Low-carbon vegetative concrete cementitious material and preparation method thereof

Abstract

The application discloses a low-carbon plant-growing concrete cementing material and a preparation method thereof. The cementing material comprises the following raw materials in percentage by mass: 45-65% of mineral powder, 15-25% of fly ash, 0.5-6% of silica ash, 4-10% of high-strength sulphoaluminate cement clinker, and 5-30% of gypsum. The application uses super-sulphate cement to replace ordinary Portland cement as the plant-growing concrete cementing material, and the plant-growing concrete cementing material has the characteristics of early strength and fast hardening, can be formed under room temperature conditions, and does not need curing. The cement content is low, the plant-growing concrete is more low-carbon and environment-friendly, the problem of excessively high internal pore alkalinity of the plant-growing concrete is solved fundamentally, the plant-growing performance of the plant-growing concrete is improved, and the plant-growing concrete is more suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building engineering materials, and particularly relates to a low-carbon plant-growing concrete cementitious material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of cities, the application of concrete is increasingly wide. As the most widely used artificial building material in the world, concrete not only needs to have good building practical performance, but also needs to consider its environmental impact.

[0003] The traditional Portland cement concrete consumes a large amount of natural resources and significantly destroys the ecology. Cement production is a major industry of CO2 emission. According to the statistics, the carbon emission of producing one ton of Portland cement clinker is about one ton. At the same time, the pore solution pH value of ordinary Portland cement concrete is as high as 12-13. The excessively high pH value causes the soil of plant-growing concrete to contain a large amount of exchangeable sodium ions and hydroxide ions, resulting in soil particle dispersion and hardening after drying, which affects the growth and development of plants. Therefore, exploring low-carbon and low-alkali cementitious materials plays a significant role in the development of plant-growing concrete.

[0004] Foreign research and practice results show that the main method for reducing the pH value of plant-growing concrete cementitious material is to add active materials to consume calcium hydroxide produced in the cement hydration process or to change the cement clinker so that no or little calcium hydroxide is produced in the cement hydration process. So far, there are many patent documents about low-pH-value concrete or cementitious materials and their preparation methods. For example, Chinese patent CN107548949A discloses a low-alkalinity cementitious material for plant-growing concrete and a preparation method thereof. The material uses 20%-30% Portland cement as an auxiliary cementitious material, and the pH value of the soaking liquid after solidification is 9.0-9.5, which can provide growth conditions for plants. Chinese patent CN112876183B provides a plant-growing lightweight porous concrete and a preparation method thereof. The cementitious material is composed of slag Portland cement, water, river sand, sludge ceramic, fly ash, silica fume, acrylic emulsion and polycarboxylic acid water reducer. The pH value of the material is less than 11, and the mechanical performance required by plant-growing concrete can be met. However, an alkali reduction soaking treatment step is still needed after molding, and the low-pH-value cementitious material mainly uses geopolymer-based cement or a large amount of Portland cement as the base material. However, using these raw materials still needs a large amount of energy consumption, and the cost is high. The proportion of Portland cement is about 20-30%, which does not meet the green and environmental protection concept. SUMMARY

[0005] The present application aims to provide a low-carbon plant-growing concrete binder and a preparation method thereof. The plant-growing concrete binder has good adhesion, early strength and fast hardening characteristics, can be formed at room temperature without curing, has a low pH value to meet the normal growth of plants, has a low raw material cost, a simple preparation process, and meets the requirements of green environmental protection.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] A low-carbon plant-growing concrete binder comprises the following raw materials in mass percentage:

[0008] Mineral powder 45%-65%;

[0009] Fly ash 15%-25%;

[0010] Silica fume 0.5%-6%;

[0011] High-strength sulphoaluminate cement clinker 4%-10%;

[0012] Gypsum 5%-30%.

[0013] Preferably, the specific surface area of the high-strength sulphoaluminate cement clinker is 460 m 2 kg -1 , and the 7d compressive strength can reach 28.5MPa.

[0014] Preferably, the plant-growing concrete binder further comprises ≤3% of an additive in mass percentage.

[0015] Preferably, the additive comprises a water-reducing agent and / or a retarder.

[0016] Preferably, the water-reducing agent is a polycarboxylic acid water-reducing agent, and the retarder is sodium borate.

[0017] Preferably, the mineral powder is a mineral powder with an alkaline coefficient M0 less than 1, and the 28d activity index of the mineral powder is 103%.

[0018] Preferably, the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0019] Preferably, the fly ash is a first-grade fly ash produced by a power plant.

