A kind of phosphorus building gypsum-based supersulfate cement and preparation method thereof
By stirring a specific proportion of phosphorus building gypsum, ultrafine slag powder and ripe lime in ultrasulfate cement, the problem of phosphorus building gypsum pollution and low compressive strength of ultrasulfate cement is solved, and efficient resistance is achieved Pressure strength enhancement and environmentally friendly production process.
Patent Information
- Application Number
- CN202211220463.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-28
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2042-09-28
AI Technical Summary
Environmental pollution caused by industrial waste slag phosphorus building gypsum and the problems of low compressive strength of ultrasulfate cement in the early stage.
By stirring phosphorus building gypsum, ultrafine slag powder and ripe lime evenly in a specific proportion, adding water, stirring at low speed to form ultrasulfate cement, forming ettringite to improve compressive strength, and reducing phosphorus building gypsum in an appropriate amount to avoid cracking, ripe lime As an alkaline agent activates hydrolysis.
It significantly improves the early compressive strength of ultrasulfate cement, reduces the self-shrinkage and environmental pollution of the specimens, and reduces energy consumption and CO2 emissions.
Smart Images
Figure CN115536292B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of new cementitious materials, and in particular relates to supersulfate cement and a preparation method thereof. Background Art
[0002] Phosphogypsum is an industrial waste produced when phosphoric acid is produced by wet process using phosphate rock as raw material. On average, about 5 tons of phosphogypsum will be produced for every ton of phosphoric acid produced. Its main component is calcium sulfate dihydrate. The use of phosphogypsum, ultrafine slag powder and slaked lime to prepare supersulfate cement can not only solve the environmental pollution problem caused by industrial waste, but also reduce carbon dioxide emissions. Since the production process of supersulfate cement does not require high-temperature calcination, it reduces energy consumption and CO2 emissions. Compared with silicate cement, supersulfate cement has the advantages of low hydration heat, excellent resistance to chloride ion and sulfate (except magnesium sulfate) corrosion, etc. Summary of the invention
[0003] In order to solve the environmental pollution caused by a large amount of industrial waste slag phosphorus building gypsum, and also to improve the current situation of low early compressive strength of super sulfated cement, the present invention provides a method for preparing super sulfated cement. The technical solution provided by the present invention is as follows:
[0004] The components of early high compressive strength super sulfate cement include: 0% to 20% phosphorus building gypsum, 70% to 95% superfine slag powder and 5% to 10% slaked lime in terms of mass percentage.
[0005] In the above technical solution:
[0006] When phosphorus building gypsum is added to the slaked lime-slag powder system, a new hydration product, ettringite, is generated, which is beneficial to improve the early compressive strength of the specimen. An appropriate amount of phosphorus building gypsum can reduce the adverse effects of specimen shrinkage. However, its addition should not be too high, otherwise the specimen will easily produce too much ettringite, causing the specimen to crack and reduce the compressive strength. At the same time, when phosphorus building gypsum is added to the slaked lime-slag powder system, it can solidify part of the soluble phosphorus and fluorine in the phosphorus building gypsum, reducing pollution to the environment.
[0007] As an alkaline agent activator, the appropriate alkalinity is conducive to the hydrolysis of slag and the stability of ettringite. Too high a slaked lime content will inhibit the formation of ettringite and cause the compressive strength of the specimen to shrink.
[0008] The invention discloses a method for preparing super sulfate cement, and the specific operation steps are: weighing ultrafine slag powder, phosphorus building gypsum and slaked lime and stirring them evenly, then adding water into a stirring device, and then adding the mixed raw materials into the stirring device, stirring at a low speed for 2 minutes. After stirring, super sulfate cement is obtained. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the compressive strength of supersulfate cement hardened paste involved in Example 1 of the present invention;
[0010] Figure 2 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the autogenous shrinkage of supersulfate cement hardened paste involved in Example 1 of the present invention;
[0011] Figure 3 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the compressive strength of supersulfate cement hardened paste involved in Example 2 of the present invention;
[0012] Figure 4 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the autogenous shrinkage of supersulfate cement hardened paste involved in Example 2 of the present invention;
[0013] Figure 5 This is a schematic diagram of the effects of phosphorus building gypsum and slaked lime on the compressive strength of supersulfate cement hardened paste involved in Comparative Example 1 in the embodiments of the present invention;
[0014] Figure 6 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the autogenous shrinkage of supersulfate cement hardened paste involved in Comparative Example 1 in the embodiments of the present invention;
[0015] Figure 7 This is a schematic diagram of the effects of phosphorus building gypsum and slaked lime on the compressive strength of supersulfate cement hardened paste involved in Comparative Example 2 in the embodiments of the present invention;
[0016] Figure 8 This is a schematic diagram of the effect of phosphorus building gypsum and slaked lime on the autogenous shrinkage of supersulfate cement hardened paste involved in Comparative Example 2 in the embodiments of the present invention; DETAILED DESCRIPTION
[0017] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0018] Example 1
[0019] Raw material ratio: Phosphorus building gypsum accounts for 10% of the total cementitious materials, ultrafine slag powder accounts for 80% of the total cementitious materials, and slaked lime accounts for 10% of the total cementitious materials. In the blank group, ultrafine slag powder accounts for 90% of the total cementitious materials, and slaked lime accounts for 10% of the total cementitious materials.
[0020] Preparation method: First, weigh the ultrafine slag powder, phosphorus building gypsum and slaked lime and mix them evenly, then add water into the stirring device, then add the mixed raw materials into the stirring device and stir at a low speed for 2 minutes. After stirring, super sulfate cement is obtained.
