Formula and production process of lightweight gypsum block

Abstract

The invention discloses a formula and a production process of a lightweight gypsum block, and relates to the technical field of building materials and solid waste resource utilization, the lightweight gypsum block is prepared from the following raw materials by mass: 80-92% of industrial by-product gypsum; 8%-20% of cement; 1%-10% of glass beads; the industrial by-product gypsum is one or more of phosphogypsum, desulfurized gypsum or titanium gypsum; the cement is ordinary Portland cement, and the additive comprises a curing agent and / or a reinforcing agent; preferably, the curing agent is an alkaline activator and is selected from one or more of quick lime, slaked lime and sodium silicate; the reinforcing agent is one or more of cellulose ether and latex powder. According to the formula and the production process of the light gypsum block, the light aggregate is introduced into the pressed gypsum block, the unification of light weight and high strength is realized, and the softening coefficient is up to 0.8 or above.

Description

Technical Field

[0001] This invention relates to the field of building materials and solid waste resource utilization technology, specifically to a formula and production process for lightweight gypsum blocks. Background Technology

[0002] Industrial by-product gypsum (such as phosphogypsum and desulfurization gypsum) is a major solid waste generated during industrial production, and its main component is calcium sulfate dihydrate. Currently, the main method for its resource utilization is to first calcine it into building gypsum (hemihydrate gypsum) and then produce gypsum blocks using casting or semi-dry methods. However, the production process using hemihydrate gypsum is energy-intensive, increasing costs. While the casting method produces blocks with a light density (typically >1100 kg / m³), the drying speed is slow. The semi-dry method produces blocks with a fast drying speed, but the block density is heavy (typically >1300 kg / m³), increasing the building load. Another method is to mix it with cement and press it into shape, but the resulting blocks have a high density (typically >1300 kg / m³), limiting its application in high-rise buildings and applications requiring lightweight insulation.

[0003] Those skilled in the art generally agree that achieving lightweight blocks through compression molding typically comes at the cost of strength. While using simple aggregates (such as ceramsite or polystyrene granules) can reduce density, poor interfacial bonding between the aggregate and cementitious material, along with the low strength of the aggregate itself, leads to a significant decrease in block strength, making it difficult to meet the mechanical performance requirements of building wall materials. Summary of the Invention

[0004] The purpose of this invention is to provide a formula and production process for lightweight gypsum blocks to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a formula for lightweight gypsum blocks, made from the following raw materials in the indicated mass percentages: industrial by-product gypsum: 80%–92%; cement: 8%–20%; vitrified microspheres: 1%–10%; admixtures: 0.1%–2%.

[0006] Furthermore, the industrial by-product gypsum is one or more of phosphogypsum, desulfurized gypsum, or titanium gypsum; the cement is ordinary silicate cement.

[0007] Furthermore, the additives include curing agents and / or reinforcing agents; preferably, the curing agent is an alkaline activator selected from one or more of quicklime, hydrated lime, and sodium silicate; the reinforcing agent is one or more of cellulose ether and latex powder.

[0008] Furthermore, the block has a solid density of less than 1200 kg / m³, a 28-day compressive strength of greater than 5 MPa, and a softening coefficient of greater than 0.80.

[0009] A manufacturing process for preparing the formula for lightweight gypsum blocks as described above includes the following steps:

[0010] (1) Pretreatment: Industrial by-product gypsum is crushed into powder;

[0011] (2) Premixing: Industrial by-product gypsum, vitrified microspheres, cement, admixtures and water are mixed and stirred to obtain a mixture;

[0012] (3) Press molding: The mixture is pressed into block blanks under a pressure of 10-25 MPa;

[0013] (4) Curing: The block blank is cured at 20-40℃ and humidity ≥90% for 24-72 hours to obtain the lightweight gypsum block.

[0014] Furthermore, in step (2), the amount of water added accounts for 5%-8% of the total mass of the dry material.

[0015] Furthermore, in step (3), the pressing adopts a bidirectional pressurization method with a pressurization rate of 0.5-1.5 MPa / s.

[0016] This invention provides a formula and production process for lightweight gypsum blocks, which has the following beneficial effects: When the vitrified microspheres in this application are added at a dosage of 1%-10%, they can not only effectively reduce the density of the blocks, but their spherical particles can also promote material flow and compaction during the pressing process; introducing lightweight aggregates into pressed gypsum blocks achieves a balance between lightweight and high strength, with a softening coefficient of over 0.8, broadening the application range, allowing for use in exterior walls, directly utilizing industrial by-product gypsum dihydrate, saving calcination energy consumption; and significantly reducing solid waste. Detailed Implementation

[0017] The present invention will be described in detail below with reference to the embodiments, so as to fully demonstrate the specific implementation process and technical effects of the present invention. The raw materials used in all embodiments and comparative examples are as follows: industrial by-product gypsum (phosphogypsum or desulfurized gypsum) is crushed and ground to pass through a 4.75mm sieve before use, and its moisture content is measured; the cement is ordinary Portland cement of grade P.O42.5 conforming to GB175-2007 standard; the vitrified microspheres are closed-cell expanded perlite with a bulk density of 90-110 kg / m³; the admixtures are industrial-grade quicklime, hydrated lime, and hydroxypropyl methylcellulose (HPMC).

