Rigidity gradient structure of anti-bed load impact wear concrete bottom plate and construction method of rigidity gradient structure

Abstract

The invention discloses an anti-bed load impact wear concrete bottom plate rigidity gradient structure and a construction method thereof, which are used for protecting a hydraulic structure bottom plate from impact wear damage and improving the ability of concrete to resist bed load impact wear damage. Aiming at the acting force characteristics of suspended load and bed load at the bottom plate part, a three-layer composite design (a surface layer, a middle layer and a bottom layer) is adopted to form an integral rigidity gradient structure of the anti-bed load impact wear concrete bottom plate. The structure can effectively improve the bed load abrasion resistance of the bottom plate of the hydraulic structure. According to the rigidity gradient structure of the anti-bed load abrasion concrete bottom plate and the construction method of the rigidity gradient structure, the impact energy of rolling block stones can be effectively absorbed, the surface hardness of the concrete bottom plate is guaranteed, the anti-bed load abrasion capacity of the concrete bottom plate is remarkably improved, and the service life is prolonged; the concrete is suitable for construction of anti-abrasion concrete bottom plates of buildings and hydraulic concrete structures with the requirement for resisting abrasion of high-speed water flow.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic concrete structures, and relates to a concrete bottom plate stiffness gradient structure resistant to high-speed water flow and bed load abrasion, and a construction method thereof. Background Art

[0002] Abrasion resistance is a crucial performance characteristic of hydraulic concrete structures. During their service life, hydraulic concrete structures are subjected to the impact and abrasion of water, sand, and gravel, which can severely impact their durability and even the operational safety of the project. Abrasion damage to concrete often occurs in discharge structures such as spillways, flood discharge tunnels, diversion tunnels, water diversion tunnels, sand drainage tunnels, air-raid shelters, and plunge pools.

[0003] The current technologies for reducing the risk of abrasion damage can be summarized into two aspects. The first is to optimize hydraulic structures from the perspective of hydraulic design, such as setting diversion dams and aeration troughs; the second is to improve the abrasion resistance from the material perspective, such as improving the strength of concrete and improving the crack resistance of concrete. By selecting high-quality aggregates and improving the slurry strength, such as using special admixtures and adding admixtures, improving the slurry strength can improve the wear resistance of one phase, while improving the density of the slurry and the transition zone between the slurry and the aggregate interface, thereby improving the abrasion resistance. However, when the type of aggregate is certain, the improvement of the abrasion resistance of concrete by the slurry strength is limited. In addition, for the flow rate of 40m / s~50m / s and the sand content of 7kg / m 3 ~20kg / m 3 Due to the complex impact and grinding conditions, existing technical measures are still unable to solve the above problems well, and large-scale defects such as pitting, spalling, and exposed reinforcement often occur in concrete.

[0004] Epoxy resins are currently the most widely used materials for abrasion-resistant repairs. Epoxy mortars or epoxy concrete offer high strength and excellent wear resistance. However, due to the significant performance differences between the base concrete and the surface epoxy concrete, the surface is prone to overall detachment, thus failing to effectively address abrasion issues. Some flexible materials, such as polyurea and elastic polyurethane, offer excellent abrasion resistance, but they are prone to debonding from the base, and poor interlayer bonding is a common problem.

[0005] Prior art invention patent CN119930224A discloses a method for constructing abrasion-resistant concrete, abrasion-resistant water-passing surfaces for hydraulic structures, and dams, sluices, and canals. The abrasion-resistant concrete comprises cement, gravel, sand, mixing water, and admixtures. The admixtures include at least an inert powder with a Mohs hardness rating not less than a predetermined level, with the volume of the inert powder accounting for 8% to 12% of the total volume of the powder components in the abrasion-resistant concrete. This invention primarily utilizes the high-hardness inert powder to improve the hardness of the abrasion-resistant concrete, thereby enhancing its abrasion resistance.

[0006] Invention patent CN117865579A provides a high-strength flexible anti-impact and wear material, its preparation method and application. The raw materials are as follows by mass: 165-200 parts of water, 450-800 parts of cement, 550-1100 parts of sand, 0-1100 parts of stone, 0-150 parts of silica fume, 0-50 parts of fly ash, 220-350 parts of modified rubber, 2-20 parts of fiber and 20-25 parts of calcium sulfate whiskers. The calcium sulfate whiskers increase the strength of the flexible anti-impact and wear material, and the high-strength flexible anti-impact and wear material has a buffering effect on the bedload and has good wear resistance.

[0007] Invention patent CN117188401A discloses a multi-layered, abrasion-resistant structure and construction process for hydropower projects. The structure comprises a concrete layer, an epoxy mortar layer, an epoxy interface agent layer, and a highly weather-resistant, hand-scraped polyurea layer. Triangular protrusions are located upstream of the concrete layer. The invention primarily utilizes the surface-scraped polyurea layer to buffer sediment, while the epoxy mortar layer protects the concrete layer.

