CN114163204B - Sand-free gypsum-based self-leveling mortar and preparation method thereof - Google Patents
Sand-free gypsum-based self-leveling mortar and preparation method thereof Download PDFInfo
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- CN114163204B CN114163204B CN202111391054.1A CN202111391054A CN114163204B CN 114163204 B CN114163204 B CN 114163204B CN 202111391054 A CN202111391054 A CN 202111391054A CN 114163204 B CN114163204 B CN 114163204B
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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
- C04B28/14—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 calcium sulfate cements
- C04B28/145—Calcium sulfate hemi-hydrate with a specific crystal form
- C04B28/147—Calcium sulfate hemi-hydrate with a specific crystal form beta-hemihydrate
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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
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
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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
- 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
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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
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
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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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Civil Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a sand-free gypsum-based self-leveling mortar which comprises the following components in parts by weight: beta type desulfurized building gypsum: 65-75; stone powder: 25-35; cement: 0 to 4; water retention thickener: 0.05-0.15; water reducing agent: 0.15-0.35; retarder: 0.04-0.1; defoaming agent: 0.04-0.08; adhesive: 0.04-0.1; water: 40-50. The beta-type desulfurized building gypsum is prepared by calcining flue gas desulfurized gypsum of a thermal power plant, the content of beta-type semi-hydrated calcium sulfate in the beta-type desulfurized building gypsum is not lower than 92 percent by mass, the 2h flexural strength of the beta-type desulfurized building gypsum is not lower than 3.5MPa, and the water consumption for standard consistency is not more than 58 percent. The stone powder is collected in the process of preparing the sand by adopting a limestone preparation machine, the residual 200-mesh sieve of the stone powder is less than 5 percent by mass percent, and the residual 20-mesh sieve is 0 percent by mass percent.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to a sand-free gypsum-based self-leveling mortar and a preparation method thereof.
Background
At present, the indoor ground materials of common civil buildings mainly comprise fine aggregate concrete and ceramsite concrete. When the ceramsite concrete is used, more ceramsite needs to be consumed, the ceramsite is used as the lightweight aggregate of the ceramsite concrete, calcination is needed during preparation, and the energy consumption is high. The fine stone concrete has higher density, can improve the dead weight of the building, and has poor heat preservation and sound insulation effects. In addition, the two materials need to be manually leveled and smoothed during construction, the requirement on the construction technical level of workers is high, a series of quality problems such as sanding, cracking, large flatness deviation and the like are easily caused when the operation is improper, and the construction efficiency of manual surface smoothing is generally low. In addition, the two materials are cement-based materials, maintenance is needed after construction, and development of other indoor construction operations cannot be performed during maintenance, so that the overall construction progress is influenced.
The gypsum-based self-leveling mortar has the advantages of excellent fluidity, high early strength, difficulty in hollowing, cracking and the like. During construction, only manual assistance is needed for flattening, and maintenance is not needed in the later period. In recent years, with the increase of labor cost and the higher and higher requirements on engineering quality, gypsum-based self-leveling mortar is used as a ground leveling material to replace the traditional fine stone concrete or ceramsite concrete and is gradually accepted by the market.
At present, the cementing material of the gypsum-based self-leveling mortar is mainly alpha-type high-strength gypsum or a composite of the alpha-type high-strength gypsum and beta-type building gypsum, and the aggregate is usually fine sand or fine aggregate prepared from industrial solid wastes. The gypsum-based self-leveling mortar can be prepared by mixing the cementing material with a certain proportion of filler, aggregate (fine sand) and additive. In recent years, rapid development of concrete and mortar industries leads to increasingly tense aggregate (fine sand) resources and large quality fluctuation; in addition, the high-strength gypsum is obviously higher than the price of building gypsum, so that when the alpha-type high-strength gypsum is adopted to prepare the gypsum self-leveling mortar, the cost of the gypsum self-leveling mortar is greatly increased, and the large-area popularization and application of the gypsum self-leveling mortar are limited.
The stone powder is a byproduct generated in the production process of the sandstone aggregate, and the content of the stone powder in the sand is controlled by adopting a wind separation and dust collection mode in the sandstone aggregate process. If the extracted stone powder is not treated and consumed in time, the whole production line is exploded and production is interrupted. If the stone powder is accumulated outside the warehouse, dust is easy to generate and the environment is polluted.
