A low-slump, high-strength concrete suitable for centrifugal molding, its preparation method, and its application.

Abstract

This invention discloses a low-slump, high-strength concrete suitable for centrifugal molding, its preparation method, and its application. The concrete comprises the following raw materials in parts by weight: cement: 550-650 parts; Grade I fly ash: 70-90 parts; S105 mineral powder: 70-90 parts; silica fume: 70-90 parts; quartz sand: 550-650 parts; basalt aggregate with a particle size of 5mm ≤ < 16mm: 310-380 parts; basalt aggregate with a particle size of 16mm ≤ ≤ 31.5mm: 720-790 parts; mixing water: 90-130 parts; and water-reducing agent: 9-13 parts. The low-slump, high-strength concrete does not exhibit slurry-aggregate separation during centrifugal molding. Compared to traditional concrete, the precast concrete components have advantages such as high strength, strong crack resistance, and good durability. High-performance utility poles can be manufactured using the centrifugal molding process.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a low-slump, high-strength concrete suitable for centrifugal molding, its preparation method, and its application. Background Technology

[0002] Concrete utility poles are prefabricated components used in communications, lighting, and power transmission lines. They are widely used in urbanization and infrastructure projects and are of great significance to my country's economic development.

[0003] Traditional concrete utility poles are mainly manufactured using centrifugal molding. Centrifugal molding is a very important process in the manufacture of concrete pipe piles. It is a key process to ensure that the concrete of the pipe pile achieves good density. It affects the strength of the concrete of the pipe pile and the uniformity of the concrete along the entire length of the pipe pile.

[0004] However, traditional centrifugal-molded concrete uses a large amount of cement and generally has low strength and tensile strength. After the centrifugal molding process, the pipe wall is prone to delamination cracking and large early shrinkage. During later service, concrete products are prone to problems such as low strength, poor crack resistance, and poor durability. Summary of the Invention

[0005] The purpose of this invention is to provide a low-slump high-strength concrete suitable for centrifugal molding, its preparation method, and its application. The low-slump high-strength concrete disclosed in this invention does not exhibit slurry-aggregate separation during centrifugal molding. Compared with traditional concrete, it has advantages such as high strength, strong crack resistance, and good durability. High-performance utility poles can be prepared through centrifugal molding.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A low-slump, high-strength concrete suitable for centrifugal casting comprises the following raw materials in parts by weight:

[0008] Cement: 550-650 parts;

[0009] Grade I fly ash: 70-90 parts;

[0010] S105 mineral powder: 70-90 parts;

[0011] Silica fume: 70-90 parts;

[0012] Quartz sand: 550-650 parts;

[0013] Basalt aggregate with a particle size of 5mm ≤ and 16mm: 310-380 parts;

[0014] Basalt aggregate with a particle size of 16mm ≤ 31.5mm: 720-790 parts;

[0015] Mixing water: 90-130 parts;

[0016] Water-reducing agent: 9-13 parts.

[0017] The cement is grade 52.5 ordinary Portland cement that meets the technical requirements of GB 175-2007 "General Portland Cement" and has a specific surface area of ​​300 kg / m². 3 -400kg / m 3 The compressive strength of the mortar after 28 days is ≥52.5MPa.

[0018] The Class I fly ash is Class F Class I fly ash that meets the technical requirements of GB / T1596-2017 "Fly Ash for Cement and Concrete", with a fineness of 45 micrometers, a sieve residue of <10%, a water requirement ratio of ≤95%, a loss on ignition of <5%, and a 28-day activity index of ≥80%.

[0019] The S105 mineral powder is a mineral powder that meets the technical requirements of GB / T18046-2008, with a specific surface area ≥500m². 2 / kg, 28d activity index ≥105%.

[0020] The silica fume has an average particle size of 0.1-0.3 μm and a specific surface area of ​​20-28 μm. 2 / g.

[0021] The fineness modulus of the quartz sand is 2.4-2.8.

[0022] The apparent density of the basalt aggregate is 2800–3000 kg / m³. 3 The crushing value is ≤5%; the basalt aggregate is washed and dried before feeding, and fine particles smaller than 0.15mm are removed after drying.

