Net paste material for wall brick compressive strength test and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a neat paste material for a compressive strength test of a wall brick and a preparation method of the neat paste material. The neat paste material for the compressive strength test of the wall brick comprises the following raw materials in parts by weight: 45-55 parts of high-strength gypsum powder, 5-15 parts of building gypsum powder, 40-50 parts of sand, 0-0.3 part of a water reducing agent and 0-0.2 part of a coagulant, the high-strength gypsum powder is a mixture of natural high-strength gypsum powder and regenerated high-strength gypsum powder; the regenerated high-strength gypsum powder is obtained by treating waste common gypsum plaster and anhydrous well mineral salt gypsum with a salt solution. The raw materials of the neat paste material for the compressive strength test of the wall brick comprise the construction waste gypsum and the salt gypsum, so that the source of the gypsum is widened, the problem of pollution caused by the construction waste gypsum and the salt gypsum is solved, and the cost of the neat paste material for the compressive strength test of the wall brick is reduced; the utilization rate and the utilization level of the construction waste gypsum and the salt gypsum are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a neat cement material for testing the compressive strength of masonry bricks and a preparation method thereof. Background Art

[0002] Masonry bricks are widely used as basic materials in building walls. Compressive strength is an important criterion for evaluating the quality of bricks, and the leveling of the compressive surface is a key step in testing the compressive strength. Therefore, the leveling material should not only have sufficient strength but also good workability. When using cement paste and manual leveling, it takes 3 days of curing to conduct the compressive strength test, resulting in low detection efficiency; while using gypsum paste only takes 4 hours, greatly shortening the curing and test time and improving the detection efficiency.

[0003] According to the source, gypsum can be divided into natural gypsum, chemical gypsum, and construction waste gypsum. Although China is a large country of gypsum resources, the high-quality gypsum resources are very scarce, only accounting for 8%. The annual production of chemical gypsum in China is more than 200 million tons. Especially the salt gypsum produced in the salt-making and soda-making industries is severely restricted in its utilization due to its high salt content. At the same time, a large amount of construction waste is also generated in China every year. According to statistics, the production volume reached 3.5 billion tons in 2022. The gypsum content in domestic construction waste accounts for about 4.7%, and the gypsum content in foreign construction waste fragments ranges from 1.5% to 9.1%. Currently, chemical gypsum and construction waste are mainly disposed of by landfilling. It should be noted that when chemical gypsum and construction waste are landfilled, sulfate-reducing bacteria use the sulfate provided by gypsum as an electron donor to produce hydrogen sulfide, resulting in the phenomenon of malodorous pollution in landfills, seriously affecting the surrounding air quality and the physical and mental health of residents. Therefore, the utilization and disposal of chemical gypsum and construction waste gypsum have always been a hot topic in global solid waste management.

[0004] Therefore, an improved technical solution is needed to address the above deficiencies in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide a neat cement material for testing the compressive strength of masonry bricks and a preparation method thereof, which helps to solve or improve the problems of the accumulation of construction waste gypsum and / or salt gypsum and the easy occurrence of pollution.

[0006] To achieve the above object, the present invention provides the following technical solution: A neat cement material for the compressive strength test of masonry bricks, comprising the following raw materials by weight parts: 45-55 parts of high-strength gypsum powder, 5-15 parts of building gypsum powder, 40-50 parts of sand, 0-0.3 parts of water reducing agent, and 0-0.2 parts of setting accelerator; the high-strength gypsum powder is a mixture of natural high-strength gypsum powder and recycled high-strength gypsum powder; the recycled high-strength gypsum powder is obtained by treating waste ordinary paper-faced gypsum and anhydrous well salt gypsum with a salt solution.

[0007] Preferably, in the salt solution, the concentration of ethylenediaminetetraacetic acid is 0.18%-0.22%, and the pH is 4-6; the mass ratio of the waste ordinary paper-faced gypsum to the anhydrous well salt gypsum is (90-95):(5-10), and in the mixed solution of the salt solution, waste ordinary paper-faced gypsum and salt gypsum, the concentration of sodium chloride is 14%-16%; the temperature of the salt solution treatment is 100-110°C, and the treatment time is 3.0-3.5 h.

[0008] Preferably, the mass ratio of the natural high-strength gypsum powder to the recycled high-strength gypsum powder is (8.5-9.5):1; the natural high-strength gypsum powder is natural high-strength gypsum powder of α40 and / or α50 grade.

[0009] Preferably, the building gypsum powder includes natural building gypsum powder and recycled building gypsum powder; the recycled building gypsum powder is obtained by drying, ball milling and calcining waste gypsum.

[0010] Preferably, the calcination temperature is 160-170°C, and the calcination time is 2-4 h; the natural building gypsum powder is natural building gypsum of 3.0 grade and / or 4.0 grade; the mass ratio of the natural building gypsum powder to the recycled building gypsum powder is (3.5-4.5):1.

[0011] Preferably, the sand is at least one of river sand, manufactured sand and standard sand; or, the sand is a mixed sand formed by mixing river sand and recycled construction waste sand; the recycled construction waste sand is recycled aggregate made from waste concrete by crushing and screening.

[0012] Preferably, in the mixed sand, the mass ratio of the river sand to the recycled construction waste sand is 4:1.

