High-performance environment-friendly concrete and preparation method thereof

Abstract

The invention discloses high-performance environment-friendly concrete and a preparation method thereof, and the high-performance environment-friendly concrete comprises: a cementing material including Portland cement, granulated blast furnace slag powder, fly ash and silica fume; the aggregate comprises coarse aggregate, gravels or pebbles, fine aggregate and river sand or machine-made sand; the additives comprise a polycarboxylic acid water reducer, an alkylbenzene sulfonate air entraining agent and polypropylene fibers; the preparation method comprises the following steps: putting the coarse aggregate, the fine aggregate and the cementing material into a stirrer, carrying out dry mixing until the materials are uniformly mixed, mixing the water, the polycarboxylic acid water reducer and the alkylbenzene sulfonate air entraining agent, adding the mixture into the stirrer in two times, adding the mixed solution for the first time, adding the rest of the mixed solution for the second time, adding the polypropylene fibers at the same time, and uniformly stirring. And pouring the uniformly stirred concrete mixture into a mold, vibrating and molding, and curing. Therefore, the concrete has the beneficial effects of low carbon, environmental protection, high strength, excellent durability, good construction performance and the like.

Description

Technical Field

[0001] The present invention relates to the field of concrete, and specifically refers to a high-performance environmental protection concrete and a preparation method thereof. Background Art

[0002] Traditional concrete mainly relies on cement as a gelling material in engineering applications. However, cement production is accompanied by high energy consumption and high carbon emissions. The excessive cement consumption per unit volume of concrete makes it difficult to control carbon emissions. At the same time, industrial solid wastes such as fly ash and slag powder are not fully utilized, resulting in waste of resources. In addition, the number of freeze-thaw cycles of traditional concrete is relatively low, and it is prone to cracking or spalling in cold regions or complex environments, affecting the service life of the structure. Moreover, there are also problems in the balance between the water-binder ratio and strength in its construction performance. In the prior art, although the scheme of adding mineral admixtures to replace part of the cement has certain improvements, it is not easy to achieve an effective balance among low carbon emissions, high strength, high durability and construction performance. Therefore, the research on systematically optimized high-performance environmental protection concrete is of practical significance. Summary of the Invention

[0003] The present invention aims to solve at least to some extent the technical problems in the above technologies.

[0004] To this end, on the one hand, the present invention discloses a high-performance environmental protection concrete, which includes the following components by weight:

[0005] 300-400 parts of gelling materials, and each part of the gelling materials includes:

[0006] 150-250 parts of portland cement, 80-120 parts of granulated blast furnace slag powder, 50-80 parts of fly ash and 20-40 parts of silica fume;

[0007] 1500-1700 parts of aggregate, and each part of the aggregate includes:

[0008] 900-1100 parts of coarse aggregate, gravel or pebble with a particle size of 5-25 mm, 600-800 parts of fine aggregate and river sand or manufactured sand with a fineness modulus of 2.3-3.0;

[0009] 8-15 parts of admixtures, and each part of the admixtures includes:

[0010] 3-6 parts of polycarboxylate superplasticizer with a water reduction rate ≥ 25%, 0.1-0.3 parts of alkylbenzene sulfonate air-entraining agent with an air content controlled at 3%-5% and 5-9 parts of polypropylene fiber with a diameter of 15-25 μm and a length of 6-12 mm;

[0011] 140-160 parts of water.

[0012] In addition, the high-performance environmentally friendly concrete disclosed according to the present invention may further have the following additional technical features:

[0013] In one embodiment of the present invention, the portland cement is P·II 52.5 portland cement, the specific surface area of the granulated blast furnace slag powder is 450 - 550 m 2 / kg, the fly ash is Class F Grade II fly ash and the loss on ignition ≤ 5%, and the silica fume has a silica content ≥ 92%.

[0014] In one embodiment of the present invention, the crushing value of the crushed stone in the coarse aggregate ≤ 10%, and the content of needle-like and flaky particles ≤ 5%; the mud content of the fine aggregate ≤ 2%, and the mud lump content ≤ 0.5%.

[0015] In one embodiment of the present invention, the solid content of the polycarboxylate superplasticizer is 30% - 40%, the effective ingredient content of the alkylbenzene sulfonate air-entraining agent ≥ 90%, and the tensile strength of the polypropylene fiber ≥ 500 MPa.

[0016] In one embodiment of the present invention, the weight ratio of each component in the cementitious material is: portland cement : granulated blast furnace slag powder : fly ash : silica fume = (15 - 25) : (8 - 12) : (5 - 8) : (2 - 4).

