CN118026624A - Phosphogypsum composite soil curing agent with good curing performance, preparation method thereof and derivative cured soil - Google Patents
Phosphogypsum composite soil curing agent with good curing performance, preparation method thereof and derivative cured soil Download PDFInfo
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- CN118026624A CN118026624A CN202311689974.0A CN202311689974A CN118026624A CN 118026624 A CN118026624 A CN 118026624A CN 202311689974 A CN202311689974 A CN 202311689974A CN 118026624 A CN118026624 A CN 118026624A
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- 239000002689 soil Substances 0.000 title claims abstract description 178
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 title claims abstract description 176
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 129
- 239000002131 composite material Substances 0.000 title claims abstract description 65
- 238000002360 preparation method Methods 0.000 title abstract description 27
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 63
- 238000002156 mixing Methods 0.000 claims abstract description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 58
- 239000004568 cement Substances 0.000 claims abstract description 49
- 239000002893 slag Substances 0.000 claims abstract description 48
- 239000000292 calcium oxide Substances 0.000 claims abstract description 32
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 32
- 150000002500 ions Chemical class 0.000 claims abstract description 28
- 238000003756 stirring Methods 0.000 claims abstract description 22
- 238000001723 curing Methods 0.000 claims description 204
- 238000002386 leaching Methods 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 238000010276 construction Methods 0.000 claims description 2
- 229910001385 heavy metal Inorganic materials 0.000 abstract description 7
- 239000002910 solid waste Substances 0.000 abstract description 4
- 239000003570 air Substances 0.000 abstract description 2
- 239000000428 dust Substances 0.000 abstract description 2
- 230000002787 reinforcement Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 15
- 230000000694 effects Effects 0.000 description 12
- RLJMLMKIBZAXJO-UHFFFAOYSA-N lead nitrate Chemical compound [O-][N+](=O)O[Pb]O[N+]([O-])=O RLJMLMKIBZAXJO-UHFFFAOYSA-N 0.000 description 10
- 239000000843 powder Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 238000007906 compression Methods 0.000 description 6
- RVPVRDXYQKGNMQ-UHFFFAOYSA-N lead(2+) Chemical compound [Pb+2] RVPVRDXYQKGNMQ-UHFFFAOYSA-N 0.000 description 6
- 235000012239 silicon dioxide Nutrition 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 5
- 230000006835 compression Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000000440 bentonite Substances 0.000 description 4
- 229910000278 bentonite Inorganic materials 0.000 description 4
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- 238000003776 cleavage reaction Methods 0.000 description 3
- 230000036571 hydration Effects 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- 239000010445 mica Substances 0.000 description 3
- 229910052618 mica group Inorganic materials 0.000 description 3
- 230000007017 scission Effects 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000000701 coagulant Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 229910001653 ettringite Inorganic materials 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
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- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 150000005837 radical ions Chemical class 0.000 description 1
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- 210000004127 vitreous body Anatomy 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to the technical field of soil reinforcement, and discloses an phosphogypsum composite soil curing agent with good curing performance, a preparation method thereof and derivative cured soil. The phosphogypsum composite soil curing agent is formed by mixing the following components in parts by mass: 20-30 parts of phosphogypsum, 18-33 parts of cement, 32-54 parts of slag and 3-7 parts of quicklime; when the phosphogypsum composite soil curing agent is used for curing the polluted silt, mixing and stirring the phosphogypsum composite soil curing agent with water and the polluted silt, and curing to obtain cured soil with the compressive strength of more than or equal to 2MPa; the addition amount of the pollution silt is 5-10 times of the mass of the phosphogypsum composite soil curing agent. The invention successfully solves the problem of treating phosphogypsum as pollution solid waste in the phosphating industry, and successfully cures heavy metal ions and pollution silt by using the curing agent with high curing performance, thereby preventing dust from flying to pollute air and water and soil polluted by heavy metal ions.
Description
Technical Field
The invention relates to the technical field of soil reinforcement, in particular to an phosphogypsum composite soil curing agent with good curing performance, a preparation method thereof and derivative cured soil.
