Cement-based flowable screed for floor applications and method for its preparation

Abstract

The application relates to a cement-based thick-layer leveling flowable mortar for ground and a preparation method thereof. The cement-based thick-layer leveling flowable mortar for ground comprises the following raw materials in parts by weight: cement 200-300 parts, aggregate 450-550 parts, mineral powder 100-200 parts, heavy calcium powder 30-100 parts, hard gypsum 10-30 parts, floating beads 5-10 parts, dispersible latex powder 5-10 parts, water reducing agent 0.6-1.5 parts, retarder 0.9-1.4 parts, defoaming agent 0.8-1.2 parts and cellulose ether 0.4-0.6 parts. The application realizes high flatness of the self-leveling mortar, a high construction thickness range and a longer construction time by reasonably adjusting the raw material ratio.

Description

Technical Field

[0001] This article relates to the field of building materials, and in particular to a cement-based thick-layer flowing mortar and its preparation method. Background Technology

[0002] Thick-layer flowing mortar has become a significant development direction in the field of building and construction technology in recent years, primarily used in scenarios such as self-leveling floors, large-area leveling, and rapid construction. Traditional mortars typically rely on plastering processes, which suffer from limitations in construction thickness, low efficiency, and susceptibility to hollow areas and cracking. With the increasing demands for efficiency and quality in modern construction, thick-layer flowing mortar, through optimized particle size distribution and the addition of high-performance admixtures (such as water-retaining and thickening materials, water-reducing agents, and dispersible latex powder), achieves excellent fluidity and self-compacting properties. It can achieve thicknesses of several centimeters to tens of centimeters in a single pour, and exhibits low shrinkage and stable strength development after hardening. Its core technology lies in resolving the contradiction between fluidity and segregation resistance, and between open time and early strength, to meet the needs of mechanized pumping construction and rapid delivery. It has become an important component of precast component installation, repair projects, and large-scale floor systems.

[0003] Therefore, there is an urgent need to provide a high-performance cement-based thick-layer flowing mortar and its preparation method. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0005] The first aspect of this application provides a cement-based thick-layer leveling mortar for floors, comprising the following raw materials by weight: The ingredients are: 200-300 parts cement, 450-550 parts aggregate, 100-200 parts mineral powder, 30-100 parts heavy calcium carbonate powder, 10-30 parts anhydrite, 5-10 parts cenospheres, 5-10 parts dispersible latex powder, 0.6-1.5 parts water-reducing agent, 0.9-1.4 parts retarder, 0.8-1.2 parts defoamer, and 0.4-0.6 parts cellulose ether.

[0006] In one exemplary embodiment, the cement-based thick-layer leveling mortar is composed of the following raw materials by weight: The ingredients are: 200-300 parts cement, 450-550 parts aggregate, 100-200 parts mineral powder, 30-100 parts heavy calcium carbonate powder, 10-30 parts anhydrite, 5-10 parts cenospheres, 5-10 parts dispersible latex powder, 0.6-1.5 parts water-reducing agent, 0.9-1.4 parts retarder, 0.8-1.2 parts defoamer, and 0.4-0.6 parts cellulose ether.

[0007] In one exemplary embodiment, the cement is 210-300 parts, 240-300 parts, or 210-240 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range also apply. For example, the cement is 210 parts or 240 parts.

[0008] In one exemplary embodiment, the aggregate is 450-525 parts or 525-550 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range also apply. For example, the aggregate is 525 parts.

[0009] In one exemplary embodiment, the mineral powder is 150-200 parts or 100-150 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable; for example, the mineral powder is 145 parts or 175 parts.

[0010] In one exemplary embodiment, the heavy calcium carbonate powder is 50-100 parts or 30-50 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For example, the heavy calcium carbonate powder is 50 parts.

[0011] In one exemplary embodiment, the anhydrite is 20-30 parts or 10-20 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range also apply. For example, the anhydrite is 20 parts.

[0012] In one exemplary embodiment, the dispersible latex powder is 6-10 parts or 5-6 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For example, the dispersible latex powder is 6 parts.

[0013] In one exemplary embodiment, the water-reducing agent is 0.8-1.5 parts or 0.6-0.8 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For example, the water-reducing agent is 0.8 parts.