[0023] The weight ratio of basalt aggregate with a particle size of 5mm ≤ < 16mm to basalt aggregate with a particle size of 16mm ≤ 31.5mm is 3:7.

[0024] The water-reducing agent is a high-performance polycarboxylate water-reducing agent that meets the technical requirements of GB / T8076-2008 "Concrete Admixtures" and has a water reduction rate of ≥27%.

[0025] The method for preparing low-slump high-strength concrete provided by the present invention includes the following steps: cement, grade I fly ash, S105 mineral powder, silica fume, quartz sand, and basalt aggregate are mixed and stirred for 80 seconds in sequence; then 1 / 2 to 2 / 3 of the amount of mixing water is added, and stirring is continued for 150 seconds; the remaining amount of mixing water containing water-reducing agent is slowly added, and stirring is continued for 100 to 120 seconds to obtain low-slump high-strength concrete.

[0026] The present invention also provides the application of the aforementioned low-slump high-strength concrete in the manufacture of utility poles.

[0027] In the low-slump, high-strength concrete suitable for centrifugal molding provided by this invention, the functions of each raw material are as follows:

[0028] Cement: Provides the main strength for the prepared concrete. In this invention, 52.5 grade ordinary Portland cement is preferred, which has a fast hydration rate and high strength.

[0029] S105 mineral powder: This is a concrete admixture that partially replaces cement, reduces concrete shrinkage, improves workability, and provides higher strength through secondary hydration. It also has a large specific surface area and high activity, enabling it to regulate the rheological properties of concrete. Using other grades of mineral powder increases concrete slump, decreases cohesiveness, and reduces strength, making it less suitable for centrifugal molding.

[0030] Grade I fly ash is a concrete admixture that partially replaces cement, reduces concrete shrinkage, improves concrete workability, and has a certain pozzolanic property. Under alkali activation, it can provide higher strength to concrete. If other grades of fly ash are used, the material activity decreases, resulting in poorer concrete strength.

[0031] Silica fume: Highly active powder particles used as a mineral admixture, it has a good filling effect on cementitious powder systems and also possesses ultra-high activity; its hydration products can be used as fillers. In this invention, the preferred average particle size is 0.1-0.3 μm, and the specific surface area is 20-28 μm. 2 / g of silica fume is beneficial for achieving the densest packing of concrete systems, increasing material density, and reducing defects.

[0032] Quartz sand is a fine aggregate that mainly serves as a skeleton and filler in concrete. In this invention, quartz sand with a fineness modulus of 2.4-2.8 is preferred.

[0033] Basalt aggregate: a type of coarse aggregate that mainly serves as a skeleton and filler in concrete. In this invention, basalt aggregate with a particle size of 5mm ≤ < 16mm and basalt aggregate with a particle size of 16mm ≤ 31.5mm are used in combination, which is beneficial to the uniform distribution of aggregate particles during the construction and molding process.

[0034] Water-reducing agent: It has a good water-reducing effect and is used to ensure that low water-cement ratio concrete has suitable workability. In this invention, a polycarboxylate high-performance water-reducing agent with a water reduction rate of ≥27% that meets the technical requirements of GB / T8076-2008 "Concrete Admixtures" is preferred. This type of water-reducing agent has a better water-reducing effect than other water-reducing agents.