Background
The phosphogypsum is rich in calcium sulfate dihydrate to replace natural gypsum, cement and other materials to be mixed again to prepare the soil curing agent, so that the phosphogypsum, the bentonite and other materials are used for curing the bentonite, waste materials such as the phosphogypsum and the bentonite are changed into valuable materials, the treatment cost of solid waste is reduced, the additional value of the solid waste is increased, and the effect of one stone and two birds is achieved, but the phosphogypsum contains P 2O5, free sulfuric acid and other impurities, and the mechanical properties of the cementing material are negatively influenced, so that the optimized curing agent mixing ratio is needed to be adopted, the soil curing agent with high curing performance prepared by the phosphogypsum can be fully utilized, and the performance of curing the polluted bentonite and heavy metal ions with high fluidity is improved.
The prior Chinese patent CN102531509B discloses phosphogypsum-based composite cementing material and a coagulant thereof, wherein the phosphogypsum, blast furnace slag powder, portland cement, limestone powder and quicklime are mixed according to the mass ratio of 34-48:35-42:4-10:6-16:2-6, the mixture is obtained by grinding, and high alumina cement or sodium metaaluminate is added as the coagulant to obtain the concrete with the compressive strength of more than 29MPa, so that the cost for producing cement is reduced to a certain extent, and the phosphogypsum is consumed in a large amount. However, this patent has the disadvantage that the contaminant cure properties of phosphogypsum set accelerators are further enhanced by the omission.
Disclosure of Invention
According to the condition that the curing performance of phosphogypsum curing pollutants needs to be improved in the prior art, the phosphogypsum composite soil curing agent with good curing performance is provided, has the performance of curing lead ions and pollution silt, consumes a large amount of phosphogypsum at the same time, achieves the curing effect of a rock and a bird, and has good mechanical property of cementing materials; the invention also provides a preparation method of the phosphogypsum composite soil curing agent with good curing performance, the prepared curing agent has the performance of curing lead ions and polluted silt, and consumes a large amount of phosphogypsum, so that the curing effect of a rock and a bird is achieved, and the curing soil with qualified mechanical properties is obtained; the invention also provides solidified soil prepared by using the phosphogypsum composite soil solidifying agent with good solidifying performance, which has the advantages of qualified mechanical property, solidifying a large amount of polluted silt and lead ions, and leaching the lead ions with the leaching concentration lower than 0.5mg/L; the invention also provides application of the solidified soil prepared by using the phosphogypsum composite soil solidifying agent with good solidifying performance in the field of construction, and the solidified soil has the advantages of qualified mechanical property, wide application range and low preparation cost.
The invention is realized by the following technical scheme:
The phosphogypsum composite soil curing agent with high curing performance is prepared by mixing the following components in parts by mass: 20-30 parts of phosphogypsum, 18-33 parts of cement, 32-54 parts of slag and 3-7 parts of quicklime; when the phosphogypsum composite soil curing agent is used for curing the polluted silt, mixing and stirring the phosphogypsum composite soil curing agent with water and the polluted silt, and curing to obtain cured soil with the compressive strength of more than or equal to 2MPa; the addition amount of the pollution silt is 5-10 times of the mass of the phosphogypsum composite soil curing agent.
Preferably, the polluted silt is silt polluted by one or more of heavy metal ions, radioactive pollutants, organic poisons, industrial oil and strong acid and alkali.
Preferably, the compound feed comprises the following components in parts by mass: 18-33 parts of cement, 32-54 parts of slag, 25% of phosphogypsum and 5% of quicklime.
Preferably, the compound feed comprises the following components in parts by mass: 18-33 parts of cement and 32-54 parts of slag, wherein the mass ratio of the cement to the slag is 4:6 or 3:7, phosphogypsum is 25% of the total mass of the solid, and quicklime is 5% of the total mass of the solid.
Preferably, when the phosphogypsum composite soil curing agent is used for curing polluted silt, the water addition amount is the mass of the phosphogypsum composite soil curing agent multiplied by the optimal water content, and the optimal water content is the water content corresponding to the maximum dry density of the cured soil.