[0008] Patent CN114960553A discloses a hydraulic asphalt concrete panel anti-seepage and anti-abrasion protective structure, comprising a bonding layer, an anti-seepage layer, and a polyurea layer. The polyurea layer is bonded to the anti-seepage layer to protect the surface of the anti-seepage layer from abrasion. The anti-abrasion performance of this invention primarily depends on the ability of the surface polyurea layer to absorb impact energy.

[0009] Among the traditional methods of resisting impact and abrasion damage, impact-resistant concrete cannot effectively solve the complex impact and abrasion conditions with high flow rate and high sand content, and still produces large-area defects such as craters, spalling, and exposed reinforcement. Some flexible materials, such as polyurea and elastic polyurethane, have good anti-wear properties, but they are easy to debond from the substrate, and the problem of poor interlayer bonding is relatively common. Summary of the Invention

[0010] In order to resist the scouring and abrasion caused by the combined action of suspended load and bed load in hydraulic structures and reduce the risk of scouring and abrasion damage, the present invention provides a gradually changing stiffness structure of a concrete bottom plate that resists bed load scouring and abrasion and a construction method thereof.

[0011] At present, the idea of ​​"using rigidity to overcome rigidity" using rigid materials and the idea of ​​"using flexibility to overcome rigidity" using flexible materials both have certain technical bottlenecks and are difficult to break through. Among different hydraulic structures, the degree of abrasion damage is most serious in the hydraulic cavern floor. Based on the technical principle of "combining rigidity and flexibility", the present invention has developed a hydraulic concrete abrasion-resistant floor composite structure with gradual stiffness change through a large amount of research and experiments. According to the force characteristics of suspended sediment and bedload in the floor area, a composite structure with a gradual change in elastic modulus from bottom to top is designed, and a variety of abrasion-resistant concrete with predetermined elastic modulus is prepared. The elastic moduli of the surface layer, middle layer and bottom layer concrete are 40GPa~50GPa, 25GPa~30GPa and 15GPa~20GPa respectively. The pouring and vibration processes are improved to achieve the synergistic effect of surface wear resistance and deep energy consumption of the surface layer concrete. The present invention is a creative technical solution proposed under the guidance of this idea.

[0012] The technical solution of the present invention is:

[0013] The present invention provides a gradually changing stiffness structure of a concrete base plate for resisting high-speed water flow erosion and load-carrying abrasion, and a construction method thereof. The invention is formed by summarizing the key points of base plate composite structure design, the preparation method of concrete with a predetermined elastic modulus, and the pouring and vibration process characteristics.

[0014] A concrete base plate with a gradual stiffness variation structure for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete. The stiffness thereof is arranged from small to large in the order of bottom layer < middle layer < surface layer. The elastic moduli of the concrete of the surface layer, middle layer and bottom layer are 40GPa-50GPa, 25GPa-30GPa and 15GPa-20GPa respectively.

[0015] The strength of the surface layer concrete is 60MPa~80MPa, the strength of the middle layer concrete is 40MPa~60MPa, and the strength of the bottom layer concrete is 20MPa~40MPa.

[0016] The rubber powder content in the bottom concrete is controlled at 25% to 30% of the total amount of rubber material, the maximum aggregate particle size is 15 to 20 mm, and the amount of rubber material is 450 to 500 kg / m 3 , the air content is 4% to 7%, and the elastic limit tensile value exceeds 60% of the total limit tensile value.

[0017] The surface concrete adopts high wear-resistant aggregate, high performance water reducing agent, high activity admixture and fiber, and the concrete anti-abrasion strength is ≥20h / (kg / m 2 ).

[0018] The content of rubber powder in the middle layer concrete is controlled at 15% to 20% of the total amount of rubber materials, the maximum particle size of the aggregate does not exceed 40mm, and the elastic limit tensile strain value exceeds 45% of the total limit tensile value.

[0019] 1) Bottom concrete:

[0020] The concrete is prepared by mixing 350-400 parts of cement, 50-100 parts of high-activity admixture, 135-150 parts of water, 650-700 parts of fine aggregate, 1000-1200 parts of coarse aggregate, 115-150 parts of rubber powder, 3-5 parts of air entraining agent and 3-5 parts of water reducing agent.

[0021] The high-activity admixture is fly ash, and all its properties meet the relevant technical requirements of "Mineral Admixtures for High-Strength and High-Performance Concrete" GB / T 18736-2017.

[0022] The fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm and good gradation.

[0023] The coarse aggregate is basalt crushed stone with a particle size of 5 to 40 mm and good gradation.

[0024] The air entraining agent is a rosin resin type air entraining agent.

[0025] Low stiffness (low elastic modulus, good elasticity) concrete is prepared by adding rubber powder, increasing the closed bubble content, reducing the aggregate particle size, and increasing the amount of cementitious materials.

[0026] 2) Middle layer concrete:

[0027] The concrete is prepared by mixing 350-400 parts of cement, 50-100 parts of high-activity admixture, 120-135 parts of water, 650-700 parts of fine aggregate, 1000-1200 parts of coarse aggregate, 60-100 parts of rubber powder, 3-5 parts of air entraining agent and 3-5 parts of water reducing agent.

[0028] The high-activity admixture is fly ash, and all its properties meet the relevant technical requirements of "Mineral Admixtures for High-Strength and High-Performance Concrete" GB / T 18736-2017.

