 23, and angle steels 6 for sealing the gap between two adjacent notches 5 are installed in contact with the recesses 5, and a plastic film or other easily tearable masking film can be provided at the place where the angle steels 6 are in contact with the concrete. To fix the position of the angle steels 6, screws can be provided at the two corresponding angle steels 6 on the top and bottom walls of the new / old concrete blocks to tie and fix the angle steels 6. At the same time, a support is provided between the two opposing angle steels 6 to further fix and limit them.

[0079] After the new concrete is cast and cured until the strength reaches the standard to form a new concrete block 2, a waterproof membrane 7 is fixed to the bottom wall of the recess 5. Waterstop strips 71 are provided at both ends of the waterproof membrane 7 corresponding to the recess 5. A waterproof layer 8 is cast on the top wall of the waterproof membrane 7 of the recess 5. The waterproof layer 8 can be cast by the bonding mortar 4, or it can be formed by casting and curing other waterproof mortars.

[0080] Example 2 of the present application is a waterproof structure at the joint of new and old concrete: due to the opening of the strip groove 31, the radial size of the connecting hole 3 gradually decreases from near the bottom end of the hole to the open end. After the bonding mortar 4 is poured, the bonding mortar 4 covers the inserted reinforcement 21, thereby increasing the connection surface 11 area between the connecting hole 3, and during the curing and hardening of the bonding mortar 4, the outer wall of the waterproof layer and the inner wall of the connecting hole 3 are firmly adhered and are difficult to loosen from each other; the bonding mortar 4 layer, waterproof membrane 7 and water stop strip 71 arranged on the upper part of the recess 5 make it further difficult for water to penetrate, thereby improving the bonding performance and anti-seepage effect of the connection between the new concrete block 2 and the old concrete block 1.

[0081] Examples 3-7

[0082] Examples 3-7 each provide a bonding mortar.

[0083] In the following examples, the silicate cement used was commercially available grade 32.5 composite silicate cement, and the quartz powder was quartz powder with a fineness of 120-200 mesh;

[0084] The defoaming agent is polyoxyethylene polyoxypropylene pentaerythritol ether;

[0085] The water reducer is sodium lignin sulfonate;

[0086] The waterproofing agent is hydroxy silicone oil;

[0087] The starch ether is potato starch;

[0088] The metakaolin was 1250 mesh metakaolin with a water content of less than 5% produced by Shanxi Jufeng Kaolin Co., Ltd.

[0089] Fly ash is finely ground fly ash with an activity index of more than 65%;

[0090] In Example 3-7, the active agent is composed of lime paste, starch ether, and metakaolin in a weight ratio of 21:49:55.

[0091] The preparation method of the adhesive mortar in Examples 3-7 comprises the following steps:

[0092] S1. Fly ash, defoamer, water reducer, waterproofing agent and water were added to the reaction vessel and stirred to obtain an additive solution;

[0093] S2. Add graded quartz powder, medium sand, fine sand, Portland cement, water and mix well in a mixing container;

[0094] S3. Add the auxiliary agent solution obtained in S1 into the stirring container, add the active agent and stir evenly.

[0095] The difference between the above embodiments is that the weight of each component in the adhesive mortar is specifically shown in Table 1.

[0096] Table 1 Weight parts of each component in the mortar provided in Examples 3-7

[0097]

[0098] Examples 8-9

[0099] Examples 8-9 each provide a bonding mortar.

[0100] The difference between the above embodiments and embodiment 3 is that the weight ratios of the components of the active agent in the adhesive mortar are specifically shown in Table 2.

[0101] Table 2 Addition amount of each component of the active agent in the adhesive mortar provided in Example 3 and Examples 8-9

[0102]

[0103] Examples 10-12

[0104] Examples 10-12 each provide a bonding mortar.

[0105] The difference between the above embodiments and embodiment 3 is that additives are further added to the bonding mortar, as shown in Table 3.

[0106] The preparation method of the adhesive mortar in Examples 10-12 is as follows: Figure 1 , including the following steps:

[0107] S1. Fly ash, defoamer, water reducer, waterproofing agent and water were added to the reaction vessel and stirred to obtain an additive solution;

[0108] S2. Add graded quartz powder, medium sand, fine sand, Portland cement, additives, water and mix well in a mixing container;

[0109] S3. Add the auxiliary agent solution obtained in S1 into the stirring container, add the active agent and stir evenly.

[0110] Table 3 Addition amount of additives in the paste mortar provided in Example 3 and Examples 10-12

[0111]

[0112] Example 13

[0113] Example 13 provides a bonding mortar.

[0114] The difference between the above embodiment and embodiment 3 is that in embodiment 13, the mass ratio of the components in the active agent is 10:35:45 for lime paste, starch ether and metakaolin.