Preferably, when the mass of lead ions in the solidified soil is lower than or equal to 12.5% of the mass of the phosphogypsum composite soil solidifying agent, the leaching concentration of the lead ions is lower than 0.5mg/L, and the compressive strength of the obtained solidified soil is reduced but is higher than or equal to 2MPa; the initial concentration of lead ions and the leaching concentration of lead ions are always positively correlated, the leaching process of lead ions from solidified soil is related to the compactness and the porosity of the solidified soil, and if the degree of communication among pores is too large, lead ions are easy to leach out and difficult to solidify.
The method for curing the polluted silt by using the phosphogypsum composite soil curing agent with high curing performance comprises the steps of mixing phosphogypsum, cement, slag and quicklime according to parts by mass, adding water according to the water adding amount which is 5-10 times of the mass of the phosphogypsum and the optimal water content, mixing and uniformly stirring, and curing under the room temperature environment with the humidity of 30% -60% to obtain the cured soil.
Preferably, the curing time is 14-32 d, and the curing temperature is 23-28 ℃.
A phosphogypsum composite soil curing agent with high curing performance or the cured soil prepared by the curing method.
Use of a solidified soil according to the above in a building.
The invention has the beneficial effects that:
(1) The invention successfully solves the problem of treating phosphogypsum as a polluted solid waste in the phosphating industry, adopts the physical and chemical properties of phosphogypsum and materials such as cement and the like to successfully solidify heavy metal ions and polluted silt, and prevents dust from flying to pollute air and water and soil.
(2) The phosphogypsum composite soil curing agent per unit mass can successfully cure the polluted silt with the mass of 5-10 times of the phosphogypsum composite soil curing agent per unit mass, and the compressive strength of the cured soil of the cured polluted silt is more than 2MPa.
(3) When the mass of lead ions in the solidified soil is lower than or equal to 12.5% of the mass of the phosphogypsum composite soil solidifying agent, the leaching concentration of the lead ions is lower than 0.5mg/L, and the reduction degree of the compressive strength of the obtained solidified soil is small and is more than or equal to 2MPa.
(4) When the adding amount of the phosphogypsum composite soil curing agent is increased, the curing time required for obtaining the cured soil with qualified mechanical properties is correspondingly shortened.
(5) The invention greatly improves the utilization value of phosphogypsum, expands the application range of phosphogypsum, prevents pollution, obtains the solidified soil with qualified mechanical properties, and has high market acceptability. (6) The invention has low total cost and simple preparation process, and is beneficial to large-scale industrialized popularization.
Drawings
FIG. 1 shows the effect of cement slag mass ratio as an independent variable on compressive strength.
FIG. 2 shows the effect of phosphogypsum addition on compressive strength at a fixed cement slag mass ratio.
Fig. 3 shows the optimum water content obtained when the phosphogypsum composite soil curing agent is used for curing polluted silt.
FIG. 4 shows the effect of the amount of the curing agent added on the strength loss rate when the amount of the curing agent added is an independent amount.
FIG. 5 shows the effect of curing age on compressive strength at fixed curing agent loading.
FIG. 6 shows the effect of the amount of hardener on the cleavage strength at different curing ages, with independent amounts.
FIG. 7 is a graph showing the effect of the amount of curative on the anti-compression modulus of resilience at various phosphogypsum levels.
Fig. 8 shows XRD patterns of the cured soil obtained at 28d curing age, fig. 8 (a) shows XRD patterns of the cured soil at 7 d curing age, and fig. 8 (b) shows XRD patterns of the cured soil at 28d curing age.
Fig. 9 shows a 10000-fold enlarged SEM image of the cured soil obtained with different phosphogypsum addition amounts and different curing agent addition amounts, in which fig. a) is 15% p0cs46 cured soil (7 d), fig. b) is 15% p0cs46 cured soil (28 d), fig. c) is 15% p25cs46 cured soil (7 d), fig. f) is 15% p25cs46 cured soil (28 d), fig. g) is 15% p45cs46 cured soil (7 d), and fig. h) is 15% p45cs46 cured soil (28 d).
