Lightweight ceramic tile bonding mortar and preparation method thereof

Abstract

The present application relates to the technical field of building materials, in particular to a light ceramic tile bonding mortar and a preparation method thereof. The mortar is obtained by mixing light ceramic tile bonding mortar dry powder with water, wherein the dry powder comprises coated closed-cell vitrified microsphere, fast-hardening sulphoaluminate cement, granulated blast furnace slag powder, heavy calcium carbonate powder, quartz sand, redispersible polymer powder, cellulose ether, starch ether, powdered polycarboxylic acid water reducer and L-tartaric acid. The coated closed-cell vitrified microsphere is obtained by sequentially pre-wetting the closed-cell vitrified microsphere with a pre-wetting liquid containing liquid sodium silicate, coating with a low water-solid ratio silicate coating slurry, delaying and segmenting the treatment of calcium stearate suspension and dry powder calcium stearate, low-temperature aging and drying. The water absorption of the closed-cell vitrified microsphere is reduced, the dry mixing crushing effect is reduced, the water retention rate, anti-sliding performance and tensile bonding strength on light base layers such as aerated concrete blocks and light partition wall plates of the mortar are improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a lightweight ceramic tile adhesive mortar and its preparation method. Background Technology

[0002] With the increasing demand for industrialized construction and energy conservation, tile adhesive materials are developing towards lightweight and thin-film applications. Closed-cell vitrified microspheres, due to their low density and good thermal insulation properties, are often used as lightweight aggregates in mortars to reduce overall density. However, their vitrified shells have microcracks and are porous internally, causing them to rapidly absorb moisture during mortar mixing. This leads to poor rheological properties of the mortar and a shortened open time during construction, especially on porous substrates such as aerated concrete blocks and lightweight partition boards, where they are prone to weakening of bond strength.

[0003] Existing lightweight tile adhesives mostly employ an aggregate pretreatment process of "wetting liquid impregnation and ultrafine powder mixing." While this can reduce the water absorption rate to some extent, the interfacial bonding between the wetting liquid and the subsequent coating layer is insufficient, making the coating layer prone to detachment during mixing. Simultaneously, the premature addition of a single hydrophobic component hinders the chemical bonding between the mineral cementitious material and the aggregate surface, resulting in high porosity and unstable mechanical properties in the interfacial transition zone. Furthermore, in traditional dry-mixing processes, prolonged mixing of lightweight aggregates and cementitious materials can easily lead to breakage, further exacerbating the water absorption problem and making it difficult to simultaneously meet the requirements of water retention, anti-slip properties, and adhesion to lightweight substrates under low density conditions. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a lightweight ceramic tile bonding mortar and its preparation method. Compared with ceramic tile bonding mortars that use conventional coated lightweight sand or lightweight aggregates with single hydrophobic treatment, the technical problem actually solved by this invention is to reduce the apparent density of the mortar while suppressing the water absorption and breakage of closed-cell vitrified microspheres during pretreatment, dry mixing and blending, and to improve the water retention, anti-slip and tensile bonding performance of the mortar on porous lightweight substrates such as aerated concrete blocks and lightweight partition boards.

[0005] To achieve the above objectives, the present invention provides a lightweight ceramic tile bonding mortar, which is obtained by mixing lightweight ceramic tile bonding mortar dry powder with water; the amount of water added in every 25,000 parts by weight of the lightweight ceramic tile bonding mortar dry powder is 5,400-5,800 parts by weight. Based on 50 parts by weight of closed-cell vitrified microsphere dry material, the dry powder material includes coated closed-cell vitrified microspheres obtained by surface treatment of the closed-cell vitrified microspheres and the following separately added main dry powder components: 80-95 parts by weight of rapid-hardening sulfoaluminate cement, 55-70 parts by weight of granulated blast furnace slag powder, 40-60 parts by weight of heavy calcium carbonate powder, 205-225 parts by weight of quartz sand, 12-17 parts by weight of redispersible vinyl acetate-ethylene copolymer powder, 1.6-2.2 parts by weight of modified methyl hydroxyethyl cellulose ether, 0.5-0.8 parts by weight of starch ether, 0.7-0.95 parts by weight of powdered polycarboxylate superplasticizer, and 0.28-0.40 parts by weight of L-tartaric acid; The closed-cell vitrified microspheres have a particle size of 150-600 μm; The coated closed-cell vitrified microspheres are obtained by sequentially processing the closed-cell vitrified microspheres as follows: A1: Pre-wet with a pre-wetting solution containing liquid sodium silicate until the moisture content is 8%-15%; A2: The pre-wetted closed-cell vitrified microspheres are contacted and mixed with a low water-to-solid ratio silicate coating slurry with a water-to-solid ratio of 40%-50%. The low water-to-solid ratio silicate coating slurry includes liquid sodium silicate, rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, silica fume, and L-tartaric acid. The water-to-solid ratio is calculated as the ratio of the mass of water in the low water-to-solid ratio silicate coating slurry to the mass of dry-based solid materials. The mass of water includes added water and water in the liquid sodium silicate. The mass of dry-based solid materials includes the solids in the liquid sodium silicate, rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, silica fume, and L-tartaric acid. A3: Starting from the first contact of the low water-to-solid ratio silicate coating slurry with the closed-cell vitrified microspheres, add calcium stearate suspension first, then add dry powdered calcium stearate. The calcium stearate suspension includes calcium stearate, water and powdered polycarboxylate superplasticizer. A4: Then age at 20-25℃ and 60%-75% relative humidity for 2-6 hours, and dry until the moisture content is no higher than 1%; The total dry basis feed amount of the low water-to-solid ratio silicate coating slurry, the calcium stearate suspension and the dry powder calcium stearate is 3.0%-8.0% of the dry mass of the closed-cell vitrified microspheres, and the total dry basis feed amount does not include the liquid sodium silicate solid and water in the pre-wetting liquid. The dry powder is obtained by first mixing the main dry powder components and then adding the coated closed-cell vitrified microspheres. The coated closed-cell vitrified microspheres include at least an inorganic mineral coating layer attached to the surface of the closed-cell vitrified microspheres and hydrophobic regions containing calcium stearate distributed on the outer side of the inorganic mineral coating layer or on the surface of the pores.

[0006] Furthermore, the pre-wetting solution includes water and liquid sodium silicate; based on 50 parts by weight of closed-cell vitrified microsphere dry material, the amount of water in the pre-wetting solution is 3.5-6.5 parts by weight, and the amount of liquid sodium silicate is 0.8-1.5 parts by weight.

