CN115385613A - Low-alkali ecological concrete and preparation method thereof - Google Patents
Low-alkali ecological concrete and preparation method thereof Download PDFInfo
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- CN115385613A CN115385613A CN202211121411.7A CN202211121411A CN115385613A CN 115385613 A CN115385613 A CN 115385613A CN 202211121411 A CN202211121411 A CN 202211121411A CN 115385613 A CN115385613 A CN 115385613A
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- 239000003513 alkali Substances 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 80
- 239000004568 cement Substances 0.000 claims abstract description 43
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 40
- 239000003094 microcapsule Substances 0.000 claims abstract description 29
- 238000003756 stirring Methods 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 15
- 239000011707 mineral Substances 0.000 claims abstract description 15
- 239000002002 slurry Substances 0.000 claims abstract description 15
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 239000002994 raw material Substances 0.000 claims abstract description 5
- 238000003825 pressing Methods 0.000 claims abstract description 4
- 239000002245 particle Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 13
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 9
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 8
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical group [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000007762 w/o emulsion Substances 0.000 claims description 7
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 6
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 6
- 239000003999 initiator Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- 239000010881 fly ash Substances 0.000 claims description 5
- 239000002893 slag Substances 0.000 claims description 5
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 4
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000003208 petroleum Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 239000004575 stone Substances 0.000 claims 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 18
- 239000000920 calcium hydroxide Substances 0.000 description 18
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 18
- 230000008635 plant growth Effects 0.000 description 14
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 13
- 238000006703 hydration reaction Methods 0.000 description 13
- 239000011574 phosphorus Substances 0.000 description 13
- 229910052698 phosphorus Inorganic materials 0.000 description 13
- 230000036571 hydration Effects 0.000 description 12
- 239000011148 porous material Substances 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 description 7
- 229910000389 calcium phosphate Inorganic materials 0.000 description 7
- 235000019691 monocalcium phosphate Nutrition 0.000 description 7
- 239000002585 base Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000002689 soil Substances 0.000 description 5
- 239000010878 waste rock Substances 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 241000196324 Embryophyta Species 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 3
- 239000002956 ash Substances 0.000 description 3
- 239000000378 calcium silicate Substances 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 239000002775 capsule Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 235000015097 nutrients Nutrition 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000004925 Acrylic resin Substances 0.000 description 2
- 229920000178 Acrylic resin Polymers 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000012615 aggregate Substances 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 125000002843 carboxylic acid group Chemical group 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000012010 growth Effects 0.000 description 1
- -1 hydroxyl ions Chemical class 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00017—Aspects relating to the protection of the environment
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00758—Uses not provided for elsewhere in C04B2111/00 for agri-, sylvi- or piscicultural or cattle-breeding applications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The application relates to the technical field of ecological concrete, and particularly discloses low-alkali ecological concrete and a preparation method thereof. The raw materials of the ecological concrete comprise 400-510 parts of coarse aggregate; 60-90 parts of fine aggregate; 100-130 parts of cement; 10-20 parts of mineral admixture; 9-14 parts of phosphoric acid microcapsules; the preparation method comprises the following steps: s1: adding the coarse aggregate, the cement, the mineral admixture and the phosphoric acid microcapsule into a stirrer, and uniformly stirring to obtain a mixture; s2: adding water into the mixture, uniformly stirring, then adding fine aggregate into the slurry, and uniformly stirring to obtain slurry; s3: pouring the prepared slurry into a mold, compacting, pressing and forming, maintaining for 28d, and then removing the mold to obtain the ecological concrete. It has the advantage of reducing the pH of the ecological concrete.
Description
Technical Field
The application relates to the technical field of ecological concrete, in particular to low-alkali ecological concrete and a preparation method thereof.
Background
The ecological concrete is porous concrete with continuous pores, has special structure and surface characteristics, can adapt to biological growth, is favorable for adjusting ecological balance, beautifying the environment landscape, promoting the restoration of an ecological system, playing an active role in protecting the ecological environment and constructing infrastructure, and is widely applied to the slope management of river landscape and landscaping.
