Dry-mixed mortar composition and adhesive slurry for gypsum material substrates

Abstract

The present invention provides a dry-mixed mortar composition, which comprises a binder, an aggregate and an additive, and the binder accounts for 25-40% of the total weight of the dry-mixed mortar composition. The binder is composed of slag particles, Portland cement and calcium sulfate. Wherein based on the total weight of the binder, the weight ratio of the calcium sulfate is 10%-20%, the weight ratio of the slag particles is 55%-80%, and the balance is the Portland cement. The invention further discloses adhesive slurry which is prepared by mixing the dry-mixed mortar composition and water, and the weight ratio of the dry-mixed mortar composition to the water is 100: (20-35). The technical scheme provided by the invention can be used for keeping the cohesiveness of the ceramic tile binder and a gypsum material substrate, and can be used for bonding ceramic tiles on the gypsum material substrate.

Description

Technical Field

[0001] The present invention relates to the field of building materials, in particular to a dry-mix mortar composition and a bonding slurry obtained therefrom. Background Art

[0002] Ceramic tile adhesive is a new modern decoration material used for attaching ceramic tiles, facing tiles, floor tiles, and other decorative materials. Its key features include high bond strength, water resistance, freeze-thaw resistance, aging resistance, and ease of application, making it an ideal bonding material. Typically, ceramic tile adhesive uses cement as the binder, sand as the aggregate, and appropriate additives to form a dry-mix mortar. During use, it is mixed with water to form a slurry, which is then applied to the back of the ceramic tile to bond to the base layer.

[0003] Gypsum-based flooring material is a dry powder made by uniformly mixing gypsum, aggregate, and various construction chemical additives. Typically, this mortar is directly mixed with water on site (mechanically or manually) to form a self-flowing liquid. It automatically levels and can be used for leveling indoor building floors, such as filling uneven surfaces, tiny voids, and cracks. It is widely used for leveling indoor floors such as carpet, PVC flooring, wood flooring, and tile flooring. Compared to cement-based self-leveling mortar, gypsum-based flooring material requires less time to apply.

[0004] In actual use, it is found that the bonding strength of cement-based tile adhesives will decrease when used on gypsum-based materials. Summary of the Invention

[0005] The purpose of the present invention is to maintain the bonding strength between the tile adhesive and the gypsum material substrate and to provide a tile adhesive that can be applied to the gypsum material substrate.

[0006] To this end, according to one aspect of the present invention, a dry-mix mortar composition includes a binder, an aggregate, and an additive, wherein the weight of the binder accounts for 25%-40% of the total weight of the dry-mix mortar composition.

[0007] The binder is composed of slag particles, Portland cement and calcium sulfate, wherein, based on the total weight of the binder, the weight of calcium sulfate accounts for 10% to 20%, the weight of slag particles accounts for 55% to 80%, and the rest is Portland cement.

[0008] Furthermore, based on the total weight of the binder, the weight proportion of calcium sulfate is 10%-15%, and the weight proportion of slag particles is 65%-75%, preferably 70%-75%.

[0009] Alternatively, based on the total weight of the binder, the weight proportion of calcium sulfate is 15%-20%, and the weight proportion of slag particles is 55%-75%, preferably 55%-65%.

[0010] The additives may include one or more of redispersible latex powder, a coagulant, a water-retaining agent, a water-reducing agent, a rheological agent, and an early strength agent.

[0011] The content of the redispersible latex powder is at most 5% of the total weight of the dry-mixed mortar composition. The water-retaining agent is cellulose ether, and its content is at most 1.5% of the total weight of the dry-mixed mortar composition. The early strength agent is calcium formate, and its content is at most 1% of the total weight of the dry-mixed mortar composition.

[0012] The weight ratio of the slag particles is negatively correlated with the weight ratio of the calcium sulfate.

[0013] According to another aspect of the present invention, a bonding slurry is prepared by mixing the aforementioned dry-mixed mortar composition with water, wherein the weight ratio of the dry-mixed mortar composition to water is 100:20-35.

[0014] The technical solution of the present invention can be used to maintain the adhesion between the tile adhesive and the gypsum material base, and can be used to bond ceramic tiles on the gypsum material base. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are described below with reference to examples.

