CN116040993A - Preparation method of modified phosphate-based polymer - Google Patents
Preparation method of modified phosphate-based polymer Download PDFInfo
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- CN116040993A CN116040993A CN202211669215.3A CN202211669215A CN116040993A CN 116040993 A CN116040993 A CN 116040993A CN 202211669215 A CN202211669215 A CN 202211669215A CN 116040993 A CN116040993 A CN 116040993A
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- 229920000642 polymer Polymers 0.000 title claims abstract description 71
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 125000002467 phosphate group Chemical class [H]OP(=O)(O[H])O[*] 0.000 title abstract description 35
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 92
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 42
- 239000010881 fly ash Substances 0.000 claims abstract description 38
- 239000000243 solution Substances 0.000 claims abstract description 25
- RGPUVZXXZFNFBF-UHFFFAOYSA-K diphosphonooxyalumanyl dihydrogen phosphate Chemical compound [Al+3].OP(O)([O-])=O.OP(O)([O-])=O.OP(O)([O-])=O RGPUVZXXZFNFBF-UHFFFAOYSA-K 0.000 claims abstract description 21
- 239000011259 mixed solution Substances 0.000 claims abstract description 21
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 238000003756 stirring Methods 0.000 claims abstract description 11
- 229920001523 phosphate polymer Polymers 0.000 claims abstract description 7
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 6
- 150000003016 phosphoric acids Chemical class 0.000 claims description 5
- 239000010754 BS 2869 Class F Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 2
- 230000000694 effects Effects 0.000 abstract description 14
- 238000002715 modification method Methods 0.000 abstract description 2
- 229920000876 geopolymer Polymers 0.000 description 72
- 239000011159 matrix material Substances 0.000 description 11
- 239000000126 substance Substances 0.000 description 11
- 229910019142 PO4 Inorganic materials 0.000 description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 10
- 239000010452 phosphate Substances 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 239000012190 activator Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000036571 hydration Effects 0.000 description 4
- 238000006703 hydration reaction Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 238000001878 scanning electron micrograph Methods 0.000 description 4
- 229910018516 Al—O Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229920005601 base polymer Polymers 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 3
- 235000019796 monopotassium phosphate Nutrition 0.000 description 3
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910017119 AlPO Inorganic materials 0.000 description 2
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000011413 geopolymer cement Substances 0.000 description 2
- 229920003041 geopolymer cement Polymers 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 239000004005 microsphere Substances 0.000 description 2
- 239000011414 polymer cement Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910003849 O-Si Inorganic materials 0.000 description 1
- 229910003872 O—Si Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 description 1
- ZQKXOSJYJMDROL-UHFFFAOYSA-H aluminum;trisodium;diphosphate Chemical compound [Na+].[Na+].[Na+].[Al+3].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O ZQKXOSJYJMDROL-UHFFFAOYSA-H 0.000 description 1
- 229920006125 amorphous polymer Polymers 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 150000003017 phosphorus Chemical class 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 125000002743 phosphorus functional group Chemical group 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
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- 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
- C04B28/006—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 containing mineral polymers, e.g. geopolymers of the Davidovits type
-
- 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
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/16—Acids or salts thereof containing phosphorus in the anion, e.g. phosphates
-
- 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
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/16—Acids or salts thereof containing phosphorus in the anion, e.g. phosphates
- C04B22/165—Acids
-
- 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
- C04B7/00—Hydraulic cements
- C04B7/24—Cements from oil shales, residues or waste other than slag
- C04B7/243—Mixtures thereof with activators or composition-correcting additives, e.g. mixtures of fly ash and alkali activators
-
- 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
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
Abstract
The invention provides a preparation method of a modified phosphate group polymer, which comprises the following steps: mixing 35% of aluminum dihydrogen phosphate solution and 31.5% of phosphoric acid solution to obtain a mixed solution A; and mixing the fly ash with the mixed solution A, uniformly stirring, pouring into a mold, and curing at room temperature to obtain the modified phosphate group polymer. The invention is simple and convenient, has low cost and is convenient to implement; the phosphate polymer prepared by the modification method provided by the invention has a good curing effect, and is suitable for improving the strength and stability of the phosphate polymer.
