CN113860792B - Magnesium oxychloride cement modifier, preparation method thereof and magnesium oxychloride cement - Google Patents
Magnesium oxychloride cement modifier, preparation method thereof and magnesium oxychloride cement Download PDFInfo
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- CN113860792B CN113860792B CN202111188643.XA CN202111188643A CN113860792B CN 113860792 B CN113860792 B CN 113860792B CN 202111188643 A CN202111188643 A CN 202111188643A CN 113860792 B CN113860792 B CN 113860792B
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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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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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
- C04B28/30—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 magnesium cements or similar cements
- C04B28/32—Magnesium oxychloride cements, e.g. Sorel cement
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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
- 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
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- 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
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Abstract
The invention discloses a magnesium oxychloride cement modifier, a preparation method thereof and magnesium oxychloride cement, wherein the magnesium oxychloride cement modifier comprises the following raw materials in percentage by mass: 18 to 25 percent of citric acid, 41 to 49 percent of ferrous sulfate, 28 to 38 percent of urea-formaldehyde resin emulsion and 0.1 to 0.5 percent of ammonium chloride. In the invention, 18-25% of citric acid, 41-49% of ferrous sulfate, 28-38% of urea-formaldehyde resin emulsion and 0.1-0.5% of ammonium chloride are cooperatively matched and added into a magnesium oxychloride cement solidified sludge system, so that the magnesium oxychloride cement solidified sludge system is jointly promoted to form a more compact structure, and the structural stability is enhanced. The strength and the water resistance of the magnesium oxychloride cement solidified sludge system are obviously improved, and the service life of the magnesium oxychloride cement solidified sludge system under extreme conditions is prolonged.
Description
Technical Field
The invention relates to the technical field of cement modification, in particular to a magnesium oxychloride cement modifier, a preparation method thereof and magnesium oxychloride cement.
Background
Along with the development of social progress and scientific technology, a large amount of dredging sludge is generated in industrial production and environmental protection engineering, and the sludge is difficult to be directly used as engineering filling soil in road engineering and anti-lifting engineering due to the characteristics of high water content, low strength, high compressibility, high organic matter content and the like. With the rapid development of the building industry, the use of a large amount of traditional Portland cement causes certain pollution to the environment, and the utilization rate of a large amount of industrial solid wastes is lower, so that resource waste and environmental pollution are caused. In order to reduce environmental pollution and improve the utilization rate of industrial solid waste, development of novel cement for the field of sludge solidification by using industrial solid waste becomes a research focus.
Magnesium oxychloride cement is a special cement invented by French Sorel in 1867, so that it is also called Sorel cement, uses magnesium oxide as main component, and has the advantages of quick setting, low cost and less pollution, etc. it is concerned by people, and is extensively used as building decorative material and roadbed concrete, etc.. However, the existing magnesium oxychloride cement has poor water resistance, and has durability failure in the use process, thus influencing the service life; in addition, some magnesium oxychloride cements are not strong. Therefore, the magnesium oxychloride curing system with good water resistance is researched and developed, and the defects of the magnesium oxychloride curing system can be overcome to play engineering properties and expand application fields.
Therefore, how to prepare a magnesium oxychloride cement modifier capable of improving the water resistance and strength of the magnesium oxychloride cement becomes a technical problem in the art.
Disclosure of Invention
The invention aims to provide a magnesium oxychloride cement modifier which can improve the water resistance and strength of magnesium oxychloride cement and prolong the service life of a magnesium oxychloride cement curing system under extreme conditions such as soaking and the like.
The invention adopts the following technical scheme:
in a first aspect of the present invention, there is provided a magnesium oxychloride cement modifier, the magnesium oxychloride cement modifier comprising, in mass fraction, raw materials: 18 to 25 percent of citric acid, 41 to 49 percent of ferrous sulfate, 28 to 38 percent of urea-formaldehyde resin emulsion and 0.1 to 0.5 percent of ammonium chloride.
Further, the magnesium oxychloride cement modifier comprises the following raw materials in percentage by mass: citric acid: 25% of ferrous sulfate: 41%, urea-formaldehyde resin emulsion: 33.7 percent of ammonium chloride: 0.3%.
Further, the magnesium oxychloride cement modifier comprises the following raw materials in percentage by mass: citric acid: 18%, ferrous sulfate: 49%, urea-formaldehyde resin emulsion: 32.9% of ammonium chloride: 0.1%.