[0014] In one exemplary embodiment, the retarder is 1.1-1.4 parts, 1.3-1.4 parts, or 1.1-1.3 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For example, the retarder is 1.1 parts or 1.3 parts.

[0015] In one exemplary embodiment, the defoamer is 1.0-1.2 parts or 0.8-1.0 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For example, the defoamer is 1.0 parts.

[0016] In one exemplary embodiment, the cellulose ether is 0.5-0.6 parts or 0.4-0.5 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable; for example, the cellulose ether is 0.5 parts.

[0017] In one exemplary embodiment, the cement is sulfoaluminate cement, for example, sulfoaluminate cement with specification R·SAC 42.5, loss on ignition ≤3.0%, and specific surface area ≥400㎡ / kg.

[0018] In one exemplary embodiment, the aggregate is selected from one or more of manufactured sand, quartz sand, and river sand; optionally, the particle size of the aggregate is 0.1-2.5 mm.

[0019] In one exemplary embodiment, the aggregate is manufactured sand, wherein the manufactured sand has a mud content ≤3.0%, a mud lump content ≤0.2%, flaky particles ≤10%, and an apparent density of not less than 2500 kg / m³. 3 .

[0020] In one exemplary embodiment, the aggregate is a mixture of particles with diameters of 0.1-0.5 mm, 0.5-1.0 mm, and 1.0-2.5 mm, in a weight ratio of (250-300):(200-250):(5-10).

[0021] In one exemplary embodiment, the aggregate is a mixture of particles with diameters of 0.1-0.5 mm, 0.5-1.0 mm, and 1.0-2.5 mm, in a weight ratio of 295.6:220:10 or 295.4:220:10.

[0022] In one exemplary embodiment, the mineral powder is granulated blast furnace slag powder.

[0023] In one exemplary embodiment, the granulated blast furnace slag powder comprises, by weight, 30-75 parts CaO, 28-38 parts SiO2, 8-18 parts Al2O3, 5-12 parts MgO, 0.1-2 parts MnO, and 0.1-3 parts sulfides.

[0024] In one exemplary embodiment, the granulated blast furnace slag powder comprises, by weight, 35-45 parts of CaO (calcium oxide), 30-38 parts of SiO2, 10-18 parts of Al2O3, 5-10 parts of MgO, and small amounts of Fe2O3, MnO, SO3, etc.

[0025] In one exemplary embodiment, the particle size of the granulated blast furnace slag powder is 1-60 μm.

[0026] In one exemplary embodiment, the main component of the heavy calcium carbonate powder is CaCO3, wherein the weight percentage of CaCO3 is 95%-99%.

[0027] In one exemplary embodiment, the particle size of the heavy calcium carbonate powder is 1-70 μm, for example 45 μm.

[0028] In one exemplary embodiment, the main component of the anhydrite is CaSO4, wherein the weight percentage of CaSO4 is 85%-99%, for example ≥92%.

[0029] In one exemplary embodiment, the anhydrite has a particle size of 10-100 μm, for example, 10 μm.

[0030] In one exemplary embodiment, the microspheres are artificial hollow glass microspheres or hollow ceramic microspheres.

[0031] In one exemplary embodiment, the composition of the bead, by weight percentage, includes: 50%-75% SiO2 and 20%-40% Al2O3, for example, 60%-70% SiO2 and 25%-30% Al2O3.

[0032] In one exemplary embodiment, the dispersible latex powder is selected from one or more of ethylene-vinyl acetate copolymer (EVA), vinyl acetate-vinyl tert-carbonate copolymer (VA / VeoVa), styrene-acrylate copolymer, pure acrylate copolymer, and styrene-butadiene copolymer, for example, Wacker Chemie's ethylene-vinyl acetate copolymer with specification 4115N.

[0033] In one exemplary embodiment, the water-reducing agent is a polycarboxylate superplasticizer (PCE).

[0034] In one exemplary embodiment, the retarder is a mixture of tartaric acid and a special retarder.

[0035] In one exemplary embodiment, the special retarder is a sugar / polyhydroxy compound retarder, whose main components are sugars or calcium sugars, as well as hydroxycarboxylate salts or hydroxycarboxylic acids, and may be compounded with a small amount of dispersant, stabilizer or synergist (such as phosphate, lignin sulfonate derivative); for example, the special retarder is Kebang retarder, purchased from Tianjin Kebang New Materials Co., Ltd.