[0035] To achieve low slump and high strength concrete, this invention provides a low-slump, high-strength concrete suitable for centrifugal molding. The raw materials and particle sizes of each material satisfy the principle of closest packing. High-strength and impact-resistant basalt is used as coarse aggregate, and quartz sand as fine aggregate. The powder particles are selected based on a "large element + medium element + small element" packing design. Cement particles are chosen as the "large element" in the closest packing system, ultrafine mineral powder and fly ash as the "medium element," and silica fume with a particle size less than 0.3 micrometers as the "small element." The amount of these powder particles is controlled within a suitable ratio, allowing for close packing within the aggregate, minimizing porosity, and improving material homogeneity. Under the physical packing effect of the powder particles, the hydrated paste exhibits ultra-high strength. Furthermore, the filling effect of the powder particles further releases free water from the interparticle gaps, resulting in an extremely low water-cement ratio while maintaining good fluidity. In order to make concrete materials more suitable for centrifugal molding process, based on specific construction needs and application environment, this invention selects S105 mineral powder with larger specific surface area and higher activity to adjust the rheological properties of concrete.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The low-slump, high-strength concrete prepared by this invention possesses characteristics such as high cohesiveness, low slump, and ultra-high strength, making it suitable for centrifugal molding processes. The material's high cohesiveness and low slump prevent aggregate segregation during centrifugal molding. Verification has shown that concrete cubes prepared using this invention exhibit a 28-day compressive strength exceeding 90 MPa.

[0038] 2. The composite system designed based on the theory of closest packing of multi-component powders in this invention can fully utilize the contribution of the closest packing of powder particles to the material strength. It not only generates strength through hydration reactions to produce hydration products, but also achieves ultra-high strength through the closest physical packing of powder particles. The composite incorporation of low-cost S105 mineral powder and fly ash has a good powder particle filling effect, which can effectively reduce the amount of cement and silica fume in the mix proportion of ultra-high strength concrete, reduce material costs, and minimize material shrinkage. Furthermore, the compressive strength of the material is significantly higher than that of the pure cement design scheme, demonstrating good economic efficiency and applicability.

[0039] 3. The low-slump high-strength concrete prepared by this invention uses high-strength, high-elasticity basalt aggregate as coarse aggregate, which helps to ensure the strength and impact resistance of the concrete.

[0040] 4. This invention uses a high proportion of silica fume and S105 active mineral powder, which have a high water requirement and high activity, and can quickly generate hydration products, providing early strength for concrete materials. It also makes the slurry have high yield stress and plastic viscosity, low slump of concrete materials, and good cohesion, which helps to avoid segregation and bleeding of aggregate slurry in centrifugal molding process.

[0041] 5. Even though a relatively high amount of low-strength fly ash and S105 mineral powder are used to replace part of the cement and silica fume in this invention, the concrete can still have ultra-high compressive strength due to the reasonable combination and dosage of each raw material, which significantly reduces the cost of concrete and has good economic efficiency. Detailed Implementation

[0042] The requirements for each raw material in the examples are as follows:

[0043] Cement: Grade 52.5 ordinary Portland cement that meets the technical requirements of GB 175-2007 "General Portland Cement", with a specific surface area of ​​300kg / m3-400kg / m3 and a 28-day mortar compressive strength ≥52.5MPa.

[0044] Grade I fly ash: Class I fly ash of type F that meets the technical requirements of GB / T1596-2017 "Fly ash for cement and concrete", with a fineness of <10% residue on a 45-micron sieve, a water requirement ratio of ≤95%, a loss on ignition of <5%, and a 28-day activity index of ≥80%.

[0045] S105 mineral powder: Mineral powder that meets the technical requirements of GB / T18046-2008, with a specific surface area ≥500m2 / kg and a 28d activity index ≥105%.

[0046] Silica fume: average particle size is 0.1-0.3μm, specific surface area is 20-28m2 / g.

[0047] Quartz sand: fineness modulus is 2.4-2.8.

[0048] Basalt aggregate: apparent density is approximately 2800–3000 kg / m³, crushing value ≤5%.

[0049] Water-reducing agent: Polycarboxylate high-performance water-reducing agent that meets the technical requirements of GB / T8076-2008 "Concrete Admixtures", with a water reduction rate of ≥27%.

[0050] The present invention will now be described in detail with reference to the embodiments.

[0051] Example 1

[0052] A low-slump, high-strength concrete suitable for centrifugal construction is composed of the following raw materials in parts by weight: 571 parts of P.O52.5 cement; 82 parts of silica fume; 82 parts of S105 mineral powder; 82 parts of Grade I fly ash; 603 parts of quartz sand; 1121 parts of basalt aggregate, of which 785 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 336 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 103 parts of mixing water; and 11.81 parts of water-reducing agent.