Remarks: 15% P0CS46 is curing agent with 15% mixing amount, wherein the mixing amount of phosphogypsum in the curing agent is 0%, and the mass ratio of cement slag is 4:6;
5% P25CS46 is 5% of curing agent, wherein the mixing amount of phosphogypsum in the curing agent is 25%, and the mass ratio of cement slag is 4:6;
15% P25CS46 is curing agent with 15% mixing amount, wherein the mixing amount of phosphogypsum in the curing agent is 25%, and the mass ratio of cement slag is 4:6;
15% P45CS46 is curing agent with 15% mixing amount, wherein the mixing amount of phosphogypsum in the curing agent is 45%, and the mass ratio of cement slag is 4:6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following examples; it should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the invention; in the examples, all means used are conventional in the art unless otherwise specified; the terms "comprises," "comprising," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion; for example, a composition, step, method, article, or apparatus that comprises a list of elements may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus; in addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other; all experimental raw materials are commercial products.
Example 1
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 25 parts of phosphogypsum, 28 parts of cement, 42 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of phosphogypsum multiplied by 15.66%, adding pollution silt with the addition amount of 5.67 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50% to obtain the cured soil.
Example 2
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 25 parts of phosphogypsum, 21 parts of cement, 49 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, adding the pollution silt with the mass 5.67 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil.
Comparative example 1
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 25 parts of phosphogypsum, 7 parts of cement, 63 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of phosphogypsum multiplied by 15.66%, adding pollution silt with the water addition amount of 5.67 times of the mass of phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28d in a room temperature environment with the humidity of 50% to obtain the cured soil.
Comparative example 2
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 25 parts of phosphogypsum, 14 parts of cement, 56 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of phosphogypsum multiplied by 15.66%, adding pollution silt with the water addition amount of 5.67 times of the mass of phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28d under the room temperature environment with the humidity of 50% to obtain the cured soil.
Comparative example 3
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 25 parts of phosphogypsum, 35 parts of cement, 35 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, adding the pollution powder soil which is 5.67 times of the mass of the phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil.
Comparative example 4
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
mixing 25 parts of phosphogypsum, 42 parts of cement, 28 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, adding the pollution powder soil which is 5.67 times of the mass of the phosphogypsum curing agent, uniformly mixing and stirring, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil.
Example 3
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 20 parts of phosphogypsum, 22.5 parts of cement, 52.5 parts of slag and 5 parts of quicklime, adding water with the water addition amount of 15.66% of the mass of the phosphogypsum, adding pollution silt with the addition amount of 6.7 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50% to obtain the cured soil.
Example 4
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
mixing 20 parts of phosphogypsum, 30 parts of cement, 45 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, adding the pollution silt with the mass 5.67 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil.
Example 5
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
mixing 25 parts of phosphogypsum, 32 parts of cement, 48 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, adding the pollution silt with the mass which is 6.7 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil.
Example 6
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 5 parts of phosphogypsum, 36 parts of cement, 54 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of phosphogypsum multiplied by 15.66%, adding pollution silt with the addition amount of 6.7 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28d under the room temperature environment with the humidity of 50% to obtain the cured soil.
Example 7
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
15 parts of phosphogypsum, 32 parts of cement, 48 parts of slag and 5 parts of quicklime are mixed according to the mass parts of the water added into the phosphogypsum and the water added by 15.66%, the pollution silt is added into the phosphogypsum and the soil curing agent by 6.7 times of the phosphogypsum, the mixture is mixed and stirred uniformly, and the curing is carried out for 28 days under the room temperature environment with the humidity of 50%, so as to obtain the curing soil.
Comparative example 5
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 30 parts of phosphogypsum, 19.5 parts of cement, 45.5 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of 15.66% of the mass of the phosphogypsum, adding pollution silt with the addition amount of 5.67 times of the mass of the phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50% to obtain the cured soil.
Comparative example 6
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 35 parts of phosphogypsum, 24 parts of cement, 36 parts of slag and 5 parts of quicklime by mass, adding water with the water addition amount of 15.66% of the mass of the phosphogypsum, adding pollution powder soil with the water addition amount of 5.67 times of the mass of the phosphogypsum curing agent, uniformly mixing and stirring, and curing for 28d in a room temperature environment with the humidity of 50% to obtain the cured soil.