Description
Technical Field
The invention belongs to the technical field of material performance enhancement, and particularly relates to a preparation method of a modified phosphate group polymer.
Background
The phosphate-based geopolymer belongs to one branch of geopolymer, and is prepared from a material containing Si and Al by taking phosphoric acid as an exciting agent. The raw materials required for preparing the phosphate-based polymers are derived from natural minerals, readily available and widely available. The phosphate group polymer has high mechanical strength, and the maximum strength of the phosphate group polymer can be higher than that of the alkali-excited polymer. The polymer of the phosphate group has better application, such as being applied to the treatment of heavy metal polluted sites in an acidic environment, etc., but the polymer of the phosphate group has the problems of strength and durability, which limits the application of the polymer of the phosphate group.
During the polymerization of phosphoric acid, the Al-O layer in the silicon aluminum precursor is the reactive structure site for the reaction. The main structural units of the polymer with the phosphate group are Al-O-P, si-O-P, si-O-Si, si-O-Al and Si-O-Al-O-P. When phosphoric acid is used as an activator to prepare a polymer of phosphate groups, the concentration and amount of phosphoric acid are key factors affecting the strength of the polymer. When the concentration of phosphoric acid is lower, the free water is contained in the excitant and escapes during the hardening process of the geopolymer, so that the geopolymer generates more pores, and the strength of the geopolymer is reduced. When the concentration of phosphoric acid is too high, the excessive phosphoric acid in the system can cause charge imbalance in the system to damage the formed geopolymer structure, and meanwhile, the phosphoric acid solution with higher concentration can prevent the depolymerization of the silicon aluminum material, so that the pressure intensity of the geopolymer is negatively influenced. Of the polymers of phosphate groups, the optimum Al/P molar ratio is generally 1, the polymer strength of the phosphate group being highest when Al/P=1, and the excess phosphoric acid or excess water being impaired by the polymer strength when Al/P molar ratio < 1; when the Al/P molar ratio is >1, the geopolymer may lose strength and structural stability due to insufficient phosphoric acid amount. Only when the phosphoric acid concentration is the optimal concentration, the geopolymer strength has better stability, namely, the geopolymer strength is increased without collapsing along with the increase of the curing age. Therefore, the quality of the geopolymer prepared using phosphoric acid is more difficult to control.
ExcitationThe type of the agent has important influence on the strength of the geopolymer, phosphoric acid and phosphate (potassium dihydrogen phosphate and sodium aluminum phosphate) have certain excitation effects on fly ash and metakaolin, but the excitation effect of the potassium dihydrogen phosphate is inferior to that of phosphoric acid, the strength of the geopolymer prepared by exciting the fly ash by using the potassium dihydrogen phosphate is lower, but the strength of the geopolymer cannot be inverted along with the increase of the curing age, and the strength of the geopolymer is good in long-term stability. As the Al-O layer is an active point of the polymer reaction of the phosphate group, the content of the Al-O group in the reaction system is increased, which is beneficial to improving the strength of the geopolymer. Due to the low early strength of the polymers of phosphorus groups, the polymers can be prepared by adding Al 3+ A source-modified phosphate activator; after the aluminum source is added into the excitant, hexacoordinated aluminum required for gel substance formation in the polymerization reaction of the phosphoric acid group can be improved, so that geopolymer gel substances can be quickly formed in early stage, the setting time of the phosphoric acid geopolymer at room temperature is improved, and the early strength is improved. The phosphate-based polymer has the problems of unstable strength, low early strength and collapse of strength with the increase of curing age, so that the phosphate-based polymer is difficult to be applied in engineering.
In view of this, the present study uses fly ash as a raw material, and proposes to use aluminum dihydrogen phosphate Activator (ADP) by adding Al 3+ The invention can improve the early strength of the geopolymer, the early mechanical strength of the phosphate geopolymer and the long-term stability of the modified phosphate geopolymer, and has important significance for further engineering application and popularization of the phosphate geopolymer.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of a modified phosphate group polymer, which is simple and convenient, has low cost and is convenient to implement; the phosphate polymer prepared by the modification method provided by the invention has a good curing effect, and is suitable for improving the strength and stability of the phosphate polymer.