[0053] The method for preparing low-slump, high-strength concrete suitable for centrifugal molding includes the following steps:

[0054] (1) Pre-treatment of raw materials: The basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate. After drying, the stone powder and fine particles that may be attached to the basalt aggregate are screened out.

[0055] (2) Weigh out the basalt coarse aggregate, quartz sand, P.O52.5 cement, fly ash, S105 mineral powder, and silica fume according to the above weight proportions, and put the P.O52.5 cement, Grade I fly ash, S105 mineral powder, silica fume, quartz sand, and basalt aggregate into the concrete mixer in the order of powder first and then aggregate, and mix for 80 seconds.

[0056] (3) After ensuring that the powder and aggregate are mixed evenly, add 1 / 2 of the amount of mixing water and stir again for 150 seconds.

[0057] (4) Gradually add the remaining amount of mixing water containing the water-reducing agent to the concrete mixer and continue mixing for 120 seconds until the mixture is in a low-flow slurry state.

[0058] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens according to GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0059] Example 2

[0060] A low-slump, high-strength concrete suitable for centrifugal construction is composed of the following raw materials in parts by weight: 619 parts of P.O52.5 cement; 88 parts of silica fume; 88 parts of S105 mineral powder; 88 parts of Grade I fly ash; 583 parts of quartz sand; 1100 parts of basalt aggregate, of which 770 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 330 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 124 parts of mixing water; and 12.54 parts of water-reducing agent.

[0061] The method for preparing low-slump, high-strength concrete suitable for centrifugal molding includes the following steps:

[0062] (1) Pre-treatment of raw materials: Basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate. After drying, stone powder and fine particles that may be attached to the basalt aggregate are screened out.

[0063] (2) Weigh out the basalt coarse aggregate, quartz sand, P.O52.5 cement, fly ash, S105 mineral powder, and silica fume according to the above weight proportions, and put the P.O52.5 cement, Grade I fly ash, S105 mineral powder, silica fume, quartz sand, and basalt aggregate into the concrete mixer in the order of powder first and then aggregate, and mix for 80 seconds;

[0064] (3) After ensuring that the powder and aggregate are mixed evenly, add 2 / 3 of the amount of mixing water and stir again for 120-150 seconds;

[0065] (4) Gradually add the remaining amount of mixing water containing the water-reducing agent to the concrete mixer and continue mixing until the mixture is in a low-flow slurry state.

[0066] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens according to GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0067] Example 3

[0068] A low-slump, high-strength concrete suitable for centrifugal construction is composed of the following raw materials in parts by weight: 592 parts of P.O52.5 cement; 83 parts of silica fume; 83 parts of S105 mineral powder; 83 parts of Grade I fly ash; 568 parts of quartz sand; 1041 parts of basalt aggregate, of which 729 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 312 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 130 parts of mixing water; and 12.88 parts of water-reducing agent.

[0069] The method for preparing low-slump, high-strength concrete suitable for centrifugal molding includes the following steps:

[0070] (1) Pre-treatment of raw materials: Basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate. After drying, stone powder and fine particles that may be attached to the basalt aggregate are screened out.

[0071] (2) Weigh out the basalt coarse aggregate, quartz sand, P.O52.5 cement, fly ash, S105 mineral powder, and silica fume according to the above weight proportions, and put the P.O52.5 cement, Grade I fly ash, S105 mineral powder, silica fume, quartz sand, and basalt aggregate into the concrete mixer in the order of powder first and then aggregate, and mix for 80 seconds;

[0072] (3) After ensuring that the powder and aggregate are mixed evenly, add 2 / 3 of the amount of mixing water and stir again for 150 seconds;

[0073] (4) Gradually add the remaining amount of mixing water containing the water-reducing agent to the concrete mixer and continue mixing for 120 seconds until the mixture is in a low-flow slurry state.

[0074] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens according to GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0075] Comparative Example 1

[0076] A low-slump concrete is composed of the following raw materials in parts by weight: 719 parts of P.O52.5 cement; 98 parts of silica fume; 603 parts of quartz sand; 1121 parts of basalt aggregate, of which 785 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 336 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 103 parts of mixing water; and 8.52 parts of water-reducing agent.