Further, the magnesium oxychloride cement modifier comprises the following raw materials in percentage by mass: citric acid: 19.5 percent of ferrous sulfate: 42%, urea-formaldehyde resin emulsion: 38%, ammonium chloride: 0.5%.
Further, the magnesium oxychloride cement modifier comprises the following raw materials in percentage by mass: citric acid: 23.7 percent of ferrous sulfate: 48%, urea-formaldehyde resin emulsion: 28%, ammonium chloride: 0.3%.
Further, the citric acid is technical grade citric acid.
Further, the ferrous sulfate is ferrous sulfate heptahydrate.
Further, the urea-formaldehyde resin emulsion is urea-formaldehyde resin with the solid content of 60-65wt%.
In a second aspect of the present invention, there is provided a method of preparing a magnesium oxychloride cement modifier, the method comprising: and uniformly mixing the raw materials of the magnesium oxychloride cement modifier according to the weight ratio to obtain the magnesium oxychloride cement modifier.
In a third aspect of the present invention, there is provided a magnesium oxychloride cement comprising, in weight fractions:
100 parts of silt soil;
5-7 parts of magnesium oxide;
3-5 parts of magnesium chloride;
0.15 to 0.5 portion of magnesium oxychloride cement modifier.
One or more technical solutions in the embodiments of the present invention at least have the following technical effects or advantages:
1. according to the magnesium oxychloride cement modifier provided by the invention, 18-25% of citric acid, 41-49% of ferrous sulfate, 28-38% of urea resin emulsion and 0.1-0.5% of ammonium chloride are cooperatively matched and added into a magnesium oxychloride cement curing sludge system, so that the magnesium oxychloride cement curing sludge system is jointly promoted to form a more compact structure, and the structural stability is enhanced. The strength and the water resistance of the magnesium oxychloride cement solidified sludge system are obviously improved, and the service life of the magnesium oxychloride cement solidified sludge system under extreme conditions is prolonged.
2. The magnesium oxychloride cement provided by the invention, the modifier is doped, so that the negative influence of a single modifier on an MOC curing system is weakened through a series of physical and chemical effects, the strength development of the MOC curing system in a standard curing period is comprehensively improved, and the problem that the magnesium oxychloride material is poor in water resistance in a water-immersed and humid environment is solved. The strength development and the water resistance of the cured system in the standard curing process are obviously improved, the strength retention coefficient of the sample is 85% after the sample is continuously immersed in water for 28 days, the service life is prolonged, and the application range of the cured system is widened.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows unconfined compressive strengths of magnesium oxychloride solidified sludge samples obtained in comparative example 1 and examples 1-3 after natural curing for 7 days, 28 days and submerged curing for 7 days, 28 days;
FIG. 2 is a graph showing the retention factor of the strength of a magnesium oxychloride solidified sludge sample at 7 days and 28 days of immersion in water for comparative example 1 and examples 1 to 3;
FIG. 3 is a SEM comparison of magnesium oxychloride cured sludge after 28 days of standard curing and 28 days of submerged curing of comparative example 1 and example 1; wherein: fig. 3 (a) shows the result of standard curing of the sample of comparative example 1 for 28 days, fig. 3 (b) shows the result of soaking the sample of comparative example 1 for 28 days, fig. 3 (c) shows the result of standard curing of the sample of example 1 for 28 days, and fig. 3 (d) shows the result of soaking the sample of example 1 for 28 days.
Detailed Description
The advantages and various effects of the present invention will be more clearly apparent from the following detailed description and examples. It will be understood by those skilled in the art that these specific embodiments and examples are intended to illustrate the invention, not to limit the invention.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification will control.
Unless specifically indicated otherwise, the various raw materials, reagents, instruments, equipment, etc., used in the present invention are commercially available or may be obtained by existing methods.
The technical scheme of the embodiment of the application aims to solve the technical problems, and the overall thought is as follows:
according to an exemplary embodiment of the present invention, there is provided a magnesium oxychloride cement modifier, the raw materials of which include, in mass percentages: 18 to 25 percent of citric acid, 41 to 49 percent of ferrous sulfate, 28 to 38 percent of urea-formaldehyde resin emulsion and 0.1 to 0.5 percent of ammonium chloride.