In order to solve the technical problems, the invention adopts the following technical scheme: a preparation method of a modified phosphate-based polymer comprises the following steps:
s1, mixing an aluminum dihydrogen phosphate solution (aluminum dihydrogen phosphate excitant, abbreviated as PA) with a mass fraction of 35% and a phosphoric acid solution (phosphoric acid excitant) with a mass fraction of 31.5% to obtain a mixed solution A (namely PA-ADP excitant);
s2, mixing the fly ash with the mixed solution A obtained in the step S1, uniformly stirring, pouring into a mold, and curing at room temperature to obtain the modified phosphate polymer.
Preferably, the mass ratio of the phosphoric acid solution and the aluminum dihydrogen phosphate solution in the mixed solution A in S1 is 3:1-1:3 (expressed as L/S).
Preferably, the fly ash in S2 is class F fly ash with a particle size of 1250 mesh.
Preferably, in the step S2, the mass ratio of the mixed solution A to the fly ash is (0.25-0.30): 1.
preferably, the stirring time in S2 is 30S to 120S.
Preferably, the curing age of room temperature curing in S2 is 7 d-90 d.
Compared with the prior art, the invention has the following advantages:
1. the principle of the modified phosphate group polymer of the invention is as follows: the polymer reaction of phosphate group mainly comprises two processes, namely dissolution of silicon and aluminum materials in the first process, and H is consumed in the dissolution process + PO is then required during the geopolymer reaction 4 3- Is involved in the ion participation. Thus, when the concentration of phosphoric acid is constant, active Al can be provided as the concentration of aluminum dihydrogen phosphate increases 3+ The ions increase. Due to the polymerization of the phosphate groups during the reaction of Al-O-P and Si-O-Al-O-amorphous polymer matrix of P structural units and highly viscous AlPO 4 Formation of a gel mass. Thus, increasing the aluminum dihydrogen phosphate content, the more hydration products are formed by the geopolymerization, so the strength at different curing ages increases with increasing aluminum dihydrogen phosphate content. The modified phosphate-based polymers prepared according to the present invention have a geopolymer strength that increases with the aluminum dihydrogen phosphate content. As L/S increases, the strength of the geopolymer decreases, but the maximum strength of the modified phosphate geopolymer is much higher than that of a phosphate geopolymer prepared by phosphoric acid-stimulated fly ash. With the increase of curing age, the geopolymer is strongThe degree increases, the strength does not collapse, and the higher the content of aluminum dihydrogen phosphate, the faster the geopolymer strength increases. The curing age of the modified phosphate group polymer prepared by the invention is 7 d-90 d, and the compressive strength can reach 13.09 MPa-33.86 MPa.
The invention is described in further detail below with reference to the drawings and examples.
Drawings
FIG. 1 is an SEM image of modified phosphoric acid group of the invention of PA: ADP=3:1, 1:1 and 3:1 of example 4 at a curing age of 7 d.
FIG. 2 is an SEM image of a modified phosphoric acid group polymer of example 4 of the present invention, which was PA: ADP=1:1 and L/S=0.317 at the age of 7, 28, 90 days at room temperature.
FIG. 3 is a graph showing the effect of the PA concentration and L/S of example 4 of the present invention on the strength of the modified phosphate group polymer.
FIG. 4 is a graph showing the effect of the PA/ADP ratio and L/S ratio on the strength of the modified phosphoric acid group polymer in example 4 of the present invention.
FIG. 5 is a graph showing the effect of curing age on the strength of a polymer having a phosphoric acid group in example 4 of the present invention.
FIG. 6 is a graph showing the effect of the curing age of example 4 of the present invention on the strength of the modified phosphoric acid based polymer.
Detailed Description
The main chemical compositions and contents of the class F fly ash powders used in the examples below are shown in table 1.