[0036] In one exemplary embodiment, the mass ratio of tartaric acid to the special retarder in the retarder is 1:(1.1-1.5); for example, 0.5:0.6 or 0.6:0.7.

[0037] In one exemplary embodiment, the mass ratio of tartaric acid to the special retarder in the retarder is 1:(1.1-1.2).

[0038] In one exemplary embodiment, the defoamer is selected from one or more of polysiloxane defoamers, polyether defoamers, tributyl phosphate, mineral oil defoamers, and alkynyl alcohol defoamers, for example, a polyether defoamer, specifically a polyether-modified defoamer.

[0039] In one exemplary embodiment, the cellulose ether is selected from one or more of methylcellulose ether, hydroxypropyl methylcellulose ether, and carboxymethylcellulose ether. For example, the cellulose ether is hydroxypropyl methylcellulose ether with a viscosity of 40,000-50,000 mPa·s.

[0040] In one exemplary embodiment, the cement-based thick-layer leveling mortar comprises, by weight, the following raw materials: 210 parts sulfoaluminate cement, 10 parts 1.0-2.5mm manufactured sand, 220 parts 0.5-1.0mm manufactured sand, 295.6 parts 0.1-0.5mm manufactured sand, 175 parts mineral powder, 50 parts heavy calcium carbonate powder, 20 parts anhydrite, 10 parts cenospheres, 6.0 parts dispersible latex powder, 0.8 parts water-reducing agent, 0.5 parts tartaric acid, 0.6 parts special retarder, 1.0 part defoamer, 0.5 parts cellulose ether.

[0041] In one exemplary embodiment, the cement-based thick-layer leveling mortar comprises, by weight, the following raw materials: 240 parts sulfoaluminate cement, 10 parts 1.0-2.5mm manufactured sand, 220 parts 0.5-1.0mm manufactured sand, 295.4 parts 0.1-0.5mm manufactured sand, 145 parts mineral powder, 50 parts heavy calcium carbonate powder, 20 parts anhydrite, 10 parts cenospheres, 6.0 parts dispersible latex powder, 0.8 parts water-reducing agent, 0.6 parts tartaric acid, 0.7 parts special retarder, 1.0 part defoamer, 0.5 parts cellulose ether.

[0042] The second aspect of this application provides a method for preparing the above-mentioned cement-based thick-layer leveling mortar for ground, comprising the following steps: The aggregates are screened. According to the formula, cellulose ether, defoamer, retarder, water-reducing agent, dispersible latex powder, bleaching beads, heavy calcium carbonate powder and anhydrite are added to the mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Cement, mineral powder, aggregate, and the premixed material are measured and added to a mixer in sequence. After mixing evenly, a cement-based thick-layer leveling flowable mortar is obtained.

[0043] The third aspect of this application provides a cement-based thick-layer leveling mortar for ground prepared by the above method.

[0044] In one exemplary embodiment, when in use, the cement-based thick-layer leveling mortar for the ground is mixed with water, wherein the mass ratio of the cement-based thick-layer leveling mortar for the ground to water is 1:0.16 to 1:0.18, for example, 1:0.18.

[0045] Compared with existing related technologies, the cement-based thick-layer flowing mortar described in this application has the following technical advantages: Based on the results of setting time and workability, the combination of tartaric acid and special retarder with less and more economical retarder addition appropriately extended the workability time after water addition, retained the self-leveling ability of the mortar, and the mortar had a longer setting time and workability time, resulting in better performance. Increasing the amount of cement or appropriately increasing the amount of retarder will significantly improve the product's strength properties without affecting its workability; By properly adjusting the aggregate gradation, sedimentation and surface bleeding of the slurry after adding water can be avoided, without affecting workability and overall strength. By appropriately adjusting the amount of water-reducing agent added, the initial fluidity of the mortar can be controlled, avoiding problems such as aggregate sedimentation, surface bleeding, and uncontrolled dimensional changes. By appropriately adjusting the proportion of aggregate, higher strength can be obtained with the same amount of water, reducing the dimensional change rate of the hardened mortar, and avoiding problems such as low initial fluidity of the mortar, insufficient construction time, and reduced strength caused by changes in the amount of water added.