[0007] Furthermore, the pre-wetting process involves spraying the pre-wetting liquid into the closed-cell vitrified microspheres while the drum is continuously rotating. The spraying time is 3-5 minutes, and the drum continues to rotate for 5-8 minutes after spraying.

[0008] Furthermore, based on 50 parts by weight of closed-cell vitrified microsphere dry material, the low water-to-solid ratio silicate coating slurry includes 0.22-0.50 parts by weight of water, 0.80-1.60 parts by weight of liquid sodium silicate, 0.80-1.50 parts by weight of rapid-hardening sulfoaluminate cement, 0.35-0.90 parts by weight of granulated blast furnace slag powder, 0.12-0.45 parts by weight of silica fume, and 0.012-0.035 parts by weight of L-tartaric acid.

[0009] Furthermore, the low water-to-solid ratio silicate coating slurry is added to the pre-wetted closed-cell vitrified microspheres in three batches, and mixed for 2-4 minutes after each addition. After the three additions are completed, mixing continues for another 3-4 minutes.

[0010] Furthermore, based on 50 parts by weight of closed-cell vitrified microsphere dry material, the calcium stearate suspension includes 0.05-0.15 parts by weight of calcium stearate, 0.08-0.15 parts by weight of water, and 0.003-0.008 parts by weight of powdered polycarboxylate superplasticizer; the amount of the dry powdered calcium stearate is 0.05-0.15 parts by weight.

[0011] Furthermore, the calcium stearate suspension is obtained by dispersing at 1500 r / min for 8 min; the calcium stearate suspension is added at a time of 3 min, and then the mixture is continued for 3 min after addition, followed by the addition of the dry powdered calcium stearate and continued mixing for 3 min.

[0012] Furthermore, the thickness of the material layer during aging is no more than 30mm, and the material is turned over once every 1 hour during the aging process, with each turning lasting 30 seconds; the drying is carried out at 40℃ with ventilation, and the dried material is then sieved through an 850μm sieve.

[0013] Furthermore, the liquid sodium silicate has a modulus of 2.6-2.8 and a solid content of 36%; the rapid-hardening sulfoaluminate cement is grade 42.5 rapid-hardening sulfoaluminate cement; and the granulated blast furnace slag powder is grade S95 granulated blast furnace slag powder.

[0014] Furthermore, the particle size of the quartz sand is 100-600 μm; the heavy calcium carbonate powder is 1200 mesh heavy calcium carbonate powder; and the redispersible vinyl acetate-ethylene copolymer powder is redispersible latex powder.

[0015] Furthermore, the present invention also provides a method for preparing lightweight ceramic tile adhesive mortar, comprising the following steps: S1. Quick-hardening sulfoaluminate cement, granulated blast furnace slag powder, heavy calcium carbonate powder, quartz sand, redispersible vinyl acetate-ethylene copolymer powder, modified methyl hydroxyethyl cellulose ether, starch ether, powdered polycarboxylate superplasticizer and L-tartaric acid are first mixed at 25 r / min for 4 min, and then coated closed-cell vitrified microspheres are added and mixed at 15 r / min for 2 min to obtain lightweight ceramic tile bonding mortar dry powder. S2: Mix the lightweight ceramic tile adhesive mortar dry powder with water at 140 r / min for 120 s, let it stand for 5 min, and then mix at 140 r / min for 60 s to obtain the lightweight ceramic tile adhesive mortar.

[0016] In this invention, the water-to-solid ratio of the low water-to-solid ratio silicate coating slurry is calculated as follows: Water-to-solid ratio = Mass of water in the slurry / Mass of dry-based solids in the slurry × 100%. When using liquid sodium silicate with a solid content of 36%, 64% of the mass of the liquid sodium silicate is included in the mass of water, and 36% is included in the mass of dry-based solids; the masses of rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, silica fume, and L-tartaric acid are all included in the mass of dry-based solids. By adjusting the amount of added water, the water-to-solid ratio of the low water-to-solid ratio silicate coating slurry is controlled at 40%-50%.

[0017] The beneficial effects of this invention are: This invention precisely controls the moisture content of closed-cell vitrified microspheres through a sodium silicate pre-wetting solution, providing a stable interface foundation for subsequent mineral coating. It also innovatively employs a low water-to-solid ratio silicate slurry and delayed-added calcium stearate in a synergistic effect. The former forms a chemically bonded inorganic reinforcing layer on the aggregate surface, while the latter constructs a gradient hydrophobic barrier. This dual mechanism significantly reduces the water absorption rate of the aggregate and enhances the interfacial bonding force.

[0018] This invention promotes early consolidation of the coating layer through low-temperature aging at 20-25℃ and 60%-75% relative humidity. Combined with a short-time mixing process in the main dry mixing stage—"mixing the cementitious components first, then adding the coating aggregate"—it avoids lightweight aggregate breakage and ensures effective interface treatment, successfully solving the technical challenge of simultaneously controlling water absorption and enhancing interface of lightweight aggregates. Furthermore, the precisely defined dry basis weight of the coating layer (3.0%-8.0%) and the synergistic proportioning of multiple components result in a mortar with an apparent density of 1448-1521 kg / m³. 3 Within the specified range, it possesses a water retention rate of ≥96.8%, anti-slip performance of ≤0.34mm, and a lightweight base layer tensile bond strength of ≥0.72MPa, demonstrating significantly superior overall performance compared to traditional products. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] Raw material source and model: The closed-cell vitrified microspheres are products sold by Yunnan Yunling Perlite Technology Development Co., Ltd. Before use, they are sieved through a 150μm sieve and a 600μm sieve to obtain particles between 150μm and 600μm. The rapid-hardening sulfoaluminate cement used is grade 42.5 rapid-hardening sulfoaluminate cement from Tangshan Arctic Bear Building Materials Co., Ltd. Granulated blast furnace slag powder uses S95 grade blast furnace slag powder from Shanghai Baosteel New Building Materials Technology Co., Ltd. The silica fume used is Elkem Microsilica 940 dry silica fume; The liquid sodium silicate used is sodium silicate product from Qingdao Haiwan Chemical Co., Ltd., with a modulus of 2.6-2.8 and a solid content of 36%. The calcium stearate powder used is calcium stearate product of Zanyu Technology Group Co., Ltd., and complies with HG / T2424-2012; The powdered polycarboxylate superplasticizer used is Sika ViscoCrete-225P powdered polycarboxylate superplasticizer from Sika Corporation; The quartz sand used is refined quartz sand from Shihou Quartz Plant in Donghai County, and the sieve size before use is 100μm-600μm; The heavy calcium carbonate powder used is 1200 mesh calcium carbonate powder from Guangxi Hezhou Guihua Powder Co., Ltd. The redispersible vinyl acetate-ethylene copolymer powder used is VINNAPAS 5044 N from Wacker Chemie. The modified methyl hydroxyethyl cellulose ether used was Ashland's Culminal UP1540; The starch ether used is BASF's Starvis SE35F; The L-tartaric acid used is industrial grade L-tartaric acid with a mass fraction of not less than 99%. Tap water is used.