[0013] More preferably, the sand is fine sand with a nominal maximum particle size less than 1.18 mm.

[0014] Preferably, the water reducing agent is polycarboxylate water reducing agent and / or amino sulfonate water reducing agent.

[0015] Preferably, the water reducing agent is a mixture of a polycarboxylate water reducing agent and an aminobenzenesulfonic acid water reducing agent, and the mass ratio of the polycarboxylate water reducing agent to the aminobenzenesulfonic acid water reducing agent is (4.5-5.5):1.

[0016] Preferably, the coagulant is potassium sulfate or sodium sulfate; or, the coagulant is a mixed coagulant including potassium sulfate and potassium bisulfate.

[0017] Preferably, in the mixed coagulant, the mass ratio of potassium sulfate to potassium bisulfate is (0.9-1.1):1.

[0018] The present invention also provides a method for preparing the neat paste material for the compressive strength test of the masonry brick as described above, which adopts the following technical solution: The method for preparing the neat paste material for the compressive strength test of the masonry brick as described above includes the following steps: Step 1, preparation of the admixture solution: Add the water reducing agent and the coagulant into water, and stir evenly to obtain the admixture solution; Step 2, powder mixing: Mix the high-strength gypsum powder and the building gypsum powder evenly to obtain the powder; Step 3, add the powder into the admixture solution, stir for 1.0-1.5 min, then add the sand, and stir evenly to obtain the neat paste material for the compressive strength test of the masonry brick.

[0019] Preferably, the amount of water used is 15%-30% of the total amount of the high-strength gypsum powder, the building gypsum powder and the sand.

[0020] Beneficial effects:

[0021] The raw materials of the neat paste material for the compressive strength test of the masonry brick of the present invention include construction waste gypsum and salt gypsum, which broadens the source of gypsum, solves the problem of pollution of construction waste gypsum and salt gypsum, has good sustainability, and also helps to reduce the cost of the neat paste material for the compressive strength test of the masonry brick, and improves the utilization rate and utilization level of construction waste gypsum and salt gypsum.

[0022] Ordinary paper-faced gypsum board (code name P) is a building board mainly made of building gypsum, admixed with appropriate lightweight aggregates, fiber reinforcing materials and admixtures to form a core material, and firmly bonded with facing paper. It is mainly used for partitions, ceilings, facing panels, etc. of buildings. A retarder is usually added during the preparation of ordinary paper-faced gypsum board. The inventor found in the research that:

[0023] (1) During the process of treating waste ordinary gypsum plasterboard (after removing the facing paper) and anhydrous well salt gypsum with a salt solution, the retarder in the waste ordinary gypsum plasterboard can play a certain role in crystal regulation, reducing the water demand of the prepared recycled high-strength gypsum, and thus helping to improve the strength of the gypsum paste. This is mainly because the retarder added during the preparation of ordinary gypsum plasterboard can change the size of the dihydrate gypsum crystals, with the short-axis scale becoming larger and the long-axis scale becoming smaller, showing an obvious thickening phenomenon of the dihydrate gypsum crystals (if no retarder is added during the production of gypsum products, the dihydrate gypsum crystals are needle-shaped crystals with a large aspect ratio). Therefore, when using a salt solution to treat waste ordinary gypsum plasterboard to prepare recycled high-strength gypsum, it helps the recycled high-strength gypsum to still retain the original crystal morphology of the dihydrate gypsum, thereby helping to reduce the standard consistency water demand of the recycled high-strength gypsum.

[0024] (2) The main component of anhydrous well salt gypsum is anhydrous calcium sulfate, with a salt content of more than 10%. It has a large salt content and low activity. If it is to be utilized, the biggest problem lies in how to remove the salt it contains and activate its activity. In the present invention, by using a salt solution to treat waste ordinary gypsum plasterboard and anhydrous well salt gypsum simultaneously, the salt in the salt gypsum can be fully utilized, avoiding the increase in economic costs caused by desalting the salt gypsum. At the same time, the main component of waste ordinary gypsum plasterboard is dihydrate gypsum, which can act as a seed crystal, promoting the hydration of anhydrous well salt gypsum and activating the activity of anhydrous well salt gypsum.

[0025] (3) Ethylenediaminetetraacetic acid in the salt solution is a chelating agent that can bind to calcium ions, which is beneficial to the dissolution of anhydrous well salt gypsum and the acceleration of the formation of the supersaturation of dihydrate gypsum.

[0026] The paste material for the compressive strength test of the masonry bricks of the present invention has a short curing period, high strength, good stability and low cost, and can be used for the compressive strength test of masonry bricks.

[0027] The paste material for the compressive strength test of the masonry bricks of the present invention is non-radioactive, non-toxic and harmless to the human body. In addition, the market price of the paste material for the compressive strength test of the masonry bricks of the present invention is low, and it has good environmental, social and economic benefits. Detailed implementation manners

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0029] The present invention will be described in detail below in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0030] Aiming at the problems of the current accumulation of construction waste gypsum and / or salt gypsum, which are prone to cause pollution, the present invention provides a neat cement material for the compressive strength test of masonry bricks.