[0020] Preferably, the silica fume has an average particle size of 0.12µm and a loss on ignition of 3.72%-4%.

[0021] Another purpose of the present application is to provide a preparation method of the low-carbon vegetated concrete cementitious material, comprising the following steps: uniformly mixing 45%-65% of mineral powder, 15%-25% of fly ash, 5%-30% of gypsum, 4%-10% of high-strength sulphoaluminate cement clinker and 0.5%-6% of silica fume, uniformly mixing the mixture by adding water solution or additive agent according to a water-binder ratio of 0.3-0.5, and obtaining the low-carbon vegetated concrete cementitious material.

[0022] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0023] 1. The present application uses super-sulphate cement to replace ordinary Portland cement as the vegetated concrete cementitious material, which has the characteristics of early strength and fast hardening, can be formed under room temperature conditions, and does not need curing; the cement content used is low, which is more low-carbon and environmentally friendly, and can fundamentally solve the problem of excessively high internal pore alkalinity of the vegetated concrete and improve the vegetated performance of the vegetated concrete.

[0024] 2. The vegetated concrete cementitious material provided by the present application uses polycarboxylate water reducer and sodium borate retarder as additive agents, which can prolong the setting time of the cementitious material, reduce the water consumption and improve the material strength under the premise of ensuring the working performance of the cementitious material.

[0025] 3. The vegetated concrete cementitious material provided by the present application has a pH value of less than 9, a 3d flexural strength of 3.8-6MPa, a compressive strength of 25-28MPa, a 28d flexural strength of 8-11MPa, and a 28d compressive strength of 46.8-53MPa, and has good performance in all aspects.

[0026] 4. The vegetated concrete cementitious material provided by the present application has good adhesive effect, has the characteristics of early strength and fast hardening, can be formed under room temperature conditions, does not need curing, has a low pH value that can meet the normal growth of plants, has low raw material cost, has simple preparation process, and meets the requirements of green environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a process flow chart of the low-carbon vegetated concrete cementitious material;

[0028] Figure 2 It is a vegetated effect diagram of tall fescue in Example 1 and the comparative example;

[0029] Figure 3 It is a vegetated effect diagram of alfalfa in Example 1 and the comparative example.

[0030] Note: Figure 2 、 Figure 3 The left diagram in the middle is the vegetated effect of the comparative example, and the right diagram is the vegetated effect of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0032] Embodiment 1

[0033] A preparation method of a low-carbon plant-growing concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica fume: high-strength sulphoaluminate cement: gypsum = 55%: 15%: 6%: 4%: 20%.

[0034] The preparation method of the low-carbon plant-growing concrete cementitious material comprises the following steps:

[0035] (1) The required various component materials are weighed, and each cementitious material component is separately ground to a corresponding fineness, and then uniformly mixed.

[0036] The specific surface area of the mineral powder is 530 m 2 / kg, the 28d activity index is 103%, the water requirement ratio of the fly ash is 95%, the fineness is 45 μm residue on a 11% sieve, and the specific surface area is 470 m 2 / kg; the average particle size of the silica fume is 0.12 µm, the loss on ignition is 3.72%-4%, the specific surface area of the high-strength sulphoaluminate cement clinker is 460 m 2 / kg, and the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0037] (2) 30% water is added to the mixture in mass ratio, the water-binder ratio is adjusted to 0.3, and the mixture is uniformly mixed and stirred to obtain the low-carbon plant-growing concrete cementitious material.

[0038] Embodiment 2

[0039] A preparation method of a low-carbon plant-growing concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica fume: high-strength sulphoaluminate cement: gypsum = 55%: 15%: 6%: 4%: 20%.

[0040] The preparation method of the low-carbon plant-growing concrete cementitious material comprises the following steps:

[0041] (1) The required various component materials are weighed, and each cementitious material component is separately ground to a corresponding fineness, and then uniformly mixed.

[0042] The specific surface area of the mineral powder is 530 m 2 / kg, 28d activity index is 103%; fly ash water demand ratio is 95%, fineness is 45 μm residue 11%, specific surface area is 470 m 2 / kg; silica ash average particle size is 0.12 µm, loss on ignition is 3.72%-4%; high-strength sulphoaluminate cement clinker specific surface area is 460 m 2 / kg, gypsum is anhydrous gypsum, main mineral is calcium sulfate.

[0043] (2) 0.8% polycarboxylic acid water reducer, 0.5% sodium borate retarder, 30% water are added to the mixture, the water-binder ratio is adjusted to 0.30, and the low-carbon plant concrete cementitious material is obtained after uniform mixing and stirring.