[0017] On the other hand, the present invention discloses a method for preparing the high-performance environmentally friendly concrete as described above, comprising the following steps:

[0018] S1. Put the coarse aggregate, fine aggregate, and cementitious material into a mixer and dry mix for 30 - 60 seconds until evenly mixed;

[0019] S2. After mixing water, polycarboxylate superplasticizer, and alkylbenzene sulfonate air-entraining agent, add them to the mixer in two portions. Add 60% - 70% of the mixed liquid for the first time and stir for 60 - 90 seconds. Add the remaining mixed liquid for the second time, and at the same time add polypropylene fiber and continue to stir for 90 - 120 seconds;

[0020] S3. Pour the evenly stirred concrete mixture into a mold. After vibrating and forming, carry out initial setting and curing for 12 - 24 hours in an environment with a temperature of 20 ± 2°C and a relative humidity ≥ 95%. After demolding, transfer it to a standard curing room for curing for 28 days.

[0021] In addition, the preparation method disclosed according to the present invention may further have the following additional technical features:

[0022] In one embodiment of the present invention, the mixer in step S1 is a twin-shaft forced mixer, and the stirring speed is 80 - 120 revolutions per minute.

[0023] In one embodiment of the present invention, the polypropylene fibers need to be subjected to surface hydrophilization treatment before being added. The treating agent is an aqueous solution of silane coupling agent with a concentration of 0.5%-1%, and the treatment time is 5-10 minutes.

[0024] In one embodiment of the present invention, in step S3, a plug-type vibrator is used for vibrating and forming, and the vibration time is controlled at 20-30 seconds per point until the concrete surface shows exudation of mortar and no air bubbles overflow.

[0025] In one embodiment of the present invention, the slump of the concrete mixture is 180-220 mm, the spread is 450-550 mm, the air content is 3%-5%, the initial setting time is ≥45 minutes, and the final setting time is ≤10 hours.

[0026]

[0027]

[0028] Table 1

[0029]

[0030] Table 2

[0031] Among them, Table 1 is a performance comparison table between the embodiments and the comparative examples of the present invention, and Table 2 is a performance parameter table of the embodiments of the present invention under different curing conditions.

[0032] According to the high-performance environmental protection concrete and its preparation method disclosed by the present invention, it has beneficial effects such as low-carbon environmental protection, high strength, excellent durability, and good construction performance.

[0033] The additional content and advantages of the present invention will be given in the following description or understood through the practice of the present invention. Brief Description of the Drawings

[0034] The technical solution and beneficial effects of the present invention will become obvious and easy to understand from the following content in combination with the drawings, where:

[0035] Figure 1 is a process flow chart of the high-performance environmental protection concrete and its preparation method of the present invention. Detailed Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0037] Next, the high-performance environmental protection concrete and its preparation method disclosed by the present invention will be described with reference to the drawings.

[0038] AsFigure 1 As shown in Figure 1 , a high-performance environmentally friendly concrete, by weight, comprises the following components:

[0039] 300 - 400 parts of cementitious materials, and each part of the cementitious materials includes:

[0040] 150 - 250 parts of Portland cement, 80 - 120 parts of granulated blast furnace slag powder, 50 - 80 parts of fly ash, and 20 - 40 parts of silica fume;

[0041] 1500 - 1700 parts of aggregate, and each part of the aggregate includes:

[0042] 900 - 1100 parts of coarse aggregate, crushed stone or pebble with a particle size of 5 - 25 mm, 600 - 800 parts of fine aggregate, and river sand or manufactured sand with a fineness modulus of 2.3 - 3.0;

[0043] 8 - 15 parts of admixture, and each part of the admixture includes:

[0044] 3 - 6 parts of polycarboxylate superplasticizer with a water reduction rate ≥ 25%, 0.1 - 0.3 parts of alkylbenzene sulfonate air-entraining agent with an air content controlled at 3% - 5%, and 5 - 9 parts of polypropylene fiber with a diameter of 15 - 25 μm and a length of 6 - 12 mm;

[0045] 140 - 160 parts of water.

[0046] The Portland cement is P·II52.5 grade Portland cement, the specific surface area of the granulated blast furnace slag powder is 450 - 550 m 2 / kg, the fly ash is F-class II fly ash with a loss on ignition ≤ 5%, and the silica fume has a silica content ≥ 92%.

[0047] In the coarse aggregate, the crushing value of the crushed stone ≤ 10%, and the content of needle-like and flaky particles ≤ 5%; in the fine aggregate, the mud content ≤ 2%, and the mud lump content ≤ 0.5%.