[0029] The fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm and good gradation.

[0030] The coarse aggregate is basalt crushed stone with a particle size of 5 to 40 mm and good gradation.

[0031] The air entraining agent is a rosin resin type air entraining agent.

[0032] By adjusting the amount of cementitious materials, aggregate particle size, water-cement ratio, and active admixture dosage, a transition layer and middle layer concrete with performance connecting the bottom layer and the surface layer is prepared.

[0033] 3) Surface concrete:

[0034] The composite material is obtained by mixing 350-400 parts of cement, 50-100 parts of high-activity admixture, 110-125 parts of water, 650-700 parts of fine aggregate, 1000-1200 parts of high-wear-resistant aggregate, 20-30 parts of fiber, 3-5 parts of anti-cracking and viscosity-reducing agent, and 3-5 parts of water-reducing agent.

[0035] The high-activity admixture is fly ash.

[0036] The fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm and good gradation.

[0037] The highly wear-resistant aggregate is basalt, granite, monzonite, tuff, cast stone, iron ore, brown corundum, etc., and the maximum particle size can be enlarged to 40mm to 80mm.

[0038] The fiber is an end hook steel fiber with a length of 30 to 40 mm and a diameter of 0.5 to 0.7 mm.

[0039] The anti-cracking and viscosity reducing agent is an inorganic salt anti-cracking and viscosity reducing agent, preferably a calcium salt.

[0040] High wear-resistant aggregate, high-performance water-reducing agent, high-activity admixture and fiber are used to reduce the amount of cementitious materials and prepare high-rigidity (high elastic modulus, high wear resistance) concrete.

[0041] Furthermore, the said anti-lodged load abrasion concrete stiffness gradient structure comprises three parts: surface layer, middle layer and bottom layer, and its mix proportion composition characteristics and technical requirements are as follows:

[0042] 1) The surface concrete needs to use highly wear-resistant aggregates, such as basalt, granite, monzonite, tuff, cast stone, iron ore, brown corundum, etc., and the maximum particle size can be enlarged to 40mm~80mm; add special anti-abrasion admixtures, such as anti-cracking viscosity reducers, high-performance water reducers, etc., to improve the transition zone between the slurry and aggregate interface and improve wear resistance; under the premise of ensuring workability and wrapping, based on the mix design principle of minimum adhesive dosage, reduce the slurry content, improve crack resistance, and improve comprehensive anti-abrasion performance. The surface concrete has the highest strength, elastic modulus and anti-abrasion performance, with a strength of generally 60MPa~80MPa, an elastic modulus of 40GPa~50GPa, and an anti-abrasion strength ≥20h / (kg / m 2 ).

[0043] 2) The middle layer of concrete is an important component connecting the surface concrete and the bottom layer of concrete. It plays a connecting role and can dissipate part of the impact energy. This layer of concrete requires both high strength and elasticity. The mix composition does not require the use of high-wear-resistant aggregates and special anti-wear admixtures, but rubber powder must be added, with the amount being 15% to 20% of the total amount of rubber. In addition, the maximum particle size of the aggregate should not exceed 40mm. The strength and elastic modulus of the middle layer of concrete are relatively low, with slightly better elasticity, and the strength grade is generally C. 90 40. The elastic modulus is 25-30 GPa, the elastic limit tensile strain value exceeds 45% of the total limit tensile value, and there is no requirement for impact and abrasion resistance.

[0044] 3) The amount of rubber powder added to the bottom concrete should be controlled at 25% to 30% of the total amount of rubber. The maximum particle size of the aggregate should be reduced to 15 to 20 mm, and the amount of rubber should be 450 to 500 kg / m 3 , introduce 4% to 7% of closed bubbles to ensure the paste's encapsulation of aggregate and rubber powder, reducing the inherent constraints of the concrete system's expansion and contraction deformation. No need to use highly wear-resistant aggregates or special anti-abrasion admixtures. The bottom concrete has the lowest strength and elastic modulus, and the best elasticity. The strength grade is generally C 90 20. The elastic modulus is 15 to 20 GPa, and the elastic limit tensile value exceeds 60% of the total limit tensile value.

[0045] Furthermore, based on the existing technology, the anti-abrasion concrete base plate is designed with a composite structure in which the elastic modulus gradually changes from bottom to top. A variety of anti-abrasion concrete with predetermined elastic moduli are prepared, which consists of a surface layer, a middle layer, and a bottom layer of concrete. The stiffness is in the following order from small to large: bottom layer < middle layer < surface layer. The elastic moduli of the surface layer, middle layer, and bottom layer concrete are 40GPa-50GPa, 25GPa-30GPa, and 15GPa-20GPa, respectively. The concrete mix ratio of the base plate is designed as follows:

[0046] 1) Concrete mix design shall comply with the relevant provisions of the "Code for Design of Hydraulic Concrete Mix" (DL / T 5330-2015).

[0047] 2) Concrete mix strength is calculated according to formula (1)

[0048] f cu,0 =f cu,k +tσ (1)

[0049] Where, f cu,0 - Concrete mix strength (MPa)

[0050] f cu,k - Standard value of concrete cube compressive strength (MPa)

[0051] t - probability coefficient, its value is selected according to the strength guarantee rate, see Table 1 for details.