[0016] According to the present invention, a dry-mix mortar composition, which can be used as a tile adhesive, comprises a binder, an aggregate, an additive and optionally a filler.

[0017] The binder is composed of slag particles, Portland cement and calcium sulfate.

[0018] Granulated blast furnace slag, commonly known as slag, is the waste slag produced when iron and steel mills smelt pig iron. In the blast furnace ironmaking process, in addition to iron ore and fuel (coke), an appropriate amount of limestone and dolomite is added as flux to reduce the smelting temperature. The calcium oxide and magnesium oxide obtained by their decomposition in the blast furnace, the waste ore in the iron ore, and the ash in the coke are melted to form a molten material with silicates and aluminosilicates as the main components. The molten material floats on the surface of the molten iron and is regularly discharged from the slag outlet. It is quenched by air or water to form granular particles called slag. Typically, slag contains more than 95% of glass and minerals such as dicalcium silicate, calcite, wollastonite, etc., which are close to the composition of cement. In the example of this application, the slag particles can be products that comply with the Chinese standard GB / T 18046-2017 and can be obtained through commercial channels.

[0019] Portland cement is generally a product that complies with the Chinese standard GB175-2020 and can be obtained through commercial channels. For example, general-purpose Portland cement with a P·I 42.5 specified in the aforementioned standard or other grades of Portland cement can be used.

[0020] Calcium sulfate can also be obtained commercially. Generally, calcium sulfate may or may not contain water of crystallization. In practical applications, calcium sulfate may also contain a small amount of free water, depending on the source of the specific commodity.

[0021] Typically, the binder comprises 25% to 40% by weight of the total dry-mix mortar composition. Within this binder, slag particles comprise 55% to 80% by weight, calcium sulfate comprises 10% to 20% by weight, and the remainder is Portland cement. The weight percentage of slag particles is inversely correlated with the weight percentage of calcium sulfate; that is, as the weight percentage of calcium sulfate increases, the weight percentage of slag particles decreases.

[0022] Aggregates can include fine aggregate and coarse aggregate. Fine aggregate refers to particles with a particle size of less than 0.3 mm, while coarse aggregate refers to particles with a particle size between 0.3 and 0.8 mm. Particle size is a parameter describing particle size obtained by sieve analysis based on national standards GBT 17431.2-2010 or ASTM C136. The sand used as aggregate can be standard sand, such as ISO standard sand, which can be obtained commercially. Typically, depending on the specific application, the weight of the aggregate accounts for 50% to 70% of the total weight of the dry-mix mortar composition.

[0023] The additives include one or more of redispersible latex powder, accelerator, water-retaining agent, water-reducing agent, rheological agent and early strength agent. The additives can be preparations commonly used in mortar products and can be obtained through commercial channels. In this application, when the content is not specified, the amount of additives can refer to the usual amount in the art. For example, the content of redispersible latex powder is at most 5% of the total weight of the dry-mixed mortar composition. For example, the water-retaining agent is cellulose ether, and its content is at most 1.5% of the total weight of the dry-mixed mortar composition. For example, the early strength agent is calcium formate, and its content is at most 1% of the total weight of the dry-mixed mortar composition.

[0024] The dry-mixed mortar composition is mixed with water to obtain a bonding slurry, which can be used to bond ceramic tiles. Generally, the weight ratio of the dry-mixed mortar composition to water is 100:20-35.

[0025] Specific examples of the present invention and test results are given below.

[0026] Referring to Table 1, the components and amounts of the dry-mixed mortar compositions of Examples 1 to 6 are listed in parts by weight. Table 1 also shows the amount of water used to prepare the adhesive slurry, also in parts by weight.