[0077] A method for preparing low-slump concrete includes the following steps:

[0078] (1) Pre-treatment of raw materials: Basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate.

[0079] (2) Add P.O52.5 cement, silica fume, quartz sand and basalt aggregate to the concrete mixer in the order of powder first and then aggregate according to the above weight parts, and mix for 80 seconds.

[0080] (3) After ensuring that the powder and aggregate are mixed evenly, add 1 / 2 of the amount of mixing water and stir again for 150 seconds.

[0081] (4) Gradually add the remaining amount of mixing water containing the water-reducing agent to the concrete mixer and continue mixing for 120 seconds until the mixture is in a low-flow slurry state.

[0082] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens in accordance with GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0083] Comparative Example 2

[0084] A low-slump concrete is composed of the following raw materials in parts by weight: 653 parts of P.O52.5 cement; 82 parts of silica fume; 82 parts of mineral powder; 603 parts of quartz sand; 1121 parts of basalt aggregate, of which 785 parts are basalt aggregate with a particle size of 16mm ≤ particle size ≤ 31.5mm and 336 parts are basalt aggregate with a particle size of 5mm ≤ particle size < 16mm; 103 parts of mixing water; and 13.50 parts of water-reducing agent.

[0085] A method for preparing low-slump concrete includes the following steps:

[0086] (1) Pre-treatment of raw materials: Basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate;

[0087] (2) Add cement, quartz sand, silica fume, mineral powder and basalt aggregate to the concrete mixer in the order of powder first and then aggregate according to the above weight parts, and mix for 80 seconds.

[0088] (3) After ensuring that the powder and aggregate are mixed evenly, add 2 / 3 of the amount of mixing water and stir again for 150 seconds;

[0089] (4) Gradually add the remaining amount of mixing water containing the water-reducing agent to the concrete mixer and continue mixing for 120 seconds until the mixture is in a low-flow slurry state.

[0090] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens in accordance with GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0091] Comparative Example 3

[0092] A low-slump concrete is composed of the following raw materials in parts by weight: 817 parts of P.O52.5 cement; 603 parts of quartz sand; 1121 parts of basalt aggregate, of which 785 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 336 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 103 parts of mixing water; and 10.81 parts of water-reducing agent.

[0093] A method for preparing low-slump concrete includes the following steps:

[0094] (1) Pretreatment of raw materials: The basalt aggregate is washed with water to remove the influence of mud powder and other substances on the aggregate. After drying, the stone powder and fine particles that may be attached to the basalt aggregate are screened out.

[0095] (2) Add cement, quartz sand and basalt aggregate to the concrete mixer in the order of powder first and then aggregate according to the above weight proportions, and mix for 80 seconds.

[0096] (3) After ensuring that the powder and aggregate are mixed evenly, add 2 / 3 of the amount of mixing water and stir again for 150 seconds.

[0097] (4) Gradually add the remaining mixing water containing the corresponding weight of water-reducing agent to the concrete mixer and continue mixing for 120 seconds until the mixture is in a low-flow slurry state.

[0098] (5) Unload the concrete mixture from the concrete mixer, prepare concrete cube specimens according to GB50081 "Standard for Test Methods of Mechanical and Physical Properties of Concrete", and cure them under the specified conditions for 28 days to test their compressive strength.

[0099] Comparative Example 4

[0100] Everything else is the same as in Example 1, except that the basalt aggregate in the raw materials is replaced with limestone aggregate.

[0101] Comparative Example 5

[0102] Everything else is the same as in Example 2, except that the S105 mineral powder in the raw materials is replaced with S95 mineral powder.

[0103] Comparative Example 6

[0104] The rest is the same as in Example 1, except that the water washing step of basalt aggregate in step (1) is omitted.

[0105] Comparative Example 7

[0106] The rest is the same as in Example 1, except that the basalt aggregate with a particle size of 5mm ≤ particle size < 16mm in the raw materials is changed to 448 parts, and the basalt aggregate with a particle size of 16mm ≤ particle size ≤ 31.5mm is changed to 673 parts.