[0021] Example 1: Step 1: Add 50kg of closed-cell vitrified microspheres into a drum mixer, setting the drum speed to 18r / min; add 4400g of water and 1000g of liquid sodium silicate to a plastic bucket and stir for 2 minutes to obtain a pre-wetting solution; under continuous drum rotation, spray all the pre-wetting solution into the 50kg of closed-cell vitrified microspheres over 4 minutes, and continue rolling for 6 minutes after spraying; take 20g of the pre-wetted closed-cell vitrified microspheres and dry them at 105℃ until the difference between two consecutive weighings does not exceed 0.02g. Calculate the moisture content by dividing the difference in mass before and after drying by the mass after drying. The moisture content is 10%. Step 2: Add 300g water, 1200g liquid sodium silicate, 1100g rapid-hardening sulfoaluminate cement, 600g granulated blast furnace slag powder, 300g silica fume, and 20g L-tartaric acid to a mixing tank and stir at 600r / min for 3min to obtain a low water-to-solids ratio silicate coating slurry. Based on the solid content of 36% liquid sodium silicate, the water-to-solids ratio of this low water-to-solids ratio silicate coating slurry is 44%. While the pre-wetted closed-cell vitrified microspheres obtained in Step 1 continue to roll at 18r / min, add all the low water-to-solids ratio silicate coating slurry in 3 portions, rolling for 3min after each addition. After the 3 additions are completed, continue rolling for 3min to allow the coating slurry to adhere to the surface of the pre-wetted closed-cell vitrified microspheres. Step 3: Add 100g of calcium stearate powder, 100g of water, and 5g of powdered polycarboxylate superplasticizer to a disperser and disperse at 1500r / min for 8min to obtain a calcium stearate suspension; 12 minutes after the low water-to-solid ratio silicate coated slurry first contacts the closed-cell vitrified microspheres, add all the calcium stearate suspension to the material obtained in Step 2 over 3 minutes while the drum is rotating at 18r / min, and continue rolling for 3 minutes; then add 100g of calcium stearate powder and roll for another 3 minutes. Step 4: Spread the wet-coated closed-cell vitrified microspheres obtained in Step 3 in a polyethylene tray, with the material layer thickness controlled to be less than 30 mm. Aged in an environment of 25℃ and 75% relative humidity for 4 hours, turning it over once every 1 hour for 30 seconds each time. After aging, dry it under ventilation conditions at 40℃. Then take 20 g of sample and determine the moisture content according to the 105℃ drying method. The drying endpoint is controlled to have a moisture content of no more than 1%. After drying, sieve it with an 850 μm sieve to remove large agglomerates and obtain the coated closed-cell vitrified microspheres. Step 5: Add 85,000g of rapid-hardening sulfoaluminate cement, 65,000g of granulated blast furnace slag powder, 50,000g of heavy calcium carbonate powder, 220,000g of quartz sand, 14,000g of redispersible vinyl acetate-ethylene copolymer powder, 1,800g of modified methyl hydroxyethyl cellulose ether, 600g of starch ether, 800g of powdered polycarboxylate superplasticizer, and 300g of L-tartaric acid to a conventional dry mortar mixer and mix at 25r / min for 4min; then add all the dried and coated closed-cell vitrified microspheres obtained in Step 4 and mix at 15r / min for 2min to obtain lightweight ceramic tile bonding mortar dry powder. Step Six: For on-site use, take 25000g of the lightweight ceramic tile adhesive mortar dry powder obtained in Step Five, add 5500g of water, stir at 140r / min for 120s, let stand for 5min, and then stir at 140r / min for 60s to obtain the lightweight ceramic tile adhesive mortar. Apply the lightweight ceramic tile adhesive mortar to the surface of aerated concrete blocks and lightweight partition boards using a 6mm×6mm notched trowel, controlling the application thickness to 3mm-5mm, and then press 300mm×600mm ceramic tiles onto them.

[0022] Example 2: Step 1: Add 50kg of closed-cell vitrified microspheres into a drum mixer, setting the drum speed to 18r / min; add 3500g of water and 800g of liquid sodium silicate to a plastic bucket and stir for 2 minutes to obtain a pre-wetting solution; under continuous drum rotation, spray all the pre-wetting solution into the 50kg of closed-cell vitrified microspheres over 4 minutes, and continue rolling for 5 minutes after spraying; take 20g of the pre-wetted closed-cell vitrified microspheres and dry them at 105℃ until the difference between two consecutive weighings does not exceed 0.02g. Calculate the moisture content by dividing the difference in mass before and after drying by the mass after drying. The moisture content is 8%. Step 2: Add 220g water, 800g liquid sodium silicate, 800g rapid-hardening sulfoaluminate cement, 350g granulated blast furnace slag powder, 120g silica fume, and 12g L-tartaric acid to a mixing tank and stir at 600r / min for 3min to obtain a low water-to-solids ratio silicate coating slurry. Based on the solid content of 36% liquid sodium silicate, the water-to-solids ratio of this low water-to-solids ratio silicate coating slurry is 47%. While the pre-wetted closed-cell vitrified microspheres obtained in Step 1 continue to roll at 18r / min, add all the low water-to-solids ratio silicate coating slurry in 3 portions, rolling for 2min after each addition. After the 3 additions are completed, continue rolling for 4min to allow the coating slurry to adhere to the surface of the pre-wetted closed-cell vitrified microspheres. Step 3: Add 50g of calcium stearate powder, 80g of water, and 3g of powdered polycarboxylate superplasticizer to a disperser and disperse at 1500r / min for 8min to obtain a calcium stearate suspension. Counting from the 10th minute after the low water-to-solid ratio silicate-coated slurry first contacts the closed-cell vitrified microspheres, while maintaining the drum rotation at 18r / min, add all the calcium stearate suspension to the material obtained in Step 2 over 3 minutes, and continue rolling for another 3 minutes. Then add 50g of calcium stearate powder and roll for another 3 minutes. Step 4: Spread the wet-coated closed-cell vitrified microspheres obtained in Step 3 in a polyethylene tray, with the material layer thickness controlled to be less than 30 mm. Aged in an environment of 20℃ and 60% relative humidity for 2 hours, turning it over once every 1 hour for 30 seconds each time. After aging, dry it under ventilation conditions at 40℃. Then take 20 g of sample and determine the moisture content according to the 105℃ drying method. The drying endpoint is controlled to have a moisture content of no more than 1%. After drying, sieve it with an 850 μm sieve to remove large agglomerates and obtain the coated closed-cell vitrified microspheres. Step 5: Add 80,000g of rapid-hardening sulfoaluminate cement, 70,000g of granulated blast furnace slag powder, 60,000g of heavy calcium carbonate powder, 225,000g of quartz sand, 12,000g of redispersible vinyl acetate-ethylene copolymer powder, 1,600g of modified methyl hydroxyethyl cellulose ether, 500g of starch ether, 700g of powdered polycarboxylate superplasticizer, and 280g of L-tartaric acid to a conventional dry mortar mixer and mix at 25r / min for 4min; then add all the dried and coated closed-cell vitrified microspheres obtained in Step 4 and mix at 15r / min for 2min to obtain lightweight ceramic tile bonding mortar dry powder. Step Six: For on-site use, take 25000g of the lightweight ceramic tile adhesive mortar dry powder obtained in Step Five, add 5400g of water, stir at 140r / min for 120s, let stand for 5min, and then stir at 140r / min for 60s to obtain the lightweight ceramic tile adhesive mortar. Apply the lightweight ceramic tile adhesive mortar to the surface of aerated concrete blocks and lightweight partition boards using a 6mm×6mm notched trowel, controlling the application thickness to 3mm-5mm, and then press 300mm×600mm ceramic tiles onto them.