[0021] Test conditions: The compressive strength of the supersulfate cement hardened paste was tested at the ages of 3d, 7d, 28d, 90d and 180d. The shrinkage of the specimens at 30d was tested. The test results are as follows: Figure 1 He Ru Figure 2 When the content of slaked lime was 10%, the content of phosphorus building gypsum increased to 10%, and the compressive strength of the hardened cement paste increased by 183.3%, 67.1%, 70.3%, 52.7% and 20.6% at the ages of 3d, 7d, 28d, 90d and 180d respectively compared with the blank group. The reduction rate of autogenous shrinkage of the hardened cement paste at 30d was 53.6%.
[0022] Example 2
[0023] Raw material ratio: Phosphorus building gypsum accounts for 20% of the total cementitious materials, ultrafine slag powder accounts for 70% of the total cementitious materials, and slaked lime accounts for 10% of the total cementitious materials. In the blank group, ultrafine slag powder accounts for 90% of the total cementitious materials, and slaked lime accounts for 10% of the total cementitious materials.
[0024] Preparation method: First, weigh the ultrafine slag powder, phosphorus building gypsum and slaked lime and mix them evenly, then add water into the stirring device, then add the mixed raw materials into the stirring device and stir at a low speed for 2 minutes. After stirring, super sulfate cement is obtained.
[0025] Test conditions: The compressive strength of the supersulfate cement hardened paste was tested at the ages of 3d, 7d, 28d, 90d and 180d. The shrinkage of the specimens at 30d was tested. The test results are as follows: Figure 3 He Ru Figure 4 When the content of slaked lime was 10%, and the content of phosphorus building gypsum increased to 20%, the compressive strength of the hardened cement paste increased by 173.4%, 106.9%, 114.6%, 87.0% and 72.8% at the ages of 3d, 7d, 28d, 90d and 180d respectively compared with the blank group. The hardened cement paste showed expansion characteristics at 30d, with an expansion rate of 0.35mm / m.
[0026] Comparative Example 1
[0027] Raw material ratio: Phosphorus building gypsum accounts for 10% of the total cementitious materials, ultrafine slag powder accounts for 85% of the total cementitious materials, and slaked lime accounts for 5% of the total cementitious materials. In the blank group, ultrafine slag powder accounts for 95% of the total cementitious materials, and slaked lime accounts for 5% of the total cementitious materials.
[0028] Preparation method: First, weigh the ultrafine slag powder, phosphorus building gypsum and slaked lime and mix them evenly, then add water into the stirring device, then add the mixed raw materials into the stirring device and stir at a low speed for 2 minutes. After stirring, super sulfate cement is obtained.
[0029] Test conditions: The compressive strength of the supersulfate cement hardened paste was tested at the ages of 3d, 7d, 28d, 90d and 180d. The shrinkage of the specimens at 30d was tested. The test results are as follows: Figure 5 He Ru Figure 6 When the content of slaked lime is 5%, and the content of phosphorus building gypsum increases to 10%, the compressive strength of the hardened cement paste increases by 131.8%, 96.8%, 43.4%, 55.4% and 40.3% at the ages of 3d, 7d, 28d, 90d and 180d respectively compared with the blank group. The reduction rate of autogenous shrinkage of the hardened cement paste at 30d is 65.5%.
[0030] Comparative Example 2
[0031] Raw material ratio: Phosphorus building gypsum accounts for 20% of the total cementitious materials, ultrafine slag powder accounts for 75% of the total cementitious materials, and slaked lime accounts for 5% of the total cementitious materials. In the blank group, ultrafine slag powder accounts for 95% of the total cementitious materials, and slaked lime accounts for 5% of the total cementitious materials.
[0032] Preparation method: First, weigh the ultrafine slag powder, phosphorus building gypsum and slaked lime and mix them evenly, then add water into the stirring device, then add the mixed raw materials into the stirring device and stir at a low speed for 2 minutes. After stirring, super sulfate cement is obtained.
[0033] Test conditions: The compressive strength of the supersulfate cement hardened paste was tested at the ages of 3d, 7d, 28d, 90d and 180d. The shrinkage of the specimens at 30d was tested. The test results are as follows: Figure 7 He Ru Figure 8 When the content of slaked lime is 5%, the content of phosphorus building gypsum increases to 20%, and the compressive strength of hardened cement paste increases by 240.9%, 181.0%, 91.4%, 111.6% and 64.2% at the ages of 3d, 7d, 28d, 90d and 180d respectively. The reduction rate of autogenous shrinkage of hardened cement paste at 30d is 77.7%.
Claims
1. A supersulfate cement based on phosphorus building gypsum, Features It is composed of ultra-fine slag powder, phosphorus building gypsum and slaked lime, and the weight percentage of each component is: 20% phosphorus building gypsum, 70% ultra-fine slag powder, and 10% slaked lime; The calcium hydroxide content of the slaked lime is 95.15%; The specific surface area of the ultrafine slag powder is 967m 2 / kg, the median particle size was 2.151 μm, and the activity index at 7 and 28 days was 127% and 106%, respectively; The main component of the phosphorus building gypsum is hemihydrate gypsum, and the pH value is 5.6; The preparation method of the above-mentioned phosphorus building gypsum-based supersulfate cement comprises the following steps: weighing ultrafine slag powder, phosphorus building gypsum and slaked lime and stirring them evenly, then adding water into a stirring device, adding the mixed raw materials into the stirring device, stirring at a low speed for 2 minutes, and obtaining supersulfate cement after stirring.