Preparation process of green high-performance concrete

Abstract

The invention discloses a green high-performance concrete preparation process which comprises the following steps: S1, preparation before production, including material inspection, equipment calibration and sandstone water content measurement; s2, stage I: pre-wetting the aggregate, adding the coarse aggregate and the fine aggregate, adding part of water, and stirring for 30 seconds; s3, stage II: coating with slurry, adding all the cementing materials, and carrying out dry mixing for 30 seconds; s4, stage III: efficiently stirring, and adding a diluent (containing PCE, nano SiO2 and 100 kg of residual water) of a water reducing agent and nano SiO2; s5, stage 4: throwing fibers, namely uniformly scattering 0.9 kg of polypropylene fibers; s6, stage 5: final stirring: continuously stirring for more than or equal to 120 seconds until the materials are uniform; s7, discharging and detecting the performance, and measuring the slump / expansion degree, the volume weight and the temperature; s8, discharging, transporting and pouring are carried out if the product is qualified; and S9, maintaining. According to the preparation process of the green high-performance concrete, green performance, high performance and industrial prefabrication are fused together by compounding a gel system and optimizing a feeding and stirring process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete preparation process, in particular to a green high-performance concrete preparation process. BACKGROUND

[0002] As the most widely used building material in the world, concrete is widely used in various civil engineering such as building, bridge, tunnel and water conservancy. However, the traditional concrete industry has the outstanding problems of high energy consumption, high resource consumption and high environmental load. Among them, cement, as the main cementitious material in concrete, needs to consume a large amount of natural resources such as limestone, clay and coal during the production process, and emits a large amount of carbon dioxide (CO2) and other greenhouse gases. According to statistics, about 0.8-1.0 tons of CO2 are emitted per ton of cement produced, and the CO2 emissions of the cement industry account for about 7% of the total global human activity emissions. Therefore, reducing the amount of cement is the core approach for the concrete industry to achieve low-carbon and green development.

[0003] High-performance concrete (HPC) generally refers to concrete with high workability, high strength and high durability. The main technical route for preparing HPC at present is to rely on the use of high-performance water reducing agent and low water-binder ratio. Although this method can effectively improve the strength, it often depends on a higher cement dosage and expensive materials such as fine silica fume, and does not fundamentally solve the problem of green environmental protection. In addition, low water-binder ratio and high powder dosage also make the viscosity of concrete mixture increase sharply, the fluidity becomes poor, which brings difficulties to construction and pouring, and increases the risk of cracking.

[0004] In order to reduce the amount of cement, industrial waste such as fly ash and granulated blast furnace slag powder is commonly used as a mineral admixture to partially replace cement. This not only consumes solid waste, but also improves some properties of concrete to some extent, such as reducing the hydration heat, improving the long-term strength and durability. However, simply replacing a large proportion of cement often brings new technical problems, such as slow early strength development of concrete, viscous mixture, poor fluidity, easy bleeding segregation, etc., which is difficult to meet the stringent requirements of modern engineering for the workability, strength and durability of high-performance concrete. SUMMARY

[0005] Therefore, it is necessary to provide a green high-performance concrete preparation process aiming at the technical problems of insufficient workability of existing environmentally friendly concrete.

[0006] A green high-performance concrete preparation process, which comprises the following steps:

[0007] S1, production preparation, including material inspection, equipment calibration, and sandstone moisture content measurement;

[0008] S2, stage one: pre-wetting aggregate, put coarse and fine aggregate, add part of water (40 kg), stir for 30 s;

[0009] S3, stage two: wrapping slurry, put in all cementitious materials (cement, mineral powder, fly ash), dry mix for 30 s;

[0010] S4, stage three: high-efficiency stirring, put in water reducing agent and nano-SiO2 diluent (containing PCE, nano-SiO2, and the remaining water 100 kg);

[0011] S5, stage four: put in fiber, evenly scatter 0.9 kg of polypropylene fiber;

[0012] S6, stage five: final stirring, continue stirring for ≥120 s to be uniform;

[0013] S7, machine output and performance testing, measure slump / extension, bulk density, and temperature;

[0014] S8, qualified, discharge, transport, and pour;

[0015] S9, curing.

[0016] The green high-performance concrete comprises the following components: gel material, aggregate, chemical admixture, and fiber. The gel material comprises cement, mineral admixture 1, mineral admixture 2, and nano-modifier; the aggregate comprises fine aggregate and coarse aggregate; the chemical admixture comprises high-performance polycarboxylate superplasticizer (PCE); and the fiber comprises modified polypropylene fiber.