TABLE 1 Main chemical composition and content chemical composition of fly ash powder
| Chemical composition | Na 2 O | MgO | Al 2 O 3 | SiO 2 | P 2 O 5 | SO 3 | K 2 O | CaO | Fe 2 O 3 | Others |
| Content (%) | 0.06 | 0.55 | 32.38 | 49.07 | 1.01 | 1.57 | 1.65 | 3.43 | 7.80 | 2.48 |
The phosphoric acid used had a purity of 85.4% and a density of 1.874g/mL, and was monoaluminum phosphate [ Al (H) 2 PO 4 ) 3 ]The solution belongs to an industrial grade product, the pH is 1.4, the mass fraction is 35%, and the relative density is 1.44.
Example 1
The preparation method of the modified phosphate group polymer in the embodiment comprises the following steps:
s1, mixing an aluminum dihydrogen phosphate solution (namely an aluminum dihydrogen phosphate excitant, abbreviated as ADP) with a mass fraction of 35 percent and a phosphoric acid solution (abbreviated as PA) with a mass fraction of 31.5 percent to obtain a mixed solution A (namely an PA-ADP excitant); the mass ratio of the phosphoric acid solution to the aluminum dihydrogen phosphate solution in the mixed solution A in the step S1 is 1:3, a step of;
s2, mixing the fly ash with the mixed solution A obtained in the step S1, stirring for 60 seconds, uniformly stirring, and pouring the mixture into a container with the specification of 20 multiplied by 20m 3 d, curing for 7d at room temperature in the rigid mold to obtain a modified phosphate group polymer; the fly ash is F-class fly ash with the particle size of 1250 meshes; the mass ratio of the mixed solution A to the fly ash is 0.3:1 (denoted as L/S).
The maximum strength of the unmodified phosphate-based polymer is 3.26MPa when the polymer is cured for 7d, and the compressive strength of the modified polymer prepared in the embodiment is 13.09MPa, so that the early strength is improved greatly.
Example 2
The preparation method of the modified phosphate group polymer in the embodiment comprises the following steps:
s1, mixing an aluminum dihydrogen phosphate solution (namely an aluminum dihydrogen phosphate excitant, abbreviated as ADP) with a mass fraction of 35 percent and a phosphoric acid solution (abbreviated as PA) with a mass fraction of 31.5 percent to obtain a mixed solution A (namely an PA-ADP excitant); the mass ratio of the aluminum dihydrogen phosphate solution to the phosphoric acid solution in the mixed solution A is 1:1, a step of;
s2, mixing the fly ash with the mixed solution A obtained in the step S1, stirring for 120S, uniformly stirring, and pouring the mixture into a container with the specification of 20 multiplied by 20m 3 d, curing for 56d at room temperature in the rigid mold to obtain a modified phosphate group polymer; the fly ash is F-class fly ash with the particle size of 1250 meshes; the mass ratio of the mixed solution A to the fly ash is 0.25:1 (denoted as L/S).
The compressive strength of the geopolymer prepared by the embodiment can reach 24.04MPa.
Example 3
The preparation method of the modified phosphate group polymer in the embodiment comprises the following steps:
s1, mixing an aluminum dihydrogen phosphate solution (namely an aluminum dihydrogen phosphate excitant, abbreviated as ADP) with a mass fraction of 35 percent and a phosphoric acid solution (abbreviated as PA) with a mass fraction of 31.5 percent to obtain a mixed solution A (namely an PA-ADP excitant); the mass ratio of the aluminum dihydrogen phosphate solution to the phosphoric acid solution in the mixed solution A is 3:1, a step of;
s2, mixing the fly ash with the mixed solution A obtained in the step S1, stirring for 30S, uniformly stirring, and pouring the mixture into a container with the specification of 20 multiplied by 20m 3 d, curing for 90d at room temperature in the rigid mold to obtain a modified phosphate group polymer; the fly ash is F-class fly ash with the particle size of 1250 meshes; the mass ratio of the mixed solution A to the fly ash is 0.30:1 (denoted as L/S).
