A kind of planted porous concrete and preparation method thereof

Abstract

The invention discloses a porous concrete for planting, comprising a skeleton concrete and a filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 190-200 parts of silicate cement, 18-28 parts of fly ash, 1380-1400 parts of coarse aggregate, 70-90 parts of fertilizer particles, 6-8 parts of reinforcing agent, 94-95 parts of water, and 1.3-1.5 parts of polycarboxylate high-efficiency water reducing agent. By pouring the filler into the skeleton concrete, the prepared concrete has high strength, low alkalinity, excellent water and fertilizer retention performance, and good planting property.

Description

Technical Field

[0001] The invention relates to the technical field of ecological concrete, in particular to a kind of ecological porous concrete and a preparation method thereof. Background Art

[0002] Vegetative porous concrete uses porous concrete as the skeleton. Some soil and nutrient matrix are filled into the gaps between the aggregates of the porous concrete, and a layer of soil is covered on the surface of the porous concrete. At the same time, plant seeds are mixed in the soil. After a period of maintenance, the plants germinate and grow, and the roots of the plants extend inside the porous concrete, eventually forming a slope protection material with certain strength and good permeability. It can not only achieve the infiltration and storage of rainwater runoff, but also absorb and purify pollutants, and promote the restoration of slope vegetation, combining protection and ecology.

[0003] A lot of research has been done on vegetation concrete in the prior art. Among them, the formula of water-retaining and fertilizer-retaining vegetation cement-based materials developed by Li Laibo in his paper "Preparation and Performance Research of Water-Retaining and Fertilizer-Retaining Vegetation Cement-Based Materials" includes: sulphoaluminate cement, water-absorbing resin, inorganic porous material, urea, coarse aggregate, water reducer, mixing water. The addition of water-absorbing resin and urea to cement is to increase the water-retaining and fertilizer-retaining properties of vegetation concrete. This method can indeed greatly increase the vegetation performance of vegetation cement-based materials, but there are also certain problems: First, directly adding urea to the raw materials may cause the loss of fertilizer components during the cement hydration process and cannot be fully utilized by plants. Second, the large-scale use of urea and water-absorbing resin will affect the bonding strength of cement, and ultimately affect the compressive strength of cement-based materials. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a vegetative porous concrete to address the deficiencies of the prior art. Filling materials are poured into the skeleton concrete to prepare concrete with high strength, low alkalinity, excellent water and fertilizer retention properties, and good vegetative properties.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A kind of planted porous concrete comprises skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 190-200 parts of silicate cement, 18-28 parts of fly ash, 1380-1400 parts of coarse aggregate, 70-90 parts of fertilizer particles, 6-8 parts of reinforcing agent, 94-95 parts of water, and 1.3-1.5 parts of polycarboxylic acid high-efficiency water reducing agent.

[0007] Furthermore, the fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1:2-3:0.3, water is added and stirred evenly, and the mixture is extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm.

[0008] Furthermore, the binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring, heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of corn starch, polyvinyl alcohol and glycerol is 5:4:0.5-1.

[0009] Furthermore, the voids in the skeleton concrete are filled with fillers, and the fillers are prepared by the following steps:

[0010] Dissolve polyvinyl alcohol in hot water to prepare a 2wt% solution, add carboxymethyl chitosan, sodium alginate and organic matter and stir evenly, dissolve calcium chloride and boric acid in an appropriate amount of water to form a crosslinker solution, and stir the above two solutions evenly. The weight ratio of polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 2-3:3:4-5:8:4:1.

[0011] Furthermore, the organic matter is prepared by mixing and crushing humic acid, organic fertilizer and plant fiber in a weight ratio of 2:1:1.

[0012] Furthermore, the reinforcing agent is a mixture of polyvinyl acetate emulsion, calcium carbonate whisker and montmorillonite in a weight ratio of 1:1:1, and the calcium carbonate whisker has a length of 20-30 μm and a diameter of 0.5-2 μm.

