Low-alkali solid waste cementing material-based plant-growing concrete and preparation method thereof

Abstract

The invention discloses low-alkali solid waste cementing material-based plant-growing concrete and a preparation method thereof. The vegetation concrete comprises a base layer framework and a surface layer material laid on the framework. Wherein the base layer framework is prepared from the following raw material components in parts by weight: 160 to 200 parts of low-alkali solid waste cement, 15 to 25 parts of phosphogypsum, 1380 to 2100 parts of mineralized concrete recycled aggregate, 62 to 102 parts of mineral admixture and 60 to 90 parts of mixing water. The surface layer material comprises the following raw material components: 1-5% of sodium alginate, 1-10% of calcium superphosphate, 1-10% of urea and the balance of soil. The mineralized concrete recycled aggregate is prepared by the following steps: soaking the concrete recycled aggregate in a diammonium hydrogen phosphate solution, and separating out the aggregate after soaking is completed, thereby obtaining the mineralized concrete recycled aggregate. According to the plant-growing concrete, alkalinity in concrete pores can be remarkably reduced, and the plant-growing concrete has stable later strength and good plant germination rate.

Description

Technical Field

[0001] The invention relates to the technical field of concrete material preparation, and in particular to a low-alkali solid waste cementitious material-based bioremediation concrete and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] With the continuous development of society, building an ecological civilization has become an inevitable trend. At the same time, extreme high temperature events in some areas have become more frequent and stronger, extreme heavy precipitation events have increased, and the climate risk index has shown an upward trend. Therefore, based on extreme environmental problems and ecological construction requirements, ecological slope protection technology has received increasing attention.

[0004] Traditional slope protection has problems such as large resource consumption, low water pollutant reduction performance, poor ecological environment integration ability, and unclear ecological environment restoration effect. While vegetation concrete has excellent soil and water conservation and slope protection stability, it is not restricted by the environment and can effectively meet the development requirements of eco-friendly and soil and water stability, and has broad application prospects. However, in practical applications, the vegetation concrete prepared with ordinary Portland cement has problems such as insufficient alkali reduction effect, complex alkali reduction process and difficult construction, which have an adverse effect on plant growth. Although the vegetation concrete prepared with sulphoaluminate cement has lower alkalinity and is conducive to plant growth, this vegetation concrete will have unstable strength or even shrinkage in the later stage, and the cost is high, which is not conducive to engineering application. Summary of the invention

[0005] In view of the above problems, the present invention provides a new system of low-alkali solid waste cementitious material-based vegetation concrete and a preparation method thereof, which can significantly reduce the alkalinity in the pores of concrete and has stable late strength and good plant germination rate. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention discloses a low-alkali solid waste cementitious material-based bio-concrete, including a base skeleton and a surface material laid on the skeleton. Wherein: the raw materials of the base skeleton include the following components: 160-200 parts by weight of low-alkali solid waste cement, 15-25 parts of phosphogypsum, 1380-2100 parts by weight of mineralized concrete recycled aggregate, 62-102 parts by weight of mineral admixture, and 60-90 parts by weight of mixing water. The low-alkali solid waste cement includes the following components: 18-23 parts by weight of ordinary Portland cement clinker, 55-70 parts by weight of slag, 8-14 parts by weight of fly ash, and 5-12 parts by weight of desulfurized gypsum. The raw materials of the surface material include the following components: 1-5% sodium alginate, 1-10% superphosphate, 1-10% urea, and the rest is soil.

[0007] Furthermore, the mineralized concrete recycled aggregate is prepared by the following method: the recycled concrete aggregate is soaked in a diammonium hydrogen phosphate solution, and then the aggregate is separated to obtain the mineralized concrete recycled aggregate.

[0008] Further, the ratio of the recycled concrete aggregate to the diammonium hydrogen phosphate solution is 1 kg: 1-2 L. Optionally, the concentration of the diammonium hydrogen phosphate solution is 0.5-2 mol / L.