The geopolymer prepared in this example had a compressive strength of 33.86MPa, with the strength having the greatest value.
Example 4
This example is a comparison of the performance of different reaction parameters in the preparation of the modified phosphate based polymer of the present invention.
FIG. 1 is an SEM image of modified phosphate group polymers of 7d curing age at PA: ADP=3:1, 1:1 and 3:1. As can be seen from FIG. 1, as the ADP content in PA-ADP increases, less undissolved cenospheres of fly ash can be observed in the geopolymer matrix structure, the hydration product formed increases and the matrix structure becomes more compact. When PA: adp=3:1, the geopolymer matrix is loose in structure, uneven in matrix distribution and poor in compactness, and the formed hydrate is distributed in a particulate shape. When PA: adp=1:1, the amount of hydrate formed increases, the matrix structure becomes more dense, and the fly ash cenospheres are almost surrounded by hydrate. When the PA to ADP ratio is reduced from 3:1 to 1:3, the geopolymer matrix structure becomes more dense and the continuity of the matrix is better, at which point the geopolymer has the greatest compressive strength. It is obvious that the geopolymer matrix structure prepared by exciting the fly ash by PA-ADP with low ADP content can not endow the geopolymer with greater strength, and the exciting agent with high ADP content has better exciting effect on the fly ash. In addition, "X" type cracks were observed in the PA: adp=1:1 geopolymer SEM spectra, and "X" type and "Y" type cracks were observed in the PA: adp=1:3 geopolymer.
FIG. 2 is an SEM image of a modified phosphate polymer cured at room temperature at 7, 28, 90 days of age, PA: ADP=1:1, L/S=0.317. From the figure, it can be observed that: the different curing ages are observed to be inconsistent in geopolymer gel matrix morphology. At the age of 7 days, preliminary formation of the gelled substance was observed, and the gelled substance formed was mostly in the form of pellets, flocs and lumps. At the same time, a number of undissolved fly ash cenospheres were also observed in the figure. Some granular and flocculent hydrate can be observed in 28-day age, and although the matrix structure of the geopolymer is still loose in 28-day age, the binding property of the gelled substance is good, and the quantity of undissolved fly ash hollow microspheres can be obviously reduced. However, at the age of 90 days, the morphology of the gelled substance in the geopolymer is obviously changed, long strip-shaped thin block-shaped hydration products can be observed, and the number of undissolved fly ash hollow microspheres is less than that of the particles at the age of 7 days and 28 days. It is apparent that as the curing age increases, the hydration product formed in the geopolymer increases and the amount of undissolved fly ash cenospheres decreases, which is the main reason why the strength of the geopolymer increases as the curing age increases.
(1) The polymers of phosphorus acid groups and modified phosphorus acid groups, which had room temperature curing ages of 7d, 14d, 28d, 56d and 90d, respectively, were subjected to an unconfined compressive strength test.
Phosphate group polymer: the geopolymer prepared using the phosphoric acid activator alone, i.e., the unmodified geopolymer.
The test process comprises the following steps: the strength is tested by a CBR bearing capacity tester produced by Nanjing soil, the loading rate is constant at 1mm/min during the test, and each group of tests is repeated 3 times. The test results are shown in FIGS. 3 and 4.
FIG. 3 shows the ratio of PA-ADP, the L/S ratio to the polymer strength (q) u ) Is a function of (a) and (b).