[0031] The neat cement material for the compressive strength test of masonry bricks according to the embodiment of the present invention, by weight, includes the following raw materials: 45-55 parts of high-strength gypsum powder (for example, 45 parts, 47 parts, 49 parts, 51 parts, 53 parts or 55 parts), 5-15 parts of building gypsum powder (for example, 5 parts, 8 parts, 11 parts, 13 parts or 15 parts), 40-50 parts of sand (for example, 40 parts, 42 parts, 44 parts, 46 parts, 48 parts or 50 parts), 0-0.3 parts of water reducing agent (for example, 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts or 0.3 parts) and 0.05-0.2 parts of setting accelerator (for example, 0.05 parts, 0.1 parts, 0.15 parts or 0.2 parts); the high-strength gypsum powder is a mixture of natural high-strength gypsum powder and recycled high-strength gypsum powder; the recycled high-strength gypsum powder is obtained by treating waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well salt gypsum with a salt solution.

[0032] Among them, the primary problem to be solved in preparing the neat cement material for the compressive strength test of masonry bricks with construction waste gypsum and salt gypsum is the slow setting of the recycled high-strength gypsum, recycled building gypsum and mixed sand. When leveling the neat cement material for the compressive strength test of masonry bricks, it is required that the neat cement material for the compressive strength test of masonry bricks has a certain operable time and quickly sets after the construction is completed. Therefore, the initial setting time is required to be between 15-19 minutes, and the final setting time is not longer than 30 minutes. Using a setting accelerator helps to solve the problem of slow setting of the recycled high-strength gypsum, recycled building gypsum and mixed sand.

[0033] In the preferred embodiment of the paste material for the compressive strength test of the masonry wall bricks of the present invention, in the salt solution, the concentration of ethylenediaminetetraacetic acid is 0.18%-0.22% (for example, 0.18%, 0.19%, 0.2%, 0.21% or 0.22%), and the pH is 4-6 (for example, 4, 5 or 6); the mass ratio of waste ordinary paper-faced gypsum to the anhydrous well-mined salt gypsum is (90-95):(5-10) (for example, 90:10, 95:5, 93:8, 95:10, 90:5, 92:7, etc.). In the mixed solution of the salt solution, waste ordinary paper-faced gypsum and anhydrous well-salt gypsum, the concentration of sodium chloride is 14%-16% (for example, 14%, 15% or 16%). Among them, if the dosage ratio of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum is too large (such as 100%), it is not conducive to the recycling of anhydrous well-mined salt gypsum, and more NaCl needs to be added to the salt solution to ensure the smooth preparation of the recycled high-strength gypsum. At the same time, due to the large specific surface area of waste ordinary paper-faced gypsum and many defects, when mixed with water, water molecules can be adsorbed on the surface of the recycled high-strength gypsum more quickly and fully, accelerating the hydration reaction of the recycled high-strength gypsum; in addition, the large specific surface area provides more sites for calcium ion and sulfate ion exchange, shortening the ion diffusion path and accelerating the diffusion speed, promoting the progress of the hydration reaction, thus shortening the setting time of the recycled high-strength gypsum; if the dosage ratio of waste ordinary paper-faced gypsum is too small, due to the low activity of anhydrous well-mined salt gypsum, the strength of the recycled high-strength gypsum will be significantly reduced. In addition, in practical applications, the addition amount of sodium chloride in the salt solution can also be calculated according to the salt content of the anhydrous well-salt gypsum; for example, if the salt content of the anhydrous well-salt gypsum is 10%, the slurry concentration is 30%, and the ratio of waste ordinary paper-faced gypsum to salt gypsum is 90:10, if the NaCl concentration is to reach 15%, that is, the water is 100 g, the NaCl is 15 g, the total of waste ordinary paper-faced gypsum and salt gypsum is 30 g, the salt gypsum is 3 g, and the salt brought is 0.3 g, then (15 - 0.3) = 14.7 g of NaCl needs to be added.

[0034] More preferably, the temperature for the salt solution treatment is 100-110 °C (for example, 100 °C, 102 °C, 104 °C, 106 °C, 108 °C or 110 °C), and the treatment time is 3.0-3.5 h (for example, 3.0 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h or 3.5 h).

[0035] In the preferred embodiment of the paste material for the compressive strength test of the masonry wall bricks of the present invention, the mass ratio of natural high-strength gypsum powder to recycled high-strength gypsum powder is (8.5-9.5):1 (for example, 8.5:1, 8.7:1, 8.9:1, 9.1:1, 9.3:1 or 9.5:1); the natural high-strength gypsum powder is natural high-strength gypsum powder of α40 and / or α50 grade.

[0036] In a preferred embodiment of the neat paste material for the compressive strength test of the masonry bricks of the present invention, the building gypsum powder includes natural building gypsum powder and recycled building gypsum powder; the recycled building gypsum powder is obtained by drying, ball milling and calcining waste gypsum.