[0023] Example 3: Step 1: Add 50kg of closed-cell vitrified microspheres into a drum mixer, setting the drum speed to 18r / min; add 5300g of water and 1200g of liquid sodium silicate to a plastic bucket and stir for 2 minutes to obtain a pre-wetting solution; under continuous drum rotation, spray all the pre-wetting solution into the 50kg of closed-cell vitrified microspheres over 4 minutes, and continue rolling for 7 minutes after spraying; take 20g of the pre-wetted closed-cell vitrified microspheres and dry them at 105℃ until the difference between two consecutive weighings does not exceed 0.02g. Calculate the moisture content by dividing the difference in mass before and after drying by the mass after drying. The moisture content is 12%. Step 2: Add 450g water, 1500g liquid sodium silicate, 1400g rapid-hardening sulfoaluminate cement, 800g granulated blast furnace slag powder, 450g silica fume, and 30g L-tartaric acid to a mixing tank and stir at 600r / min for 3min to obtain a low water-to-solids ratio silicate coating slurry. Based on the solid content of 36% liquid sodium silicate, the water-to-solids ratio of this low water-to-solids ratio silicate coating slurry is 44%. While the pre-wetted closed-cell vitrified microspheres obtained in Step 1 continue to roll at 18r / min, add all the low water-to-solids ratio silicate coating slurry in 3 portions, rolling for 3min after each addition. After the 3 additions are completed, continue rolling for 3min to allow the coating slurry to adhere to the surface of the pre-wetted closed-cell vitrified microspheres. Step 3: Add 125g of calcium stearate powder, 125g of water, and 6g of powdered polycarboxylate superplasticizer to a disperser and disperse at 1500r / min for 8min to obtain a calcium stearate suspension. Counting from the 12th minute after the low water-to-solid ratio silicate-coated slurry first contacts the closed-cell vitrified microspheres, while maintaining the drum rotation at 18r / min, add all the calcium stearate suspension to the material obtained in Step 2 over 3 minutes, and continue rolling for another 3 minutes. Then add 125g of calcium stearate powder and roll for another 3 minutes. Step 4: Spread the wet-coated closed-cell vitrified microspheres obtained in Step 3 in a polyethylene tray, with the material layer thickness controlled to be less than 30 mm. Aged in an environment of 25℃ and 75% relative humidity for 5 hours, turning it over once every 1 hour for 30 seconds each time. After aging, dry it under ventilation conditions at 40℃. Then take 20 g of sample and determine the moisture content according to the 105℃ drying method. The drying endpoint is controlled to have a moisture content of no more than 1%. After drying, sieve it with an 850 μm sieve to remove large agglomerates and obtain the coated closed-cell vitrified microspheres. Step 5: Add 90,000g of rapid-hardening sulfoaluminate cement, 60,000g of granulated blast furnace slag powder, 45,000g of heavy calcium carbonate powder, 210,000g of quartz sand, 16,000g of redispersible vinyl acetate-ethylene copolymer powder, 2,000g of modified methyl hydroxyethyl cellulose ether, 700g of starch ether, 900g of powdered polycarboxylate superplasticizer, and 350g of L-tartaric acid to a conventional dry mortar mixer and mix at 25r / min for 4min; then add all the dried and coated closed-cell vitrified microspheres obtained in Step 4 and mix at 15r / min for 2min to obtain lightweight ceramic tile bonding mortar dry powder. Step Six: For on-site use, take 25000g of the lightweight ceramic tile adhesive mortar dry powder obtained in Step Five, add 5600g of water, stir at 140r / min for 120s, let stand for 5min, and then stir at 140r / min for 60s to obtain the lightweight ceramic tile adhesive mortar. Apply the lightweight ceramic tile adhesive mortar to the surface of aerated concrete blocks and lightweight partition boards using a 6mm×6mm notched trowel, controlling the application thickness to 3mm-5mm, and then press 300mm×600mm ceramic tiles onto them.