In the related technology, the ecological concrete is a porous concrete with certain strength and certain pores, which is formed by mixing and pouring coarse aggregate, cement, water and an additive, thin-layer cement slurry coated on the surface of the coarse aggregate is mutually bonded to form a honeycomb structure with uniformly distributed pores, and a base material such as soil, fertilizer, a water-retaining agent and the like is filled in a base layer of the ecological concrete, so that plant roots can grow and extend in the base layer, nutrients can be obtained from the base layer, and a growing space can be provided for plants.
In the above-mentioned related art, in the process of preparing ecological concrete by using ordinary portland cement, calcium silicate, which is a main component in cement, reacts with water to generate hydration products of calcium silicate and calcium hydroxide, wherein an alkaline solution of calcium hydroxide exists in pores of ecological concrete in a large amount, and is released to result in a low plant growth rate, and in order to reduce the pH inside concrete, the amount of a gelling material is reduced in a large amount in a formulation, which results in further reduction of the strength of porous ecological concrete, so that it is necessary to reduce the pH of ecological concrete while maintaining the strength of ecological concrete unchanged.
Disclosure of Invention
In order to reduce the pH value of ecological concrete, the application provides low-alkali ecological concrete and a preparation method thereof.
In a first aspect, the application provides a low-alkali ecological concrete, which adopts the following technical scheme:
the low-alkali ecological concrete is prepared from the following raw materials in parts by weight:
400-510 parts of coarse aggregate;
60-90 parts of fine aggregate;
100-130 parts of cement;
10-20 parts of mineral admixture;
9-14 parts of phosphoric acid microcapsules.
By adopting the technical scheme, the coarse aggregate plays a skeleton role in concrete, the fine aggregate fills pores among the coarse aggregates, cement is used as a cementing material to bond the coarse aggregates to form a pore structure, the mineral admixture improves the strength and durability of the concrete, calcium hydroxide can be generated in the cement hydration process to ensure that the pH value in the concrete is about 12-13 and is not beneficial to plant growth, phosphoric acid microcapsules are added into the ecological concrete, and in the cement hydration process, phosphoric acid is slowly released from the microcapsules to neutralize the hydration product calcium hydroxide to generate calcium superphosphate Ca (H) through reaction 2 PO 4 ) 2, thereby reducing the pH value of the ecological concrete, simultaneously providing nutrient elements such as calcium, phosphorus and the like required by plant growth and being beneficial to the later growth of plants.
Preferably, the coarse aggregate is mine waste rock.
Through adopting above-mentioned technical scheme, the mine barren rock not only occupies a large amount of lands as solid useless, and the polluted environment moreover utilizes these mine barren rock resources fungible part natural grit aggregate, reaches the purpose that solid useless recovery was recycled, and the mine barren rock plays the effect of skeleton in ecological concrete's preparation in-process, and the mine rubble possesses certain intensity and tightness, can resist freeze thawing and natural weathering effect, guarantees the intensity and the durability of concrete.
Preferably, the particle size of the coarse aggregate is 10-40mm.
By adopting the technical scheme, the specific surface area is determined by the particle size of the aggregate, when the particle size of the aggregate is increased, the specific surface area is reduced, the cement consumption of concrete is reduced, and when the particle size of the aggregate is reduced, the specific surface area is increased.
Preferably, the mineral admixture is fly ash and blast furnace slag.
By adopting the technical scheme, the fly ash and the blast furnace slag are taken as solid wastes and are cementing materials which can partially replace cement, so that on one hand, the consumption of part of cement can be reduced, and the environmental pollution caused in the cement production process can be relieved; on the other hand, in the cement hydration process, the silica and calcium oxide contained in the fly ash and the blast furnace slag generate hydrated calcium silicate, which plays a role in reinforcing the ecological concrete.