Therefore, it is necessary to develop a method for preparing sand-free gypsum-based ground leveling mortar by replacing alpha-type high-strength gypsum with common beta-type building gypsum and replacing traditional aggregate (fine sand) with stone powder. On one hand, the resource utilization degree of solid wastes such as desulfurized gypsum, stone powder and the like is improved, and the tension of aggregate supply is relieved; on the other hand, the invention can improve the output rate of gypsum self-leveling, further improve the cost performance of gypsum self-leveling mortar and assist the popularization and application of the gypsum self-leveling mortar.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a sand-free gypsum-based self-leveling mortar and a preparation method thereof.
The invention has the technical scheme that the invention firstly provides the sand-free gypsum-based self-leveling mortar which comprises the following components:
65-75 parts by weight of beta-type desulfurized building gypsum;
25-35 parts by weight of stone powder;
0-4 parts by weight of cement;
0.05-0.15 weight part of water-retaining thickening agent;
0.15-0.35 parts by weight of a water reducing agent;
0.04-0.1 weight part of retarder;
0.04-0.08 part by weight of a defoaming agent;
0.04-0.1 part by weight of a binder;
40-50 parts by weight of water.
In a preferred embodiment of the invention, the beta-type desulfurized building gypsum is prepared by calcining flue gas desulfurization gypsum of a thermal power plant, wherein the content of beta-type calcium sulfate hemihydrate is not lower than 92% by mass, the 2h flexural strength of the beta-type desulfurized building gypsum is not lower than 3.5MPa, and the water consumption for standard consistency is not higher than 58%.
The composition of the existing national standard GB/T9776-2008 'building gypsum' 6.1 is stipulated, the content of beta calcium sulfate hemihydrate in the building gypsum is not less than 60%, the content of beta calcium sulfate hemihydrate required by the invention is not less than 92% by mass percent, and the building gypsum can be realized by controlling the grade of a desulfurizing agent and the fluctuation of a desulfurization process in a coal-fired power plant, compared with the conventional desulfurized gypsum with the beta calcium sulfate hemihydrate content of 65%, the requirement of 92% by mass content does not obviously improve the cost, but compared with the alpha high-strength gypsum used in the prior art, the raw material cost can be obviously reduced, and meanwhile, the self-leveling mortar with the beta desulfurized building gypsum with the beta calcium sulfate hemihydrate content of not less than 92% by mass percent as the main component has the performance not lower than that of the self-leveling mortar with the alpha high-strength gypsum as the main component.
Meanwhile, because the beta-type calcium sulfate hemihydrate is higher in content, namely the active ingredient (purity) is high, the 2h flexural strength of the beta-type desulfurized building gypsum is not lower than 3.5MPa, the water consumption for the standard consistency is not more than 58 percent, and the water consumption for the standard consistency is lower, so that the beta-type desulfurized building gypsum is very suitable for preparing the self-leveling mortar with good fluidity.
In a preferred embodiment of the invention, the stone powder is collected in the process of preparing sand by a limestone preparation machine, the residual 200-mesh sieve is less than 5% by mass percent, and the residual 20-mesh sieve is 0% by mass percent.
In a preferred embodiment of the invention, the cement is PO42.5 cement with a 3d compressive strength of more than 28MPa, and the PO42.5 cement used is produced by cube corner group production, because of the high quality and high cement clinker content in the cement, the compressive strength is high.
In a preferred embodiment of the present invention, the water-retaining thickener is hydroxypropyl methylcellulose ether with a viscosity of 400-.
In a preferred embodiment of the present invention, the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is not less than 28%. The water reducing rate of the high-performance water reducing agent is not less than 25% as specified in the current national standard GB/T9776-2008 'concrete admixture', and the water reducing agent used in the invention is a special polycarboxylic acid water reducing agent for gypsum-based materials, and the water reducing rate is not less than 28%.
In a preferred embodiment of the present invention, the retarder is a protein retarder.
In a preferred embodiment of the present invention, the defoaming agent is a silicone defoaming agent.
In a preferred embodiment of the present invention, the binder is polyvinyl alcohol 1788.
The invention also provides a preparation method of the sand-free gypsum-based self-leveling mortar, which comprises the steps of uniformly mixing the beta-desulfurized building gypsum, stone powder, cement, a water-retention thickening agent, a water reducing agent, a retarder, a defoaming agent and a binder in a mixer for later use; and stirring the uniformly mixed material and water in a cement mortar stirrer for 180 seconds to prepare the sand-free gypsum-based self-leveling mortar slurry.