[0037] In a preferred embodiment of the neat paste material for the compressive strength test of the masonry bricks of the present invention, the calcination temperature is 160 - 170 °C (for example, 160 °C, 162 °C, 164 °C, 166 °C, 168 °C or 170 °C), and the calcination time is 2 - 4 h (for example, 2 h, 2.5 h, 3 h, 3.5 h or 4 h); the natural building gypsum powder is natural building gypsum of grade 3.0 and / or grade 4.0; the recycled building gypsum powder is building gypsum powder of grade 3.0 or above; the mass ratio of the natural building gypsum powder to the recycled building gypsum powder is (3.5 - 4.5):1 (for example, 3.5:1, 3.7:1, 3.9:1, 4.1:1, 4.3:1 or 4.5:1). Among them, grade 3.0 building gypsum refers to the building gypsum of grade 3.0 in the standard of GB / T 9776 - 2022 "Building Gypsum", and it needs to meet the following requirements: the initial setting time ≥ 3 min, the final setting time ≤ 30 min, the wet flexural strength at 2 h ≥ 3.0 MPa, the wet compressive strength at 2 h ≥ 6.0 MPa, the dry flexural strength ≥ 5.0 MPa, the dry compressive strength ≥ 12.0 MPa, and the internal exposure index and external exposure index of the generated radionuclide limit should both be no greater than 1.0. Grade 4.0 building gypsum refers to the building gypsum of grade 4.0 in the standard of GB / T 9776 - 2022 "Building Gypsum", and it needs to meet the following requirements: the initial setting time ≥ 3 min, the final setting time ≤ 30 min, the wet flexural strength at 2 h ≥ 4.0 MPa, the wet compressive strength at 2 h ≥ 8.0 MPa, the dry flexural strength ≥ 7.0 MPa, the dry compressive strength ≥ 15.0 MPa, and the internal exposure index and external exposure index of the generated radionuclide limit should both be no greater than 1.0.

[0038] In a preferred embodiment of the neat paste material for the compressive strength test of the masonry bricks of the present invention, the sand is at least one of river sand, manufactured sand and standard sand; or, the sand is a mixed sand composed of river sand and recycled construction waste sand; the recycled construction waste sand is recycled aggregate made from waste concrete by crushing and screening.

[0039] Preferably, in the mixed sand, the mass ratio of river sand to recycled construction waste sand is (3.5 - 4.5):1 (for example, 3.5:1, 3.7:1, 3.9:1, 4.1:1, 4.3:1 or 4.5:1).

[0040] More preferably, the sand is fine sand with a nominal maximum particle size less than 1.18 mm.

[0041] In the preferred embodiment of the neat paste material for the compressive strength test of the masonry brick of the present invention, the water reducing agent is a polycarboxylate water reducing agent and / or an amino sulfonic acid water reducing agent. Among them, the waste ordinary paper gypsum and salt gypsum have high porosity, and the recycled high-strength gypsum and recycled building gypsum prepared from construction waste gypsum and salt gypsum have low strength, making it difficult to meet the requirement of the neat paste material for the compressive strength test of masonry bricks for the 4-hour compressive strength; the present invention improves the fluidity of the neat paste material for the compressive strength test of masonry bricks, reduces the water consumption, and increases its strength by adding a polycarboxylate superplasticizer and an amino sulfonate superplasticizer. Specifically, the polycarboxylate superplasticizer has a comb-shaped molecular structure, and its main chain contains polar groups such as carboxyl groups, which can adsorb on the surfaces of high-strength gypsum powder and building gypsum powder particles, while the side chains extend into the solution; through the steric hindrance effect, the high-strength gypsum powder and building gypsum powder particles are fully dispersed in water, avoiding particle aggregation, so that the gypsum paste has better fluidity and can fill the mold more evenly during the molding process, creating a good microstructure foundation for improving the strength. The amino sulfonate superplasticizer molecule contains strongly polar groups such as amino sulfonic acid groups, which will ionize a large number of anions in the aqueous solution and adsorb on the surfaces of high-strength gypsum powder and building gypsum powder particles, making the particle surfaces carry the same negative charge. According to the principle of like charges repelling each other, electrostatic repulsion is generated between the high-strength gypsum powder and building gypsum powder particles, so that they are dispersed from each other, improving the fluidity and uniformity of the gypsum paste, and helping to increase the strength of the gypsum products.

[0042] Preferably, the water reducing agent is a mixture of a polycarboxylate water reducing agent and an amino sulfonic acid water reducing agent, and the mass ratio of the polycarboxylate water reducing agent to the amino sulfonic acid water reducing agent is (4.5 - 5.5):1 (for example, 4.5:1, 5:1 or 5.5:1).

[0043] In the preferred embodiment of the neat paste material for the compressive strength test of the masonry brick of the present invention, the coagulant is potassium sulfate or sodium sulfate; or, the coagulant is a mixed coagulant including potassium sulfate and potassium bisulfate. Among them, the present invention uses sulfate coagulants such as potassium sulfate, sodium sulfate and potassium bisulfate, which are completely ionized in water and can provide a large amount of sulfate ions. During the hydration process of the recycled high-strength gypsum and recycled building gypsum, the increase in the sulfate ions makes the concentration of sulfate in the solution increase. According to the principle of inorganic chemical reactions, it is beneficial to the crystallization precipitation of gypsum dihydrate, thus accelerating the setting and hardening process of the recycled high-strength gypsum and recycled building gypsum. The presence of potassium ions, sodium ions, etc. can reduce the surface tension of the solution, making the contact between the recycled high-strength gypsum and recycled building gypsum particles and water more sufficient, accelerating the dissolution rate of the recycled high-strength gypsum and recycled building gypsum, and further providing more material basis for the crystallization of gypsum dihydrate, promoting the setting of gypsum.