Comparative example 7
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
15 parts of phosphogypsum, 24 parts of cement, 56 parts of slag and 5 parts of quicklime are mixed according to the mass parts of the added water which is the mass of the phosphogypsum multiplied by 15.66%, the added amount of the pollution powder soil is 5.67 times of the mass of the phosphogypsum curing agent, and the mixture is uniformly mixed and stirred, and cured for 28 days under the room temperature environment with the humidity of 50% to obtain the curing soil.
Example 8
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 25 parts of phosphogypsum, 28 parts of cement, 42 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, wherein the water is mixed with lead nitrate, the mass of lead ions is 7.09 percent of the mass of the phosphogypsum curing agent, the addition of polluted silt is 5.67 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the cured soil. 15% of curing agent, 2.57MPa of compressive strength and 0.28mg/L of lead ion leaching concentration.
Example 9
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
mixing 25 parts of phosphogypsum, 28 parts of cement, 42 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, wherein the water is mixed with lead nitrate, the mass of lead ions is 8.38 percent of the mass of the phosphogypsum composite soil curing agent, the addition of the pollution powder soil is 6.7 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the curing soil. The curing agent has 13 percent of compressive strength of 2.44MPa and the lead ion leaching concentration is 0.31mg/L.
Example 10
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 25 parts of phosphogypsum, 28 parts of cement, 42 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, wherein the water is mixed with lead nitrate, the mass of lead ions is 10.13 percent of the mass of the phosphogypsum composite soil curing agent, the addition of the pollution powder soil is 8.1 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28 days in a room temperature environment with the humidity of 50 percent to obtain the curing soil. 11% of curing agent, 2.26MPa of compressive strength and 0.36mg/L of lead ion leaching concentration.
Example 11
The preparation method of the phosphogypsum composite soil curing agent derived cured soil with high curing performance comprises the following steps:
Mixing 25 parts of phosphogypsum, 21 parts of cement, 49 parts of slag and 5 parts of quicklime according to the mass of the phosphogypsum by 15.66 percent of water, wherein the water is mixed with lead nitrate, the mass of lead ions is 7.09 percent of the mass of the phosphogypsum composite soil curing agent, the addition of the pollution powder soil is 5.67 times of the mass of the phosphogypsum composite soil curing agent, mixing and stirring uniformly, and curing for 28d under the room temperature environment with the humidity of 50 percent to obtain the curing soil. 15% of curing agent, 2.27MPa of compressive strength and 0.33mg/L of lead ion leaching concentration.
Comparative example 8
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 25 parts of phosphogypsum, 28 parts of cement, 42 parts of slag and 5 parts of quicklime according to the mass ratio of the water added to the phosphogypsum multiplied by 15.66%, adding water with lead nitrate, wherein the mass ratio of lead ions to the phosphogypsum curing agent is 12.5%, adding pollution silt with the mass ratio of 10 times of the phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28d in a room temperature environment with the humidity of 50% to obtain the curing soil. 9% of curing agent, 1.84MPa of compressive strength and 0.42mg/L of lead ion leaching concentration.
Comparative example 9
The preparation method of phosphogypsum curing agent derived cured soil comprises the following steps:
Mixing 25 parts of phosphogypsum, 21 parts of cement, 49 parts of slag and 5 parts of quicklime according to the mass ratio of the water added to the phosphogypsum multiplied by 15.66%, adding water with lead nitrate, wherein the mass ratio of lead ions to the phosphogypsum curing agent is 12.5%, adding pollution silt with the mass ratio of 10 times of the phosphogypsum curing agent, mixing and stirring uniformly, and curing for 28d in a room temperature environment with the humidity of 50% to obtain the curing soil. 9% of curing agent, 1.71MPa of compressive strength and 0.49mg/L of lead ion leaching concentration.