[0024] Example 4: Step 1: Add 50 kg of closed-cell vitrified microspheres into a drum mixer, setting the drum speed to 18 r / min; add 6500 g of water and 1500 g of liquid sodium silicate to a plastic bucket and stir for 2 min to obtain a pre-wetting solution; under continuous drum rotation, spray all the pre-wetting solution into 50 kg of closed-cell vitrified microspheres over 5 min, and continue rolling for 8 min after spraying; take 20 g of the pre-wetted closed-cell vitrified microspheres and dry them at 105℃ until the difference between two consecutive weighings does not exceed 0.02 g. Calculate the moisture content by dividing the difference in mass before and after drying by the mass after drying. The moisture content is 15%. Step 2: Add 500g water, 1600g liquid sodium silicate, 1500g rapid-hardening sulfoaluminate cement, 900g granulated blast furnace slag powder, 450g silica fume, and 30g L-tartaric acid to a mixing tank and stir at 600r / min for 4min to obtain a low water-to-solids ratio silicate coating slurry. Based on the solid content of 36% liquid sodium silicate, the water-to-solids ratio of this low water-to-solids ratio silicate coating slurry is 44%. While the pre-wetted closed-cell vitrified microspheres obtained in Step 1 continue to roll at 18r / min, add all the low water-to-solids ratio silicate coating slurry in 3 portions, rolling for 4min after each addition. After the 3 additions are completed, continue rolling for 3min to allow the coating slurry to adhere to the surface of the pre-wetted closed-cell vitrified microspheres. Step 3: Add 150g of calcium stearate powder, 150g of water, and 8g of powdered polycarboxylate superplasticizer to a disperser and disperse at 1500r / min for 8min to obtain a calcium stearate suspension. 15min after the low water-to-solid ratio silicate coated slurry first contacts the closed-cell vitrified microspheres, add all the calcium stearate suspension to the material obtained in Step 2 over 3min while maintaining the drum rotation at 18r / min, and continue rolling for 3min. Then add 150g of calcium stearate powder and roll for another 3min. Step 4: Spread the wet-coated closed-cell vitrified microspheres obtained in Step 3 in a polyethylene tray, with the material layer thickness controlled to be less than 30 mm. Aged in an environment of 25℃ and 70% relative humidity for 6 hours, turning it over once every 1 hour for 30 seconds each time. After aging, dry it under ventilation conditions at 40℃. Then take 20 g of sample and determine the moisture content according to the 105℃ drying method. The drying endpoint is controlled to have a moisture content of no more than 1%. After drying, sieve it with an 850 μm sieve to remove large agglomerates and obtain the coated closed-cell vitrified microspheres. Step 5: Add 95,000g of rapid-hardening sulfoaluminate cement, 55,000g of granulated blast furnace slag powder, 40,000g of heavy calcium carbonate powder, 205,000g of quartz sand, 17,000g of redispersible vinyl acetate-ethylene copolymer powder, 2,200g of modified methyl hydroxyethyl cellulose ether, 800g of starch ether, 950g of powdered polycarboxylate superplasticizer, and 400g of L-tartaric acid to a conventional dry mortar mixer and mix at 25r / min for 4min; then add all the dried and coated closed-cell vitrified microspheres obtained in Step 4 and mix at 15r / min for 2min to obtain lightweight ceramic tile bonding mortar dry powder. Step Six: For on-site use, take 25000g of the lightweight ceramic tile adhesive mortar dry powder obtained in Step Five, add 5800g of water, stir at 140r / min for 120s, let stand for 5min, and then stir at 140r / min for 60s to obtain the lightweight ceramic tile adhesive mortar. Apply the lightweight ceramic tile adhesive mortar to the surface of aerated concrete blocks and lightweight partition boards using a 6mm×6mm notched trowel, controlling the application thickness to 3mm-5mm, and then press 300mm×600mm ceramic tiles onto them.

[0025] Comparative Example 1: The difference from Example 1 is that: in step one, liquid sodium silicate is not added, and 5000g of water is sprayed into 50kg of closed-cell vitrified microspheres as a pre-wetting liquid, so that the water content of the pre-wetted closed-cell vitrified microspheres is 10%; and in step five, the amount of heavy calcium carbonate powder is increased by 360g to make up for the amount of liquid sodium silicate that was not added. The other conditions are the same as in Example 1.

[0026] Comparative Example 2: The difference from Example 1 is that in step one, the moisture content of the pre-wetted closed-cell vitrified microspheres is controlled to be 5.0%. Specifically, 1880g of water and 1000g of liquid sodium silicate are added to a plastic bucket and stirred for 2 minutes before being sprayed into 50kg of closed-cell vitrified microspheres; the other conditions are the same as in Example 1.

[0027] Comparative Example 3: The difference from Example 1 is that: in step two, rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder and silica fume are not added. In step two, only 300g of water, 1200g of liquid sodium silicate and 20g of L-tartaric acid are added to the mixing tank to prepare the treatment solution and the pre-wetted closed-cell vitrified microspheres obtained in step one are added. At the same time, in step five, the amount of quartz sand is increased by 2000g to make up for the total amount of rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder and silica fume not added in step two. The other conditions are the same as in Example 1.

[0028] Comparative Example 4: The difference from Example 1 is that the dry basis feed amount of silicate coating slurry in step two is reduced to 1.57% of the dry weight of closed-cell vitrified microspheres, and the total dry basis feed amount of the coating treatment is about 1.98% of the dry weight of closed-cell vitrified microspheres, which is lower than the 3.0% lower limit specified in this invention. Specifically, the amount of rapid-hardening sulfoaluminate cement in step two is changed to 300 g, the amount of granulated blast furnace slag powder is changed to 180 g, the amount of silica fume is changed to 80 g, the amount of liquid sodium silicate is changed to 600 g, the amount of water is changed to 150 g, and the amount of L-tartaric acid is changed to 8 g; at the same time, the amount of quartz sand in step five is increased by 1844 g to make up for the reduced amount of dry basis material, and the other conditions are the same as in Example 1.

[0029] Comparative Example 5: The difference from Example 1 is that: in step three, calcium stearate is not added at the 12th minute from the first contact of the low water-to-solid ratio silicate coating slurry with the closed-cell vitrified microspheres, but rather 200g of calcium stearate powder is directly added to 50kg of closed-cell vitrified microspheres and rolled for 3 minutes before the pre-wetting liquid is sprayed in step one; in step three, only a mixture of 100g of water and 5g of powdered polycarboxylate superplasticizer is added, and calcium stearate powder is no longer added, while the other conditions are the same as in Example 1.

[0030] Comparative Example 6: The difference from Example 1 is that: in step three, calcium stearate suspension is not prepared, nor is the calcium stearate suspension and dry powder calcium stearate powder added in stages; 12 minutes after the low water-to-solid ratio silicate coated slurry first contacts the closed-cell vitrified microspheres, 100g of water and 5g of powdered polycarboxylate superplasticizer are added to the material obtained in step two, and then 200g of calcium stearate powder is added all at once immediately, and the other conditions are the same as in Example 1.

[0031] Comparative Example 7: The difference from Example 1 is that: in step four, the 4-hour aging treatment at 25°C and 75% relative humidity is not performed; the wet-coated closed-cell vitrified microspheres obtained in step three are directly dried at 40°C under ventilation conditions until the moisture content is not higher than 1%; the other conditions are the same as in Example 1.