[0052] σ - standard deviation of concrete cube compressive strength (MPa), the value of which is selected according to Table 2.

[0053] Table 1 Compressive strength guarantee rate and probability coefficient

[0054]

[0055] Table 2 Selected values ​​of standard deviation σ

[0056]

[0057] 3) The water-cement ratio of each layer of concrete should not be greater than 0.45; the total amount of cementitious materials should be less than 500kg / m 3 .

[0058] 4) Normal concrete should be used as much as possible, and the slump on site before pouring should be 50-70mm; for pumped concrete, the slump on site before pouring should be 15-17mm.

[0059] Furthermore, the technical requirements for the raw materials of the base slab concrete are as follows:

[0060] 1) Use medium- or low-heat Portland cement (P·MH or P·LH) of stable quality, produced in rotary kilns. The strength margin should be greater than 1.15. If the cement is fresh from the factory and still has a certain amount of heat, it should be stored for one to two days, but not more than ten days.

[0061] 2) The fineness modulus of fine aggregate is controlled between 2.5 and 3.0, and the particle gradation should be within grading zone I or II; the crushing index is less than 10%, the content of particles less than 0.08 mm is 1% to 2%, and the mud content is less than 2%.

[0062] 3) The compressive strength of the coarse aggregate parent rock must exceed the concrete design strength and be greater than 75 MPa. The particle size should be 5-20 mm and 20-40 mm. The crushing index should be less than 8%, the mud content should be less than 0.5%, and the firmness should be ≤8.0%.

[0063] 4) The quality of fly ash should meet the requirements of Class I fly ash in "Fly ash used in cement and concrete" (GB / T1596-2017), and the dosage should be 15% to 25%.

[0064] 5) The fineness of rubber powder should be 40 mesh.

[0065] 6) The anti-abrasion admixture is in powder form. Under the premise that the water-binder ratio, adhesive composition, air content and aggregate type are consistent, the anti-abrasion admixture should increase the anti-abrasion strength by 2h / (kg / m 2 )above.

[0066] 7) The water reducer should be a polycarboxylic acid-based high-performance water reducer.

[0067] A construction process for a concrete base plate with a gradual stiffness change structure that resists displacement and abrasion, specifically comprising the following steps:

[0068] S1: Pre-construction preparation: Determine the base plate composite structure and the layered design thickness of the surface, middle, and bottom layers of concrete, which are 3-5cm, 12-15cm, and 12-15cm respectively. Determine the mix ratio based on the strength grade, elastic modulus, deformation capacity, and other requirements of each layer of concrete;

[0069] S2: Prepare the bottom concrete: Mix cement, sand, stone, water, fly ash, rubber powder, water reducer and air entraining agent evenly;

[0070] S3: Transporting bottom concrete: Use concrete tankers or dump trucks to transport concrete to the working surface. The type of vehicle used is determined by the flow state of the concrete.

[0071] S4: Pouring the bottom concrete: Spread naturally and vibrate with an inserted vibrator, following the principle of "insert quickly and withdraw slowly" until large bubbles are expelled and the surface is slightly slurry;

[0072] S5: Prepare the middle layer concrete: Mix cement, sand, stone, water, fly ash, rubber powder, water reducing agent and air entraining agent evenly;

[0073] S6: Transporting middle layer concrete: Use concrete tankers or dump trucks to transport concrete to the working surface. The type of vehicle used is determined by the concrete flow pattern.

[0074] S7: pouring middle layer concrete: the middle layer concrete must be vibrated before the initial setting of the bottom layer concrete, and the tamping rod should be inserted into the bottom layer concrete 5 to 15 cm, preferably about 10 cm;

[0075] S8: Prepare surface concrete: Mix cement, sand, stone, water, fly ash, water reducer, air entraining agent, and anti-abrasion admixture evenly;

[0076] S9: Transporting surface concrete: Use concrete tankers or dump trucks to transport concrete to the working surface. The type of vehicle used is determined by the flow state of the concrete.

[0077] S10: pouring surface concrete: the surface concrete needs to be vibrated before the middle layer concrete begins to set, and the tamping rod is inserted into the middle layer concrete by 5 to 15 cm, preferably about 10 cm.

[0078] Said steps S7 and S10: This vibration method can achieve a gradual change in stiffness between concretes with different elastic moduli, so that the stiffness between layers changes gradually and the inter-layer bonding effect is better.

[0079] Principle of the invention:

[0080] 1) The process principle of the gradual change of concrete stiffness design of the base plate composite structure: The base plate composite structure is shown as follows: Figure 1 As shown, the concrete structure is divided into three parts: the surface layer, the middle layer, and the bottom layer. The surface layer concrete has high stiffness, strength, and wear resistance, ensuring the structural surface's resistance to impact and abrasion. The bottom layer concrete has low stiffness and good elasticity, absorbing the impact energy of rolling rocks through elastic deformation. This energy absorption, transfer, and transformation dissipates impact energy, mitigating impact damage to the surface concrete. The middle layer concrete's stiffness, strength, and wear resistance are intermediate between the surface and bottom layers, serving as a bridge between the upper and lower layers. This ensures a continuous and progressive change in stiffness, preventing excessive amplitudes from adversely affecting the composite structure. The elastic moduli of the surface, middle, and bottom layers are 40-50 GPa, 25-30 GPa, and 15-20 GPa, respectively.