[0046] Therefore, this application achieves high smoothness, a wide range of construction thickness, and a longer workable time for self-leveling mortar by rationally adjusting the proportions of mortar raw materials. The cement-based thick-layer flowing mortar described in this application has an initial flowability ≥240mm, a final setting time of 1.5-2.5h, a workable time of 40-50min, a bond strength >1MPa, a 24h flexural strength >2.5MPa, a 24h compressive strength >8MPa, a 28d flexural strength >6.5MPa, a 28d compressive strength >30MPa, and a dimensional change rate under limiting conditions of -0.5mm / m to +0.5mm / m. Its physical properties all meet the technical requirements for building leveling mortar products in JC / T 2326-2015 "Leveling Mortar for Building".

[0047] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the methods described in the description. Detailed Implementation

[0048] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0049] The present application will be further described in detail below with reference to specific embodiments, but these embodiments should not be construed as limiting the present application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this invention.

[0050] The raw materials used in this application are all conventional products on the market.

[0051] Unless otherwise specified, all materials and reagents used in the embodiments of this application are commercially available.

[0052] Experimental methods not specified in the examples are generally performed under standard conditions or as recommended by the manufacturer.

[0053] In the following examples and comparative examples: The cement was purchased from Tangshan Arctic Bear Building Materials Co., Ltd. The main component of this cement is calcium sulfoaluminate, with specifications R·SAC 42.5, loss on ignition ≤3.0%, and specific surface area ≥400㎡ / kg.

[0054] The aggregate was manufactured sand purchased from Bomit Building Materials (Suzhou) Co., Ltd. in Suzhou. The manufactured sand had a particle size of 0.1~2.5mm, a mud content ≤3.0%, a mud lump content ≤0.2%, flaky particles ≤10%, and an apparent density of not less than 2500kg / m³. 3 .

[0055] The ore powder is granulated blast furnace slag powder purchased from Shanghai Baotian New Building Materials Co., Ltd., and its grade is S95. The main components are: CaO (calcium oxide) ≈ 35%-45%, SiO2 (silicon dioxide) ≈ 30%-38%, Al2O3 (alumina) ≈ 10%-18%, MgO (magnesium oxide) ≈ 5%-10%, and small amounts of Fe2O3, MnO, SO3, etc.

[0056] The heavy calcium carbonate powder was purchased from Anhui Zhongshi Building Materials Co., Ltd. The fineness of the heavy calcium carbonate powder is 325 mesh (45μm particle size), and the CaCO3 content is >95%.

[0057] The anhydrite was purchased from Nanjing Funante Building Materials Co., Ltd. The anhydrite has a fineness of 1500 mesh (particle size 10μm) and contains ≥92% CaSO4.

[0058] The cenospheres were purchased from Tangshan Arctic Bear Building Materials Co., Ltd. (hollow glass microspheres), and their density is 0.6 g / cm³. 3 The main components, by weight percentage, are approximately 60%-70% SiO2 and approximately 25%-30% Al2O3.

[0059] The dispersible latex powder was purchased from Wacker Chemie (Nanjing) Co., Ltd. The specification of the dispersible latex powder is 4115N, the ash content is 13%~14.5%, and the bulk density is 490-590g / L.

[0060] The water-reducing agent was purchased from Shanghai Shenhua New Material Technology Co., Ltd., and its model number is PC-100.

[0061] The retarder is a mixture of tartaric acid purchased from Shanghai Shenhua New Material Technology Co., Ltd. and a special retarder purchased from Tianjin Kebang New Material Co., Ltd. The special retarder is a sugar / polyhydroxy compound type retarder, which may be compounded with small amounts of dispersants, stabilizers, or synergists (such as phosphates or lignin sulfonate derivatives), but the main component is still sugar / hydroxycarboxylic acid, and its appearance is similar to transparent fine granules of white sugar.

[0062] The defoamer was purchased from Shanghai Shenhua New Material Technology Co., Ltd. (polyether modified silicone defoamer), model number DF-94.