[0017] In one embodiment, the above-mentioned chemical admixture further comprises a preset amount of retarder and early strength agent.

[0018] In one embodiment, the above-mentioned cement uses one of 42.5R and 52.5R ordinary portland cement.

[0019] In one embodiment, the above-mentioned mineral admixture 1 uses a mixture of one or more of S95 grade granulated blast furnace slag powder and higher-grade granulated blast furnace slag powder.

[0020] In one embodiment, the above-mentioned mineral admixture 2 uses a mixture of one or both of first-grade fly ash and superfine fly ash.

[0021] In one embodiment, the above-mentioned nano-modifier uses one of nano-silica sol or nano-silica particles.

[0022] In one embodiment, the above-mentioned fine aggregate uses machine-made sand with a stone powder content of less than 10%.

[0023] In one embodiment, the coarse aggregate described above adopts 5-22mm continuous gradation macadam, the needle flake content is less than 5%, and the crushing index is less than 10%.

[0024] In one embodiment, the modified polypropylene fiber described above is limited in length to 12-19mm, and the mixing amount is limited to 0.6-1.0kg / m 3 .

[0025] In one embodiment, the step S9 described above includes the following steps:

[0026] S91, immediately after the pouring is completed, immediately cover the plastic film, spray the curing agent, and prevent water evaporation;

[0027] S92, after the final setting, the automatic spraying system is used to keep the surface continuously wet, and the curing is maintained for more than 14 days.

[0028] In one embodiment, the step S92 described above can use water storage curing.

[0029] In one embodiment, the stirring process in the steps S2 to S6 described above adopts a forced stirrer, so as to ensure that the nanomaterial and the fiber are uniformly dispersed through a longer stirring time; at the same time, when the stirring temperature exceeds the preset limit value during the stirring process, ice water can be mixed to spray water to cool the aggregate, so as to avoid that the high temperature causes the slump loss to be too fast.

[0030] In one embodiment, in the step S7 described above, the slump, the spread, the volume weight, and the air content are detected immediately after the concrete is discharged from the machine.

[0031] In one embodiment, the preferred green high-performance concrete includes the following components in terms of mass fraction: cement (P·O52.5R): 250 parts; slag powder (S95): 150 parts; fly ash (I grade): 100 parts; nano-SiO2 slurry (solid content 30%): 16.7 parts; water: 140 parts; polycarboxylic acid type water reducing agent (PCE, solid content 20%): 30.0 parts; machine-made sand (medium sand, II zone): 700 parts; macadam (5-20mm, continuous gradation): 1050 parts; polypropylene fiber (19mm): 0.9 parts.

[0032] In one embodiment, the preferred water-binder ratio (W / B) is 0.28; the total amount of cementitious materials is 500kg / m 3 ; the mixing amount of the water reducing agent (based on the weight of the cementitious materials) is 1.2%; and the mixing amount of the nano-SiO2 (based on the weight of the cementitious materials) is 1.0%.

[0033] The preparation process of the green high-performance concrete successfully combines green, high performance and industrialization by using a composite cementitious system (high content of mineral powder / fly ash + nano material), optimizing the feeding and mixing process and precise and strict curing system. Specifically, the first pre-indication aggregate and slurry wrapping process of steps S2 and S3 first forms a water film on the surface of the aggregate, and then the aggregate is wrapped with cementitious materials, which greatly optimizes the particle size distribution and reduces the mixing resistance. The cementitious materials are uniformly wrapped on the surface of the aggregate, forming an optimal "mortar wrapped stone" structure, which fundamentally solves the contradiction between high fluidity and anti-segregation under low water-binder ratio. The polycarboxylic acid superplasticizer (PCE) provides strong dispersion force, and the nano-SiO2 sol can further adsorb water and superplasticizer due to its high specific surface area and reactivity, thereby releasing the wrapped water, significantly reducing the yield stress and viscosity of the slurry, and enabling the concrete to obtain excellent rheological properties under low water consumption. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0035] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0036] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and other terms should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] In the present application, unless specifically stated and limited otherwise, a first feature is "on" or "under" a second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Also, the first feature "over", "above" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in horizontal level than the second feature. The first feature "under", "below" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in horizontal level than the second feature.