[0044] Preferably, in the composite setting accelerator, the mass ratio of potassium sulfate to potassium bisulfate is (0.8 - 1.2):1 (for example, 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1).

[0045] The present invention also provides a method for preparing the neat paste material for testing the compressive strength of masonry bricks as described above. The method for preparing the neat paste material for testing the compressive strength of masonry bricks according to the embodiments of the present invention is characterized by including the following steps: Step 1, preparation of the admixture solution: adding a water reducing agent and a setting accelerator into water, and stirring evenly to obtain the admixture solution; Step 2, powder mixing: mixing high-strength gypsum powder and building gypsum powder evenly to obtain the powder; Step 3, adding the powder into the admixture solution, stirring for 1.0 - 1.5 min, then adding sand and stirring evenly to obtain the neat paste material for testing the compressive strength of masonry bricks.

[0046] In a preferred embodiment of the method for preparing the neat paste material for testing the compressive strength of masonry bricks of the present invention, the amount of water used is 15% - 30% of the total amount of high-strength gypsum powder, building gypsum powder and sand (for example, 15%, 18%, 20%, 22%, 25%, 27% or 30%).

[0047] The neat paste material for testing the compressive strength of masonry bricks of the present invention and its preparation method will be described in detail below through specific examples.

[0048] The main raw materials used in the following examples: the natural high-strength gypsum powder is the natural high-strength gypsum powder of α40 grade; the natural building gypsum powder is the natural building gypsum powder of 3.0 grade; the amount of water used in the following examples or comparative examples is the corresponding standard consistency water consumption, which is determined according to the neat paste standard for testing the compressive strength of masonry bricks.

[0049] Example 1

[0050] The neat paste material for testing the compressive strength of masonry bricks in this example includes the following raw materials: 49.5 kg of natural high-strength gypsum, 5.5 kg of recycled high-strength gypsum, 4 kg of building gypsum, 1 kg of recycled building gypsum, 40 kg of river sand, 0.05 kg of amino sulfonate superplasticizer and 22 kg of water.

[0051] The regenerated high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper gypsum (after removing the protective paper) and waterless well salt gypsum to a salt solution, heating to 100°C for reaction for 3.5 hours, removing impurities and purifying after the reaction to obtain the regenerated high-strength gypsum powder. The mass ratio of waste ordinary paper gypsum to waterless well salt gypsum is 90:10, the total amount of waste ordinary paper gypsum and waterless well salt gypsum and the solid-liquid ratio of the salt solution is 30%, and after the waste ordinary paper gypsum and waterless well salt gypsum are evenly mixed with the salt solution, the concentration of sodium chloride is 16%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.22%, and the pH is 4.

[0052] The recycled building gypsum is prepared by a method comprising the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800-1000m 3 / kg) and then calcined (the calcination temperature is 160°C and the calcination time is 3h) to obtain recycled building gypsum.

[0053] The method for preparing the slurry material for the compressive strength test of wall bricks in this embodiment comprises the following steps: (1) preparation of admixture solution: weigh the water reducer and the coagulant according to the predetermined mass and proportion, add them into 22 kg of water, stir evenly, and obtain the admixture solution; (2) mixing of powders: mix the natural high-strength gypsum powder, the recycled high-strength gypsum powder, the building gypsum powder and the recycled building gypsum powder evenly to obtain powder; (3) preparation of the slurry material for the compressive strength test of wall bricks: add the mixed powder into the admixture solution, stir for 1.0 min, then add sand, and after sufficient stirring, obtain the slurry material for the compressive strength test of wall bricks in this embodiment.

[0054] The pure mortar material for compressive strength test of masonry bricks of this embodiment was tested in accordance with GB / T 25183-2010 "Pure mortar material for compressive strength test of masonry bricks" standard; after testing, the basic properties of the pure mortar material for compressive strength test of masonry bricks of this embodiment are: compressive strength (4h) is 20.8MPa, fluidity (bucket method) is 161mm, initial setting time is 18min, and final setting time is 29min.

[0055] Example 2

[0056] The slurry material for compressive strength test of wall bricks in this embodiment includes the following raw materials: 45 kg of natural high-strength gypsum, 5 kg of recycled high-strength gypsum, 8 kg of building gypsum, 2 kg of recycled building gypsum, 40 kg of river sand, 0.1 kg of accelerator (potassium sulfate), 0.05 kg of aminosulfonate high-efficiency water reducing agent and 21 kg of water.

[0057] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 105 °C and reacting for 3 h, and performing impurity removal and purification after the reaction to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well-salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 15%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.21%, and the pH is 5.

[0058] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum and ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then performing calcination (the calcination temperature is 160 °C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0059] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducing agent according to the predetermined mass and ratio, add it to 21 kg of water, and stir evenly to obtain the admixture solution; (2) Powder mixing: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder to the admixture solution, stir for 1.5 min, and then add sand. After sufficient stirring, the neat paste material for the compressive strength test of the masonry bricks in this embodiment is obtained.