[0032] Comparative Example 8: The difference from Example 1 is that in step five, instead of mixing other dry powder materials first and then adding the dried coated closed-cell vitrified microspheres and mixing at 15 r / min for 2 min, all the dried coated closed-cell vitrified microspheres obtained in step four are simultaneously added to a conventional dry mortar mixer along with rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, heavy calcium carbonate powder, quartz sand, redispersible vinyl acetate-ethylene copolymer powder, modified methyl hydroxyethyl cellulose ether, starch ether, powdered polycarboxylate superplasticizer, and L-tartaric acid, and mixed at 25 r / min for 6 min. The remaining conditions are the same as in Example 1.

[0033] Performance testing: The samples used for performance testing were the lightweight ceramic tile adhesive mortar dry powders obtained in Examples 1-4 and Comparative Examples 1-8. For Example 1 and Comparative Examples 1-8, 25000g of dry powder was added to 5500g of water; for Example 2, 25000g of dry powder was added to 5400g of water; for Example 3, 25000g of dry powder was added to 5600g of water; and for Example 4, 25000g of dry powder was added to 5800g of water. All samples were mixed using the same mortar mixer at 140 rpm for 120 seconds, allowed to stand for 5 minutes, and then mixed again at 140 rpm for 60 seconds before being used for fresh mixing performance and molding tests. The ceramic tiles used in the tests conformed to GB / T 4100-2015. 50mm×50mm ceramic tiles were used for the tensile bond test, and 100mm×100mm ceramic tiles were used for the slip test. The standard concrete slab size was 400mm×400mm×40mm. Autoclaved aerated concrete blocks conforming to GB / T 11968-2020 (A3.5, B06) were cut into 400mm×400mm×80mm test substrates. Lightweight partition boards conforming to GB / T 23451-2023 were cut into 400mm×400mm×60mm test substrates. All substrates were placed at 23℃ and 50% relative humidity for 7 days before testing. Surface dust was removed with a stiff brush before testing, and surface particles were cleaned with a vacuum cleaner.

[0034] Thickness of the coating layer on the surface of the closed-cell vitrified microspheres: 5g each of the closed-cell vitrified microspheres obtained in step four of Examples 1-4 and Comparative Examples 1-8 were dried at 105℃ for 2 hours and then cooled to room temperature. 30 particles were randomly selected from each sample, embedded in epoxy resin, and cut along the direction of the particle's maximum projected diameter. The cut surfaces were polished sequentially with 600-grit, 1200-grit, and 2000-grit sandpaper and then sputter-coated with gold. The particle cross-section was observed using a scanning electron microscope at an accelerating voltage of 10kV. Micrometer-level length measurements were performed according to GB / T 16594-2008. The distance from the outer edge of the vitreous core to the outer edge of the rough mineral layer in the scanning electron microscope image was used as the coating layer thickness. Eight points were measured equidistantly along the circumference of each particle, resulting in 240 thickness data points for each sample. The arithmetic mean was taken as the average coating layer thickness, expressed in μm.

[0035] 1-hour water absorption rate of coated closed-cell vitrified microspheres: Take 50g each of the coated closed-cell vitrified microspheres obtained in step four of Examples 1-4 and Comparative Examples 1-8, dry them at 105℃ until the difference between two consecutive weighings does not exceed 0.02g, and weigh them as the dry weight. Referring to the test method for water absorption rate of lightweight aggregates in GB / T 17431.2-2010, immerse the entire sample in water at 23℃ for a fixed immersion time of 1 hour. After immersion, collect the sample using a 150μm sieve, let it stand to drain for 120s, then gently touch the sample surface with absorbent paper for 10s to remove obvious surface water, and immediately weigh the wet weight. Calculate the 1-hour water absorption rate by dividing the difference between the wet weight and the dry weight by the dry weight. Test each sample in parallel three times, and take the arithmetic mean, in percentages (%).

[0036] Apparent density and water retention of freshly mixed mortar: After preparing the freshly mixed lightweight ceramic tile bonding mortars of Examples 1-4 and Comparative Examples 1-8 according to the sample preparation method in this section, the tests were conducted within 3 minutes after mixing. The apparent density of the freshly mixed mortar was determined according to the test method for freshly mixed mortar in JGJ / T 70-2009 and GB / T 29756-2013. A 1L metal measuring cylinder was used, filled in two layers, and each layer was tamped evenly 15 times around the circumference with a tamping rod. After leveling, the apparent density was weighed and calculated. The unit is kg / m³. 3 The water retention rate was determined according to the water retention test method in JGJ / T 70-2009. Filter paper, metal filter screen, test mold and water-absorbing material were placed in an environment of 23℃ and 50% relative humidity for 24 hours before testing. Each sample was tested in parallel 3 times, and the arithmetic mean was taken. The unit is %.

[0037] Slippage: Specimens were prepared according to the slippage test method for ceramic tile adhesives in GB / T 12954.1-2008. Freshly mixed lightweight ceramic tile adhesive mortar obtained in Examples 1-4 and Comparative Examples 1-8 was applied to a vertically placed standard concrete slab using a 6mm × 6mm notched trowel, maintaining a vertical orientation. Within 2 minutes of application, a 100mm × 100mm ceramic tile was placed on the slab and pressed down with a 20N load for 30 seconds. The load was then removed, and an initial mark was made between the upper edge of the ceramic tile and the substrate. After the specimen was placed vertically at 23℃ and 50% relative humidity for 20 minutes, the downward displacement of the ceramic tile relative to the initial mark was measured using a vernier caliper with an accuracy of 0.01mm. The slippage value was recorded in mm. Five specimens were prepared for each sample, and the arithmetic mean was taken.

[0038] Tensile bond strength after 20-minute curing: Specimens were prepared according to the test method for curing time of ceramic tile adhesives in GB / T 12954.1-2008. Freshly mixed lightweight ceramic tile adhesive mortar obtained in Examples 1-4 and Comparative Examples 1-8 was applied to a standard concrete slab using a 6mm×6mm notched trowel, with a thickness controlled at 4mm. After application, the mortar was allowed to stand for 20 minutes at 23℃ and 50% relative humidity, and then 50mm×50mm ceramic tiles were placed on it, each tile being pressed with a 20N load for 30 seconds. After curing the specimens for 27 days at 23℃ and 50% relative humidity, pull-out heads were bonded with high-strength epoxy adhesive, and the specimens were allowed to stand for another 24 hours. Tensile testing was then conducted at a loading rate of 250N / s, and the failure load was recorded and converted into tensile bond strength in MPa. Ten specimens were tested for each sample, and the arithmetic mean was taken after removing data showing obvious non-interfacial abnormal failures.