Preferably, the preparation of the phosphoric acid microcapsule comprises the following steps:
s1: firstly, dissolving sodium dodecyl sulfate in a petroleum ether solvent, and adding a phosphoric acid aqueous solution to obtain a water-in-oil emulsion;
s2: mixing and stirring methacrylic acid and methyl acrylate uniformly, adding a chloroform solvent, and stirring uniformly to prepare a prepolymer solution;
s3: and adding the prepolymer solution into the water-in-oil emulsion, then adding an initiator, and filtering, separating and drying to obtain the phosphoric acid microcapsule.
According to the technical scheme, methacrylic acid, methyl acrylate and an initiator are dissolved in chloroform to form an organic solution, the organic solution is added into a water-in-oil emulsion, the methacrylic acid and the methyl acrylate are polymerized in situ to generate acrylic resin, phosphoric acid water drops are wrapped to prepare the phosphoric acid microcapsule, in the cement hydration process, along with continuous generation of calcium hydroxide, hydroxyl ions ionize carboxylic acid groups on a polymer main chain under an alkaline condition, molecules of the carboxylic acid groups are ionized, negative charges are generated along the polymer main chain, like charges repel each other to relax the molecular chains, a swelling phenomenon is generated, the acrylic resin net structure is damaged, then phosphoric acid is slowly released from the microcapsule to neutralize calcium hydroxide generated by hydration, the pH value of the ecological concrete is reduced, and a favorable environment is provided for plant growth.
Preferably, the initiator is ammonium persulfate.
By adopting the technical scheme, ammonium persulfate is used as an initiator, so that the polymerization rate can be increased and the phenomenon that the polymerization rate is too slow, the molecular weight of a polymer is reduced, the conversion rate is reduced, the formed reticular structure can not completely wrap phosphoric acid water drops in the reticular structure can be prevented in the polymerization process of methacrylic acid and methyl acrylate, the slow-release effect of the microcapsule can not be reflected in the cement hydration process, and the strength of the ecological concrete is reduced due to excessive phosphoric acid.
In a second aspect, the present application provides a method for preparing ecological concrete, which adopts the following technical scheme:
the preparation method of the ecological concrete comprises the following steps:
s1: adding the coarse aggregate, the cement, the mineral admixture and the phosphoric acid microcapsule into a stirrer, and uniformly stirring to obtain a mixture;
s2: adding water into the mixture, uniformly stirring, then adding fine aggregate into the slurry, and uniformly stirring to obtain slurry;
s3: pouring the prepared slurry into a mold, compacting and pressing for forming, maintaining for 28 days, and then removing the mold to obtain the ecological concrete.
By adopting the technical scheme, firstly, the coarse aggregate, the cement, the mineral admixture and the phosphoric acid microcapsule are added into a stirring machine to be uniformly stirred, then the fine aggregate is added to fill the pores among the coarse aggregates, the cement is used as a cementing material to coagulate the aggregates to form a pore structure, meanwhile, the cement is hydrated to generate calcium hydroxide, the strong basicity dissociates the acrylic monomer chain segments, the electrostatic repulsion action of negative charges enables the macromolecular chains to be rapidly expanded and spread, the three-dimensional network structure is destroyed, the phosphoric acid encapsulated and coated by the capsule is slowly released to react with the calcium hydroxide to generate calcium superphosphate, and the continuously generated calcium hydroxide is neutralized, so that the pH value of the concrete is reduced, and the ecological concrete suitable for plant growth is prepared.
Preferably, the weight ratio of water to cement in the preparation process of the ecological concrete is (0.35-0.52): 1.
By adopting the technical scheme, water participates in cement hydration reaction on one hand and plays a role in lubricating materials on the other hand, as the ecological concrete has larger porosity for being suitable for plant growth, fewer glue joints among aggregates in the concrete are reduced, and the strength is naturally reduced, the workability and cohesiveness of the concrete are good by adopting the water-cement weight ratio, and the good cohesiveness is played for coarse aggregates with large particle size, so that the strength of the ecological concrete meets the requirement.
