A lightweight gypsum self-leveling mortar with high volume and low shrinkage

Abstract

The present invention belongs to the technical field of gypsum building materials, and in particular discloses a lightweight gypsum self-leveling mortar with high volume and low shrinkage. The lightweight gypsum self-leveling mortar with high volume and low shrinkage improves the water-to-material ratio of the gypsum self-leveling mortar from 0.3 to 0.5 in the prior art to 0.6 to 1.35 by optimizing the amount of water reducing agent, optimizing the viscosity and amount of water retaining agent, thereby reducing the material consumption of the gypsum self-leveling mortar from 12.5 kg to 16 kg to 6 kg to 10 kg per square meter when constructing a 1 cm thickness, greatly improving its volume, and greatly reducing the shrinkage; and under such a high water consumption, the product still does not have water seepage and stratification. It not only solves the problem of hollowing and cracking that may be caused by existing products in the later stage, but also solves the problem that products prepared by adding lightweight aggregates are prone to stratification and water seepage and lack of strength on the surface during construction on the construction site, and balances the comprehensive performance requirements of the gypsum self-leveling mortar such as light weight, high volume, and no water seepage in actual construction, and significantly reduces the material cost.

Description

Technical Field

[0001] The invention belongs to the technical field of gypsum building materials, and in particular relates to a lightweight gypsum self-leveling mortar with high volume and low shrinkage. Background Art

[0002] As the problem of the aging population in China becomes more serious, the labor cost of construction workers continues to rise, and self-leveling products with automatic leveling performance are increasingly favored by people. Among them, gypsum self-leveling mortar is widely used in floor leveling construction such as indoor concrete, floor heating or insulation board because of its easy mixing construction, high strength, small shrinkage after drying, strong adhesion, and no hollowing and cracking.

[0003] Most of the gypsum self-leveling mortar products commonly used in the market are heavy gypsum self-leveling mortar, which has low water consumption and small volume. For every square meter of ground construction with a thickness of 1 cm, 12.5 to 16 kilograms of gypsum self-leveling mortar is required, and its anti-shrinkage performance is average. When constructed on the base of floor heating or insulation board, the gypsum self-leveling mortar may still have the possibility of hollowing and cracking in the later stage.

[0004] At present, there is little development and application of lightweight gypsum self-leveling mortar, and engineering construction is basically in a blank state. This is mainly caused by two factors: 1) By adding lightweight aggregates (such as perlite, vitrified microspheres, expanded clay, etc.), the water consumption of the product is increased and the volume density of the product is reduced, thereby reducing the unit area consumption of gypsum self-leveling products; however, this technology can be used normally in laboratory tests, but during construction on the construction site, a slight change in water consumption will cause a change in the viscosity of the slurry, which will cause the lightweight aggregate to float on the surface and cause the product to have stratification problems; 2) Gypsum self-leveling products are used as ground leveling materials, and high requirements are placed on the appearance after construction. Therefore, defoamers are generally included in the formula, which will make it impossible to use admixtures such as air entraining agents and foaming agents that can reduce the density of gypsum self-leveling mortar.

[0005] There is no good solution to the problem of light weight, volume and delamination of gypsum self-leveling mortar in actual engineering construction. Therefore, it is urgent to provide a solution to this problem to promote the application and development of gypsum self-leveling mortar in engineering construction. Summary of the invention

[0006] In order to balance the comprehensive properties of gypsum self-leveling mortar such as light weight, high volume, and no water seepage in actual construction, while taking into account the technical performance requirement of crack resistance, the present invention provides an improved scheme for gypsum self-leveling mortar, and obtains a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which not only solves the problem of hollowing and cracking that may be caused by shrinkage in the later stage of existing gypsum self-leveling mortar, but also solves the problem that lightweight gypsum self-leveling mortar prepared with lightweight aggregate is prone to stratification and water seepage and lack of surface strength during construction on site, and can be widely used in the field of building ground base leveling.

[0007] The specific technical solutions of the present invention are as follows:

[0008] A lightweight gypsum self-leveling mortar with high volume and low shrinkage, comprising the following components uniformly mixed in parts by mass:

[0009]

[0010] The water retaining agent is a cellulose-based water retaining agent and / or a cellulose ether-based water retaining agent having a viscosity of 4000 mPa·s to 200000 mPa·s.

[0011] The water retaining agent with a specific viscosity can not only provide water retaining performance, but also increase the output of lightweight gypsum self-leveling mortar and reduce the amount of material used per unit area.

[0012] Furthermore, the gypsum powder is β-hemihydrate gypsum powder and / or α-hemihydrate gypsum powder.

[0013] Furthermore, the water reducing agent is a polycarboxylic acid water reducing agent; the water reducing agent is mainly used to adjust the water consumption of the lightweight gypsum self-leveling mortar and improve the construction fluidity of the lightweight gypsum self-leveling mortar.