In the invention, 18-25% of citric acid, 41-49% of ferrous sulfate, 28-38% of urea resin emulsion and 0.1-0.5% of ammonium chloride are cooperatively matched and added into a magnesium oxychloride cement solidified sludge system, so that the magnesium oxychloride cement solidified sludge system is jointly promoted to form a more compact structure, and the structural stability is enhanced. The strength and the water resistance of the magnesium oxychloride cement solidified sludge system are obviously improved, and the service life of the magnesium oxychloride cement solidified sludge system under extreme conditions is prolonged. Specifically:
citric acid 18-25%, and citric acid ion group is adsorbed on magnesium oxide surface to form CA n -→Mg(OH)(H 2 O) x-1 The group plays a role in retarding, inhibits early hydration reaction of magnesium oxide in the system and reduces Mg (OH) in the system 2 The amount of the produced needle-like 5-phase structure is changed into a plate-like structure, and [ CA n- →Mg(OH)(H 2 O) x-1 ]The group can still generate 5-phase crystals, so that the later strength of the system is improved. Therefore, the citric acid plays a role in retarding the composite modifier to inhibit the strength development, simultaneously enhances the strength development of the system in the later period of maintenance, and simultaneously improves the water resistance through influencing the appearance of 5 phases and the generation amount of 5 phases in the system. If the mass fraction of the citric acid is less than 18%, the adverse effects of limited formation of coordination bonds and coordination structures which participate in the reaction to generate 5-phase crystals are caused; if the mass fraction of the citric acid is more than 25%, the adverse effects of obviously prolonging the setting and hardening time, reducing the alkalinity of a system and further inhibiting the generation and development of 5 phases are achieved;
ferrous sulfate 41-49%, sulfurous acidIron generates Fe (OH) in the system 3 The gel structure and the M/C-S-H-Cl gel can block pores and capillary channels, and improve water resistance. The gel structure generated in early maintenance and MOC hydration product together play a role in improving strength, so that the influence of citric acid on the early strength development of the system can be reduced, the early strength development is enhanced, meanwhile, the generated gel structure fills pores through physical action, the penetration erosion channel of water is reduced, the water resistance of the system is further improved, but the generated gel structure consumes OH in the system - Is unfavorable for the generation of the later-stage 5-phase crystal and weakens the strength of the later curing stage. If the mass fraction of the ferrous sulfate is less than 41%, the gel generation amount is insufficient to effectively seal pores and wrap crystals; if the mass fraction of the ferrous sulfate is more than 49%, the system alkalinity is deeply reduced, mgO is coated, and the adverse effect of 5-phase generation is hindered;
28-38% of urea-formaldehyde resin emulsion, wherein urea-formaldehyde resin polymer has good diffusion and uniform distribution properties through ammonium chloride excitation activity, and is synergistically agglomerated and wrapped with gel products generated by ferrous sulfate to play a role of hardening and crosslinking, and the strength of the system is jointly improved together with 5 phases, and meanwhile, the urea-formaldehyde resin polymer can wrap 5 phases of crystals to form a hydrophobic protection layer, reduce contact of chloride ions and water, and improve water resistance. If the mass fraction of the urea resin emulsion is less than 28%, the hardening effect is limited and the 5-phase generation rate is low; if the mass fraction of ammonium chloride is more than 38%, the water absorption of the ammonium chloride reduces the content of free water in the sample, which has the adverse effect of preventing the chemical reaction from proceeding continuously;
ammonium chloride 0.1-0.5%, which fully excites the activity of urea-formaldehyde resin polymer to improve Mg in the system 2+ More 5 phases are generated by concentration, and extra chloride ions are provided for the magnesium oxychloride cement system to participate in complexation and hydroxylation reaction, so that the cross lapping growth of crystals is promoted, and a net structure with stronger cohesive force and binding force is formed. If the mass fraction of ammonium chloride is less than 0.1%, the adverse effect of limited number of participating reaction ions is provided; if the mass fraction of the ammonium chloride is more than 0.5%, the system alkalinity is excessively reduced, and the generation of a cementing product is influenced;
in conclusion, the components are matched in a synergistic way, the synergistic effect is enhanced, and the strength and the water resistance of the magnesium oxychloride cement curing sludge system are obviously improved.