[0048] The solid content of the polycarboxylate superplasticizer is 30% - 40%, the effective ingredient content of the alkylbenzene sulfonate air-entraining agent ≥ 90%, and the tensile strength of the polypropylene fiber ≥ 500 MPa.

[0049] The weight ratio of each component in the cementitious materials is: Portland cement: granulated blast furnace slag powder: fly ash: silica fume = (15 - 25):(8 - 12):(5 - 8):(2 - 4).

[0050] A preparation method of the high-performance environmentally friendly concrete is characterized by comprising the following steps:

[0051] S1. Put the coarse aggregate, fine aggregate, and cementitious materials into a mixer and dry mix for 30 - 60 seconds until evenly mixed;

[0052] S2. After mixing water, polycarboxylate superplasticizer, and alkylbenzene sulfonate air-entraining agent, add them to the mixer in two batches. Add 60%-70% of the mixed solution for the first time and stir for 60-90 seconds. Then add the remaining mixed solution for the second time, and at the same time add polypropylene fiber and continue to stir for 90-120 seconds;

[0053] S3. Pour the evenly stirred concrete mixture into the mold. After vibrating and forming, conduct initial setting curing in an environment with a temperature of 20±2°C and a relative humidity of ≥95% for 12-24 hours. After demolding, transfer it to the standard curing room for 28 days of curing.

[0054] In step S1, the mixer is a twin-shaft forced mixer with a stirring speed of 80-120 revolutions per minute.

[0055] In step S2, the polypropylene fiber needs to be subjected to surface hydrophilization treatment before addition. The treatment agent is an aqueous solution of silane coupling agent with a concentration of 0.5%-1%, and the treatment time is 5-10 minutes.

[0056] In step S3, an insertion vibrator is used for vibrating and forming, and the vibration time is controlled at 20-30 seconds per point until the concrete surface shows slurry and no air bubbles overflow.

[0057] The slump of the concrete mixture is 180-220mm, the spread is 450-550mm, the air content is 3%-5%, the initial setting time is ≥45 minutes, and the final setting time is ≤10 hours.

[0058] Example 1

[0059] For this high-performance environmentally friendly concrete, the weight ratio of each component in the cementitious material is 25:12:8:4.

[0060] (1) Composition of raw materials (by weight):

[0061] Cementitious material (380 parts), 250 parts of P·II 52.5 grade Portland cement, 120 parts of granulated blast furnace slag powder (specific surface area 500 m 2 / kg), 80 parts of Class F II fly ash (loss on ignition 4%), 40 parts of silica fume (SiO2 content 95%);

[0062] Aggregate (1600 parts), 1000 parts of crushed stone with a particle size of 5-25mm (crushing value 8%, needle and flake particles 4%), 600 parts of river sand with a fineness modulus of 2.6 (mud content 1.5%, mud lump content 0.3%);

[0063] Admixture (15 parts), 6 parts of polycarboxylate superplasticizer (solid content 35%, water reduction rate 30%), 0.3 parts of alkylbenzene sulfonate air-entraining agent (active ingredient 92%), 8.7 parts of polypropylene fiber (diameter 20μm, length 12mm, tensile strength 600MPa);

[0064] Water, 150 parts by weight.

[0065] (2) Preparation steps:

[0066] Dry mixing: Put crushed stone, river sand, and cementitious materials into a double-horizontal-shaft forced mixer (rotation speed: 100 revolutions per minute) and dry mix for 45 seconds until homogeneous.

[0067] Wet material injection: After mixing water, water reducer, and air-entraining agent, first add 65% of the mixture and stir for 70 seconds, then add the remaining 35% of the mixture and polypropylene fibers treated with 0.8% aqueous solution of silane coupling agent for 10 minutes, and continue to stir for 100 seconds.

[0068] Molding and curing: Pour the mixture (slump: 200 mm, air content: 4.2%) into a mold, vibrate with an inserted vibrator for 25 seconds per point until bleeding and no bubbles appear, and cure for 18 hours under the initial setting condition at 20°C and 98% humidity. After demolding, cure under standard conditions for 28 days.

[0069] (3) Performance testing:

[0070] The 28-day compressive strength is 65 MPa, the freeze-thaw cycle resistance is 350 times, the CO2 emission per unit volume is 75 kg / m 3 , the shrinkage rate is 350×10 -6 , and the chloride ion penetration coefficient is 800 C.

[0071] Example 2

[0072] For this high-performance environmentally friendly concrete, the weight ratio of each component in the cementitious material is 20:10:6:4.