Compared with the prior art, the invention has the advantages that:
1. the invention comprehensively adopts the beta-type building gypsum with lower price to replace the high-strength gypsum with higher price, and adopts the stone powder collected in the process of preparing the sand by using the limestone machine as the filler to replace the natural river sand to prepare the sand-free gypsum-based self-leveling mortar. The beta-type building gypsum used by the gypsum-based self-leveling mortar is prepared by calcining desulfurized gypsum discharged by a coal-fired power plant at low temperature, and the desulfurized gypsum and stone powder are industrial wastes encouraged, popularized and applied by China, so that the desulfurized gypsum and stone powder are fully utilized, waste materials can be changed into things of value, and the exploitation of natural sand can be reduced.
2. Compared with the prior common gypsum self-leveling mortar with the squareness rate of 60-65%, the sand-free gypsum-based ground leveling mortar has higher squareness rate which can reach 75-85%. Under the condition that the construction thickness and the area are the same, the novel sand-free gypsum-based self-leveling mortar is adopted to replace the traditional gypsum-based self-leveling mortar, the using amount of mortar materials can be greatly reduced, the material cost is further reduced, and a foundation is laid for the popularization of the sand-free gypsum-based self-leveling mortar.
3. The product obtained by the invention is tested according to JC/T1023-2021 gypsum-based self-leveling mortar, the fluidity is 140-150mm, the fluidity loss is 1-4mm in 30min, the 24h flexural strength is 2.0-3.5MPa, the 24h compressive strength is 6.5-11.5MPa, the 28d absolute dry flexural strength is 6.0-7.5MPa, the 28d absolute dry compressive strength is 20-25MPa, the absolute dry tensile bonding strength is 1.0-1.5MPa, and the drying shrinkage is 0.01-0.04%.
4. The sand-free gypsum-based self-leveling mortar has the characteristics of light weight, high squaring rate and high cost performance. The absolute dry volume density of the common gypsum-based self-leveling mortar is about 1600-kg/m 3 . The absolute dry volume density of the sand-free gypsum-based ground leveling mortar material is 1350-sodium silicate (sodium silicate) and 1450kg/m 3 (ii) a The output rate of the common gypsum-based self-leveling mortar is 60-65%, the output rate of the sand-free gypsum-based ground leveling mortar is 75-85%, and the output rate is obviously higher than that of the existing gypsum-based self-leveling mortar; the common building gypsum is adopted to replace high-strength gypsum, and the stone powder is adopted to replace high-quality river sand, so that the cost of each ton of mortar material is reduced by about 30 percent, and the market competitiveness of the sand-free gypsum-based ground leveling mortar material is remarkably improved.
According to the invention, the stone powder with lower density is used for replacing river sand, the density of the prepared sand-free gypsum self-leveling mortar is obviously reduced, the water addition amount is obviously increased, and the sand-free gypsum self-leveling yield is obviously higher than that of the traditional sand-containing gypsum self-leveling mortar due to the two factors.
Detailed Description
The invention will now be described in detail with reference to specific embodiments thereof, but it should be understood that the scope of the invention is not limited thereto.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Example 1
1. Weighing the following raw materials by weight: 700g of desulfurized building gypsum powder, 300g of stone powder, 1.0g of cellulose ether, 0.5g of polyvinyl alcohol, 0.4g of organic silicon defoamer, 2.5g of polycarboxylic acid water reducer and 0.4g of retarder.
2. Uniformly mixing the powder for later use;
3. 430g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring at a low speed for 180 seconds by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
According to the performance index of JC/T1023-2021 gypsum-based self-leveling mortar standard test, the fluidity is 142mm, the fluidity loss is 2mm in 30min, the 24h flexural strength is 2.8MPa, the 24h compressive strength is 8.5MPa, the 28d absolute dry flexural strength is 6.7MPa, the 28d absolute dry compressive strength is 21.5MPa, the absolute dry tensile bonding strength is 1.2MPa, and the drying shrinkage is 0.02 percent.
Example 2
1. Weighing the following raw materials by weight: 750g of desulfurized building gypsum powder, 210g of stone powder, 40g of cement, 0.9g of cellulose ether, 0.5g of polyvinyl alcohol, 0.6g of organic silicon defoamer, 2.5g of polycarboxylic acid water reducer and 0.5g of retarder.
2. Uniformly mixing the powder for later use;
3. 460g of water is weighed into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring at a low speed for 180 seconds by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
The performance index of the material prepared according to JC/T1023-gesilicon 2021 gypsum-based self-leveling mortar standard test shows that the fluidity is 145mm, the fluidity loss is 3mm in 30min, the 24h flexural strength is 2.9MPa, the 24h compressive strength is 9.1MPa, the 28d oven dry flexural strength is 7.5MPa, the 28d oven dry compressive strength is 23.6MPa, the oven dry tensile bonding strength is 1.1MPa, and the drying shrinkage is 0.04 percent.