As an alternative embodiment, the magnesium oxychloride cement modifier comprises the following raw materials in mass percent: citric acid: 25% of ferrous sulfate: 41%, urea-formaldehyde resin emulsion: 33.7 percent of ammonium chloride: 0.3%.
As an alternative embodiment, the magnesium oxychloride cement modifier comprises the following raw materials in mass percent: citric acid: 18%, ferrous sulfate: 49%, urea-formaldehyde resin emulsion: 32.9% of ammonium chloride: 0.1%.
As an alternative embodiment, the magnesium oxychloride cement modifier comprises the following raw materials in mass percent: citric acid: 19.5 percent of ferrous sulfate: 42%, urea-formaldehyde resin emulsion: 38%, ammonium chloride: 0.5%.
As an alternative embodiment, the magnesium oxychloride cement modifier comprises the following raw materials in mass percent: citric acid: 23.7 percent of ferrous sulfate: 48%, urea-formaldehyde resin emulsion: 28%, ammonium chloride: 0.3%.
In the technical scheme, the citric acid is industrial grade citric acid. The ferrous sulfate is ferrous sulfate heptahydrate. The urea-formaldehyde resin is urea-formaldehyde resin with the solid content of 60-65wt%. The raw materials are all available through purchase.
According to another exemplary embodiment of the present invention, there is provided a method for preparing a magnesium oxychloride cement modifier, the method comprising: and uniformly mixing the magnesium oxychloride cement modifier raw materials according to the weight ratio to obtain the magnesium oxychloride cement modifier.
According to another exemplary embodiment of the present invention, there is provided a magnesium oxychloride cement, which includes, in weight fractions:
100 parts of silt soil;
5-7 parts of magnesium oxide;
3-5 parts of magnesium chloride;
0.15 to 0.5 portion of magnesium oxychloride cement modifier.
The adoption of the proportion can obviously improve the strength and the water resistance of the magnesium oxychloride cement solidified sludge system and prolong the service life of the magnesium oxychloride cement solidified sludge system under extreme conditions. The negative influence of a single modifier on the MOC curing system is weakened by the incorporation of the composite modifier through series of physical and chemical effects, the strength development of the MOC curing system in the standard curing period is comprehensively improved, and the problem of poor water resistance of the magnesium oxychloride material in the immersed and humid environment is solved. The strength development and the water resistance of the cured system in the standard curing process are obviously improved, the strength retention coefficient of the sample is 85% after the sample is continuously immersed in water for 28 days, the service life is prolonged, and the application range of the cured system is widened.
As a preferred embodiment, the magnesium oxychloride cement is 10 parts.
The preparation method comprises mixing the above materials.
A magnesium oxychloride cement modifier of the present application will be described in detail below with reference to examples, comparative examples and experimental data.
Example 1
The following weight proportions of 25% citric acid, 41% ferrous sulfate, 33.7% urea-formaldehyde resin emulsion and 0.3% ammonium chloride are weighed to prepare modifier, the modifier is sequentially added into silt soil and fully stirred uniformly, magnesium oxychloride cement (comprising magnesium oxide and magnesium chloride and the same as the following) with the proportions shown in table 1 is then mixed for curing, an unconfined compressive strength test is carried out after curing to the corresponding age, a continuous soaking test is carried out after standard curing for 28 days, a strength test is carried out after the corresponding age, and a strength retention coefficient is calculated.
When the mixing amount of the modifier is 3% of the mass of magnesium oxide in the curing agent, the standard curing strength is 1.45MPa in 7 days and 1.70MPa in 28 days. The strength after 7 days of soaking is 1.47MPa, the strength retention coefficient is 86.5%, the strength after 28 days of soaking is 1.40MPa, and the strength retention coefficient is 82.3%.
When the mixing amount of the modifier is 5% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.51MPa and 28 days with the strength of 1.80MPa. The strength after 7 days of soaking is 1.59MPa, the strength retention coefficient is 88.4%, the strength after 28 days of soaking is 1.54MPa, and the strength retention coefficient is 85.6%.