[0013] A method for preparing a planted porous concrete comprises the following steps:

[0014] (1) Mix coarse aggregate, fertilizer granules and 50% water and stir for 1.5 minutes;

[0015] (2) Add 50% Portland cement and fly ash and continue stirring for 2 minutes;

[0016] (3) Then add the remaining raw materials and mix for 2 minutes. Fill the mold with the mixture in three layers. Each time a layer is filled, use a stick to tamp 20 times, then vibrate mechanically for 20 seconds, and apply 0.5Mpa pressure to compact. Curing for 7 days, skeleton concrete is obtained;

[0017] (4) The filling material is poured into the gaps and surface of the skeleton concrete by pressure grouting and then cured for 21 days to obtain the vegetated porous concrete.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present application discloses a kind of porous concrete for vegetation. Filling material is poured into the skeleton concrete, which can not only reduce alkali, but also has good water and fertilizer retention effects. The 28d compressive strength is 19-21.5MPa, the pH value is about 8.0, the water absorption and water retention properties are high, and the germination rate of ryegrass planted in the vegetation test can reach 96-97%.

[0020] 2. The present application prepares vegetative porous concrete, and the coarse aggregate is not graded, so there are a large number of connected holes in the prepared concrete. In order to improve the water and fertilizer retention performance of the vegetative concrete, reduce the alkalinity, and at the same time not affect the bonding strength of the aggregate and cement interface, the present application injects filler into the gaps of the skeleton concrete after curing for 7 days. The filler is a multi-network gel system formed by calcium chloride and boric acid as cross-linking agents, sodium alginate, carboxymethyl chitosan and polyvinyl alcohol, and has strong water absorption and water retention properties; wherein the organic matter mixed with humic acid, organic fertilizer and plant fiber is filled in the gel system. On the one hand, the carboxyl group and humic acid in the gel system can play a role in reducing alkali and improving the alkaline environment in the concrete voids. On the other hand, the organic matter can provide nutrition for plant growth, and the filler can play a role in retaining water and fertilizer, thereby increasing the erosion resistance and vegetative properties of the concrete.

[0021] 3. The strength of concrete depends on the compressive strength of aggregates and the bonding strength of the transition interface between aggregates and cement. In order to increase the interfacial bonding strength, reinforcing agents are added: a mixture of calcium carbonate whiskers, montmorillonite and polyvinyl acetate emulsion. Montmorillonite improves the microstructure of cement slurry, increases density, and thus enhances toughness; calcium carbonate whiskers can inhibit the generation and development of cracks in the cement matrix, improve the toughness of the interface, and have a synergistic toughening effect with montmorillonite; and a small amount of vinyl acetate emulsion can not only increase the dispersibility of calcium carbonate whiskers in the binder, but also play a role in reducing alkali and strengthening the structure.

[0022] 4. In order to further increase the vegetation performance of concrete, a small amount of fertilizer granules is added to the concrete. The fertilizer granules are slow-release fertilizers extruded from urea and biochar as raw materials and starch and polyvinyl alcohol as binders. A small amount of water is added during the preparation process, which can allow some urea molecules to be adsorbed in the biochar, increasing the slow-release effect. The fertilizer granules can further increase the fertilizer-increasing and fertilizer-retaining effects of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The water retention performance test curves of Examples 1-4 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific implementation modes.

[0025] Example 1

[0026] A kind of planted porous concrete includes skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 190 parts of 42.5 silicate cement, 28 parts of fly ash, 1380 parts of coarse aggregate, 90 parts of fertilizer particles, 6 parts of reinforcing agent, 94 parts of water, and 1.3 parts of polycarboxylic acid high-efficiency water reducing agent.

[0027] The fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1::0.3, 20% water (total amount of urea, biochar and binder) is added and stirred evenly, and the mixture is extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm.

[0028] The binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring (the mass fraction of the solute is 10%), heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of the corn starch, polyvinyl alcohol and glycerol is 5:4:0.5.