[0014] Furthermore, the retarder is a protein or amino acid retarder, which is commercially available and is mainly used to adjust the setting time. The specific dosage is such that the setting time of the lightweight gypsum self-leveling mortar is greater than 30 minutes under the premise of satisfying the above-mentioned mass fractions.

[0015] Furthermore, the defoaming agent is one or a combination of at least two of grease, polyether, silicone, polyether-modified silicon or polysiloxane defoaming agents; the defoaming agent is used to reduce and eliminate bubbles and increase the smoothness of the construction surface.

[0016] Furthermore, the anti-water seepage agent is one of modified starch, modified mineral powder, diutan gum, or a combination of at least two of them.

[0017] Furthermore, the hard filler is stone powder and / or sand.

[0018] The lightweight gypsum self-leveling mortar with high output and low shrinkage provided by the present invention can improve the water-to-material ratio of the gypsum self-leveling mortar from 0.3-0.5 in the prior art to 0.6-1.35 by optimizing the amount of water reducing agent and optimizing the viscosity and amount of water retaining agent, thereby reducing the material consumption of the gypsum self-leveling mortar from 12.5kg-16kg to 6kg-10kg per square meter when constructing a 1cm thickness, thereby greatly improving the output; and under such a high water consumption, water seepage and stratification still do not occur.

[0019] The present invention can greatly improve the water-to-material ratio of gypsum self-leveling mortar by using a specific viscosity water retaining agent. In the gypsum self-leveling system, the water molecules required for hydration of gypsum powder (the water molecules required for hydration of hemihydrate gypsum is 18.6% of the mass of hemihydrate gypsum) are removed, and the other excess water will evaporate in the later drying process. The gaps left by evaporation make it easy for the gypsum self-leveling mortar to form a porous structure, thereby achieving the purpose of lightweight without adding lightweight aggregate. This solves the problem of floating and stratification of lightweight aggregates in engineering construction when traditional gypsum self-leveling mortar uses lightweight aggregates to achieve the purpose of lightweight.

[0020] In addition, the high-volume, low-shrinkage lightweight gypsum self-leveling mortar provided by the present invention optimizes the 28d dimensional change rate from -0.06% to -0.02% of the general gypsum self-leveling mortar in the prior art to -0.01% to 0.01%, significantly reducing the late shrinkage of the gypsum self-leveling mortar, and optimizing its dimensional change to low shrinkage or slight expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a scene construction effect diagram of the gypsum self-leveling mortar provided according to Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0022] For a better understanding of the present invention, the following examples are further illustrative of the present invention and are only used to explain the content of the present invention, but not to limit the present invention. All similar examples listed based on the present invention should fall within the protection scope thereof.

[0023] In the following embodiments and comparative examples, the cement is 42.5R ordinary Portland cement; the water reducer is a polycarboxylic acid water reducer; the retarder is an amino acid retarder; the defoamer is a polyether defoamer; the anti-watering agent is a compound of modified starch and diutan gum in a mass ratio of 9:1; the above-mentioned cementitious materials and admixtures are all commercially available.

[0024] Of course, the specific selection of the above-mentioned secondary components can also be other conventional selections in the field within the scope of protection of the present invention. For example, as long as the defoaming agent ensures the construction effect, a silicone defoaming agent can also be selected, which are not listed here one by one.

[0025] Example 1

[0026] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0027]

[0028] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0029] Example 2

[0030] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0031]

[0032] Among them, the water retaining agent is a cellulose water retaining agent with a viscosity specification of 60000mPa·s.

[0033] Example 3

[0034] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0035]

[0036] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 200000 mPa·s.

[0037] Example 4

[0038] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0039]

[0040] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0041] Example 5

[0042] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0043]

[0044] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0045] Example 6

[0046] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0047]

[0048] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 4000 mPa·s.

[0049] Example 7

[0050] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0051]

[0052]

[0053] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 15000 mPa·s.

[0054] Example 8

[0055] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0056]

[0057] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0058] Example 9

[0059] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0060]

[0061] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0062] Example 10

[0063] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0064]

[0065] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0066] Embodiment 11

[0067] This embodiment provides a lightweight gypsum self-leveling mortar with high volume and low shrinkage, which is mixed with the following raw materials in parts by mass:

[0068]

[0069] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 200000 mPa·s.

[0070] In order to demonstrate the advantages of the above-mentioned lightweight gypsum self-leveling mortar with high volume and low shrinkage of the present invention, and the necessity of limiting some of its components, the following comparative experiments were conducted.

[0071] Comparative Example 1

[0072] This comparative example provides a gypsum self-leveling mortar, which is composed of a mixture of the following raw materials in parts by mass:

[0073]

[0074]

[0075] The water retaining agent is a cellulose ether water retaining agent, and the viscosity specification is 400 mPa·s.