[0081] 2) Preparation principle of high elastic concrete: add 15% to 30% of the total amount of fine aggregate into the concrete, and use the "linear elastic mechanical effect" of rubber powder to improve the elastic deformation capacity; at the same time, appropriately increase the air content (4% to 7%), reduce the maximum particle size of aggregate (15mm to 20mm), increase the amount of cementitious material (450kg / m 3 ~500kg / m 3 ), ensuring the slurry's encapsulation of aggregate and rubber powder, and reducing the inherent constraints of the concrete system's expansion and contraction deformation.

[0082] The stiffness gradient structure of the concrete base plate resistant to displacement and abrasion provided by the present invention and its construction method can effectively absorb the impact energy of rolling stones, ensure the surface hardness of the concrete base plate, significantly improve the concrete base plate's ability to resist displacement and abrasion, and extend its service life. It is suitable for the construction of building resistant concrete base plates and hydraulic concrete structures that need to resist high-speed water flow abrasion.

[0083] Compared with the existing anti-impact and wear technology, the present invention adopts a gradually changing stiffness base plate, and realizes a gradual change of the elastic modulus from high to low by adjusting the concrete ratio of the three-layer structure of the surface layer, the middle layer and the bottom layer, and adjusting the rubber powder content. It not only ensures the high wear resistance of the surface layer, but also utilizes the elastic deformation of the bottom layer to absorb the impact energy, realizes the step-by-step dissipation of energy, and forms an overall synergistic anti-impact and wear system, which effectively takes into account the dual abrasion effects of suspended sediment and moved sediment, and has excellent effect in resisting the impact and wear of moved sediment.

[0084] Advantages of the present invention: Compared with the existing hydraulic concrete anti-abrasion technology, the present invention has the following advantages:

[0085] (1) The present invention provides a gradual stiffness variation structure and construction method for a concrete base plate resistant to displacement abrasion, which can significantly improve the concrete's resistance to displacement abrasion. It is to improve the concrete's external resistance to abrasion, achieve wear resistance of the surface concrete, and achieve deep energy consumption of the bottom concrete to resist displacement erosion. It can further improve the concrete's resistance to abrasion on the basis of its own resistance to abrasion.

[0086] (2) The abrasion-resistant concrete base plate structure and construction method provided by the present invention can effectively resist the dual abrasion of suspended sediment and bedload, and is suitable for the construction of abrasion-resistant concrete base plates of buildings such as flood discharge tunnels, diversion tunnels, water diversion tunnels, sand drainage tunnels, air-raid shelters, and water cushion ponds. It is also suitable for other hydraulic concrete structures that need to resist the abrasion of high-speed water flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 Schematic diagram of the base plate composite structure. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to examples. The specific examples described here are only used to explain the technical solutions of the present invention.

[0089] Cement should be medium-heat or low-heat silicate cement (P·MH or P·LH) with stable quality and produced in a rotary kiln, and the strength surplus coefficient should be greater than 1.15.

[0090] The fineness modulus of fine aggregate is controlled at 2.6, and the particle gradation should be within gradation zone II.

[0091] The compressive strength of the coarse aggregate parent rock needs to exceed the design strength of concrete and be greater than 75MPa, and the particle size should be in two levels: 5-20mm and 20-40mm.

[0092] The fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm and good gradation.

[0093] The coarse aggregate is basalt crushed stone with a particle size of 5 to 40 mm and good gradation.

[0094] The high-activity admixture is fly ash, and all its properties meet the relevant technical requirements of "Mineral Admixtures for High-Strength and High-Performance Concrete" GB / T 18736-2017.

[0095] The water reducer is a polycarboxylic acid high-efficiency water reducer.

[0096] Example 1

[0097] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete, with thicknesses of 3 cm, 12 cm and 12 cm respectively.

[0098] Surface concrete: 350 parts of cement, 50 parts of fly ash, 110 parts of water, 650 parts of fine aggregate, 1000 parts of granite aggregate with a maximum particle size of 80 mm, 20 parts of end hook steel fiber, 3 parts of calcium phosphate anti-cracking viscosity reducer, and 3 parts of water reducer are mixed to obtain the surface concrete with a compressive strength of 68.5 MPa, an elastic modulus of 44.3 GPa, and an abrasion resistance of 21.6 (h·kg / m 2 ).

[0099] Middle layer concrete: It is obtained by mixing 350 parts of cement, 50 parts of fly ash, 120 parts of water, 650 parts of fine aggregate, 1000 parts of coarse aggregate, 60 parts of rubber powder, 3 parts of rosin resin air entraining agent, and 3 parts of water reducer. The compressive strength of the middle layer concrete is 45.8MPa, the elastic modulus is 28.2GPa, and the elastic ultimate tensile value exceeds 20% of the total ultimate tensile value.