The cured soil performance data obtained for each of the above examples and comparative examples are shown in tables 1 and 2:
Table 1 data of examples and comparative examples without lead nitrate
Table 2 data of examples and comparative examples in which lead nitrate was added
As shown in Table 1, the compressive strength of examples 1 to 7 is more than 3MPa, and the compressive strength of comparative examples 1 to 7 is less than 3MPa, which means that the mechanical properties of the obtained solidified soil are determined by the addition amount of phosphogypsum, the mass ratio of cement and slag, the mass ratio of the solidified contaminated silt is 5.67 to 6.7 times, the mass ratio of phosphogypsum composite soil curing agent is 13 to 15 percent of the total solid mass ratio, and the obtained solidified soil can be stabilized above 3MPa within the range; the contaminated silts cured up to 10 times as compared to comparative examples 8 and 9 of Table 2, while the compressive strength was significantly reduced compared to examples 8 to 11, in which lead nitrate was also added, so that it was found that the curing of the contaminated silts resulted in a reduction in the mechanical strength of the cured soil, and as shown in Table 2, the addition of lead nitrate in example 8 reduced the compressive strength by 26.4% compared to example 1in Table 1, thereby indicating that the cured lead ions reduced the mechanical strength of the cured soil; however, the lead leaching concentrations of examples 8 to 11 and comparative examples 8 and 9 were kept stable below 0.5mg/L all the time, and it was found that the present invention solidified heavy metal ions and was remarkable in the effect of preventing leaching of heavy metal ions.
As shown in FIG. 1, the compression strength of the solidified soil obtained between cement and slag at mass ratios of (3:7) to (4:6) was the highest.
As shown in figure 2, the phosphogypsum doping amount is between 20% and 30%, so that the compression strength of the solidified soil is the highest, and the longer the time is, the higher the compression strength of the solidified soil is.
As shown in FIG. 3, the optimal water content is obtained according to the highest dry density value after the mixture ratio and the mixing amount of the curing agent are fixed and the polluted silt is added.
As shown in FIG. 4, the effect of phosphogypsum content and the amount of the curing agent on the strength loss rate. Since the more the contaminated silt is added, the strength of the solidified soil is lost, and fig. 3 shows that the strength loss rate of the resulting solidified soil due to the contaminated silt is the lowest, by 15% of the amount of the solidifying agent, 25% of the amount of phosphogypsum in the solidifying agent, and the mass ratio of cement slag 3:7.
As shown in FIG. 5, the mixing amount of the curing agent is 15%, the mixing amount of phosphogypsum in the curing agent is 25%, and when the mass ratio of the cement slag is 4:6, the compressive strength rises to more than 3MPa at the highest speed, and the mixing amount of the curing agent is in direct proportion to the rising speed of the compressive strength along with the curing age.
As shown in fig. 6, the cleavage strength increases with an increase in the amount of the curing agent, and the amount of the curing agent added is 15%, the amount of phosphogypsum added in the curing agent is 25%, and the cement slag mass ratio is 4:6, the cleavage strength is highest at the later stage of the curing age.
As shown in FIG. 7, the amount of the curing agent added was increased, the compression modulus of elasticity was increased, and the compression modulus of elasticity was generally highest when the cement slag mass ratio was 4:6 at 25% of the amount of the curing agent added.
As shown in FIG. 8, FIG. 8 (a) shows XRD patterns of cured soil at the curing age of 7 days, and FIG. 8 (b) shows XRD patterns of cured soil at the curing age of 28 days, wherein each set of cured soil samples has larger quartz and mica peak values, the maximum peak value is the mixing amount of 5% of the curing agent, the mixing amount of phosphogypsum in the curing agent is 25%, the mass ratio of cement to slag is 4:6, the proportion of polluted silt in the cured soil is large, quartz and mica in the silt are main components, and the peak value of quartz and mica obviously increases as the curing agent is fewer; as the age grows, the peak values of C-S-H and ettringite increase, and the peak value of quartz becomes smaller gradually. CaO in the curing agent reacts with water to generate Ca (OH) 2, an alkaline environment is provided to activate the activity of the vitreous bodies such as calcium oxide, silicon dioxide, aluminum oxide and the like in slag, and Ca 2+ and acid radical ions are decomposed to form hydrated calcium silicate gel; meanwhile, ca (OH) 2 soil particles generated by hydration react with a large amount of SiO2 existing in slag to generate C-S-H gel, so that the strength of the pollution powder is effectively improved. Compared with the curing agent without phosphogypsum, the 45% of the mixing amount of phosphogypsum is more than the peak of the semi-hydrated CaSO 4 and the peak of the dihydrate CaSO 4, and the peak of the C-S-H and the ettringite is lower, mainly because the former phosphogypsum is 45%, the phosphogypsum is excessive, the cement and slag are less, and the generated hydration products are less, so that excessive phosphogypsum is unreacted and remains in the cured soil.