[0009] Furthermore, the soaking time is not less than 7 days. Optionally, the particle size of the recycled aggregate for concrete is 15-25 mm.

[0010] Furthermore, the mineral admixture comprises the following components: 20-30 parts by weight of silica fume, 10-25 parts by weight of steel slag, 22-37 parts by weight of slag, and 7-15 parts by weight of fly ash microbeads.

[0011] Furthermore, the raw materials of the base skeleton also include 1 to 1.6 parts by weight of a water reducer. Optionally, the water reducer includes at least one of a polycarboxylate water reducer, a naphthalene-based water reducer, a lignin sulfonate water reducer, and the like.

[0012] Furthermore, the soil includes humus, which helps to further reduce the alkalinity of the base skeleton and improve the growth environment of plants.

[0013] Secondly, the present invention discloses a method for preparing the low-alkali solid waste cementitious material-based bioremediation concrete, comprising the following steps: (1) The low-alkali solid waste cement, phosphogypsum and mineral admixture are mixed evenly, and then the mineralized concrete recycled aggregate is added and mixed evenly. After completion, the mixing water is added and mixed evenly, and the obtained slurry is poured, hardened, formed and cured to obtain the base skeleton.

[0014] (2) The raw materials of the surface layer material are mixed evenly and then laid on the base skeleton to obtain the low-alkali solid waste cementitious material-based bioremediation concrete.

[0015] Furthermore, step (1) further includes the step of adding the water reducing agent after adding the mixing water.

[0016] Furthermore, in step (2), the thickness of the surface layer material is not less than 1 cm. The appropriate thickness can be selected according to actual needs, and the present invention will not elaborate on it.

[0017] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: First, the present invention uses low-alkali solid waste cement as a cementitious material, wherein the content of calcium hydroxide produced by the hydration reaction is small, which effectively reduces the alkalinity of the concrete, and the internal pore alkalinity of the obtained vegetation concrete is not more than 9, and the cost is lower. Secondly, the present invention uses diammonium hydrogen phosphate to mineralize the recycled aggregate of the concrete, thereby improving the density of the vegetation concrete and improving the pore environment for plant growth. This is because diammonium hydrogen phosphate reacts with calcium ions and hydroxide ions produced by the hydration of the cementitious material to generate dense hydroxyapatite, which not only consumes the alkaline hydration products, but also helps to reduce the precipitation of alkaline hydration products in the vegetation concrete. At the same time, the mechanical strength of the recycled aggregate and the vegetation concrete is improved. Since the hydration products of the vegetation concrete of the present invention are all highly stable components, the phenomenon of unstable strength or even shrinkage during service is well avoided. Thirdly, the vegetation concrete of the present invention contains phosphogypsum, and the acidic substances contained in it can undergo acid-base neutralization with the alkaline substances in the vegetation concrete, thereby reducing the alkalinity of the vegetation concrete. Finally, the present invention also adopts a method of combining a base skeleton and a surface material laid on the skeleton, wherein the sodium alginate not only enables the surface material to have a good water retention capacity, but also, if alkaline substances such as calcium ions and hydroxides diffuse out of the base skeleton during service, the sodium alginate can realize the solidification of calcium ions by means of its cross-linking reaction with calcium ions, and the hydroxide ions can be neutralized by the acidic environment provided by humus. In addition, the superphosphate and urea can also react with calcium ions and hydroxides, thereby consuming alkaline substances, reducing the adverse effects on the surface material, and can also provide necessary nutrients such as N and P for plant growth, further improving the vegetation performance of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 The germination and growth of plants on the vegetation concrete prepared in Example 1 below; Figure 2 The germination and growth of plants on the vegetation concrete prepared in Example 5 below; Figure 3 The germination and growth of plants on the vegetation concrete prepared in Example 7 below. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0021] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions.

[0022] In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention. The technical solution of the present invention is further described in conjunction with the accompanying drawings and specific embodiments.