[0018] Example 1: Lightweight phosphogypsum blocks

[0019] The formula in this embodiment is as follows (based on 100% total dry material mass): 80.5% phosphogypsum (moisture content 16%, calculated on a dry basis), 14% cement, 5% vitrified microspheres, and 0.5% quicklime, with added water at 6.5% of the total dry material mass. During preparation, the phosphogypsum, cement, and quicklime are first dry-mixed for 3 minutes, then the vitrified microspheres are added and dry-mixed for 2 minutes, and finally water is added and wet-mixed for 5 minutes until homogeneous. The mixture is then filled into a mold and pressurized at a rate of 1.0 MPa / s to 15 MPa using a bidirectional pressure method, holding the pressure for 3 seconds to form the green body. The resulting green body is cured in a standard curing room at 25±2℃ and humidity ≥95% for 28 hours before being removed from the kiln and then naturally cured for another 28 days. Performance test results show that the block has a solid density of 1180 kg / m³, a 28-day compressive strength of 5.8 MPa, a softening coefficient of 0.83, a drying shrinkage value of 0.055%, and a thermal conductivity of 0.28 W / (m·K), all of which are excellent.

[0020] Example 2: Lightweight desulfurized gypsum blocks

[0021] The formulation of this embodiment is as follows: 81.4% desulfurized gypsum (moisture content 15%, calculated on a dry basis), 14% cement, 4% vitrified microspheres, 0.5% quicklime, 0.1% HPMC, and 5.0% added water. The preparation process is basically the same as in Example 1, except that the pressing pressure is adjusted to 12 MPa. Test results show that the resulting blocks have a density of 1150 kg / m³, a 28-day compressive strength of 5.5 MPa, a softening coefficient of 0.81, a drying shrinkage value of 0.053%, and a thermal conductivity of 0.27 W / (m·K), achieving the same comprehensive effect of being lightweight, high-strength, and water-resistant.

[0022] Comparative example: Traditional gypsum blocks without vitrified microspheres

[0023] For comparison, a comparative example was set up with the following formula: 85% phosphogypsum (moisture content 16%, calculated on a dry basis), 15% cement, 0.5% quicklime, and 7.0% water. The preparation process parameters were completely consistent with those of Example 1. Performance test results showed that the solid density of the comparative block was as high as 1450 kg / m³, but the 28-day compressive strength was only 4.2 MPa, the softening coefficient was 0.78, and the thermal conductivity was 0.40 W / (m·K).

[0024] The comparison between the examples and comparative examples clearly shows that the present invention, by pressing and molding within a specific pressure range (10-25MPa) and introducing a specific proportion (1%-10%) of vitrified microspheres into a composite with industrial by-product gypsum, cement, and admixtures, produces a significant synergistic effect. This significantly reduces the density of the blocks (to below 1200kg / m³) while simultaneously increasing their compressive strength to over 5MPa and ensuring excellent water resistance (softening coefficient >0.8). This demonstrates that the technical solution of the present invention successfully solves the technical problem of achieving both "lightweight and high strength" in the field of lightweight building materials, achieving unexpected technical results and providing an innovative solution for the high-value utilization of industrial by-product gypsum.

[0025] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, and the existence of an infinite number of specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A formula for lightweight gypsum blocks, characterized in that, It is made from the following raw materials in the indicated weight percentages: industrial by-product gypsum: 80%–92%; cement: 8%–20%; vitrified microspheres: 1%–10%; admixtures: 0.1%–2%.

2. The formula for a lightweight gypsum block according to claim 1, characterized in that, The industrial by-product gypsum is one or more of phosphogypsum, desulfurized gypsum, or titanium gypsum; the cement is ordinary silicate cement.

3. The formula for a lightweight gypsum block according to claim 2, characterized in that, The additives include curing agents and / or reinforcing agents; preferably, the curing agent is an alkaline activator selected from one or more of quicklime, hydrated lime, and sodium silicate; the reinforcing agent is one or more of cellulose ether and latex powder.

4. The formula for a lightweight gypsum block according to claim 2, characterized in that, The block has a solid density of less than 1200 kg / m³, a 28-day compressive strength of greater than 5 MPa, and a softening coefficient of greater than 0.

80.

5. A production process for preparing the lightweight gypsum blocks as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Pretreatment: Industrial by-product gypsum is crushed into powder; (2) Premixing: Industrial by-product gypsum, vitrified microspheres, cement, admixtures and water are mixed and stirred to obtain a mixture; (3) Press molding: The mixture is pressed into block blanks under a pressure of 10-25 MPa; (4) Curing: The block blank is cured at 20-40℃ and humidity ≥90% for 24-72 hours to obtain the lightweight gypsum block.

6. The production process of the lightweight gypsum block formula according to claim 5, characterized in that, In step (2), the amount of water added accounts for 5%-8% of the total mass of the dry material.

7. The production process of the lightweight gypsum block formula according to claim 5, characterized in that, In step (3), the pressing adopts a bidirectional pressurization method with a pressurization rate of 0.5-1.5MPa / s.