[0044] Example 3

[0045] A preparation method of a low-carbon plant concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica ash: high-strength sulphoaluminate cement: gypsum = 55%: 15%: 6%: 4%: 20%.

[0046] The preparation method of the low-carbon plant concrete cementitious material comprises the following steps:

[0047] (3) The required various component materials are weighed, and each cementitious material component is separately ground to the corresponding fineness, and then uniformly mixed.

[0048] The specific surface area of the mineral powder is 530 m 2 / kg, 28d activity index is 103%; fly ash water demand ratio is 95%, fineness is 45 μm residue 11%, specific surface area is 470 m 2 / kg; silica ash average particle size is 0.12 µm, loss on ignition is 3.72%-4%; high-strength sulphoaluminate cement clinker specific surface area is 460 m 2 / kg, gypsum is anhydrous gypsum, main mineral is calcium sulfate.

[0049] (4) 40% water is added to the mixture, the water-binder ratio is adjusted to 0.4, and the low-carbon plant concrete cementitious material is obtained after uniform mixing and stirring.

[0050] Example 4

[0051] A preparation method of a low-carbon plant concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica ash: high-strength sulphoaluminate cement: gypsum = 55%: 15%: 6%: 4%: 20%.

[0052] The preparation method of the low-carbon plant concrete cementitious material comprises the following steps:

[0053] (1) The required various component materials are weighed, each cementitious material component is separately ground to the corresponding fineness, and then mixed uniformly.

[0054] The specific surface area of the mineral powder is 530 m 2 / kg, the 28d activity index is 103%, the water demand ratio of fly ash is 95%, the fineness is 45 μm sieve residue 11%, the specific surface area is 470 m 2 / kg, the average particle size of silica ash is 0.12 µm, the loss on ignition is 3.72%-4%, the specific surface area of high-strength sulphoaluminate cement clinker is 460 m 2 / kg, the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0055] (2) 1.2% of polycarboxylic acid water reducer, 1% of sodium borate retarder, and 50% of water are added to the mixture, the water-binder ratio is adjusted to 0.5, and the mixture is uniformly mixed and stirred to obtain the low-carbon plant-growing concrete cementitious material.

[0056] Example 5

[0057] A preparation method of a low-carbon plant-growing concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica ash: high-strength sulphoaluminate cement: gypsum = 50%: 25%: 2%: 6%: 17%.

[0058] The preparation method of the low-carbon plant-growing concrete cementitious material comprises the following steps:

[0059] (1) The required various component materials are weighed, each cementitious material component is separately ground to the corresponding fineness, and then mixed uniformly.

[0060] The specific surface area of the mineral powder is 530 m 2 / kg, the 28d activity index is 103%, the water demand ratio of fly ash is 95%, the fineness is 45 μm sieve residue 11%, the specific surface area is 470 m 2 / kg, the average particle size of silica ash is 0.12 µm, the loss on ignition is 3.72%-4%, the specific surface area of high-strength sulphoaluminate cement clinker is 460 m 2 / kg, the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0061] (2) 30% of water is added to the mixture, the water-binder ratio is adjusted to 0.3, and the mixture is uniformly mixed and stirred to obtain the low-carbon plant-growing concrete cementitious material.

[0062] Example 6

[0063] A preparation method of a low-carbon plant-growing concrete cementitious material, raw material ingredients in percentage by mass: mineral powder: fly ash: silica ash: high-strength sulphoaluminate cement: gypsum = 60%: 20%: 3%: 8%: 9%.

[0064] The preparation method of the low-carbon plant concrete cementitious material comprises the following steps:

[0065] (1) The required various component materials are weighed, and each cementitious material component is separately ground to the corresponding fineness and then uniformly mixed.

[0066] The specific surface area of the mineral powder is 530 m 2 / kg, the 28d activity index is 103%, the fly ash water requirement ratio is 95%, the fineness is 45 μm sieve residue 11%, and the specific surface area is 470 m 2 / kg; the average particle size of the silica fume is 0.12 µm, the loss on ignition is 3.72%-4%, the specific surface area of the high-strength sulphoaluminate cement clinker is 460 m 2 / kg, the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0067] (2) Water accounting for 30% of the mixture is added to the mixture, the water-binder ratio is adjusted to 0.3, and the mixture is uniformly mixed and stirred to obtain the low-carbon plant concrete cementitious material.

[0068] Example 7

[0069] A preparation method of a low-carbon plant concrete cementitious material, according to the mass percentage of raw material ingredients: mineral powder: fly ash: silica fume: high-strength sulphoaluminate cement: gypsum = 60%: 15%: 5%: 10%: 10%.