[0023] Example 1 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg), 15 parts by weight of mineralized concrete recycled aggregate, 1380 parts by weight of mineral admixture, 62 parts by weight of mixing water. The mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 0.5 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1L and then soaked for 12 days to obtain the product. The mineral admixture includes the following components: 20 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 10 parts by weight, slag powder (specific surface area 400m 2 / kg) 22 parts by weight, fly ash microspheres (fineness 5μm) 10 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 ordinary Portland cement clinker 20 parts by weight, slag powder (specific surface area 400m 2 / kg) 62 parts by weight, fly ash 10 parts by weight, desulfurized gypsum powder (specific surface area 400m 2 / kg) 8 parts by weight.

[0024] (2) Prepare the raw materials for the surface layer in the following mass percentages: 1% sodium alginate, 2% superphosphate, 2% urea, and the rest humus soil (pH=5.31).

[0025] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and stir evenly, pour the obtained slurry and harden it into shape, and then naturally cure it for 28 days to obtain a base skeleton.

[0026] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0027] 1. Tall fescue was planted on the vegetation concrete prepared in this embodiment to test the plant growth. The results are as follows: Figure 1 As shown, it can be seen that the germination rate of plants is high and the growth is good, indicating that the vegetation concrete is very suitable for plant growth.

[0028] 2. According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0029] Example 2 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg) 20 parts by weight, 1650 parts by weight of mineralized concrete recycled aggregate, 80 parts by weight of mineral admixture, and 70 parts by weight of mixing water. Wherein: the mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471kg / m 3 , compact packing density 1439kg / m 3 ) and 1 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1L and then soaked for 10 days to obtain the product. The mineral admixture includes the following components: 25 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 15 parts by weight, slag powder (specific surface area 400m 2 / kg) 30 parts by weight, fly ash microspheres (fineness 5μm) 13 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 ordinary Portland cement clinker 23 parts by weight, slag powder (specific surface area 400m 2 / kg) 70 parts by weight, fly ash 14 parts by weight, desulfurized gypsum (specific surface area 400m 2 / kg ) 12 parts by weight.

[0030] (2) Prepare the raw materials for the surface layer in the following mass percentages: 2% sodium alginate, 2% superphosphate, 2% urea, and the rest humus soil (pH=5.31).

[0031] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and 1.0 parts by weight of polycarboxylate water reducer and stir evenly. Cast the obtained slurry and harden it into shape, then naturally cure it for 28 days to obtain a base skeleton.

[0032] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0033] According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0034] Example 3 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg) 25 parts by weight, 2100 parts by weight of mineralized concrete recycled aggregate, 102 parts by weight of mineral admixture, and 90 parts by weight of mixing water. Wherein: the mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 2 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:2L and then soaked for 8 days to obtain the product. The mineral admixture includes the following components: 30 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 25 parts by weight, slag powder (specific surface area 400m 2 / kg) 37 parts by weight, fly ash microspheres (fineness 5μm) 15 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 parts by weight of ordinary Portland cement clinker, 18 parts by weight of slag powder (specific surface area 400m 2 / kg) 55 parts by weight, fly ash 8 parts by weight, desulfurized gypsum 5 (specific surface area 400m 2 / kg) parts by weight.

[0035] (2) Prepare the raw materials for the surface layer in the following mass percentages: 2% sodium alginate, 1% superphosphate, 1% urea, and the rest humus soil (pH=5.31).

[0036] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and 1.6 parts by weight of polycarboxylate water reducer and stir evenly. Cast the obtained slurry and harden it into shape, then naturally cure it for 28 days to obtain a base skeleton.

[0037] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0038] According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0039] Example 4 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 200 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg) 20 parts by weight, 1700 parts by weight of mineralized concrete recycled aggregate, 85 parts by weight of mineral admixture, and 85 parts by weight of mixing water. The mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 2 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1.5L and then soaked for 7 days to obtain the product. The mineral admixture includes the following components: 25 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 20 parts by weight, slag powder (specific surface area 400m 2 / kg) 30 parts by weight, fly ash microspheres (fineness 5μm) 7 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 parts by weight of ordinary Portland cement clinker, 21 parts by weight of slag powder (specific surface area 400m 2 / kg) 65 parts by weight, fly ash 12 parts by weight, desulfurized gypsum (specific surface area 400m 2 / kg ) 10 parts by weight.