[0063] The cellulose ether was purchased from Shanghai Huiguang Fine Chemical Co., Ltd. The cellulose ether model was PMK20Z, the viscosity was 40000-50000 mPa·s, and the water content was ≤8%.

[0064] Example 1 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0065] Example 2 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.6 parts by weight of tartaric acid, 0.7 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 240 parts by weight of sulfoaluminate cement, 145 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.4 parts by weight of 0.1-0.5mm manufactured sand, and 89.6 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0066] Comparative Example 1 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 parts by weight of defoamer, 1.1 parts by weight of tartaric acid, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite were added to a mixer in sequence for premixing. After mixing evenly, a premix was obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0067] Comparative Example 2 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. Add 0.5 parts by weight of cellulose ether, 1.0 parts by weight of defoamer, 1.1 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0068] Comparative Example 3 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 100 parts by weight of 1.0-2.5mm manufactured sand, 200 parts by weight of 0.5-1.0mm manufactured sand, 225.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0069] Comparative Example 4 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of citric acid, 0.6 parts by weight of sodium gluconate, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0070] The retarder used in Comparative Example 4 was a mixture of citric acid and sodium gluconate purchased from Tianjin Kebang New Materials Co., Ltd.

[0071] Comparative Example 5 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of sodium gluconate, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 175 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0072] The retarder used in Comparative Example 5 was a combination of tartaric acid purchased from Shanghai Shenhua New Material Technology Co., Ltd. and sodium gluconate purchased from Tianjin Kebang New Material Co., Ltd.

[0073] Comparative Example 6 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of special retarder, 2.0 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 173.8 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 220 parts by weight of 0.5-1.0mm manufactured sand, 295.6 parts by weight of 0.1-0.5mm manufactured sand, and 90.6 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0074] Comparative Example 7 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 50 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 125 parts by weight of mineral powder, 15 parts by weight of 1.0-2.5mm manufactured sand, 240 parts by weight of 0.5-1.0mm manufactured sand, 320.6 parts by weight of 0.1-0.5mm manufactured sand, and 89.4 parts by weight of premixed material are sequentially measured and added to a mixer for mixing. After mixing evenly, the cement-based thick-layer flowing mortar is obtained.

[0075] Comparative Example 8 The manufactured sand is crushed and screened to three particle sizes: 0.1-0.5mm, 0.5-1.0mm, and 1.0-2.5mm. 0.5 parts by weight of cellulose ether, 1.0 part by weight of defoamer, 0.5 parts by weight of tartaric acid, 0.6 parts by weight of special retarder, 0.8 parts by weight of water-reducing agent, 6.0 parts by weight of dispersible latex powder, 10 parts by weight of cenospheres, 85 parts by weight of heavy calcium carbonate powder, and 20 parts by weight of anhydrite are added to a mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Then, 210 parts by weight of sulfoaluminate cement, 230 parts by weight of mineral powder, 10 parts by weight of 1.0-2.5mm manufactured sand, 180 parts by weight of 0.5-1.0mm manufactured sand, 245.6 parts by weight of 0.1-0.5mm manufactured sand, and 124.4 parts by weight of premixed material are measured and added to a mixer in sequence and mixed evenly to obtain cement-based thick-layer flowing mortar.

[0076] Performance testing The cement-based thick-layer flowing mortars prepared in the examples and comparative examples were mixed with water at a mass ratio of 1:0.18 (for a construction thickness of 3-10 mm). After thorough mixing, tests were conducted according to the Chinese building materials industry standard JC / T 2326-2015 "Leveling Mortar for Buildings". The test results are shown in Table 1 below.

[0077] Table 1 As shown in Table 1, the initial flowability of the cement-based thick-layer flowing mortar in the example is ≥240mm, the final setting time is 1.5-2.5h, the workable time is 40-50min, the bond strength is >1MPa, the 24h flexural strength is >2.5MPa, the 24h compressive strength is >8MPa, the 28d flexural strength is >6.5MPa, the 28d compressive strength is >30MPa, and the dimensional change rate under the limiting conditions is -0.5mm / m to +0.5mm / m. Its physical properties all meet the technical requirements for building leveling mortar products in JC / T 2326-2015 "Leveling Mortar for Building".