[0100] Base concrete: It is mixed with 350 parts of cement, 50 parts of fly ash, 135 parts of water, 650 parts of fine aggregate, 1000 parts of coarse aggregate, 115 parts of rubber powder, 4 parts of rosin resin air entraining agent, and 3 parts of water reducer. The strength is 28.6MPa, the elastic modulus is 16.4GPa, and the elastic ultimate tensile value reaches 62.8% of the total ultimate tensile value.

[0101] A construction process for a concrete base plate with a gradual stiffness change structure that resists displacement and abrasion, specifically comprising the following steps:

[0102] S1: Prepare the base concrete: Mix cement, fine aggregate, coarse aggregate, water, fly ash, rubber powder, water reducer and air entraining agent evenly;

[0103] S2: Pouring the bottom concrete: Spread naturally and vibrate with an inserted vibrator, following the principle of "insert quickly and withdraw slowly" until large bubbles are expelled and the surface is slightly slurry;

[0104] S3: Prepare the middle layer concrete: Mix cement, fine aggregate, coarse aggregate, water, fly ash, rubber powder, water reducer and air entraining agent evenly;

[0105] S4: Casting surface concrete: The surface concrete must be vibrated before the bottom concrete begins to set, and the tamping rod must be inserted about 10 cm into the bottom concrete;

[0106] S5: Prepare surface concrete: Mix cement, fine aggregate, coarse aggregate, water, fly ash, water reducer, air entraining agent, and anti-cracking and viscosity reducing agent evenly;

[0107] S6: Pouring surface concrete: The surface concrete must be vibrated before the middle layer concrete begins to set, and the tamping rod must be inserted about 10 cm into the middle layer concrete.

[0108] The vibration method can achieve a gradual change in stiffness between concretes with different elastic moduli, resulting in a gradual change in stiffness between layers and a better inter-layer bonding effect.

[0109] Example 2

[0110] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete, with thicknesses of 4 cm, 12 cm and 14 cm respectively.

[0111] Surface concrete: 400 parts of cement, 100 parts of high-activity admixture, 120 parts of water, 690 parts of fine aggregate, 1150 parts of granite aggregate, 20 parts of end hook steel fiber, 4 parts of inorganic salt anti-cracking and viscosity reducing agent, and 5 parts of water reducing agent are mixed to obtain the surface concrete compressive strength meeting C 90 60, elastic modulus is 48.3GPa, impact and abrasion resistance is 20.4(h·kg / m 2 ).

[0112] Middle layer concrete: 400 parts of cement, 100 parts of high-activity admixture, 130 parts of water, 680 parts of fine aggregate, 1150 parts of coarse aggregate, 85 parts of rubber powder, 3 parts of air entraining agent, 5 parts of water reducer are mixed to obtain the middle layer concrete compressive strength meeting C 90 40, the elastic modulus is 26.4 GPa, and the elastic ultimate tensile value exceeds 25% of the total ultimate tensile value.

[0113] Base concrete: 400 parts of cement, 100 parts of high-activity admixture, 150 parts of water, 680 parts of fine aggregate, 1150 parts of coarse aggregate, 140 parts of rubber powder, 3 parts of air entraining agent, 5 parts of water reducer are mixed to meet the strength grade C 90 20. The elastic modulus is 15.2GPa, and the elastic limit tensile value reaches 69% of the total limit tensile value.

[0114] The specific implementation steps are the same as those in Example 1.

[0115] Example 3

[0116] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete, with thicknesses of 4 cm, 12 cm and 14 cm respectively.

[0117] Surface concrete: 380 parts of cement, 100 parts of high-activity admixture, 120 parts of water, 660 parts of fine aggregate, 1100 parts of granite aggregate, 15 parts of fiber, 5 parts of inorganic salt anti-cracking and viscosity reducing agent, 3 parts of water reducing agent are mixed to obtain the surface concrete compressive strength meeting C90 60, elastic modulus is 41.9GPa, impact and abrasion resistance is 21.6(h·kg / m 2 ).

[0118] Middle layer concrete: 350 parts of cement, 60 parts of high-activity admixture, 130 parts of water, 670 parts of fine aggregate, 1150 parts of coarse aggregate, 75 parts of rubber powder, 3 parts of air entraining agent, and 3 parts of water reducer are mixed to obtain the middle layer concrete compressive strength meeting C 90 40, the elastic modulus is 25.8GPa, and the elastic ultimate tensile value exceeds 22% of the total ultimate tensile value.

[0119] Base concrete: 400 parts cement, 80 parts high-activity admixture, 140 parts water, 680 parts fine aggregate, 1120 parts coarse aggregate, 150 parts rubber powder, 3 parts air entraining agent, 5 parts water reducer are mixed to meet the strength grade C 90 20. The elastic modulus is 15.4GPa, and the elastic limit tensile value reaches 65% of the total limit tensile value.

[0120] The specific implementation steps are the same as those in Example 1.

[0121] Comparative Example 1

[0122] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer and a bottom layer of concrete, with thicknesses of each layer being 4 cm and 16 cm respectively.