[0040] (2) Prepare the raw materials for the surface layer in the following mass percentages: 5% sodium alginate, 10% superphosphate, 10% urea, and the rest humus soil (pH=5.31).

[0041] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and 1.5 parts by weight of sodium lignin sulfonate water reducer and stir evenly. Cast the obtained slurry and harden it into shape, then naturally cure it for 28 days to obtain a base skeleton.

[0042] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 1 cm to obtain the vegetation concrete.

[0043] According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0044] Example 5 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of 42.5 ordinary Portland cement, phosphogypsum (specific surface area 452m 2 / kg), 15 parts by weight of mineralized concrete recycled aggregate, 1380 parts by weight of mineral admixture, 62 parts by weight of mixing water. The mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 0.5 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1L and then soaked for 12 days to obtain the product. The mineral admixture includes the following components: 20 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 10 parts by weight, slag powder (specific surface area 400m2 / kg) 22 parts by weight, fly ash microbeads (fineness 5μm) 10 parts by weight.

[0045] (2) Prepare the raw materials for the surface layer in the following mass percentages: 1% sodium alginate, 2% superphosphate, 2% urea, and the rest humus soil (pH=5.31).

[0046] (3) First, stir the 42.5 ordinary Portland cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and stir evenly, pour the obtained slurry, harden it into shape, and then naturally cure it for 28 days to obtain a base skeleton.

[0047] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0048] 1. Tall fescue was planted on the vegetation concrete prepared in this embodiment to test the plant growth. The results are as follows: Figure 2 As shown, it can be seen that the germination rate and growth of the plants are significantly lower than those in Example 1. The main reason is that the pH of the vegetation concrete prepared in this example is higher than that in Example 1, which is not suitable for plant growth.

[0049] 2. According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0050] Example 6 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg) 15 parts by weight, 1380 parts by weight of recycled aggregate, 62 parts by weight of mineral admixture, and 60 parts by weight of mixing water. Among them: the particle size distribution of the recycled aggregate in concrete is between 15 and 25 mm, the crushing index value is ≤18%, and the apparent density is 2471 kg / m 3 , compact packing density 1439kg / m 3 The mineral admixture includes the following components: 20 parts by weight of silica fume (fineness 0.1 μm), steel slag (specific surface area 400 m 2 / kg) 10 parts by weight, slag powder (specific surface area 400m 2 / kg) 22 parts by weight, fly ash microspheres (fineness 5μm) 10 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 ordinary Portland cement clinker 20 parts by weight, slag powder (specific surface area 400m 2 / kg) 62 parts by weight, fly ash 10 parts by weight, desulfurized gypsum powder (specific surface area 400m 2 / kg) 8 parts by weight.

[0051] (2) Prepare the raw materials for the surface layer in the following mass percentages: 1% sodium alginate, 2% superphosphate, 2% urea, and the rest humus soil (pH=5.31).

[0052] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, and then add the recycled aggregate in concrete and stir for 120 seconds. After completion, add the mixing water and stir evenly, pour the obtained slurry, harden it into shape, and then naturally cure it for 28 days to obtain a base skeleton.

[0053] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0054] According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0055] Example 7 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg), 15 parts by weight of mineralized concrete recycled aggregate, 1380 parts by weight of mineral admixture, 62 parts by weight of mixing water. The mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 0.5 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1L and then soaked for 12 days to obtain the product. The mineral admixture includes the following components: 20 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 10 parts by weight, slag powder (specific surface area 400m 2 / kg) 22 parts by weight, fly ash microspheres (fineness 5μm) 10 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 ordinary Portland cement clinker 20 parts by weight, slag powder (specific surface area 400m 2 / kg) 62 parts by weight, fly ash 10 parts by weight, desulfurized gypsum powder (specific surface area 400m 2 / kg) 8 parts by weight.