As shown in fig. 9, as the curing age increases, hydration products penetrate into the interstices of the silt particles and bind with the soil particles, and the interstices between the silt particles at the 28d age are significantly less than those at the 7d age. Comparing the solidified soil with 5% and 15% of the solidifying agent, it is known that the larger the solidifying agent, the more hydrated product, the more various materials are connected into a whole, the bigger the contact surface between the particles, and the less the existence of the pores and cracks. The microstructure with the mixing amount of the solidified soil being 15% is more compact than 5%, and is the reason that the strength of the solidified soil is improved along with the increase of the mixing amount.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention, and it is intended to cover in the appended claims the protection of this invention as defined by the claims.
Claims (9)
1. The phosphogypsum composite soil curing agent with high curing performance is characterized by comprising the following components in parts by mass: 20-30 parts of phosphogypsum, 18-33 parts of cement, 32-54 parts of slag and 3-7 parts of quicklime; when the phosphogypsum composite soil curing agent is used for curing the polluted silt, mixing and stirring the phosphogypsum composite soil curing agent with water and the polluted silt, and curing to obtain cured soil with the compressive strength of more than or equal to 2MPa; the addition amount of the pollution silt is 5-10 times of the mass of the phosphogypsum composite soil curing agent.
2. The phosphogypsum composite soil curing agent with high curing performance according to claim 1, which is characterized by comprising the following components in parts by mass: 18-33 parts of cement, 32-54 parts of slag, 25% of phosphogypsum and 5% of quicklime.
3. The phosphogypsum composite soil curing agent with high curing performance according to claim 1, which is characterized by comprising the following components in parts by mass: 18-33 parts of cement and 32-54 parts of slag, wherein the mass ratio of the cement to the slag is 4:6 or 3:7, phosphogypsum is 25% of the total mass of the solid, and quicklime is 5% of the total mass of the solid.
4. The phosphogypsum composite soil curing agent with high curing performance according to claim 1, wherein when the phosphogypsum composite soil curing agent is used for curing polluted silt, the water addition amount is the mass of the phosphogypsum curing agent multiplied by the optimal water content, and the optimal water content is the water content corresponding to the maximum dry density of the cured soil.
5. The phosphogypsum composite soil curing agent with high curing performance according to claim 1, wherein when the mass of lead ions contained in the cured soil is less than or equal to 12.5% of the mass of the phosphogypsum composite soil curing agent, the leaching concentration of the lead ions is less than 0.5mg/L, and the compressive strength of the obtained cured soil is reduced but is greater than or equal to 2MPa.
6. A curing method for curing pollution silt by using the phosphogypsum composite soil curing agent with high curing performance according to any one of claims 1 to 5 is characterized in that phosphogypsum, cement, slag and quicklime are mixed according to parts by mass, water is added according to the mass of the phosphogypsum multiplied by the optimal water content, the adding amount of the pollution silt is 5 to 10 times of the mass of the phosphogypsum composite soil curing agent, the mixture is uniformly mixed and stirred, and the curing is carried out under the room temperature environment with the humidity of 30 to 60 percent to obtain the curing soil.
7. The curing method according to claim 5, wherein the curing time is 14 to 32d and the curing temperature is 23 to 28 ℃.
8. A solidified soil prepared using the phosphogypsum composite soil solidifying agent with high solidifying performance according to any one of claims 1 to 5 or the solidifying method according to claim 6 or 7.
9. Use of the solidified soil according to claim 8 in the field of construction.
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