[0115] Example 14

[0116] Example 14 provides a bonding mortar.

[0117] The difference between the above embodiment and embodiment 3 is that in embodiment 14, the waterproofing agent is replaced by melamine-formaldehyde resin instead of hydroxy silicone oil.

[0118] Example 15

[0119] Example 15 provides a bonding mortar.

[0120] The difference between the above embodiment and embodiment 3 is that fly ash is replaced by calcium oxide.

[0121] Performance testing

[0122] Test standard: JC / T984-2011 polymer cement waterproof mortar industry standard

[0123] GB23440-2009 National Standard "Inorganic Waterproof and Leakage-Proofing Materials"

[0124] Test Purpose: To test the impermeability, bonding strength, and other mechanical properties of the adhesive mortar. Test Conditions: Laboratory testing and dry curing: Temperature (23±2)°C, Relative Humidity (50±10)%. Curing in a curing room (or cabinet): Temperature (20±3)°C, Relative Humidity ≥90%. Curing tank: Temperature (20±2)°C.

[0125] Test steps:

[0126] 1. Ingredients

[0127] The test was carried out according to the mix ratio of each of the above embodiments, using a planetary cement mortar mixer, stirring at a low speed, stirring for 3 minutes and then resting for (1 to 3) minutes.

[0128] 2. After mixing evenly, fill the anti-seepage test mold at once, vibrate on a vibration table for 2 minutes, and conduct the test according to 6.5.2 of GB23440-2009.

[0129] 3. Anti-seepage pressure test

[0130] The specimens were cured to 7 days of age and tested according to 6.5.1.2 and 6.5.1.4 of GB23440-2009. The maximum pressure value of four of the six specimens in each group without water seepage was taken as the anti-seepage pressure of the specimens.

[0131] 4. Bond strength test

[0132] Use a concrete slab that meets the requirements of 6.3 of JC / T985-2011 and a tensile bond strength forming frame as specified in 6.4.5. Soak the concrete slab in water for 24 hours as specified in 6.1.3, remove it, wipe off any surface water stains, and then conduct the test in accordance with 6.8 of JC / T985-2005.

[0133] 5. Other mechanical properties tests shall be carried out in accordance with JC / T984-2011.

[0134] The mechanical properties of the adhesive mortar in Example 3 were tested as follows:

[0135] Table 4 Mechanical properties of the mortar in Example 3

[0136]

[0137]

[0138] Table 5 Mechanical properties of the mortar in Example 12

[0139]

[0140] According to the test results of Example 3 in Table 4, after the lime paste, starch ether and metakaolin in the active agent are added according to the above proportions, the 7d anti-seepage pressure is as high as 1.65Mpa, and the 28d anti-seepage pressure increases to 1.99Mpa, with an increase rate of 20.61%; the 7d bonding strength is 1.32Mpa, and the 28d bonding strength increases to 20.61Mpa, with an increase rate of 32.58%. It can be seen that the improvement rate of its anti-seepage pressure and bonding strength changes significantly, and the mechanical properties of the bonding mortar exceed the standard and reach the qualified level, with excellent anti-seepage and bonding effects.

[0141] According to the test results of Example 12 in Table 5, after adding 42 parts by mass of red mud and palm fiber in a ratio of 1:1, the flexibility and other mechanical properties of the bonding mortar are improved, the water absorption rate and shrinkage rate are reduced, among which the anti-seepage pressure and bonding strength are significantly increased. The 7-day anti-seepage pressure and bonding strength are 1.74 MPa and 1.41 MPa, respectively, and increase to 2.48 MPa and 2.11 MPa after 28 days, with an increase rate of 42.53% and 49.65%, respectively.

[0142] This may be because, after adding the additives, the evenly distributed red mud and palm fiber form a network support system in the bonding mortar. The red mud assists the palm fiber in enhancing the bonding performance and supporting strength, effectively reducing the internal stratification, water seepage, and cavity formation of the mortar, and also reducing the settlement cracks of the aggregate. At the same time, the combination of hydroxyl silicone oil and additives has a strong adhesion, and the two further jointly improve the anti-seepage, compressive resistance and bonding performance of the bonding mortar.