[0029] The voids in the skeleton concrete are filled with fillers, which are prepared by the following steps: polyvinyl alcohol is dissolved in hot water to form a 2wt% solution, carboxymethyl chitosan, sodium alginate and organic matter are added and stirred evenly, calcium chloride and boric acid are dissolved in an appropriate amount of water to form a crosslinking agent solution, and the two solutions are stirred evenly, the weight ratio of the polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 2:3:5:8:4:1, and the amount of the filler is 30% of the dry weight of the skeleton concrete after curing for 7 days.

[0030] The organic matter is humic acid, organic fertilizer and plant fiber mixed and crushed in a weight ratio of 2:1:1. The organic fertilizer is purchased from the market and the plant fiber is straw fiber. The reinforcing agent is polyvinyl acetate emulsion, calcium carbonate whisker and montmorillonite mixed in a weight ratio of 1:1:1. The length of the calcium carbonate whisker is 20-30μm and the diameter is 0.5-2μm. The coarse aggregate is limestone with a particle size of 11-20mm and an apparent density of 2610kg / m 3 , bulk density 1500kg / m 3 , water absorption rate 2.1%.

[0031] A method for preparing a planted porous concrete comprises the following steps:

[0032] (1) Mix coarse aggregate, fertilizer granules and 50% water and stir for 1.5 minutes;

[0033] (2) Add 50% Portland cement and fly ash and continue stirring for 2 minutes;

[0034] (3) Then add the remaining raw materials and mix for 2 minutes. Fill the mold with the mixture in three layers. Each time a layer is filled, use a stick to tamp 20 times, then vibrate mechanically for 30 seconds, and apply a pressure of 0.5 MPa to compact it. Curing for 7 days, skeleton concrete is obtained;

[0035] (4) Fill the filler into the gaps and surface of the skeleton concrete by pressure grouting. The amount of filler is 30% of the weight of the skeleton concrete. Most of the filler is filled into the gaps of the skeleton concrete, and a small amount remains on the surface of the skeleton concrete. After the filler solidifies, continue to cure for 21 days to obtain vegetated porous concrete.

[0036] Example 2

[0037] A kind of planted porous concrete includes skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 195 parts of silicate cement, 25 parts of fly ash, 1390 parts of coarse aggregate, 80 parts of fertilizer particles, 6.5 parts of reinforcing agent, 95 parts of water, and 1.3 parts of polycarboxylic acid high-efficiency water reducing agent.

[0038] The fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1:2.5:0.3, 20% water is added, stirred evenly, and extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm.

[0039] The binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring, heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of the corn starch, polyvinyl alcohol and glycerol is 5:4:0.6.

[0040] The voids in the skeleton concrete are filled with fillers, which are prepared by the following steps: polyvinyl alcohol is dissolved in hot water to form a 2wt% solution, carboxymethyl chitosan, sodium alginate and organic matter are added and stirred evenly, calcium chloride and boric acid are dissolved in an appropriate amount of water to form a crosslinking agent solution, and the two solutions are stirred evenly, wherein the weight ratio of the polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 3:3:4:8:4:1.

[0041] The other processes are the same as those in Example 1.

[0042] Example 3

[0043] A kind of planted porous concrete includes skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 198 parts of silicate cement, 20 parts of fly ash, 1395 parts of coarse aggregate, 75 parts of fertilizer particles, 7 parts of reinforcing agent, 95 parts of water, and 1.4 parts of polycarboxylic acid high-efficiency water reducing agent.

[0044] The fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1:2.5:0.3, 20% water is added, stirred evenly, and extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm.

[0045] The binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring, heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of the corn starch, polyvinyl alcohol and glycerol is 5:4:0.8.

[0046] The voids in the skeleton concrete are filled with fillers, which are prepared by the following steps: polyvinyl alcohol is dissolved in hot water to form a 2wt% solution, carboxymethyl chitosan, sodium alginate and organic matter are added and stirred evenly, calcium chloride and boric acid are dissolved in an appropriate amount of water to form a crosslinking agent solution, and the two solutions are stirred evenly, wherein the weight ratio of the polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 2.5:3:4.5:8:4:1.