Example 2
The following weight proportions of 18% citric acid, 49% ferrous sulfate, 32.9% urea-formaldehyde resin emulsion and 0.1% ammonium chloride are weighed to prepare modifier, the modifier is sequentially added into silt soil and fully and uniformly stirred, magnesium oxychloride cement with the proportion shown in table 1 is then mixed for curing, an unconfined compressive strength test is carried out after curing to a corresponding age, a continuous soaking test is carried out after standard curing for 28 days, a strength test is carried out after the corresponding age, and a strength retention coefficient is calculated.
When the mixing amount of the modifier is 3% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.55MPa and 28 days with the strength of 1.65MPa. The strength after 7 days of immersion was 1.44MPa, the strength retention factor was 87.3%, the strength after 28 days of immersion was 1.37MPa, and the strength retention factor was 83.0%.
When the mixing amount of the modifier is 5% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.60MPa and 28 days with the strength of 1.73MPa. The strength after 7 days of soaking is 1.55MPa, the strength retention coefficient is 89.6%, the strength after 28 days of soaking is 1.45MPa, and the strength retention coefficient is 83.8%.
Example 3
The following weight proportions of 19.5% citric acid, 42% ferrous sulfate, 38% urea-formaldehyde resin emulsion and 0.5% ammonium chloride are weighed to prepare modifier, the modifier is sequentially added into silt soil and fully and uniformly stirred, magnesium oxychloride cement with the proportion shown in table 1 is then mixed for curing, an unconfined compressive strength test is carried out after curing to a corresponding age, a continuous soaking test is carried out after standard curing for 28 days, a strength test is carried out after the corresponding age, and a strength retention coefficient is calculated.
When the mixing amount of the modifier is 3% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.50MPa and 28 days with the strength of 1.67MPa. The strength after 7 days of soaking is 1.40MPa, the strength retention coefficient is 84%, the strength after 28 days of soaking is 1.30MPa, and the strength retention coefficient is 78.4%.
When the mixing amount of the modifier is 5% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.56MPa and 28 days with the strength of 1.78MPa. The strength after 7 days of soaking is 1.51MPa, the strength retention coefficient is 84.8%, the strength after 28 days of soaking is 1.43MPa, and the strength retention coefficient is 80.3%.
Example 4
The following weight proportions of 19.5% citric acid, 42% ferrous sulfate, 38% urea-formaldehyde resin emulsion and 0.5% ammonium chloride are weighed to prepare modifier, the modifier is sequentially added into silt soil and fully and uniformly stirred, then magnesium oxychloride cement with the proportion shown in table 1 is cured, an unconfined compressive strength test is carried out after curing to a corresponding age, a continuous soaking test is carried out after standard curing for 28 days, a strength test is carried out after the corresponding age, and a strength retention coefficient is calculated.
When the mixing amount of the modifier is 3% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.52MPa and 28 days with the strength of 1.65MPa. The strength after 7 days of soaking is 1.42MPa, the strength retention coefficient is 84.1%, the strength after 28 days of soaking is 1.35MPa, and the strength retention coefficient is 78.6%.
When the mixing amount of the modifier is 5% of the mass of magnesium oxide in the curing agent, the standard curing is carried out for 7 days with the strength of 1.54MPa and 28 days with the strength of 1.71MPa. The strength after 7 days of soaking is 1.50MPa, the strength retention coefficient is 84.3%, the strength after 28 days of soaking is 1.41MPa, and the strength retention coefficient is 80.1%.
Comparative example 1
In the comparative example, no magnesium oxychloride cement modifier is added, specifically: and (3) mixing magnesium oxychloride cement accounting for 10% of the mass of the silt, curing, fully and uniformly stirring, curing to the corresponding age, carrying out an unconfined compressive strength test, carrying out a continuous soaking test after standard curing for 28 days, carrying out a strength test after the corresponding age, and calculating a strength retention coefficient.
Standard curing is carried out for 7 days with the strength of 1.37MPa and 28 days with the strength of 1.54MPa. The strength after 7 days of soaking is 1.21MPa, the strength retention coefficient is 78.5%, the strength after 28 days of soaking is 1.00MPa, and the strength retention coefficient is 64.9%.
Comparative example 2
In this comparative example, a magnesium oxychloride cement modifier is provided, excluding citric acid; the other steps were the same as in example 1.
Comparative example 3
In this comparative example, a magnesium oxychloride cement modifier is provided, excluding ferrous sulfate; the other steps were the same as in example 1.