[0078] Based on the results of setting time and workable time, the retarding effect of using only tartaric acid as a retarder in Comparative Example 1 and using only a special retarder in Comparative Example 2 is shorter than that of Examples 1-2. This indicates that the combined use of tartaric acid and a special retarder will have a better effect with a smaller and more economical amount of retarder added.

[0079] Compared with Example 1, Example 2 shows that increasing the amount of cement and appropriately increasing the amount of retarder will significantly improve the product's strength performance without affecting its workability, but it will also increase costs.

[0080] In Comparative Example 3, changing the aggregate gradation and adding too much coarse sand will cause sedimentation and surface bleeding in the slurry after adding water, affecting workability and overall strength.

[0081] The combinations of citric acid and sodium gluconate in Comparative Example 4 and tartaric acid and sodium gluconate in Comparative Example 5 showed little difference in performance in self-leveling mortar. Tests revealed that the use of tartaric acid or citric acid in combination with sodium gluconate caused the mortar to lose its self-leveling ability prematurely while it was still flowable. Therefore, changing the combination of retarders did not achieve a longer workable time after adding water, and the mortar would lose its self-leveling ability prematurely.

[0082] In Comparative Example 6, when the proportion of dry powder aggregate remained constant, excessive addition of water-reducing agent would cause the initial fluidity to become uncontrollable, resulting in aggregate sedimentation, surface bleeding, and uncontrolled dimensional changes.

[0083] Comparative Example 7 increased the aggregate ratio to 565.6 parts, which is greater than the maximum set ratio of 550 parts. At this time, with the same amount of water added, the initial fluidity is reduced due to the increased friction between the aggregates, the cementitious material is relatively less, the mortar strength will be significantly reduced, and the mortar size change rate will be significantly larger after hardening.

[0084] Comparative Example 8 reduced the aggregate ratio to 435.6 parts, which is less than the minimum set ratio of 450 parts. When the aggregate ratio is too low, if the water content remains unchanged, the initial fluidity of the paste will be low, resulting in insufficient construction time and a significant reduction in compressive and flexural strength. Increasing the water content to meet the initial fluidity will only lead to even lower strength.

[0085] Therefore, the cement-based thick-layer flowing mortar described in this application has the following technical effects: Based on the results of setting time and workability, the combination of tartaric acid and special retarder with less and more economical retarder addition appropriately extended the workability time after water addition, retained the self-leveling ability of the mortar, and the mortar had a longer setting time and workability time, resulting in better performance. Increasing the amount of cement or appropriately increasing the amount of retarder will significantly improve the product's strength properties without affecting its workability; By properly adjusting the aggregate gradation, sedimentation and surface bleeding of the slurry after adding water can be avoided, without affecting workability and overall strength. By appropriately adjusting the amount of water-reducing agent added, the initial fluidity of the mortar can be controlled, avoiding problems such as aggregate sedimentation, surface bleeding, and uncontrolled dimensional changes. By appropriately adjusting the proportion of aggregate, higher strength can be obtained with the same amount of water, reducing the dimensional change rate of the hardened mortar, and avoiding problems such as low initial fluidity of the mortar, insufficient construction time, and reduced strength caused by changes in the amount of water added.

[0086] In summary, the cement-based thick-layer leveling mortar for ground described in this application, through reasonable adjustment of raw material ratios, can achieve high flatness, a wide range of construction thickness, and a longer construction time for self-leveling mortar.

[0087] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A cement-based thick-layer leveling mortar for floors, comprising the following raw materials by weight: The ingredients are: 200-300 parts cement, 450-550 parts aggregate, 100-200 parts mineral powder, 30-100 parts heavy calcium carbonate powder, 10-30 parts anhydrite, 5-10 parts cenospheres, 5-10 parts dispersible latex powder, 0.6-1.5 parts water-reducing agent, 0.9-1.4 parts retarder, 0.8-1.2 parts defoamer, and 0.4-0.6 parts cellulose ether. The retarder is a mixture of tartaric acid and a special retarder, and the special retarder is a sugar / polyhydroxy compound retarder; The aggregate is a mixture of particles with diameters of 0.1-0.5 mm, 0.5-1.0 mm, and 1.0-2.5 mm, in a weight ratio of (250-300):(200-250):(5-10).