Example 3
1. Weighing the following raw materials by weight: 650g of desulfurized building gypsum powder, 350g of stone powder, 1.1g of cellulose ether, 0.5g of polyvinyl alcohol, 0.3g of organic silicon defoamer, 3.0g of polycarboxylic acid water reducer and 0.4g of retarder.
2. Uniformly mixing the powder for later use;
3. 410g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring for 180 seconds at a low speed by using a mortar stirrer to obtain the sand-free gypsum-based ground leveling mortar.
According to the performance index of JC/T1023-2021 gypsum-based self-leveling mortar, the fluidity is 140mm, the fluidity loss is 1mm in 30min, the 24h flexural strength is 2.1MPa, the 24h compressive strength is 7.0MPa, the 28d absolute dry flexural strength is 6.5MPa, the 28d absolute dry compressive strength is 20.5MPa, the absolute dry tensile bonding strength is 1.1MPa, and the drying shrinkage is 0.03 percent.
Comparative example 1
The comparative example provides a sand-free gypsum-based self-leveling mortar, and the preparation method comprises the following steps:
1. weighing the following raw materials by weight: 600g of desulfurized building gypsum powder, 400g of stone powder, 1.5g of water-retaining thickener, 0.5g of binder, 0.6g of defoamer, 3.0g of water reducer and 0.6g of retarder.
2. Uniformly mixing the powder for later use;
3. 400g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring at a low speed for 180 seconds by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
The performance index of the material prepared according to JC/T1023-gesilicon 2021 gypsum-based self-leveling mortar standard test shows that the fluidity is 140mm, the fluidity loss is 1mm in 30min, the 24h flexural strength is 1.8MPa, the 24h compressive strength is 6.0MPa, the 28d absolute dry flexural strength is 4.5MPa, the 28d absolute dry compressive strength is 16.5MPa, the absolute dry tensile bonding strength is 0.8MPa, and the drying shrinkage is 0.03 percent. Therefore, when the addition amount of the desulfurization building gypsum powder is too low, the mechanical property of the prepared sand-free gypsum-based self-leveling mortar cannot meet the requirements of JC/T1023-2021.
Comparative example 2
The comparative example provides a sand-free gypsum-based self-leveling mortar, and the preparation method comprises the following steps:
1. weighing the following raw materials by weight: 650g of desulfurized building gypsum powder, 320g of stone powder, 30g of cement, 0.6g of water retention thickening agent, 1.0g of binder, 0.6g of defoaming agent, 3.0g of water reducing agent and 0.6g of retarder.
2. Uniformly mixing the powder for later use;
3. 400g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring the mixture for 180 seconds at a low speed by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
According to the performance index of JC/T1023-2021 gypsum-based self-leveling mortar, the fluidity is 143mm, the fluidity loss is 0mm in 30min, the 24h flexural strength is 1.5MPa, the 24h compressive strength is 4.7MPa, the 28d absolute dry flexural strength is 3.9MPa, the 28d absolute dry compressive strength is 10.2MPa, the absolute dry tensile bonding strength is 0.5MPa, and the drying shrinkage is 0.02 percent. It should be noted that the desulfurized building gypsum powder used in the comparative example contains 80% of beta-type calcium sulfate hemihydrate, and the content of beta-type calcium sulfate hemihydrate is relatively low, so that the mechanical properties of the prepared sand-free gypsum-based self-leveling mortar cannot meet the requirements of JC/T1023-2021.
Comparative example 3
The comparative example provides a sand-free gypsum-based self-leveling mortar, and the preparation method comprises the following steps:
1. weighing the following raw materials by weight: 900g of desulfurized building gypsum powder, 100g of stone powder, 1.0g of water-retaining thickener, 0.5g of binder, 0.8g of defoamer, 3.0g of water reducer and 0.8g of retarder.