[0060] The neat paste material for the compressive strength test of the masonry bricks in this embodiment is detected according to the standard of GB / T 25183 - 2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4 h) is 19.1 MPa, the fluidity (bucket lifting method) is 162 mm, the initial setting time is 16 min, and the final setting time is 29.5 min.

[0061] Example 3

[0062] The neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following raw materials: 40.5 kg of natural high-strength gypsum, 4.5 kg of recycled high-strength gypsum, 12 kg of building gypsum, 3 kg of recycled building gypsum, 40 kg of river sand, 0.02 kg of amino sulfonate superplasticizer, 0.1 kg of polycarboxylate water reducing agent and 16.8 kg of water.

[0063] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 110 °C and reacting for 3.5 h, and after the reaction, removing impurities and purifying to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 14%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.20% and the pH is 6.

[0064] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then calcining (the calcination temperature is 160 °C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0065] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducer according to the predetermined quality and ratio, add it to 16.8 kg of water, and stir evenly to obtain the admixture solution; (2) Powder mixing: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder into the admixture solution, stir for 1.0 min, then add sand, and after sufficient stirring, obtain the neat paste material for the compressive strength test of the masonry bricks in this embodiment.

[0066] The neat paste material for the compressive strength test of the masonry bricks in this embodiment is detected according to the standard of GB / T 25183 - 2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4 h) is 19.8 MPa, the fluidity (bucket-lifting method) is 162 mm, the initial setting time is 18.5 min, and the final setting time is 29 min.

[0067] Example 4

[0068] The neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following raw materials: 45 kg of natural high-strength gypsum, 5 kg of recycled high-strength gypsum, 8 kg of building gypsum, 2 kg of recycled building gypsum, 40 kg of standard sand, 0.03 kg of amino sulfonate superplasticizer, and 23 kg of water.

[0069] The regenerated high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper gypsum (after removing the protective paper) and waterless well salt gypsum to a salt solution, heating to 100°C for reaction for 3.0 hours, removing impurities and purifying after the reaction to obtain the regenerated high-strength gypsum powder. The mass ratio of waste ordinary paper gypsum to waterless well salt gypsum is 90:10, the total amount of waste ordinary paper gypsum and waterless well salt gypsum and the solid-liquid ratio of the salt solution is 30%, and after the waste ordinary paper gypsum and waterless well salt gypsum are evenly mixed with the salt solution, the concentration of sodium chloride is 16%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.19%, and the pH is 4.

[0070] The recycled building gypsum is prepared by a method comprising the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800-1000m 3 / kg) and then calcined (the calcination temperature is 160°C and the calcination time is 3h) to obtain recycled building gypsum.

[0071] The method for preparing the slurry material for the compressive strength test of wall bricks in this embodiment comprises the following steps: (1) preparation of admixture solution: weigh the water reducer according to the predetermined mass and proportion, add it to 23 kg of water, stir evenly, and obtain the admixture solution; (2) mixing of powders: mix the natural high-strength gypsum powder, the recycled high-strength gypsum powder, the building gypsum powder and the recycled building gypsum powder evenly to obtain powder; (3) preparation of the slurry material for the compressive strength test of wall bricks: add the mixed powder to the admixture solution, stir for 1.5 min, then add sand, and after sufficient stirring, obtain the slurry material for the compressive strength test of wall bricks in this embodiment.

[0072] The pure mortar material for compressive strength test of masonry bricks of this embodiment was tested in accordance with GB / T 25183-2010 "Pure mortar material for compressive strength test of masonry bricks" standard; after testing, the basic properties of the pure mortar material for compressive strength test of masonry bricks of this embodiment are: compressive strength (4h) is 20.7MPa, fluidity (bucket method) is 160mm, initial setting time is 18min, and final setting time is 26min.

[0073] Example 5

[0074] The slurry material for compressive strength test of wall bricks in this embodiment includes the following raw materials: 40.5 kg of natural high-strength gypsum, 4.5 kg of recycled high-strength gypsum, 12 kg of building gypsum, 2 kg of recycled building gypsum, 40 kg of standard sand, 0.02 kg of aminosulfonate high-efficiency water reducing agent, 0.10 kg of polycarboxylic acid high-performance water reducing agent, and 16.6 kg of water.

[0075] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 105°C and reacting for 3.5 h, and after the reaction, removing impurities and purifying to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum and the solid-liquid ratio of the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 15%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.18%, and the pH is 5.

[0076] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then calcining (the calcination temperature is 160°C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0077] The preparation method of the neat cement material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducer according to the predetermined mass and ratio, add it to 16.6 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat cement material for the compressive strength test of the masonry bricks: Add the mixed powder materials into the admixture solution, stir for 1.0 min, and then add sand. After sufficient stirring, the neat cement material for the compressive strength test of the masonry bricks in this embodiment is obtained.

[0078] The neat cement material for the compressive strength test of the masonry bricks in this embodiment is tested according to the standard of GB / T 25183 - 2010 "Neat Cement Material for Compressive Strength Test of Masonry Bricks"; after testing, the basic properties of the neat cement material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4 h) is 20.8 MPa, the fluidity (bucket lifting method) is 163 mm, the initial setting time is 19 min, and the final setting time is 28.5 min.