Fig. 3 (a) shows the compressive strength of 7, 14, 28, 60 and 90d curing age fly ash phosphate geopolymer cement slurries, as can be seen from fig. 3 (a): the strength of the polymer of phosphate groups increases and decreases with increasing concentration of phosphoric acid at different curing ages, and the maximum compressive strength can be obtained at a phosphoric acid concentration of 50%. For example, at the 90 day curing age, the compressive strength of a phosphoric acid based polymer cement slurry having a phosphoric acid concentration of 30% is only 4.35MPa, and when the phosphoric acid concentration is increased to 50%, the strength is increased from 4.35MPa to 21.18MPa, by a factor of 3.87. However, when the phosphoric acid concentration was further increased to 60%, the strength was not increased but decreased from 21.18MPa to 12.39MPa, which was reduced by 41.5%. It is explained that when the liquid-solid ratio is 0.3, the optimum phosphoric acid concentration of the phosphoric acid-activated fly ash is 50%, the corresponding optimum P/Al molar ratio is 0.18, and the P/Si molar ratio is 0.136. Thus, when phosphoric acid is used to excite fly ash to produce a polymer having phosphate groups, the optimum phosphoric acid concentration is 50% when the solid to liquid ratio is 0.3
FIG. 3 (b) shows the effect of the liquid-solid ratio on the compressive strength of a polymer cement having a phosphoric acid group concentration of 40%, as can be seen from FIG. 3 (b): the strength of the geopolymer cement slurry decreases with increasing liquid-to-solid ratio. Samples with a solid to liquid ratio of 0.25 had the greatest strength at different ages, while slurries with a liquid to solid ratio of 0.4 had the least strength. Specifically, the strength of the polymer slurry at the age of 7 and 90 days was 5.83 and 12.23MPa for L/S=0.25, respectively, and 0.27 and 6.55MPa for the solid-to-liquid ratio of 0.4, respectively.
FIG. 4 (a) is the effect of PA-ADP ratio on the polymer strength of the modified phosphate group. As can be seen from fig. 4 (a): at L/s=0.3, the polymer strength of the modified phosphate group increases as the ADP content in the PA-ADP activator increases. When PA: adp=3:1, the geopolymer strengths at the 7, 14, 28, 60, 90 days of age were 5.41, 5.64, 8.24, 14.66, 20.25MPa, respectively. When the PA to ADP ratio was reduced to 1:3, the polymer strength of the modified phosphate increased to 11.98, 14.78, 15.6, 21.02, 33.86MPa at the age of 7, 14, 28, 60, 90 days, respectively. It is apparent that the ADP content has a great influence on the polymer strength of the modified phosphoric acid group, and that the reason for the increase in polymer strength of the modified phosphoric acid group with the increase in ADP content is the same as that of Al provided in the ADP activator 3+ Closely related. In PA-ADP, as the ADP content increases, al is present in the modified phosphate group polymer system 3+ Increase, al 3+ Is beneficial to AlPO 4 Formation of gel mass, alPO formed 4 The gelling material is the main cause of the increase in the strength of the geopolymer. When PA: adp=1:3, L/s=0.3, the geopolymer maximum strength at 90 days age is 33.89MPa; the maximum strength of the geopolymer at L/s=0.25 at day 90 age was 25.66MPa when PA: adp=1:1. However, as L/S increases, the strength of the modified phosphate-based polymer also tends to decrease, the reason for this being that the polymer contains more water than is not consumed during the geopolymerization reaction.
FIG. 4 (b) is the effect of L/S on the strength of the modified phosphate group polymer, as can be seen from FIG. 4 (b): as L/S increases, geopolymer strength decreases.
The maximum strength of the phosphate-based polymer prepared by singly using the phosphoric acid excitant in 28 days is 22MPa (figure 3 a), the strength energy of the prepared modified phosphate-based polymer in 28 days can reach 33MPa (figure 4 a), and the modified phosphate-based polymer has good engineering application prospect.