In summary, the present application has the following beneficial effects:
1. the specific surface area of the aggregate is determined by the particle size of the aggregate, when the particle size of the aggregate is increased, the specific surface area is reduced, the cement consumption of concrete is reduced, and when the particle size of the aggregate is reduced, the specific surface area is increased.
2. In the application, phosphoric acid is preferably adopted to react with calcium hydroxide, the coarse aggregate plays a skeleton role in concrete, the fine aggregate fills pores among the coarse aggregates, cement is used as a cementing material to bond the coarse aggregates to form a pore structure, and the mineral admixture is liftedThe strength and durability of the concrete are high, calcium hydroxide can be generated in the cement hydration process, the pH value in the concrete is about 12-13, the plant growth is not facilitated, the phosphoric acid microcapsule is added into the ecological concrete, the phosphoric acid is slowly released from the microcapsule in the cement hydration process, the hydration product calcium hydroxide is neutralized, and calcium superphosphate Ca (H) is generated through reaction 2 PO 4 ) 2, thereby reducing the pH value of the ecological concrete, simultaneously providing nutrient elements such as calcium, phosphorus and the like required by plant growth and being beneficial to the later growth of plants.
3. According to the method, firstly, coarse aggregate, cement, mineral admixture and phosphoric acid microcapsule are added into a stirrer to be uniformly stirred, then fine aggregate is added to fill pores among the coarse aggregate, the cement serves as a cementing material, the aggregate is coagulated to form a pore structure, meanwhile, the cement is hydrated to generate calcium hydroxide, strong basicity enables acrylic monomer chain segments to be dissociated, the macromolecular chains are rapidly expanded and extended under the electrostatic repulsion action of negative charges, a three-dimensional network structure is damaged, phosphoric acid encapsulated and coated by the capsule is slowly released and reacts with the calcium hydroxide to generate calcium superphosphate, and the calcium hydroxide generated continuously is neutralized, so that the pH value of the concrete is reduced, and the ecological concrete suitable for plant growth is prepared.
Detailed Description
The present application will be described in further detail with reference to examples.
Preparation example of phosphoric acid microcapsules
Preparation example 1
S1, dissolving 1.1kg of sodium dodecyl sulfate surfactant in 16.3kg of petroleum ether solvent, adding 9.1kg of phosphoric acid solution under stirring of a homogenizer, and emulsifying for 10 minutes to obtain a water-in-oil emulsion;
s2, adding 5kg of methacrylic acid and 30kg of methyl acrylate into a reaction kettle, adding 20kg of chloroform solvent at the rotating speed of 100r/min, and uniformly stirring to prepare a prepolymer solution;
s3: slowly dripping the prepolymer solution into the water-in-oil emulsion at the rotating speed of 300r/min, then slowly adding 1.5kg of ammonium persulfate, reacting for 3 hours at the temperature of 60 ℃, filtering, separating and drying to obtain the phosphoric acid microcapsule.
Examples
Example 1
S1: adding mine waste rock with the particle size of 30mm, cement, a mineral admixture and the phosphoric acid microcapsule prepared in the preparation example 1 into a stirrer, and stirring for 3-5min to obtain a mixture, wherein the mineral admixture is a mixture of blast furnace slag and fly ash in a weight ratio of 1;
s2: adding water into the mixture, stirring for 2-3min, wherein the weight ratio of water to ash is 0.43, then adding fine aggregate, and stirring for 2-3min to obtain slurry;
s3: pouring the prepared slurry into a mold, compacting and pressing the slurry on a compaction table for molding, and removing the mold after curing for 28 days to obtain the ecological concrete.
Example 2
The low-alkali ecological concrete is different from the concrete in example 1 in that the particle size of mine waste rock is 10mm, and the weight ratio of water to cement in the preparation process is 0.35.
Example 3
The low-alkali ecological concrete is different from the concrete in example 1 in that the particle size of mine waste rock is 40mm, and the weight ratio of water to cement in the preparation process is 0.52.