[0056] (2) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, and then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and stir evenly, pour the obtained slurry and harden it into shape, and then naturally cure it for 28 days to obtain a base skeleton.

[0057] (3) Spread humus soil (pH=5.31) on the base skeleton with a thickness of 2 cm to obtain vegetation concrete.

[0058] 1. Tall fescue was planted on the vegetation concrete prepared in this embodiment to test the plant growth. The results are as follows: Figure 3 As shown, it can be seen that the germination rate and growth of the plants are significantly lower than those in Example 1. The main reason is that the pH of the vegetation concrete prepared in this example is too high, which seriously affects the growth of the plants.

[0059] 2. According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0060] Example 8 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of sulphoaluminate cement, phosphogypsum (specific surface area 452m 2 / kg) 20 parts by weight, 1650 parts by weight of mineralized concrete recycled aggregate, 80 parts by weight of mineral admixture, and 70 parts by weight of mixing water. Wherein: the mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471kg / m 3 , compact packing density 1439kg / m 3 ) and 1 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:1L and then soaked for 10 days to obtain the product. The mineral admixture includes the following components: 25 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 15 parts by weight, slag powder (specific surface area 400m 2 / kg) 30 parts by weight, fly ash microbeads (fineness 5μm) 13 parts by weight.

[0061] (2) Prepare the raw materials for the surface layer in the following mass percentages: 2% sodium alginate, 2% superphosphate, 2% urea, and the rest humus soil (pH=5.31).

[0062] (3) Stir the sulphoaluminate cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and 1.0 parts by weight of polycarboxylate water reducer and stir evenly. Cast the obtained slurry and harden it into shape, then naturally cure it for 28 days to obtain a base skeleton.

[0063] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0064] According to JC / T 2557-2020 "Vegetative Concrete", the 28d compressive strength and pH value of the base skeleton prepared in this embodiment were tested, and the results are shown in the following table.

[0065] Example 9 A method for preparing low-alkali solid waste cementitious material-based bioremediation concrete comprises the following steps: (1) Take the following raw materials for the base skeleton: 160 parts by weight of low-alkali solid waste cement, phosphogypsum (specific surface area 452m 2 / kg) 25 parts by weight, 2100 parts by weight of mineralized concrete recycled aggregate, 102 parts by weight of mineral admixture, and 90 parts by weight of mixing water. Wherein: the mineralized concrete recycled aggregate is prepared by the following method: concrete recycled aggregate (particle size distribution between 15 and 25 mm, crushing index value ≤18%, apparent density 2471 kg / m 3 , compact packing density 1439kg / m 3 ) and 2 mol / L diammonium hydrogen phosphate solution in a ratio of 1kg:2L and then soaked for 8 days to obtain the product. The mineral admixture includes the following components: 30 parts by weight of silica fume (fineness 0.1μm), steel slag (specific surface area 400m 2 / kg) 25 parts by weight, slag powder (specific surface area 400m 2 / kg) 37 parts by weight, fly ash microspheres (fineness 5μm) 15 parts by weight. The low-alkali solid waste cement includes the following components: 42.5 parts by weight of ordinary Portland cement clinker, 18 parts by weight of slag powder (specific surface area 400m2 / kg) 55 parts by weight, fly ash 8 parts by weight, desulfurized gypsum 5 (specific surface area 400m 2 / kg) parts by weight.

[0066] (2) Prepare the raw materials for the surface layer in the following mass percentages: 2% sodium alginate, 1% superphosphate, 1% urea, and the rest neutral brown soil (pH=7.03).

[0067] (3) First, stir the low-alkali solid waste cement, phosphogypsum and mineral admixture in step (1) for 90 seconds, then add the mineralized concrete recycled aggregate and stir for 120 seconds. After completion, add the mixing water and 1.6 parts by weight of polycarboxylate water reducer and stir evenly. Cast the obtained slurry and harden it into shape, then naturally cure it for 28 days to obtain a base skeleton.