[0027] Table 1

[0028] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 slag particles 24 22 20 17 22 19 Portland cement 3 5 7 10 2 5 calcium sulfate 3 3 3 3 6 6 calcium formate 0.5 0.5 0.5 0.5 0.5 0.5 limestone powder 13.2 13.2 13.2 13.2 13.2 13.2 sand 55 55 55 55 55 55 Cellulose ether 0.3 0.3 0.3 0.3 0.3 0.3 Redispersible latex powder 1 1 1 1 1 1 water 21 21 21 21 21 21

[0029] The test samples were prepared as follows:

[0030] First, provide a gypsum substrate. Pour a standard gypsum-based self-leveling mortar into a fixed-size substrate, such as one that complies with JC / T 1023-2021 Gypsum-Based Self-Leveling Mortar. For example, each substrate is a cube measuring 60 cm long, 30 cm wide, and 3 cm thick. Cure the gypsum substrate for one day under standard curing conditions (20°C ambient temperature / 65% relative humidity).

[0031] Then, according to the test method in the standard "JCT 547-2017 Ceramic Tile Adhesive", 5 samples were prepared for each example to test the tensile bond strength after 7 days, 28 days, high temperature curing for 28 days, low temperature curing for 28 days, and freeze-thaw cycle for 28 days.

[0032] The 28-day high-temperature curing period consists of 14 days of normal temperature curing at 20°C and 14 days of high-temperature curing at 70°C. The 28-day low-temperature curing period consists of 14 days of normal temperature curing at 20°C and 14 days of low-temperature curing at 5°C. The freeze-thaw cycle consists of 25 cycles of temperature changes, with the temperature range ranging from -15°C to +15°C.

[0033] Table 2 gives the test results of Examples 1 to 6.

[0034] Table 2

[0035] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Tensile bond strength after 7 days of standard curing MPa 1.02 1.1 1.08 1.29 0.73 0.81 Tensile bond strength after 28 days of standard curing MPa 1.75 1.93 1.58 1.38 1.51 1.5 Tensile bond strength after 28 days of high temperature curing MPa 0.81 1.43 1.06 0.87 0.29 0.72 Tensile bond strength after 28 days of low temperature curing MPa 1.55 2.8 1.54 1.28 1.41 1.06 Freeze-thaw cycle 28 days tensile bond strength MPa 1.61 1.66 1.5 1.5 1.66 1.07

[0036] It can be seen that Examples 1 to 6 can generally maintain the tensile bonding strength with the gypsum material substrate.

[0037] In the above description, the details of the technical solution of the present invention are explained. However, those skilled in the art will appreciate that the present invention is not limited to the specific details listed in the above embodiments, but may vary within the scope defined by the claims.

Claims

1. A dry-mix mortar composition comprising a binder, an aggregate and an additive, wherein: Based on the total weight of the dry-mixed mortar composition, the weight proportion of the binder is 25%-40%, wherein the binder is composed of slag particles, silicate cement and calcium sulfate, wherein, based on the total weight of the binder, the weight proportion of calcium sulfate is 10-20%, the weight proportion of the slag particles is 55%-80%, and the rest is silicate cement.

2. The dry-mix mortar composition according to claim 1, wherein Based on the total weight of the binder, the weight proportion of the calcium sulfate is 10%-15%, and the weight proportion of the slag particles is 65%-75% or 70-75%.

3. The dry-mix mortar composition according to claim 1, wherein Based on the total weight of the binder, the weight proportion of the calcium sulfate is 15%-20%, and the weight proportion of the slag particles is 55%-75% or 55%-65%.

4. The dry-mix mortar composition according to claim 1, wherein The additives include one or more of redispersible latex powder, a coagulant, a water-retaining agent, a water-reducing agent, a rheological agent and an early strength agent.

5. The dry-mix mortar composition according to claim 4, wherein The content of the redispersible latex powder is at most 5% of the total weight of the dry-mixed mortar composition.

6. The dry-mix mortar composition according to claim 4, wherein: The water retaining agent is cellulose ether, and its content is at most 1.5% of the total weight of the dry-mixed mortar composition.

7. The dry-mix mortar composition according to claim 4, wherein: The early strength agent is calcium formate, and its content is at most 1% of the total weight of the dry-mixed mortar composition.

8. The dry-mix mortar composition according to claim 1, wherein The weight proportion of the slag particles is negatively correlated with the weight proportion of the calcium sulfate.

9. A bonding slurry, which is prepared by mixing the dry-mixed mortar composition according to any one of claims 1 to 8 with water, wherein: The weight ratio of the dry-mixed mortar composition to water is 100:20-35.