[0123] Surface concrete: 380 parts of cement, 100 parts of fly ash, 110 parts of water, 660 parts of fine aggregate, 1100 parts of granite aggregate, 15 parts of fiber, 3 parts of inorganic salt anti-cracking and viscosity reducing agent, and 3 parts of water reducing agent are mixed to obtain the surface concrete with a compressive strength of 71.4 MPa, an elastic modulus of 44.9 GPa, and an abrasion resistance of 22.4 (h·kg / m 2 ).

[0124] Base concrete: It is mixed with 380 parts of cement, 80 parts of high-activity admixture, 150 parts of water, 680 parts of fine aggregate, 1120 parts of coarse aggregate, 150 parts of rubber powder, 3 parts of air entraining agent and 5 parts of water reducer. The strength grade is 23.6MPa, the elastic modulus is 15.9GPa, and the elastic ultimate tensile value reaches 65% of the total ultimate tensile value.

[0125] Comparative Example 2

[0126] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete, with thicknesses of each layer being 2 cm, 6 cm and 10 cm respectively.

[0127] Surface concrete: 380 parts of cement, 100 parts of high-activity admixture, 120 parts of water, 660 parts of fine aggregate, 1150 parts of granite aggregate, 15 parts of fiber, 4 parts of inorganic salt anti-cracking and viscosity reducing agent, and 3 parts of water reducer are mixed to obtain the surface concrete with a compressive strength of 62.5 MPa, an elastic modulus of 43.6 GPa, and an abrasion resistance of 20.8 (h·kg / m 2 ).

[0128] Middle layer concrete: It is mixed with 350 parts of cement, 60 parts of high-activity admixture, 123 parts of water, 670 parts of fine aggregate, 1150 parts of coarse aggregate, 75 parts of rubber powder, 3 parts of air entraining agent and 4 parts of water reducer. The compressive strength of the middle layer concrete is 44.8MPa, the elastic modulus is 23.8GPa, and the elastic ultimate tensile value exceeds 20% of the total ultimate tensile value.

[0129] Base concrete: It is mixed with 400 parts of cement, 80 parts of high-activity admixture, 140 parts of water, 680 parts of fine aggregate, 1120 parts of coarse aggregate, 150 parts of rubber powder, 3 parts of air entraining agent and 5 parts of water reducer. The strength grade is 24.8, the elastic modulus is 15.9GPa, and the elastic ultimate tensile value reaches 65% of the total ultimate tensile value.

[0130] Comparative Example 3

[0131] A concrete base plate with gradually varying stiffness for resisting displacement and abrasion is provided, which is composed of a surface layer, a middle layer and a bottom layer of concrete, with thicknesses of 4 cm, 12 cm and 14 cm respectively.

[0132] Surface concrete: 380 parts of cement, 100 parts of high-activity admixture, 150 parts of water, 660 parts of fine aggregate, 1000 parts of granite aggregate, 15 parts of fiber, 3 parts of inorganic salt anti-cracking and viscosity reducing agent, and 3 parts of water reducer are mixed to obtain the surface concrete with a compressive strength of 63.6 MPa, an elastic modulus of 36.9 GPa, and an abrasion resistance of 18.6 (h·kg / m 2 ).

[0133] Middle layer concrete: It is mixed with 350 parts of cement, 60 parts of high-activity admixture, 130 parts of water, 650 parts of fine aggregate, 1050 parts of coarse aggregate, 60 parts of rubber powder, 3 parts of air entraining agent and 3 parts of water reducer. The compressive strength of the middle layer concrete is 55.6MPa, the elastic modulus is 30.8GPa, and the elastic ultimate tensile value exceeds the total ultimate tensile value by 24%.

[0134] Bottom layer concrete: It is mixed with 400 parts of cement, 80 parts of high-activity admixture, 140 parts of water, 680 parts of fine aggregate, 1120 parts of coarse aggregate, 180 parts of rubber powder, 3 parts of air entraining agent and 5 parts of water reducer. The strength is 20.9MPa, the elastic modulus is 12.4GPa, and the elastic ultimate tensile value reaches 68% of the total ultimate tensile value.

[0135] Table 3 Performance of the gradual stiffness structure of the abrasion-resistant concrete base plate with different components

[0136]