FIG. 5 (a) is the effect of curing age on the strength of geopolymers prepared with different PA concentration excitants, as can be seen from FIG. 5 (a): when L/s=0.3, the trend of the geopolymer strength with increasing curing age correlated with PA concentration. When the PA concentration is the optimal concentration (50%), the geopolymer strength is always increased with the increase of the curing age, but when the PA concentration is lower than or higher than 50%, i.e., the PA concentration is 30%, 40%, 60% the geopolymer strength is mainly increased in the age of 0-28 days, and in the curing age of 28-90 days, the geopolymer strength increase rate is suddenly decreased, and the geopolymer strength is not substantially increased or increased greatly. Moreover, the rates of increase in geopolymer strength at PA concentrations of 30%, 40%, 60% are substantially consistent with increasing age of maintenance. Specifically, when L/s=0.3, the geopolymers with PA concentrations of 30%, 40%, 60% had intensities of 3.66, 8.66, 11.83MPa at 28 days, respectively, increased to 4.35, 9.63, and 12.39MPa over the 90 day age, respectively, and the intensities increased by 18.85%, 11.20%, and 4.73%, respectively. However, a geopolymer with 50% PA concentration increased in strength at 90 days of age by 84.49% relative to 28 days of age
FIG. 5 (b) is a graph showing the effect of curing age on the strength of unmodified phosphate-based polymers having PA concentrations of 40%, L/S=0.25, 0.3, 0.35, 0.4. As can be seen from fig. 5 (b): the geopolymer strength is slowly increased along with the increase of curing time, the geopolymer strength is increased rapidly in the curing age range of 7-28 days, and the increasing trend of the geopolymer strength of different L/S is basically consistent in the curing age range of 28-90 days. In the curing age of 0 to 90 days, the strength of the geopolymer is continuously increased along with the increase of the curing age, which shows that the acid group polymerization reaction is a long process.
Fig. 6 (a) is a curing age vs PA: adp=3:1, 2:1, 1:1, 1:2, 1:3, l/s=0.3 and PA: adp=1: 1, L/S=0.25, 0.3, 0.35, 0.4. As can be seen from fig. 6 (a): as the curing age increases, the geopolymer strength increases. Moreover, as the ADP content in PA-ADP increases, the geopolymer strength increase rate increases, and the Pa: adp=3:1 geopolymer strength increase rate is significantly slower than other ratios. It can also be observed from fig. 6a that: the strength of the geopolymer is increased along with the increase of the curing age, and the strength of the geopolymer does not shrink in the later stage. Moreover, as the ADP content in PA-ADP increases, the strength of the geopolymer increases greatly, and the strength of the geopolymer with the proportion of PA being ADP=3:1 increases at a significantly slower rate than that of the geopolymer with other proportions, which indicates that the ADP can improve the strength of the polymer with the phosphate group.
Fig. 6 (b) is a curing age pair PA: adp=1: 1, L/S=0.25, 0.3, 0.35, 0.4 PA-ADP. As can be seen from fig. 6 (b): when PA: adp=1:1, PA-aDP base polymer strength increased with increasing curing age, different L/S base polymer strength had a similar trend of increasing, but when L/S increased to 0.4, the base polymer strength increasing rate was greater in the curing age range of 7 to 28 days and the strength increase was insignificant in the curing age range of 28 to 90 days as the curing age increased.
The above description is only of the preferred embodiments of the present invention, and is not intended to limit the present invention. Any simple modification, variation and equivalent variation of the above embodiments according to the technical substance of the invention still fall within the scope of the technical solution of the invention.
Claims (6)
1. A preparation method of a modified phosphate-based polymer is characterized by comprising the following steps:
s1, mixing an aluminum dihydrogen phosphate solution with the mass fraction of 35% and a phosphoric acid solution with the mass fraction of 31.5% to obtain a mixed solution A;
s2, mixing the fly ash with the mixed solution A obtained in the step S1, uniformly stirring, pouring into a mold, and curing at room temperature to obtain the modified phosphate polymer.
2. The method for preparing a modified phosphate-based polymer according to claim 1, wherein the mass ratio of the phosphoric acid solution to the aluminum dihydrogen phosphate solution in the mixed solution A in S1 is 3:1-1:3.
3. The method for producing a modified phosphoric acid based polymer according to claim 1, wherein the fly ash in S2 is a class F fly ash having a particle size of 1250 mesh.
4. The method for preparing a modified phosphoric acid-based polymer according to claim 1, wherein the mass ratio of the mixed liquor A to the fly ash in S2 is (0.25-0.30): 1.
5. the process for producing a modified phosphoric acid based polymer according to claim 1, wherein the stirring time in S2 is 30S to 120S.
6. The method for producing a modified phosphoric acid based polymer according to claim 1, wherein the curing age of room temperature curing in S2 is 7d to 90d.
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