2. The floor cement-based thick-bed leveling flow mortar according to claim 1, wherein, The specific retarder is a Kobon retarder; and / or In the retarder, the mass ratio of tartaric acid to the special retarder is 1:(1.1-1.5).

3. The cement-based thick-layer leveling mortar for ground as described in claim 1 or 2, wherein, The cement is sulfoaluminate cement; and / or The aggregate is selected from one or more of manufactured sand, quartz sand, and river sand; and / or The mineral powder is granulated blast furnace slag powder; and / or The microspheres are artificial hollow glass microspheres or hollow ceramic microspheres; and / or The dispersible latex powder is selected from one or more of ethylene-vinyl acetate copolymer, vinyl acetate-vinyl tert-carbonate copolymer, styrene-acrylate copolymer, pure acrylate copolymer, and styrene-butadiene copolymer; and / or The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent; and / or The defoamer is selected from one or more of polysiloxane defoamers, polyether defoamers, tributyl phosphate, mineral oil defoamers, and alkynyl alcohol defoamers; and / or The cellulose ether is selected from one or more of methylcellulose ether, hydroxypropyl methylcellulose ether, and carboxymethylcellulose ether.

4. The cement-based thick-layer leveling mortar for ground as described in claim 3, wherein, The granulated blast furnace slag powder comprises, by weight, 30-75 parts CaO, 28-38 parts SiO2, 8-18 parts Al2O3, 5-12 parts MgO, 0.1-2 parts MnO, and 0.1-3 parts sulfides. Optionally, the particle size of the granulated blast furnace slag powder is 1-60 μm.

5. The cement-based thick-layer leveling mortar for ground as described in claim 1 or 2, wherein, The heavy calcium carbonate powder contains 95%-99% CaCO3 by weight. Optionally, the particle size of the heavy calcium carbonate powder is 1-70 μm.

6. The cement-based thick-layer leveling mortar for ground as described in claim 1 or 2, wherein, In the anhydrite, the weight percentage of CaSO4 is 85%-99%; Optionally, the particle size of the anhydrite is 10-100 μm.

7. The cement-based thick-layer leveling mortar for ground as described in claim 3, wherein, The defoamer is a polyether defoamer; and / or The cellulose ether is hydroxypropyl methylcellulose ether with a viscosity of 40,000-50,000 mPa·s.

8. The cement-based thick-layer leveling mortar for ground as described in claim 3, wherein, The cement-based thick-layer leveling mortar, by weight, comprises the following raw materials: 210 parts sulfoaluminate cement, 10 parts 1.0-2.5mm manufactured sand, 220 parts 0.5-1.0mm manufactured sand, 295.6 parts 0.1-0.5mm manufactured sand, 175 parts mineral powder, 50 parts heavy calcium carbonate powder, 20 parts anhydrite, 10 parts cenospheres, 6.0 parts dispersible latex powder, 0.8 parts water-reducing agent, 0.5 parts tartaric acid, 0.6 parts special retarder, 1.0 part defoamer, 0.5 parts cellulose ether; or 240 parts sulfoaluminate cement, 10 parts 1.0-2.5mm manufactured sand, 220 parts 0.5-1.0mm manufactured sand, 295.4 parts 0.1-0.5mm manufactured sand, 145 parts mineral powder, 50 parts heavy calcium carbonate powder, 20 parts anhydrite, 10 parts cenospheres, 6.0 parts dispersible latex powder, 0.8 parts water-reducing agent, 0.6 parts tartaric acid, 0.7 parts special retarder, 1.0 part defoamer, 0.5 parts cellulose ether.

9. A method for preparing a cement-based thick-layer leveling mortar for ground as described in any one of claims 1 to 8, comprising the following steps: The aggregates are screened. According to the formula, cellulose ether, defoamer, retarder, water-reducing agent, dispersible latex powder, bleaching beads, heavy calcium carbonate powder and anhydrite are added to the mixer in sequence for premixing. After mixing evenly, a premix is ​​obtained. Cement, mineral powder, aggregate, and the premixed material are measured and added to a mixer in sequence. After mixing evenly, a cement-based thick-layer leveling flowable mortar is obtained.

10. A cement-based thick-layer leveling mortar for ground preparation by the method of claim 9.

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