2. Uniformly mixing the powder for later use;
3. 550g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring at a low speed for 180 seconds by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
According to the performance index of JC/T1023-2021 gypsum-based self-leveling mortar, the fluidity is 143mm, the fluidity loss is 15mm in 30min, the 24h flexural strength is 3.2MPa, the 24h compressive strength is 12.5MPa, the 28d absolute dry flexural strength is 8.0MPa, the 28d absolute dry compressive strength is 26.2MPa, the absolute dry tensile bonding strength is 1.2MPa, and the drying shrinkage is 0.02 percent. The mechanical property of the prepared sand-free gypsum-based self-leveling mortar can meet the requirement of JC/T1023-2021, but the fluidity loss is 15mm in 30min, and the fluidity loss is too large, so that the sand-free gypsum-based self-leveling mortar is difficult to construct and use.
Comparative example 4
The comparative example provides a sand-free gypsum-based self-leveling mortar, and the preparation method comprises the following steps:
1. weighing the following raw materials by weight: 650g of desulfurized building gypsum powder, 350g of fine sand, 0.7g of water-retaining thickener, 0.5g of binder, 0.6g of defoamer, 2.5g of water reducer and 0.8g of retarder.
2. Uniformly mixing the powder for later use;
3. 350g of water is weighed and added into a stirring pot for standby.
4. And (3) adding the powder obtained in the step (2) into the liquid obtained in the step (3), and stirring at a low speed for 180 seconds by using a mortar stirrer to obtain the sand-free gypsum-based self-leveling mortar.
According to the performance index of JC/T1023-2021 gypsum-based self-leveling mortar, the fluidity is 143mm, the fluidity loss is 1mm in 30min, the 24h flexural strength is 3.0MPa, the 24h compressive strength is 9.5MPa, the 28d absolute dry flexural strength is 7.0MPa, the 28d absolute dry compressive strength is 21.2MPa, the absolute dry tensile bonding strength is 1.1MPa, and the drying shrinkage is 0.02 percent. The performance of the prepared gypsum-based self-leveling mortar can meet the requirements of JC/T1023-2021. Because the fine sand with higher density is used as the aggregate, the water addition amount is obviously lower, the density is higher, and the output rate is about 65 percent.
In conclusion, the sand-free gypsum-based self-leveling mortar with the performance meeting the JC/T1023-2021 requirements can be prepared by preferably selecting raw materials such as beta-type building gypsum powder, stone powder and the like and accurately controlling the proportion of each component.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (7)
1. The non-sand gypsum-based self-leveling mortar is characterized by comprising the following components:
65-75 parts by weight of beta-type desulfurized building gypsum;
25-35 parts by weight of stone powder;
0-4 parts by weight of cement;
0.05-0.15 weight part of water-retaining thickening agent;
0.15-0.35 parts by weight of a water reducing agent;
0.04-0.1 weight part of retarder;
0.04-0.08 part by weight of a defoaming agent;
0.04-0.1 parts by weight of a binder;
40-50 parts by weight of water;
the beta-type desulfurized building gypsum is prepared by calcining flue gas desulfurized gypsum of a thermal power plant, the content of beta-type semi-hydrated calcium sulfate in the beta-type desulfurized building gypsum is not lower than 92 percent by mass percent, the 2h flexural strength of the beta-type desulfurized building gypsum is not lower than 3.5MPa, and the water consumption of the standard consistency is not higher than 58 percent;
the stone powder is collected in the process of preparing sand by adopting a limestone preparation machine, the residual 200-mesh sieve of the stone powder is less than 5 percent by mass percent, and the residual 20-mesh sieve is 0 percent by mass percent;
the cement is PO42.5 cement, and the 3d compressive strength of the cement is more than 28 MPa.
2. The sand-free gypsum-based self-leveling mortar of claim 1, wherein the water-retaining thickener is hydroxypropyl methyl cellulose ether having a viscosity of 400-.
3. The sand-free gypsum-based self-leveling mortar of claim 1, wherein the water reducing agent is a polycarboxylic acid series water reducing agent, and the water reducing rate is not less than 28%.
4. The sand-free gypsum-based self-leveling mortar of claim 1, wherein the set retarder is a protein set retarder.
5. A sand-free gypsum-based self-leveling mortar according to claim 1, wherein the defoamer is a silicone defoamer.
6. A sand free gypsum based self-leveling mortar according to claim 1, wherein the binder is polyvinyl alcohol 1788.
7. A method for preparing a sand-free gypsum-based self-leveling mortar as claimed in any one of claims 1 to 6, wherein the beta-type desulfurized building gypsum, stone powder, cement, a water-retaining thickener, a water-reducing agent, a retarder, a defoamer and a binder are uniformly mixed in a mixer for later use; and stirring the uniformly mixed material and water in a cement mortar stirrer for 180 seconds to prepare the sand-free gypsum-based self-leveling mortar.
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