[0039] Tensile bond strength of standard concrete slabs and tensile bond strength after immersion in water: Specimens were prepared according to the test method for tensile bond strength of ceramic tile adhesives in GB / T 12954.1-2008. For the tensile bond strength test specimens, a standard concrete slab was used as the substrate. Freshly mixed lightweight ceramic tile adhesive mortar was applied using a 6mm×6mm notched trowel, and 50mm×50mm ceramic tiles were placed on top. Each ceramic tile was pressed with a 20N load for 30s. The specimens were cured at 23℃ and 50% relative humidity for 27 days, then a pull-out head was attached, and the specimens were left to stand for another 24 hours before being tested at a loading rate of 250N / s. For the tensile bond strength test specimens after immersion in water, the specimens were first cured at 23℃ and 50% relative humidity for 7 days, then immersed in water at 23℃ for 20 days. After removal, the surface water was wiped off, a pull-out head was attached, and the specimens were left to stand at 23℃ and 50% relative humidity for 7 hours before being tested at a loading rate of 250N / s. Ten specimens were tested for each sample under each condition, and the results are expressed in MPa.

[0040] Tensile bond strength of lightweight substrates: Following the sample preparation, curing, and loading methods of GB / T 12954.1-2008 Tensile Bond Strength Test, standard concrete slabs were replaced with aerated concrete block substrates and lightweight partition wallboard substrates, respectively. Freshly mixed lightweight ceramic tile bonding mortar obtained in Examples 1-4 and Comparative Examples 1-8 was applied to the surfaces of the aerated concrete block substrates and lightweight partition wallboard substrates using a 6mm×6mm notched trowel, with a coating thickness controlled to 4mm. 50mm×50mm ceramic tiles were then placed on top and pressed under a 20N load for 30s. After curing the specimens at 23℃ and 50% relative humidity for 27 days, pull-out heads were bonded with high-strength epoxy adhesive, and the specimens were left to stand for another 24 hours before being subjected to tensile testing at a loading rate of 250N / s. Ten specimens were tested on each type of lightweight substrate for each sample, and the tensile bond strength (in MPa) was recorded, along with the location of failure.

[0041] Table 1 Performance Test Results

[0042] As shown in Table 1, in Comparative Example 1, no liquid sodium silicate was added during the pre-wetting stage. Although the pre-wetting moisture content of the closed-cell vitrified microspheres was still controlled at 10.0%, the average thickness of its coating layer was only 0.82 μm, and the water absorption rate increased to 22.3% after 1 hour. The tensile bond strength after 20 minutes of drying, the tensile bond strength after immersion in water, the tensile bond strength of the aerated concrete block base layer, and the tensile bond strength of the lightweight partition board base layer were 0.70 MPa, 0.74 MPa, 0.59 MPa, and 0.66 MPa, respectively, all of which were lower than those in Example 1. This indicates that the pre-wetting liquid containing liquid sodium silicate is beneficial to the adhesion and function of the subsequent mineral coating materials on the surface of the closed-cell vitrified microspheres.

[0043] In Comparative Example 2, after reducing the pre-wetting moisture content to 5.0%, the water absorption rate of the coated closed-cell vitrified microspheres increased further to 24.8% in 1 hour, the water retention rate of the fresh mortar decreased to 93.9%, and the tensile bond strength after 20 minutes of drying was only 0.54 MPa. This indicates that insufficient pre-wetting will cause the closed-cell vitrified microspheres to continue to absorb water during the mixing and molding stages, which is not conducive to maintaining effective wetting of the thin-layer mortar.

[0044] Comparative Example 3 did not add rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, and silica fume to the coating slurry. The average thickness of the coating layer decreased to 0.18 μm, the water absorption rate increased to 29.4% in 1 hour, the slip increased to 0.57 mm, and the tensile bond strength of the lightweight base layer decreased significantly. Comparative Example 4 reduced the dry basis amount of the surface coating material to 1.5%, and the same phenomenon of increased water absorption rate, increased slip, and decreased bond strength was observed. This indicates that silicate treatment alone or a low coating amount is insufficient to simultaneously control the water absorption of lightweight aggregates and enhance the interface.

[0045] Comparative Example 5, where calcium stearate was added to closed-cell vitrified microspheres in advance, had a water absorption rate of 17.8% in 1 hour, but the average thickness of the coating layer, slip, and tensile bond strength were all inferior to those of Example 1. This indicates that introducing hydrophobic components too early may affect the effective bonding between the subsequent mineral coating material and the surface of the closed-cell vitrified microspheres. Comparative Example 6, which used a one-time addition of calcium stearate powder, had performance between Comparative Example 5 and Example 1, indicating that adding calcium stearate in two phases, suspension and dry powder, in a delayed, segmented manner is more beneficial for balancing hydrophobic stability and interfacial bonding.

[0046] In Comparative Example 7, omitting the aging step resulted in a decrease in both the average thickness of the coating layer and the mortar bonding performance, indicating that low-temperature aging after coating helps the coated material achieve early consolidation before entering the main dry mix. Although the average thickness of the coating layer and the 1-hour water absorption rate in Comparative Example 8 were similar to those in Example 1, the apparent density of the freshly mixed mortar increased to 1542 kg / m³ because the method of adding and short-term mixing after coating with closed-cell vitrified microspheres was not used. 3 The decrease in water retention rate and tensile bond strength indicates that the order of addition and mixing time in the main dry mixing stage will affect the integrity of lightweight aggregate and the effect of interface treatment.

[0047] Examples 1-4 all employed a combined process of pre-wetting with liquid sodium silicate, coating with low water-to-solid ratio silicate minerals, delayed and segmented addition of calcium stearate, aging and drying, and dry mixing after a short period of time. Their 1-hour water absorption rate was 11.8%-18.9%, water retention rate was 96.8%-98.6%, and slip was 0.18mm-0.34mm, all exhibiting good water absorption control and anti-slip performance. Among them, Example 3 showed the best overall performance with the following tensile bond strengths after 20 minutes of drying: 1.05MPa, 1.52MPa, 1.16MPa, 0.88MPa, and 0.96MPa, respectively, for standard concrete slabs, after immersion in water, aerated concrete block substrate, and lightweight partition wall substrate.