[0068] (4) The raw materials of the surface layer material in step (2) are mixed evenly and then laid on the base skeleton with a laying thickness of 2 cm to obtain the vegetation concrete.

[0069] According to JC / T 2557-2020 "Vegetative Concrete", the pH value of the vegetative concrete prepared in this embodiment is tested to be 9.85, which obviously exceeds the pH range suitable for plant growth.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-alkali solid waste cementitious material-based bioremediation concrete, characterized in that: It includes a base frame and a surface material laid on the frame; wherein: The raw materials of the base skeleton include the following components: 160-200 parts by weight of low-alkali solid waste cement, 15-25 parts by weight of phosphogypsum, 1380-2100 parts by weight of mineralized concrete recycled aggregate, 62-102 parts by weight of mineral admixture, and 60-90 parts by weight of mixing water; the low-alkali solid waste cement includes the following components: 18-23 parts by weight of ordinary Portland cement clinker, 55-70 parts by weight of slag, 8-14 parts by weight of fly ash, and 5-12 parts by weight of desulfurized gypsum; The raw materials of the surface layer material include the following components: 1-5% sodium alginate, 1-10% superphosphate, 1-10% urea, and the rest is soil.

2. The low-alkali solid waste cementitious material-based bioremediation concrete according to claim 1, characterized in that: The mineralized concrete recycled aggregate is prepared by the following method: the recycled concrete aggregate is immersed in a diammonium hydrogen phosphate solution, and the aggregate is separated after the soaking.

3. The low-alkali solid waste cementitious material-based bioremediation concrete according to claim 2, characterized in that: The ratio of the recycled concrete aggregate to the diammonium hydrogen phosphate solution is 1 kg: 1-2 L; optionally, the concentration of the diammonium hydrogen phosphate solution is 0.5-2 mol / L.

4. The low-alkali solid waste cementitious material-based bioremediation concrete according to claim 2, characterized in that: The soaking time is not less than 7 days.

5. The low-alkali solid waste cementitious material-based bioremediation concrete according to claim 2, characterized in that: The particle size of the recycled concrete aggregate is 15-25 mm.

6. The low-alkali solid waste cementitious material-based bioremediation concrete according to claim 1, characterized in that: The mineral admixture comprises the following components: 20-30 parts by weight of silica fume, 10-25 parts by weight of steel slag, 22-47 parts by weight of slag, and 7-15 parts by weight of fly ash microbeads.

7. The low-alkali solid waste cementitious material-based bioremediation concrete according to any one of claims 1 to 6, characterized in that: The raw materials of the base skeleton also include 1 to 1.6 parts by weight of a water reducer; optionally, the water reducer includes at least one of a polycarboxylic acid water reducer, a naphthalene-based water reducer, and a lignin sulfonate water reducer.

8. The low-alkali solid waste cementitious material-based bioremediation concrete according to any one of claims 1 to 6, characterized in that: The soil includes humus.

9. The method for preparing low-alkali solid waste cementitious material-based bioremediation concrete according to any one of claims 1 to 8, characterized in that: The steps include: (1) mixing the low-alkali solid waste cement, phosphogypsum and mineral admixtures uniformly, and then adding the mineralized concrete recycled aggregate and mixing uniformly; after completion, adding the mixing water and mixing uniformly, pouring the obtained slurry, hardening and shaping, and curing to obtain the base skeleton; (2) The raw materials of the surface layer material are mixed evenly and then laid on the base skeleton to obtain the low-alkali solid waste cementitious material-based bioremediation concrete.

10. The method for preparing low-alkali solid waste cementitious material-based bioremediation concrete according to claim 9, characterized in that: The thickness of the surface material is not less than 0.5 cm; optionally, step (1) also includes the step of adding the water reducing agent in the low-alkali solid waste cementitious material-based bioreinforced concrete according to claim 7 after the mixing water.

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