[0047] The other processes are the same as those in Example 1.

[0048] Example 4

[0049] A kind of planted porous concrete includes skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 200 parts of silicate cement, 18 parts of fly ash, 1400 parts of coarse aggregate, 70 parts of fertilizer particles, 8 parts of reinforcing agent, 95 parts of water, and 1.5 parts of polycarboxylic acid high-efficiency water reducing agent.

[0050] The fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1:3:0.3, 20% water is added, stirred evenly, and extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm.

[0051] The binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring, heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of the corn starch, polyvinyl alcohol and glycerol is 5:4:1.

[0052] The voids in the skeleton concrete are filled with fillers, which are prepared by the following steps: polyvinyl alcohol is dissolved in hot water to form a 2wt% solution, carboxymethyl chitosan, sodium alginate and organic matter are added and stirred evenly, calcium chloride and boric acid are dissolved in an appropriate amount of water to form a crosslinking agent solution, and the two solutions are stirred evenly, wherein the weight ratio of the polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 3:3:4:8:4:1.

[0053] The other processes are the same as those in Example 1.

[0054] Comparative Example 1

[0055] Comparative Example 1 is a comparative example of Example 4, and is different from Example 4 in that:

[0056] The voids in the skeleton concrete are not filled with filler.

[0057] Comparative Example 2

[0058] Comparative Example 2 is a comparative example of Example 4, and is different from Example 4 in that no fertilizer particles are added to the skeleton concrete raw materials.

[0059] Comparative Example 3

[0060] Comparative Example 3 is a comparative example of Example 4, and is different from Example 4 in that:

[0061] The reinforcing agent is a mixture of polyvinyl acetate emulsion and montmorillonite in a weight ratio of 1:1.

[0062] Performance Testing

[0063] 1. The porosity and 28d compressive strength (MPa) of the skeleton concrete specimens prepared in Examples 1-4 and Comparative Examples 1-3 were tested.

[0064] 2. The compressive strength, pH value, vegetative property, water absorption and water retention of the vegetated porous concrete specimens prepared in Examples 1-4 and Comparative Examples 1-3 were tested. The results are shown in Table 1; the compressive strength refers to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete".

[0065] pH value detection: Soak the specimen in 10L of water for 24 hours, stir thoroughly, and detect the pH value of the leaching solution.

[0066] Porosity test: First measure the apparent volume V of the concrete specimen, immerse the specimen in water at room temperature for 24 hours, shake it until there are no bubbles, and weigh its mass M suspended in the water. 1 Take out the specimen and drain until there is no water dripping from the bottom. Wipe the surface of the specimen dry and weigh its mass M. 2 , specimen porosity = (1-(M 2 -M 1 ) / ρ 水 V)*100%.

[0067] Vegetation test: A 6-7 cm thick humus soil layer was laid on top of the 100*100*100 mm vegetation porous concrete specimen, and ryegrass seeds were mixed into the soil layer. Watering was carried out every day. After germination, watering was carried out every other day. The growth height of the plants at 30 days is shown in Table 1.

[0068] Water absorption: 100*100*100mm vegetation porous concrete specimens were placed in an oven to dry for 72 hours, taken out and weighed, then soaked in water for 48 hours, wiped off the surface moisture and weighed, and the water absorption rate was calculated.

[0069] Water retention: Wipe off the surface moisture of the concrete specimen after soaking for 48 hours and record the mass m 1 , place it outdoors with good ventilation, and record the mass m of the specimen every day 2 The time for ecological concrete to be completely dried is m0, and the water loss rate is (m 1 -m 2 ) / (m 1 -m 0 )*100%, water loss rate curve see Figure 1 .