[0038] It is noted that when an element is referred to as being "on" or "disposed on" another element, it can be directly on the other element or an intervening element can also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or an intervening element can also be present. The terms "vertical", "horizontal", "up", "down", "left", "right", and similar expressions used herein are used for illustrative purposes only and are not intended to be limiting.

[0039] Example 1

[0040] The present application discloses a green high-performance concrete preparation process, which comprises the following steps:

[0041] S1, production preparation, including material inspection, equipment calibration, and sandstone moisture content measurement;

[0042] S2, phase one: pre-wetting aggregate, adding coarse and fine aggregate, adding part of water (40 kg), and stirring for 30 s;

[0043] S3, phase two: wrapping slurry, adding all cementitious materials (cement, mineral powder, and fly ash), and dry mixing for 30 s;

[0044] S4, phase three: high-efficiency stirring, adding water reducing agent and nano-SiO2 diluent (containing PCE, nano-SiO2, and remaining water 100 kg);

[0045] S5, phase four: adding fiber, uniformly scattering 0.9 kg of polypropylene fiber;

[0046] S6, phase five: final stirring, continuously stirring for ≥120 s until uniform;

[0047] S7, machine output and performance detection, measuring slump / extension, bulk density, and temperature;

[0048] S8, passing, discharging, transporting, and pouring;

[0049] S9, curing.

[0050] Further, the green high-performance concrete comprises the following components: gel material, aggregate, chemical admixture and fiber, wherein the gel material comprises cement, mineral admixture 1, mineral admixture 2 and nano modifier; the aggregate comprises fine aggregate and coarse aggregate; the chemical admixture comprises high-performance polycarboxylate superplasticizer (PCE); and the fiber comprises modified polypropylene fiber.

[0051] In one embodiment, the chemical admixture further comprises a preset amount of retarder and early strength agent.

[0052] Specifically, the cement is one of 42.5R and 52.5R ordinary portland cement; the mineral admixture 1 is a mixture of one or more of S95 grade granulated blast furnace slag powder and higher grade granulated blast furnace slag powder; the mineral admixture 2 is a mixture of one or both of first-class fly ash and superfine fly ash; and the nano modifier is one of nano silicon dioxide sol or nano silicon dioxide particles; based on this, the composite gel system can greatly reduce the cement dosage. The pozzolanic effect and micro-aggregate effect of the blast furnace slag and fly ash can optimize the pore structure and improve the later strength and durability. Nano SiO2 as a crystal nucleus accelerates hydration, fills nano-level pores and significantly enhances and toughens.

[0053] Specifically, the fine aggregate is machine-made sand with a stone powder content of less than 10%; the coarse aggregate is 5-22mm continuous gradation gravel with a needle flake content of less than 5% and a crushing index of less than 10%; based on this, the green aggregate system uses machine-made sand to reduce the dependence on river sand, and strict quality control is the basis to ensure the fluidity and strength of the concrete, thereby ensuring the green and environmentally friendly characteristics of the concrete of the present scheme.

[0054] Specifically, the modified polypropylene fiber has a length of 12-19mm and a dosage of 0.6-1.0kg / m 3Therefore, the toughness, impact resistance and crack resistance of the concrete can be improved significantly, and the early plastic shrinkage cracks can be inhibited.

[0055] Further, the step S9 comprises the following steps:

[0056] S91, immediately after the pouring is completed, the plastic film is covered immediately, and the curing agent is sprayed to prevent water evaporation;

[0057] S92, after the final setting, the automatic spraying system is used to keep the surface continuously wet, and the curing is performed for more than 14 days.

[0058] Specifically, in one embodiment, the step S92 described above can use water storage curing.

[0059] Specifically, in one embodiment, the stirring process in the steps S2 to S6 described above uses a forced stirrer, so that the nanomaterial and the fiber are uniformly dispersed by a longer stirring time; at the same time, during the stirring process, when the stirring temperature exceeds the preset limit value, ice water can be mixed to spray water on the aggregate to cool it down, so as to avoid that the high temperature causes the slump loss too fast.

[0060] Further, in the step S7 described above, the slump, the spread, the bulk density and the air content are detected immediately after the concrete is discharged.

[0061] Example 2

[0062] Different from the example 1, the green high-performance concrete in the present embodiment comprises the following components by mass fraction: cement (P·O52.5R): 250 parts; slag powder (S95): 150 parts; fly ash (I grade): 100 parts; nano-SiO2 slurry (solid content 30%): 16.7 parts; water: 140 parts; polycarboxylic acid type water reducing agent (PCE, solid content 20%): 30.0 parts; machine-made sand (medium sand, II zone): 700 parts; gravel (5-20 mm, continuous gradation): 1050 parts; polypropylene fiber (19 mm): 0.9 parts.