[0079] Example 6

[0080] The neat cement material for the compressive strength test of the masonry bricks in this embodiment includes the following raw materials: 40.5 kg of natural high-strength gypsum, 4.5 kg of recycled high-strength gypsum, 12 kg of building gypsum, 3 kg of recycled building gypsum, 40 kg of machine-made sand, 0.06 kg of amino sulfonate superplasticizer and 24.2 kg of water.

[0081] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 110°C and reacting for 3 hours, and after the reaction ends, removing impurities and purifying to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 14%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.22%, and the pH is 6.

[0082] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then calcining (the calcining temperature is 160°C and the calcining time is 3 hours) to obtain the recycled building gypsum.

[0083] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducing agent according to the predetermined mass and ratio, add it to 24.2 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder materials into the admixture solution, stir for 1.5 minutes, then add sand, and after sufficient stirring, obtain the neat paste material for the compressive strength test of the masonry bricks in this embodiment.

[0084] The neat paste material for the compressive strength test of the masonry bricks in this embodiment is detected according to the standard of GB / T 25183 - 2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4h) is 19.9 MPa, the fluidity (bucket-lifting method) is 162 mm, the initial setting time is 16 minutes, and the final setting time is 26 minutes.

[0085] Example 7

[0086] The neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following raw materials: 49.5 kg of natural high-strength gypsum, 5.5 kg of recycled high-strength gypsum, 4 kg of building gypsum, 1 kg of recycled building gypsum, 32 kg of standard river sand, 8 kg of recycled construction waste sand, 0.02 kg of amino sulfonate superplasticizer, 0.1 kg of polycarboxylate water reducing agent and 20 kg of water.

[0087] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 100 °C and reacting for 3.5 h, and performing impurity removal and purification after the reaction to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well-salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 16%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.21%, and the pH is 4.

[0088] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum and ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then performing calcination (the calcination temperature is 160 °C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0089] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducer according to the predetermined mass and ratio, add it to 20 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder materials to the admixture solution, stir for 1 min, and then add sand. After sufficient stirring, the neat paste material for the compressive strength test of the masonry bricks in this embodiment is obtained.

[0090] The neat paste material for the compressive strength test of the masonry bricks in this embodiment is tested according to the standard of GB / T 25183 - 2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after testing, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4 h) is 19.2 MPa, the fluidity (bucket-lifting method) is 163 mm, the initial setting time is 19 min, and the final setting time is 29 min.

[0091] Example 8

[0092] The neat paste material for the compressive strength test of the masonry bricks in this embodiment includes the following raw materials: 40.5 kg of natural high-strength gypsum, 4.5 kg of recycled high-strength gypsum, 4 kg of building gypsum, 1 kg of recycled building gypsum, 50 kg of river sand, 0.03 kg of amino sulfonate superplasticizer and 20.9 kg of water.

[0093] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: Discarded ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum are added to a salt solution, heated to 105°C and reacted for 3 hours. After the reaction, impurities are removed and purified to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of the discarded ordinary paper-faced gypsum to the anhydrous well-mined salt gypsum is 90:10. The total amount of the discarded ordinary paper-faced gypsum and the anhydrous well-mined salt gypsum and the solid-liquid ratio of the salt solution is 30%. After the discarded ordinary paper-faced gypsum, the anhydrous well-salt gypsum and the salt solution are mixed evenly, the concentration of sodium chloride is 15%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.20%, and the pH is 5.

[0094] The recycled building gypsum is prepared by a method including the following steps: The discarded gypsum is dried and ball-milled (ball-milled to a specific surface area of 800 - 1000 m 3 / kg) and then calcined (the calcination temperature is 160°C and the calcination time is 3 hours) to obtain the recycled building gypsum.

[0095] The preparation method of the neat cement material for the compressive strength test of the masonry bricks in this embodiment includes the following steps: (1) Preparation of the admixture solution: Weigh the water-reducing agent according to the predetermined mass and ratio, add it to 20.9 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, the recycled high-strength gypsum powder, the building gypsum powder and the recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat cement material for the compressive strength test of the masonry bricks: Add the mixed powder materials to the admixture solution, stir for 1.5 minutes, and then add sand. After sufficient stirring, the neat cement material for the compressive strength test of the masonry bricks in this embodiment is obtained.

[0096] The neat cement material for the compressive strength test of the masonry bricks in this embodiment is detected according to the standard of GB / T 25183 - 2010 "Neat Cement Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat cement material for the compressive strength test of the masonry bricks in this embodiment are: the compressive strength (4h) is 19.5 MPa, the fluidity (bucket-lifting method) is 162 mm, the initial setting time is 15 minutes, and the final setting time is 28 minutes.

[0097] Comparative Example 1

[0098] The neat cement material of this comparative example includes the following raw materials: 36 kg of natural high-strength gypsum, 4 kg of recycled high-strength gypsum, 16 kg of building gypsum, 4 kg of recycled building gypsum, 40 kg of river sand, 0.05 kg of aminosulfonic acid water-reducing agent and 26.2 kg of water.

[0099] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 105 °C and reacting for 3 h, and performing impurity removal and purification after the reaction to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum, anhydrous well-mined salt gypsum and the salt solution are mixed evenly, the concentration of sodium chloride is 15%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.2%, and the pH is 5.