Comparative example 4
In this comparative example, a magnesium oxychloride cement modifier is provided that does not include a urea formaldehyde resin emulsion; the other steps were the same as in example 1.
Comparative example 5
In this comparative example, a magnesium oxychloride cement modifier is provided, excluding ammonium chloride; the other steps were the same as in example 1.
Comparative example 6
In this comparative example, the components providing a magnesium oxychloride cement modifier comprise, in mass percent: 30% citric acid, 30% ferrous sulfate, 39% urea formaldehyde resin emulsion, 1% ammonium chloride.
Comparative example 7
In this comparative example, the components providing a magnesium oxychloride cement modifier comprise, in mass percent: 13% citric acid, 65% ferrous sulfate, 21.95% urea formaldehyde resin emulsion, 0.05% ammonium chloride.
Experimental example 1
Curing the magnesium oxychloride solidified sludge samples of each example and each comparative example to the corresponding age to develop an unconfined compressive strength test, carrying out a continuous water immersion test after standard curing for 28 days, carrying out a strength test after the corresponding age, and calculating a strength retention coefficient. The compressive strength of magnesium oxychloride solidified sludge samples immersed in water for 7 days and 28 days after natural curing for 28 days was measured respectively. And (3) adopting a WDW-50kN microcomputer to control an electronic universal testing machine, and setting the loading rate to be 1mm/min for testing.
The magnesium oxychloride cement modifier formulations of the examples and the comparative examples are shown in table 1, and the compressive strengths and strength coefficients measured for the magnesium oxychloride cements of the examples and the comparative examples are shown in table 2. Wherein the intensity retention factor is calculated by:
wherein: p (P) n Softening coefficient after immersing the sample in water n d
U 0 The compressive strength average value (MPa) of the sample at 28d of standard curing
U n Compressive strength after immersing the sample in water n dDegree average value (MPa)
TABLE 1
TABLE 2
As can be seen from the data in table 2:
in comparative example 1, the compressive strength and water resistance of the test sample were low without adding the magnesium oxychloride cement modifier of the present invention;
in comparative example 2, the magnesium oxychloride cement modifier has the defect of low long-term strength of the sample without adding citric acid;
in comparative example 3, the magnesium oxychloride cement modifier has the defect of low early strength because ferrous sulfate is not added;
in comparative example 4, the magnesium oxychloride cement modifier has the defect of poor water resistance because urea resin emulsion is not added;
in comparative example 5, the magnesium oxychloride cement modifier has the defects of slow strength development and low water resistance because ammonium chloride is not added;
in comparative example 6, the ratio of each component of the magnesium oxychloride cement modifier is out of the range of the invention, and the sample has the defects of lower strength and poor water resistance;
in comparative example 7, the magnesium oxychloride cement modifier has the defects of lower strength and poor water resistance of the sample because the proportion of each component is out of the range of the invention;
examples 1-4 the compressive strength of magnesium oxychloride solidified sludge samples immersed for 7 days, 28 days and 28 days after natural curing were higher than that of comparative example, and the retention coefficient of strength was higher than that of comparative example 1, indicating that the use of the modifier of the present example can significantly improve water resistance.
It can be seen from the above that:
comparative example 2-comparative example 5 as compared with example 1 of the present invention, the components of citric acid, ferrous sulfate, urea-formaldehyde resin emulsion and ammonium chloride are synergistically combined and added into the magnesium oxychloride cement curing sludge system to jointly promote the remarkable improvement of the strength and the water resistance of the magnesium oxychloride cement curing sludge system, thereby producing a synergistic effect.
Comparative example 6-comparative example 7 it is known that, in comparison with example 1 of the present invention, any one of the components of citric acid, ferrous sulfate, urea resin emulsion and ammonium chloride is out of the range of the examples of the present invention (18 to 25% of citric acid, 41 to 49% of ferrous sulfate, 28 to 38% of urea resin emulsion and 0.1 to 0.5% of ammonium chloride), it is difficult to produce a good synergistic effect.
Description of the drawings:
FIG. 1 shows the compressive strength of magnesium oxychloride solidified sludge samples of comparative example 1 and examples 1 to 3 after natural curing for 7 days, 28 days and 28 days after natural curing for 7 days and 28 days after soaking. The compressive strength of the modified samples obtained from FIG. 1 was higher than that of comparative example 1.