[0107] Comparative Example 8

[0108] The rest is the same as in Example 1, except that the concrete is composed of the following raw materials in parts by weight: 571 parts of P.O52.5 cement; 49 parts of silica fume; 82 parts of S105 mineral powder; 82 parts of Grade I fly ash; 603 parts of quartz sand; 1121 parts of basalt aggregate, of which 785 parts are basalt aggregate with a particle size of 5mm ≤ particle size < 16mm and 336 parts are basalt aggregate with a particle size of 16mm ≤ particle size ≤ 31.5mm; 103 parts of mixing water; and 11.81 parts of water-reducing agent.

[0109] Comparative Example 9

[0110] The other components are the same as in Example 1, except that the concrete is composed of the following raw materials in parts by weight: 571 parts of P.O52.5 cement; 82 parts of silica fume; 82 parts of S105 mineral powder; 82 parts of Grade I fly ash; 660 parts of quartz sand; 1227 parts of basalt aggregate, of which 859 parts are basalt aggregate with a particle size of 16mm ≤ 31.5mm and 368 parts are basalt aggregate with a particle size of 5mm ≤ < 16mm; 103 parts of mixing water; and 11.81 parts of water-reducing agent.

[0111] Table 1 shows the raw material composition and weight of concrete in each embodiment and comparative example.

[0112] As can be seen from the table, the amounts of cement and silica fume in the low-slump high-strength concrete in each embodiment are significantly lower than those in Comparative Examples 1 to 3. This indicates that using the multi-component powder composite system proposed in this invention can effectively reduce the proportion of high-priced raw materials such as cement and silica fume while achieving ultra-high strength, thus demonstrating good economic efficiency.

[0113] Table 1. Raw material composition and dosage (parts) of concrete in each embodiment and comparative example

[0114]

[0115]

[0116] Table 2 shows a comparison of the performance results of concrete in each embodiment and comparative example.

[0117] The results in the table show that the compressive strength of Examples 1, 2, and 3 in this invention is higher than that of Comparative Example 3, and is quite close to that of Comparative Examples 1 and 2, with a 28-day compressive strength approaching 100 MPa. The slump is consistently between 90 and 100 μm. This invention is based on the theory of the densest packing of ultra-high strength concrete. The multi-component powder composite system used effectively utilizes the particle packing effect to increase the density of the matrix while simultaneously generating strength through the hydration reaction of the cementitious materials, thus ensuring the concrete material possesses ultra-high strength and durability.

[0118] Example 1 showed a higher compressive strength than Comparative Example 4, indicating that using basalt aggregate instead of limestone aggregate is beneficial to improving the compressive strength of concrete.

[0119] Example 2 showed a higher compressive strength than Comparative Example 5 and a lower slump than Comparative Example 5. Combined with field tests, observations of the performance of freshly mixed concrete revealed that when S105 mineral powder with higher activity and specific surface area was used as a raw material, the concrete had higher yield stress and plastic viscosity, strong paste cohesion, and the aggregate was less prone to segregation, making it more suitable for centrifugal molding processes.

[0120] The data from Example 1 and Comparative Example 6 show that the pretreatment of water-washed basalt aggregate can effectively reduce the impact of fine stone powder particles and harmful substances on the aggregate surface on concrete materials and improve compressive strength.

[0121] A comparison of the data from Example 1 and Comparative Example 7 shows that when the mass ratio of basalt aggregate with a particle size of 5mm ≤ < 16mm to basalt aggregate with a particle size of 16mm ≤ < 31.5mm is 3:7, the best packing effect is achieved, resulting in good material cohesion and high compressive strength.

[0122] A comparison of the data from Example 1 and Comparative Example 8 shows that when the weight of silica fume is 70-90 parts, it has a better effect. If the amount of silica fume is too low, it will lead to a decrease in the compressive strength of concrete.