[0070] The preparation method of the low-carbon plant concrete cementitious material comprises the following steps:

[0071] (1) The required various component materials are weighed, and each cementitious material component is separately ground to the corresponding fineness and then uniformly mixed.

[0072] The specific surface area of the mineral powder is 530 m 2 / kg, the 28d activity index is 103%, the fly ash water requirement ratio is 95%, the fineness is 45 μm sieve residue 11%, and the specific surface area is 470 m 2 / kg; the average particle size of the silica fume is 0.12 µm, the loss on ignition is 3.72%-4%, the specific surface area of the high-strength sulphoaluminate cement clinker is 460 m 2 / kg, the gypsum is anhydrous gypsum, and the main mineral is calcium sulfate.

[0073] (2) Water accounting for 30% of the mixture is added to the mixture, the water-binder ratio is adjusted to 0.3, and the mixture is uniformly mixed and stirred to obtain the low-carbon plant concrete cementitious material.

[0074] In order to verify the advantages of the present application, the comparative example is compared with the ordinary portland cement (P042.5) and the high-strength sulphoaluminate cement of the present application, and other components and preparation methods are the same as those in Example 1. The prepared cementitious material sample is detected according to the "Cement mortar strength test method ISO method" (GB / T17671-1999) to detect 3d flexural strength, 3d compressive strength, 28d flexural strength and 28d compressive strength. The pH value is tested by solid-liquid extraction method, and the test results are shown in Table 1.

[0075] Table 1: Mechanical properties and pH value test results of the plant-growing concrete cementitious material of the present application

[0076] Product pH value 3d flexural strength 3d compressive strength 28d flexural strength 28d compressive strength Example 1 8.9 5.5 26.4 10.3 51.0 Example 2 8.9 5.9 28.0 11.0 53.2 Example 3 8.8 5.3 27.3 10.1 50.6 Example 4 8.6 4.7 26.8 9.4 50.0 Example 5 8.5 4.4 26.0 8.5 47.9 Example 6 8.4 4.0 25.6 8.2 47.2 Example 7 8.4 3.9 25.1 8.0 46.8 Comparative Example 12.6 3.7 24.3 7.1 45.9

[0077] In order to further illustrate the plant-growing effect of the present application, the low-carbon plant-growing concrete cementitious material in Example 1 and the ordinary portland cement in the comparative example are used to prepare plant-growing concrete with a water-binder ratio of 0.3, a bone glue ratio of 5 and 20-30mm single-sized aggregate. The target plants are tall fescue and alfalfa, and the plant-growing test effect diagram is shown in Figure 2 、 Figure 3 From the diagram, it can be seen that the pH value of the high-strength sulphoaluminate cement clinker of the present application can better meet the needs of plant growth compared with the ordinary portland cement.

[0078] In summary, the present application uses super-sulphate cement to replace ordinary portland cement as a plant-growing concrete cementitious material, which has the characteristics of early strength and fast hardening, can be formed at room temperature without curing; the cement content is low, which is more low-carbon and environmentally friendly, and can fundamentally solve the problem of high internal pore alkalinity of plant-growing concrete, improve the plant-growing performance of plant-growing concrete, and be more beneficial to the popularization and application of plant-growing concrete.

[0079] The above content is a further detailed description of the present application in combination with specific / preferred embodiments, and cannot be regarded as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, they can make several substitutions or modifications to the described embodiments without departing from the concept of the present application, and these substitutions or modifications shall be regarded as belonging to the protection scope of the present application.

Claims

1. A low-carbon vegetation concrete cementitious material, characterized by: The raw materials are as follows: Mineral powder 45%-65%; Fly ash 15%-25%; Silica fume 0.5%-6%; High-strength sulphoaluminate cement clinker 4%-10%; Gypsum 5%-30%; The bio-based concrete cementitious material further comprises an admixture with a mass ratio of ≤3%, wherein the admixture comprises a polycarboxylate water reducer and a sodium borate retarder.

2. The low-carbon vegetation concrete cementitious material according to claim 1, characterized in that: The specific surface area of ​​the high-strength sulphoaluminate cement clinker is 460 m 2 •kg -1 , the 7d compressive strength can reach 28.5MPa.

3. The low-carbon vegetation concrete cementitious material according to claim 1, characterized in that: The mineral powder has a basicity coefficient M0 of less than 1, and a 28d activity index of 103%.

4. The low-carbon vegetation concrete cementitious material according to claim 1, characterized in that: The gypsum is anhydrous gypsum.

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