Examples 1-3 the raw material components and their corresponding parts by weight are shown in table 1.
TABLE 1 materials and weights (kg) thereof in examples 1-3
| Components | Example 1 | Example 2 | Example 3 |
| Coarse aggregate | 450 | 400 | 510 |
| Fine aggregate | 70 | 60 | 90 |
| Cement | 110 | 130 | 100 |
| Mineral admixture | 15 | 8 | 20 |
| Phosphoric acid microcapsule | 12 | 14 | 9 |
Example 4
The low-alkali ecological concrete is different from the concrete in example 2 in that the particle size of mine waste rock is 5mm.
Example 5
A low-alkali ecological concrete, which is different from the concrete of example 3 in that the particle size of mine barren rocks is 50mm.
Example 6
A low-alkali ecological concrete is different from the concrete in example 2 in that the weight ratio of water to ash is 0.3.
Example 7
A low-alkali ecological concrete is different from the concrete in example 3 in that the weight ratio of water to ash is 0.6.
Example 8
A low-alkali ecological concrete, which is different from the concrete in example 2 in that the dosage of the phosphoric acid microcapsule is 17kg.
Example 9
A low-alkali ecological concrete, which is different from the concrete in example 3 in that the dosage of the phosphoric acid microcapsule is 7kg.
Comparative example
Comparative example 1
A low-alkali eco-concrete, which is different from example 1 in that the raw material does not include phosphoric acid microcapsules.
Performance test
Experimental samples: standard test blocks were prepared using the eco-concrete obtained in examples 1 to 9 and comparative example 1.
The experimental method comprises the following steps:
1. testing the content of available phosphorus: preparing grass seeds, soil and the like into slurry, pouring the slurry into a prepared ecological concrete test block, testing the content of available phosphorus in the soil after a plant grows for 30d according to NY/T1121.7-2014 standard, wherein the original available phosphorus content in the soil is about 4mg/kg, and taking the arithmetic mean value of three test values of each group of samples as an available phosphorus content value in the experimental process.
pH test: and (3) placing the ecological concrete test block prepared by curing for 28d into a container, adding distilled water for soaking, wherein the weight ratio of the ecological concrete to the distilled water is 1.
3. The compression strength test is carried out according to the standard of GB/T2542-2003 wall brick test method, and the 28d compression strength (MPa) of the aerated brick is detected.
And (3) detection results: as shown in table 2.
TABLE 2 Performance test results
| pH | Phosphorus content (mg/kg) | Compressive strength (MPa) | |
| Example 1 | 6 | 23 | 23 |
| Example 2 | 6.2 | 21 | 20 |
| Example 3 | 6.3 | 21.4 | 19.6 |
| Example 4 | 6.6 | 20 | 16 |
| Example 5 | 6.5 | 20.2 | 16.5 |
| Example 6 | 6.4 | 19 | 14.6 |
| Example 7 | 6.8 | 19.5 | 15.3 |
| Example 8 | 5 | 25 | 13 |
| Example 9 | 9 | 14 | 19 |
| Comparative example 1 | 12.5 | 2.8 | 22.7 |
Experimental samples: the ecological concrete test block of comparative example 1 was used as a base, except that the amount of cement added was different, and the test results are shown in table 3.
TABLE 3 test results of cement addition amount property test
Combining example 2 and example 8 and table 2, it can be seen that the pH of example 2 is higher than that of example 8, the phosphorus content of example 2 is lower than that of example 8, the compressive strength of example 2 is higher than that of example 8, if excessive phosphoric acid microcapsules are added, excessive released phosphoric acid can greatly reduce the pH of ecological concrete, the phosphorus element required for plant growth generated by reaction can be increased, but phosphoric acid as a medium-strong acid can affect the compressive strength and durability of ecological concrete.