[0048] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A lightweight ceramic tile adhesive mortar, characterized in that, It is obtained by mixing lightweight ceramic tile adhesive mortar dry powder with water; the amount of water added in every 25,000 parts by weight of the lightweight ceramic tile adhesive mortar dry powder is 5,400-5,800 parts by weight. Based on 50 parts by weight of closed-cell vitrified microsphere dry material, the dry powder material includes coated closed-cell vitrified microspheres obtained by surface treatment of the closed-cell vitrified microspheres and the following separately added main dry powder components: 80-95 parts by weight of rapid-hardening sulfoaluminate cement, 55-70 parts by weight of granulated blast furnace slag powder, 40-60 parts by weight of heavy calcium carbonate powder, 205-225 parts by weight of quartz sand, 12-17 parts by weight of redispersible vinyl acetate-ethylene copolymer powder, 1.6-2.2 parts by weight of modified methyl hydroxyethyl cellulose ether, 0.5-0.8 parts by weight of starch ether, 0.7-0.95 parts by weight of powdered polycarboxylate superplasticizer, and 0.28-0.40 parts by weight of L-tartaric acid; The closed-cell vitrified microspheres have a particle size of 150-600 μm; The coated closed-cell vitrified microspheres are obtained by sequentially processing the closed-cell vitrified microspheres as follows: A1: Pre-wet with a pre-wetting solution containing liquid sodium silicate until the moisture content is 8%-15%; A2: The pre-wetted closed-cell vitrified microspheres are contacted and mixed with a low water-to-solid ratio silicate coating slurry with a water-to-solid ratio of 40%-50%. The low water-to-solid ratio silicate coating slurry includes liquid sodium silicate, rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, silica fume, and L-tartaric acid. The water-to-solid ratio is calculated as the ratio of the mass of water in the low water-to-solid ratio silicate coating slurry to the mass of dry-based solid materials. The mass of water includes added water and water in the liquid sodium silicate. The mass of dry-based solid materials includes the solids in the liquid sodium silicate, rapid-hardening sulfoaluminate cement, granulated blast furnace slag powder, silica fume, and L-tartaric acid. A3: Starting from the first contact of the low water-to-solid ratio silicate coating slurry with the closed-cell vitrified microspheres, add calcium stearate suspension first, then add dry powdered calcium stearate. The calcium stearate suspension includes calcium stearate, water and powdered polycarboxylate superplasticizer. A4: Then age at 20-25℃ and 60%-75% relative humidity for 2-6 hours, and dry until the moisture content is no more than 1%; The total dry basis feed amount of the low water-to-solid ratio silicate coating slurry, the calcium stearate suspension and the dry powder calcium stearate is 3.0%-8.0% of the dry mass of the closed-cell vitrified microspheres, and the total dry basis feed amount does not include the liquid sodium silicate solid and water in the pre-wetting liquid. The dry powder is obtained by first mixing the main dry powder components and then adding the coated closed-cell vitrified microspheres. The coated closed-cell vitrified microspheres include at least an inorganic mineral coating layer attached to the surface of the closed-cell vitrified microspheres and hydrophobic regions containing calcium stearate distributed on the outer side of the inorganic mineral coating layer or on the surface of the pores.

2. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The pre-wetting solution includes water and liquid sodium silicate; based on 50 parts by weight of closed-cell vitrified microspheres, the amount of water in the pre-wetting solution is 3.5-6.5 parts by weight, and the amount of liquid sodium silicate is 0.8-1.5 parts by weight; the pre-wetting is performed by spraying the pre-wetting solution into the closed-cell vitrified microspheres under continuous rotation of the drum for 3-5 minutes, and continuing to roll for 5-8 minutes after spraying.

3. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, Based on 50 parts by weight of closed-cell vitrified microsphere dry material, the low water-to-solid ratio silicate coating slurry includes 0.22-0.50 parts by weight of water, 0.80-1.60 parts by weight of liquid sodium silicate, 0.80-1.50 parts by weight of rapid-hardening sulfoaluminate cement, 0.35-0.90 parts by weight of granulated blast furnace slag powder, 0.12-0.45 parts by weight of silica fume, and 0.012-0.035 parts by weight of L-tartaric acid.

4. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The low water-to-solid ratio silicate coating slurry was added to the pre-wetted closed-cell vitrified microspheres in three batches, with each addition followed by 2-4 minutes of mixing. After the three additions were completed, mixing continued for another 3-4 minutes.

5. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, Based on 50 parts by weight of closed-cell vitrified microsphere dry material, the calcium stearate suspension includes 0.05-0.15 parts by weight of calcium stearate, 0.08-0.15 parts by weight of water, and 0.003-0.008 parts by weight of powdered polycarboxylate superplasticizer; the amount of dry powdered calcium stearate is 0.05-0.15 parts by weight.

6. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The calcium stearate suspension was obtained by dispersing at 1500 r / min for 8 min; the calcium stearate suspension was added at a time of 3 min, and then the mixture was continued for 3 min after addition, followed by the addition of the dry powdered calcium stearate and continued mixing for 3 min.

7. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The thickness of the material layer during aging is no more than 30 mm. The material is turned over once every 1 hour during the aging process, and each turning lasts for 30 seconds. The drying process is carried out at 40°C with ventilation, and the dried material is then sieved through an 850 μm sieve.

8. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The liquid sodium silicate has a modulus of 2.6-2.8 and a solid content of 36%; the rapid-hardening sulfoaluminate cement is grade 42.5 rapid-hardening sulfoaluminate cement; and the granulated blast furnace slag powder is grade S95 granulated blast furnace slag powder.

9. The lightweight ceramic tile adhesive mortar according to claim 1, characterized in that, The quartz sand has a particle size of 100-600μm; the heavy calcium carbonate powder is 1200 mesh heavy calcium carbonate powder; and the redispersible vinyl acetate-ethylene copolymer powder is a redispersible latex powder.

10. A method for preparing lightweight ceramic tile adhesive mortar according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Quick-hardening sulfoaluminate cement, granulated blast furnace slag powder, heavy calcium carbonate powder, quartz sand, redispersible vinyl acetate-ethylene copolymer powder, modified methyl hydroxyethyl cellulose ether, starch ether, powdered polycarboxylate superplasticizer and L-tartaric acid are first mixed at 25 r / min for 4 min, and then coated closed-cell vitrified microspheres are added and mixed at 15 r / min for 2 min to obtain lightweight ceramic tile bonding mortar dry powder. S2: Mix the lightweight ceramic tile adhesive mortar dry powder with water at 140 r / min for 120 s, let it stand for 5 min, and then mix at 140 r / min for 60 s to obtain the lightweight ceramic tile adhesive mortar.

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