[0063] Further, in the above proportion, the water-binder ratio (W / B) is 0.28; the total amount of cementitious materials is 500 kg / m 3 ; the water reducing agent content (based on the weight of the cementitious materials) is 1.2%; and the nano-SiO2 content (based on the weight of the cementitious materials) is 1.0%.

[0064] In summary, the green high-performance concrete preparation process disclosed by the present application successfully combines green, high performance and industrialization by using a composite cementitious system (high content of mineral powder / fly ash+nanomaterials), optimizing the feeding and mixing process and precise and strict curing system. Specifically, the first pre-indication aggregate and slurry wrapping process of steps S2 and S3 first forms a water film on the surface of the aggregate, and then the aggregate is wrapped with cementitious materials, which greatly optimizes the particle size distribution and reduces the mixing resistance. The cementitious materials are uniformly wrapped on the surface of the aggregate, forming an optimal "mortar wrapped stone" structure, which fundamentally solves the contradiction between high fluidity and anti-segregation under low water-binder ratio. The polycarboxylic acid superplasticizer (PCE) provides strong dispersion, and the nano-SiO2 sol can further adsorb water and superplasticizer due to its high specific surface area and reactivity, thereby releasing the wrapped water, significantly reducing the yield stress and viscosity of the slurry, and enabling the concrete to obtain excellent rheological properties under low water consumption.

[0065] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0066] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A process for the production of green high performance concrete, characterized in that, Comprising the following steps: S1, pre-production preparation, including material inspection, equipment calibration, sand moisture content measurement; S2, phase one: pre-wetting aggregate, adding coarse and fine aggregate, adding part of water, stirring for 30s; S3, phase two: slurry wrapping, adding all cementitious materials, dry mixing for 30s; S4, phase three: high-efficiency stirring, adding water reducing agent and nano-SiO2 diluent; S5, phase four: adding fiber, uniformly scattering 0.9kg of polypropylene fiber; S6, phase five: final stirring, continuously stirring for ≥120s until uniform; S7, machine output and performance detection, measuring slump / extension, bulk density, temperature; S8, qualified, discharging, transportation, and pouring; S9, curing; The green high-performance concrete comprises the following components: gel material, aggregate, chemical admixture, and fiber; wherein the gel material comprises cement, mineral admixture 1, mineral admixture 2, and nano-modifier; the aggregate comprises fine aggregate and coarse aggregate; the chemical admixture comprises high-performance polycarboxylate superplasticizer; and the fiber comprises modified polypropylene fiber.

2. The green high performance concrete manufacturing process according to claim 1, characterized in that, The chemical admixture further comprises a preset amount of retarder and early strength agent.

3. The process for preparing green high performance concrete as claimed in claim 1 wherein, The cement uses one of 42.5R and 52.5R ordinary portland cement.

4. The process for preparing green high performance concrete as claimed in claim 1 wherein, The mineral admixture 1 uses a mixture of one or more of S95 grade granulated blast furnace slag powder and higher-grade granulated blast furnace slag powder.

5. The process for preparing green high performance concrete as claimed in claim 1 wherein, The mineral admixture 2 uses a mixture of one or both of first-grade fly ash and superfine fly ash.

6. The green high performance concrete manufacturing process according to claim 1, wherein, The nano-modifier uses one of nano-silica sol or nano-silica particles.

7. The green high performance concrete manufacturing process according to claim 1, wherein, The fine aggregate uses machine-made sand with a stone powder content of less than 10%.

8. The green high performance concrete manufacturing process according to claim 1, wherein, The coarse aggregate uses 5-22mm continuous gradation gravel with a needle flake content of less than 5% and a crushing index of less than 10%.

9. The process for preparing green high performance concrete as claimed in claim 1 wherein, The length of the modified polypropylene fiber is limited to 12-19 mm, and the dosage is limited to 0.6-1.0 kg / m 3 .

10. The process for preparing green high performance concrete as claimed in claim 1 wherein, The step S9 comprises the following steps: S91, immediate curing, after pouring is completed, immediately cover plastic film and spray curing agent to prevent water evaporation; S92, standard curing, after final setting, use an automatic spraying system to keep the surface continuously wet, and cure for more than 14 days.