[0073] (1) Raw material composition (by weight):

[0074] Cementitious material (350 parts by weight), 200 parts of P·II 52.5 grade portland cement, 100 parts of granulated blast furnace slag powder (specific surface area: 480 m 2 / kg), 70 parts of Class F II fly ash (loss on ignition: 3%), 30 parts of silica fume (SiO2 content: 93%);

[0075] Aggregate (1650 parts by weight), 950 parts of pebbles with a particle size of 5 - 20 mm (crushing value: 9%, needle-like and flaky particles: 3%), 700 parts of manufactured sand with a fineness modulus of 2.8 (mud content: 1.8%, mud lump content: 0.4%);

[0076] Admixture (12 parts by weight), 5 parts of polycarboxylate-based water reducer (solid content: 32%, water reduction rate: 28%), 0.2 parts of alkylbenzene sulfonate air-entraining agent (active ingredient: 91%), 6.8 parts of polypropylene fiber (diameter: 18 μm, length: 8 mm, tensile strength: 550 MPa);

[0077] Water, 145 parts by weight.

[0078] (2) Preparation steps:

[0079] Dry mixing, the mixer rotates at 90 revolutions per minute and dry mixes for 50 seconds;

[0080] Wet material is injected in portions. First, 70% of the mixture is added and stirred for 80 seconds. Then, the remaining mixture and fibers treated with 0.6% silane coupling agent for 8 minutes are added and stirred for 110 seconds;

[0081] Molding and curing, the mixture (slump 190mm, air content 3.8%) is steam-cured for 3 days (temperature 60°C, humidity 95%), and after demolding, it is cured under standard conditions until 28 days.

[0082] (3) Performance testing:

[0083] The 3-day compressive strength is 45MPa, the 28-day compressive strength is 62MPa, the freeze-thaw cycle resistance is 320 times, the CO2 emission per unit volume is 70kg / m 3 , and the carbonation depth is 4mm.

[0084] Example 3

[0085] For this high-performance environmentally friendly concrete, the weight ratio of each component in the cementitious material is 15:8:5:2.

[0086] (1) Raw material composition (by weight):

[0087] Cementitious material (400 parts), 150 parts of P·II 52.5 grade Portland cement, 80 parts of granulated blast furnace slag powder (specific surface area 550m 2 / kg), 50 parts of Class F II fly ash (loss on ignition 5%), 20 parts of silica fume (SiO2 content 92%);

[0088] Aggregate (1550 parts), 1100 parts of crushed stone with a particle size of 10 - 25mm (crushing value 10%, needle-like and flaky particles 5%), 450 parts of river sand with a fineness modulus of 2.3 (mud content 2%, mud lump content 0.5%);

[0089] Admixture (8 parts), 3 parts of polycarboxylate superplasticizer (solid content 40%, water reduction rate 25%), 0.1 part of alkylbenzene sulfonate air-entraining agent (active ingredient 90%), 5 parts of polypropylene fiber (diameter 25μm, length 6mm, tensile strength 500MPa);

[0090] Water, 160 parts by weight.

[0091] (2) Preparation steps:

[0092] Dry mixing, the mixer rotates at 120 revolutions per minute and dry mixes for 30 seconds;

[0093] Wet material dispensing: First, add 60% of the mixed liquid and stir for 90 seconds. Then, add the remaining mixed liquid and the fibers treated with 1% silane coupling agent for 5 minutes, and stir for 120 seconds.

[0094] Molding and curing: The mixture (slump 210mm, air content 4.5%) is naturally cured for 7 days (temperature 25°C, humidity 85%), and then transferred to a standard curing room until 28 days.

[0095] (3) Performance testing:

[0096] The 7-day compressive strength is 45MPa, the 28-day compressive strength is 68MPa, the freeze-thaw cycle resistance is 380 times, and the CO2 emission per unit volume is 80kg / m 3 with a shrinkage rate of 450×10 -6 .

[0097] Comparative example 1 (conventional concrete)

[0098] Its raw material composition only contains 450 parts of portland cement, 1600 parts of aggregate (the same as in Example 1), and 180 parts of water, without mineral admixtures and fibers.

[0099] Its preparation steps include: conventional single-step water addition and stirring, with a slump of 180mm and an air content of 2.5%.

[0100] In terms of its performance comparison, the main data are a 28-day compressive strength of 55MPa, a freeze-thaw cycle resistance of 200 times, and a CO2 emission of 120kg / m 3 , which is significantly lower than that of the example of the present invention.