[0070] Table 1 Performance test data

[0071]

[0072] As can be seen from Table 1, the 28d compressive strength of the porous concrete prepared by the present application is 19-21.5MPa, which is high in strength. The porosity of the skeleton concrete is between 28-29.4%, the pH value is about 8.0, and the water absorption and water retention properties are excellent. In the vegetation test, the ryegrass planted in Examples 1-4 began to germinate in 2 days, and the average height reached 2-4cm in five days. The germination rate can reach 96-97%, and the average height of the plant after 30 days of planting is 21-23cm, indicating that the concrete prepared by the present application is suitable for plant growth.

[0073] Combination Figure 1 It can be clearly seen that the porous concrete for vegetation prepared in Examples 1-4 of the present application has a good water retention effect, and the poured filler greatly reduces the water loss rate of the porous concrete and increases the water retention performance of the concrete; combined with the data of Comparative Example 1 in Table 1, it can be seen that the concrete without adding fillers has high alkalinity and low water absorption, which correspondingly affects the growth of plants. This shows that the present application fills the gaps in the skeleton concrete with fillers, which can reduce alkali, absorb water, retain water and fertilizer, thereby increasing vegetation.

[0074] From the data of Comparative Example 2, it can be seen that the fertilizer particles have a positive effect on plant growth; from the data of Comparative Example 3, it can be seen that the absence of calcium carbonate whiskers in the reinforcing agent has an impact on the strength of the concrete, indicating that the reinforcing agent has a synergistic reinforcing effect.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A planted porous concrete, characterized in that: It includes skeleton concrete and filler, wherein the skeleton concrete is made of the following raw materials in parts by weight: 190-200 parts of silicate cement, 18-28 parts of fly ash, 1380-1400 parts of coarse aggregate, 70-90 parts of fertilizer particles, 6-8 parts of reinforcing agent, 94-95 parts of water, and 1.3-1.5 parts of polycarboxylic acid high-efficiency water reducing agent; The gaps in the skeleton concrete are filled with fillers, which are prepared by the following steps: Dissolve polyvinyl alcohol in hot water to prepare a 2wt% solution, add carboxymethyl chitosan, sodium alginate, and organic matter and stir evenly, dissolve calcium chloride and boric acid in an appropriate amount of water to form a crosslinker solution, and stir the above two solutions evenly, wherein the weight ratio of polyvinyl alcohol, carboxymethyl chitosan, sodium alginate, organic matter, calcium chloride and boric acid is 2-3:3:4-5:8:4:1; The method for preparing the vegetation porous concrete comprises the following steps: (1) Mix coarse aggregate, fertilizer granules and 50% water and stir for 1.5 minutes; (2) Add 50% Portland cement and fly ash and continue stirring for 2 minutes; (3) Then add the remaining raw materials and mix for 2 minutes. Fill the mold with the mixture in three layers. Use a stick to tamp 20 times for each layer, then vibrate mechanically for 20 seconds, apply 0.5MPa pressure to compact, and cure for 7 days to obtain skeleton concrete. (4) Pour the filling material into the gaps and surface of the skeleton concrete by pressure grouting and continue to cure for 21 days to obtain the vegetated porous concrete; The fertilizer granules are prepared by the following steps: urea, biochar and a binder are mixed in a weight ratio of 1:2-3:0.3, water is added and stirred evenly, and the mixture is extruded to obtain fertilizer granules, wherein the particle size of the fertilizer granules is 6-9 mm; The reinforcing agent is a mixture of polyvinyl acetate emulsion, calcium carbonate whisker and montmorillonite in a weight ratio of 1:1:

1. The calcium carbonate whisker has a length of 20-30 μm and a diameter of 0.5-2 μm.

2. The planted porous concrete according to claim 1, characterized in that: The binder is prepared by mixing corn starch, polyvinyl alcohol and glycerol, adding water and stirring, heating to 90° C. and stirring evenly to obtain the binder, wherein the weight ratio of the corn starch, polyvinyl alcohol and glycerol is 5:4:0.5-1.

3. The planted porous concrete according to claim 1, characterized in that: The organic matter is prepared by mixing and crushing humic acid, organic fertilizer and plant fiber in a weight ratio of 2:1:1.

Images