FIG. 2 shows the retention coefficients of the strength of the magnesium oxychloride solidified sludge samples prepared in comparative example 1 and examples 1 to 3, and from the graph, it can be seen that the water resistance of examples 1 to 3 is higher than that of comparative example 1, indicating that the use of the composite modifier can significantly improve the water resistance.
FIG. 3 is a SEM comparison of the magnesium oxychloride solidified sludge after 28 days of standard curing and 28 days of submerged curing of comparative example 1 and example 1. As can be seen from FIG. 3, the modified sample produced more crystals during curing and had a well developed morphology; after soaking, the modified sample has relatively less crack structure and retains more plate-like 5-phase crystals, thus showing good retention coefficient of strength.
Finally, it is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (7)
1. The magnesium oxychloride cement modifier is characterized by comprising the following raw materials in percentage by mass: 18-25% of citric acid, 41-49% of ferrous sulfate, 28-38% of urea-formaldehyde resin emulsion and 0.1-0.5% of ammonium chloride; the citric acid is industrial grade citric acid, the ferrous sulfate is ferrous sulfate heptahydrate, and the urea-formaldehyde resin emulsion is urea-formaldehyde resin with solid content of 60% -65%.
2. The magnesium oxychloride cement modifier according to claim 1, wherein the raw materials of the magnesium oxychloride cement modifier comprise, in mass fraction: citric acid: 25% of ferrous sulfate: 41%, urea-formaldehyde resin emulsion: 33.7 percent of ammonium chloride: 0.3%.
3. The magnesium oxychloride cement modifier according to claim 1, wherein the raw materials of the magnesium oxychloride cement modifier comprise, in mass fraction: citric acid: 18%, ferrous sulfate: 49%, urea-formaldehyde resin emulsion: 32.9% of ammonium chloride: 0.1%.
4. The magnesium oxychloride cement modifier according to claim 1, wherein the raw materials of the magnesium oxychloride cement modifier comprise, in mass fraction: citric acid: 19.5 percent of ferrous sulfate: 42%, urea-formaldehyde resin emulsion: 38%, ammonium chloride: 0.5%.
5. The magnesium oxychloride cement modifier according to claim 1, wherein the raw materials of the magnesium oxychloride cement modifier comprise, in mass fraction: citric acid: 23.7 percent of ferrous sulfate: 48%, urea-formaldehyde resin emulsion: 28%, ammonium chloride: 0.3%.
6. A method of preparing the magnesium oxychloride cement modifier of any one of claims 1 to 5, wherein the method comprises: uniformly mixing the raw materials of the magnesium oxychloride cement modifier according to any one of claims 1-5 according to a weight ratio to obtain the magnesium oxychloride cement modifier.
7. The magnesium oxychloride cement is characterized by comprising the following components in percentage by weight:
100 parts of silt soil;
5-7 parts of magnesium oxide;
3-5 parts of magnesium chloride;
0.15 to 0.5 part of magnesium oxychloride cement modifier as defined in any one of claims 1 to 5.
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| CN1221839A (en) * | 1998-12-03 | 1999-07-07 | 韩敏芳 | Novel pavement colour bricks and its prepn. method |
| DE202008003247U1 (en) * | 2008-03-07 | 2008-05-08 | K-Utec Ag Salt Technologies | Swellable magnesia binder systems for flow barriers, dam structures and as injection building material |
| CN109626946A (en) * | 2019-01-04 | 2019-04-16 | 深圳市元亨环保产业有限公司 | A kind of chlorine oxygen magnesium-based raw-soil curing agent, preparation method and application |
| CN110078461B (en) * | 2019-03-27 | 2021-10-22 | 浙江卓元建设有限公司 | Waterproof and fireproof heat-insulation wall |
| CN110128094B (en) * | 2019-04-25 | 2023-12-12 | 宁波大学 | Curing device and curing method for air hardening and curing sludge |
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| CN1225345A (en) * | 1998-11-30 | 1999-08-11 | 韩敏芳 | Artificial stone products |
| CN1587547A (en) * | 2004-08-10 | 2005-03-02 | 国兴玉 | Composite manhole cover and its producing method |
| CN103553410A (en) * | 2013-11-15 | 2014-02-05 | 晋江安能建材制造有限公司 | Magnesium oxychloride modifying cement and magnesium oxychloride cement |
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