[0143] The test results of the anti-seepage pressure and bonding strength of the mortars in Examples 3-12 and 13-3 after 7 days are shown in Table 6 below. The test object is the anti-seepage pressure of 6mm mortar specimens:

[0144] Table 67d Anti-seepage pressure and bonding strength test results

[0145] Impermeability pressure / MPa(7d) Bond strength / MPa(7d) Example 3 1.65 1.32 Example 4 1.46 1.2 Example 5 1.47 1.17 Example 6 1.37 1.14 Example 7 1.32 1.12 Example 8 1.47 1.31 Example 9 1.59 1.33 Example 10 1.69 1.35 Example 11 1.71 1.36 Example 12 1.74 1.41 Example 13 1.27 1.16 Example 14 1.29 1.01 Example 15 1.61 1.11

[0146] The test results of the anti-seepage pressure and bonding strength of the bonding mortar in Example 3-15 after 28 days are shown in Table 7 below. The test objects are 6 mm bonding mortar specimens:

[0147] Table 728d Anti-seepage pressure and bonding strength test results

[0148]

[0149]

[0150] According to the test results in Table 7, by comparing the test results of Example 3 and Example 2-3, it can be seen that when the addition ratio of Portland cement, graded quartz powder, medium sand, and fine sand in the dry material is changed, the bond strength of the bonding mortar is affected, but the mechanical property requirements specified in JC / T985-2011 can still be met; this is because cement, as an adhesive material, can tightly bond the quartz powder, medium sand, and fine sand to each other, but when it is added in excess, the compressive strength of the bonding mortar will be reduced.

[0151] By comparing the test results of Example 3 and Examples 6-7, it can be seen that changing the content of each component of the auxiliary agent will also affect the anti-seepage pressure and bonding strength of the bonding mortar. When the mass ratio of defoamer: water reducer: fly ash: waterproofing agent is (0.1-0.5): (0.1-0.5): (60-100): (1-3), the anti-seepage pressure and bonding strength of the bonding mortar are above the qualified range, and the 7d-28d anti-seepage strength improvement rate of the bonding mortar can reach 13.87%-20.61%, and the bonding strength improvement rate can reach 27.19%-32.58%. Among them, when the mass ratio of defoamer: water reducer: fly ash: waterproofing agent is 0.2:0.3:80:2, the anti-seepage strength improvement rate and the bonding strength improvement rate both reach the highest.

[0152] By comparing the test results of Example 3 and Examples 8-9, it can be seen that by changing the content of each component in the active agent, when the ratio of lime paste: starch ether: metakaolin changes from (15-30): (35-60): (50-60), the anti-seepage pressure and bonding strength of the bonding mortar are reduced compared with Example 3, but can still reach or exceed the qualified level; among them, after the relative content of starch ether is increased, the 7d / 28d anti-seepage pressure and 7d / 28d bonding strength are both improved; this may be because starch ether can thicken the bonding mortar, increase the anti-sagging, anti-drooping and rheological properties of the bonding mortar, and after compounding with lime paste and metakaolin in the above ratio, it can have a better water retention and thickening effect, thereby improving the bonding strength.

[0153] By comparing the test results of Example 3 and Examples 10-12, it can be seen that after adding the additive, the anti-seepage pressure and bonding strength of the bonding mortar are significantly improved; when 42 parts of red mud are added alone, the 7d anti-seepage pressure is 1.69 MPa, and the 28d anti-seepage pressure increases to 2.15 MPa, with an increase rate of 27.22%; the 7d bonding strength is 1.35 MPa, and the 28d bonding strength increases to 1.83 MPa, with an increase rate of 35.56%; similarly, when 42 parts of palm fiber are added alone, the anti-seepage pressure and the improvement rate of the bonding strength of the bonding mortar are also significantly enhanced.

[0154] However, when 42 parts by weight of additives were added to red mud and palm fiber in a ratio of 1:1, the 7d / 28d impermeability pressure and 7d / 28d impermeability pressure of the bonding mortar reached the highest, and the impermeability strength improvement rate from 7d to 28d was as high as 42.53%, and the bonding strength improvement rate was as high as 49.65%. It can be seen that the mixed addition of red mud and palm fiber can significantly improve the mortar performance; this may be because red mud can change the surface affinity of palm fiber, and the evenly distributed red mud and palm fiber form a network support system in the bonding mortar, effectively reducing the internal stratification, water seepage, and cavity formation of the mortar, and also reducing aggregate settlement cracks. Moreover, when hydroxy silicone oil is used as a waterproofing agent, after compounding according to the above ratio, it can increase the contact area with the fiber particles, enhance the dispersion performance of the waterproofing agent, and achieve better waterproofing effect.

[0155] By comparing the test results of Example 3 and Example 13, it can be seen that when the weight ratio of lime paste, starch ether and metakaolin is changed to 10:35:45, the anti-seepage pressure and bonding strength of the bonding mortar will decrease. Although the 7d / 28d anti-seepage pressure and bonding strength can still reach the qualified level, the 7d bonding strength of the bonding mortar is only 1.27 MPa, and the bonding strength improvement rate is less than 10%.