[0101] Comparative example 2 (without adding polypropylene fibers)

[0102] Its raw material composition is the same as that of Example 1, only omitting polypropylene fibers, and the total weight of the admixtures is adjusted to 6.3 parts (6 parts of water reducer + 0.3 parts of air-entraining agent).

[0103] In terms of its performance comparison, the main data are a freeze-thaw cycle resistance of 280 times and a shrinkage rate of 420×10 -6 , which is lower than that of Example 1, verifying the improvement effect of fibers on durability.

[0104] In summary, according to the high-performance environmental protection concrete and its preparation method disclosed by the present invention, it has beneficial effects such as low-carbon environmental protection, high strength, excellent durability, and good construction performance.

[0105] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-performance environmentally friendly concrete, characterized in that: By weight, it includes the following components: 300-400 parts of gelling material, each part of the gelling material comprises: 150-250 parts of Portland cement, 80-120 parts of granulated blast furnace slag powder, 50-80 parts of fly ash and 20-40 parts of silica fume; 1500-1700 parts of aggregate, each part of the aggregate includes: 900-1100 parts of coarse aggregate, crushed stone or pebbles with a particle size of 5-25mm, 600-800 parts of fine aggregate and river sand or machine-made sand with a fineness modulus of 2.3-3.0; 8-15 parts of admixture, each part of the admixture includes: 3-6 parts of polycarboxylic acid water reducing agent with a water reducing rate of ≥25%, 0.1-0.3 parts of alkylbenzene sulfonate air entraining agent with an air content controlled at 3%-5%, and 5-9 parts of polypropylene fiber with a diameter of 15-25μm and a length of 6-12mm; 140-160 parts of water.

2. The high performance environmentally friendly concrete according to claim 1, characterized in that: The silicate cement is P·II52.5 grade silicate cement, and the specific surface area of ​​the granulated blast furnace slag powder is 450-550m 2 / kg, the fly ash is Class F, Grade II fly ash with a loss on ignition ≤5%, and the silicon dioxide content of the silica ash is ≥92%.

3. The high performance environmentally friendly concrete according to claim 1, characterized in that: The crushing value of the crushed stone in the coarse aggregate is ≤10%, and the content of needle-shaped particles is ≤5%; the mud content of the fine aggregate is ≤2%, and the mud block content is ≤0.5%.

4. The high performance environmentally friendly concrete according to claim 1, characterized in that: The solid content of the polycarboxylic acid water reducer is 30%-40%, the effective component content of the alkylbenzene sulfonate air entraining agent is ≥90%, and the tensile strength of the polypropylene fiber is ≥500MPa.

5. The high performance environmentally friendly concrete according to any one of claims 1 to 4, characterized in that: The weight ratio of each component in the cementitious material is: silicate cement: granulated blast furnace slag powder: fly ash: silica fume = (15-25): (8-12): (5-8): (2-4).

6. A method for preparing high-performance environmentally friendly concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Put coarse aggregate, fine aggregate and cementitious material into a mixer and dry mix for 30-60 seconds until they are evenly mixed; S2, after mixing water, polycarboxylic acid water reducing agent and alkylbenzene sulfonate air entraining agent, add them into the mixer twice, add 60%-70% of the mixture for the first time, stir for 60-90 seconds, add the remaining mixture for the second time, add polypropylene fiber at the same time, and continue stirring for 90-120 seconds; S3. Pour the evenly mixed concrete mixture into the mold, vibrate it into shape, and then carry out initial setting and curing for 12-24 hours in an environment with a temperature of 20±2℃ and a relative humidity of ≥95%. After demolding, transfer it to a standard curing room for curing for 28 days.

7. The preparation method according to claim 6, characterized in that: The mixer in step S1 is a twin-shaft forced mixer, and the stirring speed is 80-120 rpm.

8. The preparation method according to claim 6, characterized in that: The polypropylene fiber in step S2 needs to be subjected to surface hydrophilic treatment before being added, and the treatment agent is a silane coupling agent aqueous solution with a concentration of 0.5%-1%, and the treatment time is 5-10 minutes.

9. The preparation method according to claim 6, characterized in that: In step S3, the vibrating molding is performed using an inserted vibrating rod, and the vibrating time is controlled at 20-30 seconds / point until the concrete surface is slurry and no bubbles overflow.

10. The preparation method according to claim 6, characterized in that: The concrete mixture has a slump of 180-220 mm, an expansion of 450-550 mm, an air content of 3%-5%, an initial setting time of ≥45 minutes, and a final setting time of ≤10 hours.

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