[0123] As can be seen from the data of Example 1 and Comparative Example 9, increasing the amount of basalt aggregate in the raw materials in Comparative Example 9 led to a decrease in the paste-aggregate ratio of the system, a decrease in the filling and encapsulation properties of the paste on the aggregate, and a relative decrease in the compressive strength of the material.

[0124] Table 2. Test results of main concrete properties in each embodiment and comparative example

[0125] Group number 7d compressive strength / MPa 28-day compressive strength / MPa Slump (mm) Cohesiveness Example 1 96.60 99.10 90-100 good Example 2 82.90 99.20 90-100 good Example 3 87.50 98.70 90-100 good Comparative Example 1 90.2 105.00 90-100 good Comparative Example 2 71.3 93.2 90-100 good Comparative Example 3 69.4 87.7 90-100 good Comparative Example 4 76.3 88.1 90-100 good Comparative Example 5 65.6 87.9 60-70 generally Comparative Example 6 66.9 87.6 90-100 good Comparative Example 7 70.7 85.6 90-100 good Comparative Example 8 71.6 87.5 80-90 generally Comparative Example 9 69.8 88.6 90-100 generally

[0126] The compressive strength in the table is tested according to the standard GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete"; the slump is tested according to the standard GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures"; the cohesiveness of concrete is mainly determined based on the state of the mixture during actual construction.

[0127] The concrete discharged from the concrete mixer in the above embodiments and comparative examples is placed in a mold, closed, tensioned, and centrifuged. After static curing for 10-16 hours, it is demolded to obtain the precast utility pole component. The above-described detailed description of a low-slump, high-strength concrete suitable for centrifugal construction, its preparation method, and its application is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the invention should be within the protection scope of the invention.

Claims

1. A low-slump, high-strength concrete suitable for centrifugal casting, characterized in that, Including the following parts by weight of raw materials: Cement: 550-650 parts; Grade I fly ash: 82-90 parts; S105 mineral powder: 70-90 parts; Silica fume: 82-90 parts; Quartz sand: 550-650 parts; the fineness modulus of the quartz sand is 2.4-2.8; Basalt aggregate with a particle size of 5mm ≤ and 16mm: 310-380 parts; Basalt aggregate with a particle size of 16mm ≤ 31.5mm: 720-790 parts; Mixing water: 90-130 parts; Water-reducing agent: 9-13 parts; Before feeding, the basalt aggregate is washed and dried, and fine particles smaller than 0.15mm are removed after drying; the weight ratio of basalt aggregate with a particle size of 5mm ≤ < 16mm to basalt aggregate with a particle size of 16mm ≤ 31.5mm is 3:

7.

2. The low-slump high-strength concrete according to claim 1, characterized in that, The cement is grade 52.5 ordinary Portland cement that meets the technical requirements of GB 175-2007 "General Portland Cement" and has a specific surface area of ​​300 kg / m². 3 -400kg / m 3 The compressive strength of the mortar after 28 days is ≥52.5MPa.

3. The low-slump high-strength concrete according to claim 1, characterized in that, The Class I fly ash is Class F Class I fly ash that meets the technical requirements of GB / T1596-2017 "Fly Ash for Cement and Concrete", with a fineness of 45 micrometers, a sieve residue of <10%, a water requirement ratio of ≤95%, a loss on ignition of <5%, and a 28-day activity index of ≥80%.

4. The low-slump high-strength concrete according to claim 1, characterized in that, The S105 mineral powder is a mineral powder that meets the technical requirements of GB / T18046-2008, with a specific surface area ≥500m². 2 / kg, 28d activity index ≥105%.

5. The low-slump high-strength concrete according to claim 1, characterized in that, The silica fume has an average particle size of 0.1-0.3 μm and a specific surface area of ​​20-28 m². 2 / g.

6. The low-slump high-strength concrete according to claim 1, characterized in that, The apparent density of the basalt aggregate is 2800~3000 kg / m³. 3 Crushing value ≤ 5%.

7. The low-slump high-strength concrete according to claim 1, characterized in that, The water-reducing agent is a high-performance polycarboxylate water-reducing agent that meets the technical requirements of GB / T8076-2008 "Concrete Admixtures" and has a water reduction rate of ≥27%.

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