[0156] By comparing the test results of Example 3 and Example 14, it can be seen that when the waterproofing agent is changed to melamine-formaldehyde resin, although the performance can still meet the requirements of JC / T985-2011 and the anti-permeability strength improvement rate reaches 17.05, the 7d bonding strength and 28d bonding strength of the bonding mortar decrease significantly, and the bonding strength improvement rate is as low as 7.92%.

[0157] By comparing the test results of Example 3 and Example 15, it can be seen that when fly ash is replaced by calcium oxide, the anti-permeability performance of the bonding mortar is reduced but not significantly, the bonding strength of the bonding mortar is reduced, and the anti-permeability strength improvement rate and the bonding strength improvement rate from 7 to 28 days are as low as 7.45% and 8.11%, respectively. This may be because the active ingredients in fly ash can improve the workability of the concrete mixture; enhance the pumpability of the concrete, so that the bonding mortar has a higher hardness after hardening in the later stage.

[0158] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A construction method for a waterproof structure at the joint of new and old concrete, characterized in that: The following steps are involved: S1. Old concrete block (1) processing: opening the connection surface (11) of the old concrete block (1), chiseling the inner wall of the opening and the connection surface (11) side wall; S2. New concrete block (2) pre-casting treatment: at the connection surface (11) side support formwork (22), forming a new concrete pre-cast area (23), insert the dowel (21) into the hole opened in the old concrete block (1) and fix it; S3 grouting: The bonding mortar (4) is injected into the hole opened in step S1, and the concrete prepared using the bonding mortar (4) is poured into the new concrete precast area (23); S4 caulking: curing, forming a new concrete block (2), the template (22) is removed, blocking the gap between the new concrete block (2) and the old concrete block (1), forming a waterproof structure at the joint of the new and old concrete; In step S3, the bonding mortar includes the following components in parts by weight: 710-870 parts of dry material, 61.2-104 parts of additives, 125 parts of active agent, and 149.5-182 parts of water; The invention also comprises an additive, which consists of red mud and palm fiber in a weight ratio of (0.9-1.1):

1.

2. The construction method of a waterproof structure at the joint of new and old concrete according to claim 1, characterized in that: The S1 step further includes the following steps: S11 opening: opening a plurality of connection holes (3) on the connection surface (11) of the old concrete block (1); S12 slotting: a plurality of strip grooves (31) are opened along the axial direction of the connecting hole (3), and the side walls of the strip grooves (31) are gradually expanded from the opening of the connecting hole (3) to the closed end thereof; S13. Chiseling a notch (5): A notch (5) is opened at the top and bottom of the old concrete, and the bottom wall of the notch (5), the connecting surface (11) of the old concrete block (1) and the inner wall of the connecting hole (3) are roughened.

3. The construction method of a waterproof structure at the joint of new and old concrete according to claim 1, characterized in that: The dry material consists of silicate cement, graded quartz powder, medium sand and fine sand in a weight ratio of (230-280): (50-55): (180-230): (250-300).

4. The construction method of a waterproof structure at the joint of new and old concrete according to claim 1, characterized in that: The auxiliary agent consists of a defoamer, a water reducing agent, fly ash and a waterproofing agent in a weight ratio of (0.1-0.5): (0.1-0.5): (60-100): (1-3).

5. The construction method of a waterproof structure at the joint of new and old concrete according to claim 3, characterized in that: The active agent consists of lime paste, starch ether and metakaolin in a weight ratio of (15-30): (35-60): (50-60).

6. A waterproof structure obtained by the construction method according to any one of claims 1 to 5, characterized in that: The invention comprises a new concrete block (2) connected to an old concrete block (1), wherein a plurality of connection holes (3) are provided on the side end of a connection surface (11) of the old concrete block (1), wherein the inner wall of the connection hole (3) is provided with a strip groove (31), and the distance between the side wall of the strip groove (31) and the axis of the connection hole (3) gradually decreases from the closed end to the open end; A dowel bar (21) that can be inserted into the connection hole (3) is pre-buried in the new concrete block (2), a bonding mortar (4) is poured into the connection hole (3), and the new concrete block (2) is made by pouring the bonding mortar (4) and stones.

7. The waterproof structure obtained by the construction method of a waterproof structure at the joint of new and old concrete according to claim 6, characterized in that: Before pouring the new concrete block (2), a new concrete pre-casting area (23) is reserved on one side of the connection surface (11) of the old concrete block (1), and notches (5) are provided on the top and bottom of the old concrete block (1) and the new concrete pre-casting area (23); A waterproof roll (7) is fixedly connected to the bottom wall of the recess (5), and water stop strips (71) are provided at both ends of the waterproof roll (7) corresponding to the recess (5). A waterproof layer (8) is cast on the top wall of the waterproof roll (7) of the recess (5).

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