[0076] Comparative Example 2

[0077] This comparative example provides a gypsum self-leveling mortar, which is composed of a mixture of the following raw materials in parts by mass:

[0078]

[0079] The water retaining agent is a cellulose ether water retaining agent, and the viscosity specification is 400 mPa·s.

[0080] Comparative Example 3

[0081] This comparative example provides a gypsum self-leveling mortar, which is mixed with the following raw materials in parts by weight:

[0082]

[0083] The water retaining agent is a cellulose ether water retaining agent, and the viscosity specification is 2000mPa·s.

[0084] Comparative Example 4

[0085] This embodiment provides a gypsum self-leveling mortar, which is mixed with the following raw materials in parts by weight:

[0086]

[0087] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0088] Comparative Example 5

[0089] This embodiment provides a gypsum self-leveling mortar, which is mixed with the following raw materials in parts by weight:

[0090]

[0091] The water retaining agent is a cellulose ether water retaining agent with a viscosity specification of 60000 mPa·s.

[0092] The properties of the gypsum self-leveling mortars of the above-mentioned embodiments and comparative examples are shown in Table 1 below.

[0093] Table 1 Performance of each gypsum self-leveling mortar of Examples 1 to 11 and Comparative Examples 1 to 5

[0094]

[0095]

[0096] In the above embodiments 1 to 11, water-retaining agents of different viscosities are selected so that the material consumption of the lightweight gypsum self-leveling mortar per square meter and per centimeter thickness can be controlled within 6kg to 10kg, and the material consumption per unit area of ​​the lightweight gypsum self-leveling mortar is significantly reduced; and its 28d dimensional change rate can be optimized within the range of -0.01% to 0.01%, so that the lightweight gypsum self-leveling mortar has low shrinkage or micro-expansion.

[0097] In the above-mentioned Examples 1 to 11, the lightweight gypsum self-leveling mortar with high volume and low shrinkage provided by the present invention has a 28d dimensional change rate of -0.01% to 0.008%, which is much smaller than the 28d dimensional change rate of -0.055% to -0.025% of the ordinary gypsum self-leveling mortar currently on the market in Comparative Examples 1 to 2. In the ordinary gypsum self-leveling mortar of Comparative Examples 1 to 2, the material consumption per square meter and per centimeter thickness is 12.5kg to 16kg, the material consumption per unit area is high, the 28d dimensional change rate is large, the shrinkage is large, and hollowing and cracking are prone to occur.

[0098] In the above-mentioned comparative example 3, the gypsum self-leveling mortar uses a water-retaining agent with a viscosity specification of 2000mPa·s. Compared with the water-retaining agent with a viscosity specification of 60000mPa·s used in Example 5, to achieve the same material consumption per unit area, the amount of water-retaining agent used in comparative example 3 is 0.8 parts, while the amount of water-retaining agent used in Example 5 is only 0.1 parts. The amount of water-retaining agent used in comparative example 3 is significantly increased, which ultimately leads to a significant increase in cost.

[0099] In the above Example 9 and Comparative Example 4, it can be seen from the comparison that after changing the amount of water reducing agent, the material usage per unit area and the 28d dimensional change rate performance in Comparative Example 4 are relatively excellent, but the gypsum self-leveling mortar provided in Comparative Example 4 has water ripples and an uneven surface during actual construction. Figure 1 As shown in the on-site construction renderings, the surface flatness and appearance after solidification and hardening are not up to standard.

[0100] In the above-mentioned Example 9 and Comparative Example 5, it can be seen from the comparison that after changing the amount of the water reducing agent, the amount of material per unit area of ​​the gypsum self-leveling mortar provided in Comparative Example 5 is significantly increased, which will eventually lead to a significant increase in the production and construction application costs.

[0101] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the above embodiments without any creative contribution as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A lightweight gypsum self-leveling mortar with high volume and low shrinkage, characterized in that: It includes the following components mixed evenly in parts by mass: 100 parts of β-hemihydrate gypsum powder; 2~4.5 parts of cement; Water retaining agent 0.04~0.6 parts; Water reducing agent 0.05~0.1 part; Retarder 0~0.05 parts; Defoaming agent 0.05~0.3 parts; Anti-watering agent 0~0.5 parts; and does not contain lightweight aggregate; Wherein, the water retaining agent is a cellulose water retaining agent and / or a cellulose ether water retaining agent with a viscosity of 4000 mPa·s to 60000 mPa·s; The water-to-material ratio of the lightweight gypsum self-leveling mortar is 0.6-1.

35.

2. The lightweight gypsum self-leveling mortar according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid water reducing agent.

3. The lightweight gypsum self-leveling mortar according to claim 1, characterized in that: The retarder is a protein or amino acid retarder, so that the setting time of the lightweight gypsum self-leveling mortar is greater than 30 minutes.

4. The lightweight gypsum self-leveling mortar according to claim 1, characterized in that: The anti-water seepage agent is at least one of modified starch, modified mineral powder and diutan gum.

Images