[0137] It can be seen from Table 3 that different gradient structures, different components of each layer of concrete, elastic modulus and thickness result in different anti-abrasion effects. The gradient structure of the anti-abrasion concrete base plate in Example 1 is the optimal case. The most preferred thicknesses of each layer are: 3 cm, 12 cm and 12 cm for the surface layer, middle layer and bottom layer respectively. The most preferred proportion is: the surface layer concrete is made of 350 parts of cement, 50 parts of fly ash, 110 parts of water, 650 parts of fine aggregate, 1000 parts of granite aggregate, the maximum particle size is 80 mm, 20 parts of end hook steel fiber, 3 parts of inorganic salt anti-cracking and viscosity reducing agent, and 3 parts of water reducer. The surface layer concrete has a compressive strength of 68.5 MPa, an elastic modulus of 44.3 GPa, and an anti-abrasion strength of 21.6 (h·kg / m 2 ); the middle layer concrete is obtained by mixing 350 parts of cement, 50 parts of fly ash, 120 parts of water, 650 parts of fine aggregate, 1000 parts of coarse aggregate, 60 parts of rubber powder, 3 parts of rosin resin air entraining agent, and 3 parts of water reducer. The compressive strength of the middle layer concrete is 45.8MPa, the elastic modulus is 28.2GPa, and the elastic limit tensile value exceeds 20% of the total ultimate tensile value; the bottom layer concrete is obtained by mixing 350 parts of cement, 50 parts of fly ash, 135 parts of water, 650 parts of fine aggregate, 1000 parts of coarse aggregate, 115 parts of rubber powder, 4 parts of rosin resin air entraining agent, and 3 parts of water reducer. The strength is 28.6MPa, the elastic modulus is 16.4GPa, and the elastic limit tensile value reaches 62.8% of the total ultimate tensile value.

[0138] This composite structure of a hydraulic concrete floor with a gradient stiffness and abrasion resistance was demonstrated in the No. 2 flood discharge and sand flushing tunnel of the Xinjiang Karabeli Hydropower Project. Investigations revealed that after two flooding cycles, the concrete floor remained relatively intact, with minimal damage, and exhibited significantly better abrasion resistance than traditional high-strength concrete floors.

Claims

1. A concrete floor stiffness gradient structure for resisting displacement and abrasion, characterized by: It is composed of surface layer, middle layer and bottom layer concrete, and the stiffness is in the order of bottom layer < middle layer < surface layer. The elastic modulus of concrete of surface layer, middle layer and bottom layer are 40GPa~50GPa, 25GPa~30GPa and 15GPa~20GPa respectively.

2. The stiffness gradient structure of the concrete bottom plate for resisting displacement and abrasion according to claim 1 is characterized in that: The amount of rubber powder in the bottom concrete is controlled at 25%~30% of the total amount of rubber material, the maximum particle size of aggregate is 15~20mm, and the amount of rubber material is 450~500kg / m 3 , the air content is 4%~7%, and the elastic limit tensile value exceeds 60% of the total limit tensile value.

3. The stiffness gradient structure of the concrete floor slab for resisting displacement and abrasion according to claim 1 is characterized in that: The rubber powder content in the middle layer concrete is controlled at 15%~20% of the total amount of rubber material, the maximum particle size of the aggregate does not exceed 40mm, and the elastic limit tensile strain value exceeds 45% of the total limit tensile value.

4. The stiffness gradient structure of the concrete bottom plate for resisting displacement and abrasion according to claim 1 is characterized in that: The surface concrete adopts high wear-resistant aggregate, high performance water reducing agent, high activity admixture and fiber, and the concrete anti-abrasion strength is ≥20h / (kg / m 2 ).

5. The stiffness gradient structure of the concrete bottom plate for resisting displacement and abrasion according to claim 2 is characterized in that: The components and dosage of the base concrete are: 350~400 parts of cement, 50~100 parts of high-activity admixture, 135~150 parts of water, 650~700 parts of fine aggregate, 1000~1200 parts of coarse aggregate, 115~150 parts of rubber powder, 3~5 parts of air entraining agent, and 3~5 parts of water reducer.

6. The stiffness gradient structure of the concrete bottom plate for resisting displacement and abrasion according to claim 3 is characterized in that: The components and dosage of the middle layer concrete are: 350-400 parts of cement, 50-100 parts of high-activity admixture, 120-135 parts of water, 650-700 parts of fine aggregate, 1000-1200 parts of coarse aggregate, 60-100 parts of rubber powder, 3-5 parts of air entraining agent, and 3-5 parts of water reducer.

7. The stiffness gradient structure of the concrete bottom plate for resisting displacement and abrasion according to claim 4 is characterized in that: The components and usage of the surface layer concrete are as follows: 350-400 parts of cement, 50-100 parts of high-activity admixture, 110-125 parts of water, 650-700 parts of fine aggregate, 1000-1200 parts of high-wear-resistant aggregate, 20-30 parts of fiber, and 3-5 parts of water reducer.

8. The stiffness gradient structure of a concrete floor slab resistant to displacement and abrasion according to any one of claims 5 to 7, characterized in that: The high-activity admixture is fly ash, and the fine aggregate is one of natural sand and quartz sand.

9. A construction method for a concrete base plate with a gradual stiffness change structure that resists displacement and abrasion, characterized in that: Prepare each layer of concrete according to the designed mix ratio and pour it in layers. Pour the bottom layer first, then pour the middle layer and surface layer in sequence. The middle layer concrete must be vibrated before the bottom layer concrete begins to set, and the tamping rod must be inserted about 10cm into the bottom layer concrete. The surface layer concrete must be vibrated before the middle layer concrete begins to set, and the tamping rod must be inserted about 10cm into the middle layer concrete.

10. The construction method of a concrete floor stiffness gradient structure for resisting displacement and abrasion according to claim 9, characterized in that: The thickness of the surface, middle and bottom layer concrete are 3~5cm, 12~15cm and 12~15cm respectively.

Images