As can be seen by combining example 2 with example 9 and table 2, the pH value of example 2 is lower than that of example 9, the phosphorus content of example 2 is higher than that of example 9, and if a small amount of phosphoric acid microcapsules are added, the content of calcium hydroxide in the ecological concrete is relatively increased, the pH reduction is limited, the generated calcium superphosphate is relatively reduced, the available phosphorus content is lower, and the growth of plants is not facilitated.
As can be seen by combining the example 1 and the comparative example 1 and combining the table 2, the pH value of the example 1 is obviously lower than that of the comparative example 1, the effective phosphorus content of the example 1 is higher than that of the comparative example 1, calcium hydroxide is generated by cement hydration, the acrylic monomer chain segment is dissociated under the alkaline condition, the macromolecular chain is rapidly expanded and stretched by the electrostatic repulsion action of negative charges, the three-dimensional network structure is destroyed, the phosphoric acid encapsulated by the capsule is slowly released and reacts with the calcium hydroxide to generate calcium superphosphate, the pH value of the ecological concrete is reduced, and the calcium superphosphate provides phosphorus for soil, so that the growth of plants is more facilitated.
It can be seen from table 2 and table 3 that if the pH of the ecological concrete is adjusted without adding the phosphoric acid microcapsules, the pH of the ecological concrete is adjusted by simply reducing the dosage of the cement, and as can be seen from table 3, the dosage of the cement is reduced from 110kg to 70kg, and the compressive strength is reduced from 22.6MPa to 7MPa, which cannot meet the compressive strength standard of the ecological concrete under the actual working condition, therefore, if the dosage of the cement is reduced to reduce the pH of the ecological concrete, the degree of the reduction of the pH is limited, and the compressive strength of the ecological concrete is also affected.
The specific embodiments are only for explaining the present application and are not limiting to the present application, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but all the embodiments are protected by patent law within the scope of the claims of the present application.
Claims (8)
1. The low-alkali ecological concrete is characterized by comprising the following raw materials in parts by weight:
400-510 parts of coarse aggregate;
60-90 parts of fine aggregate;
100-130 parts of cement;
10-20 parts of mineral admixture;
9-14 parts of phosphoric acid microcapsules.
2. The low-alkali ecological concrete according to claim 1, wherein: the coarse aggregate is mine crushed stone.
3. The low-alkali ecological concrete according to claim 1, wherein: the particle size of the coarse aggregate is 10-40mm.
4. The low-alkali ecological concrete according to claim 1, wherein: the mineral admixture is fly ash and blast furnace slag.
5. The low-alkali ecological concrete according to claim 1, wherein: the preparation method of the phosphoric acid microcapsule comprises the following steps:
s1: firstly, dissolving sodium dodecyl sulfate in a petroleum ether solvent, and adding a phosphoric acid aqueous solution to obtain a water-in-oil emulsion;
s2: then, mixing and stirring the methacrylic acid and the methyl acrylate uniformly, and then adding a chloroform solvent and stirring uniformly to prepare a prepolymer solution;
s3: and adding the prepolymer solution into the water-in-oil emulsion, then adding an initiator, and filtering, separating and drying to obtain the phosphoric acid microcapsule.
6. The low-alkali ecological concrete according to claim 5, wherein: the initiator is ammonium persulfate.
7. The process for producing a low-alkali eco-concrete as claimed in any one of claims 1 to 6, wherein: the preparation method comprises the following steps:
s1: adding the coarse aggregate, the cement, the mineral admixture and the phosphoric acid microcapsule into a stirrer, and uniformly stirring to obtain a mixture;
s2: adding water into the mixture, uniformly stirring, then adding fine aggregate into the slurry, and uniformly stirring to obtain slurry;
s3: pouring the prepared slurry into a mold, compacting, pressing and forming, maintaining for 28d, and then removing the mold to obtain the ecological concrete.
8. The production process of the low-alkali ecological concrete according to claim 7, wherein the production process comprises the following steps: the weight ratio of water to cement in the preparation process of the ecological concrete is (0.35-0.52): 1.
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