[0100] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum and ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then performing calcination (the calcination temperature is 160 °C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0101] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this comparative example includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducer according to the predetermined quality and ratio, add it to 26.2 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder and recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder materials into the admixture solution, stir for 1.5 min, and then add sand. After sufficient stirring, the neat paste material for the compressive strength test of the masonry bricks in this comparative example is obtained.

[0102] The neat paste material for the compressive strength test of the masonry bricks in this comparative example is detected according to the standard of GB / T 25183-2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example are: the compressive strength (4 h) is 16.8 MPa, the fluidity (bucket-lifting method) is 162 mm, the initial setting time is 11 min, and the final setting time is 15.5 min.

[0103] Comparative Example 2

[0104] The neat paste material in this comparative example includes the following raw materials: 63 kg of natural high-strength gypsum, 7 kg of recycled high-strength gypsum, 30 kg of river sand, 0.05 kg of amino sulfonic acid water reducer and 25 kg of water.

[0105] Among them, the recycled high-strength gypsum powder is prepared by a method including the following steps: adding waste ordinary paper-faced gypsum (after removing the facing paper) and anhydrous well-mined salt gypsum into a salt solution, heating to 105 °C and reacting for 3 h, and performing impurity removal and purification after the reaction to obtain the recycled high-strength gypsum powder. Among them, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well-mined salt gypsum is 90:10, the solid-liquid ratio of the total amount of waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum to the salt solution is 30%, after the waste ordinary paper-faced gypsum and anhydrous well salt gypsum are mixed evenly with the salt solution, the concentration of sodium chloride is 15%; the concentration of ethylenediaminetetraacetic acid in the salt solution is 0.20%, and the pH is 5.

[0106] The recycled building gypsum is prepared by a method including the following steps: drying the waste gypsum, ball milling (ball milling to a specific surface area of 800 - 1000 m 3 / kg), and then performing calcination (the calcination temperature is 160 °C and the calcination time is 3 h) to obtain the recycled building gypsum.

[0107] The preparation method of the neat paste material for the compressive strength test of the masonry bricks in this comparative example includes the following steps: (1) Preparation of the admixture solution: Weigh the water reducer according to the predetermined mass and ratio, add it to 25 kg of water, and stir evenly to obtain the admixture solution; (2) Mixing of the powder materials: Mix the natural high-strength gypsum powder, recycled high-strength gypsum powder, building gypsum powder, and recycled building gypsum powder evenly to obtain the powder materials; (3) Preparation of the neat paste material for the compressive strength test of the masonry bricks: Add the mixed powder materials into the admixture solution, stir for 1.5 min, and then add sand. After sufficient stirring, obtain the neat paste material for the compressive strength test of the masonry bricks in this comparative example.

[0108] The neat paste material for the compressive strength test of the masonry bricks in this comparative example is detected according to the standard of GB / T 25183 - 2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks"; after detection, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example are: the compressive strength (4 h) is 25.9 MPa, the fluidity (bucket-lifting method) is 163 mm, the initial setting time is 20.5 min, and the final setting time is 37 min (the compressive strength of the neat paste material for the compressive strength test of the masonry bricks in this comparative example is too high and the setting time is too long).

[0109] Comparative Example 3

[0110] The difference between this comparative example and Example 1 is only that: when preparing the recycled high-strength gypsum, only anhydrous well salt gypsum is used as the raw material, and the water consumption is 5 kg; the rest are the same as in Example 1.

[0111] The neat paste material for the compressive strength test of the masonry bricks in this comparative example was tested according to the standard of GB / T 25183-2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks". After testing, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example were: the compressive strength (4h) was 0.52 MPa, the fluidity (bucket-lifting method) was 164 mm, the initial setting time was 150 min, and the final setting time was 670 min.

[0112] The above results show that: if only anhydrous well salt gypsum is used as the raw material to prepare recycled high-strength gypsum, it is difficult for anhydrous well salt gypsum to transform into α high-strength gypsum during the salt solution treatment process, which will cause the strength of the neat paste material for the compressive strength test of the masonry bricks to be too low and the setting time to be too long, unable to meet the use requirements.

[0113] Comparative Example 4

[0114] The difference between this comparative example and Example 1 is only that: when preparing recycled high-strength gypsum, only waste ordinary paper-faced gypsum was used as the raw material, and the water consumption was 24 kg; the rest were the same as in Example 1.

[0115] The neat paste material for the compressive strength test of the masonry bricks in this comparative example was tested according to the standard of GB / T 25183-2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks". After testing, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example were: the compressive strength (4h) was 21.5 MPa, the fluidity (bucket-lifting method) was 162 mm, the initial setting time was 11 min, and the final setting time was 17 min.

[0116] The above results show that: if only waste ordinary paper-faced gypsum is used as the raw material to prepare recycled high-strength gypsum, due to the large specific surface area of waste ordinary paper-faced gypsum and the existence of more defects, when mixed with water, water molecules can be adsorbed on the surface of recycled high-strength gypsum more quickly and fully, accelerating the hydration reaction of recycled high-strength gypsum; at the same time, the larger specific surface area provides more exchange sites for calcium ions and sulfate ions, shortening the ion diffusion path and accelerating the diffusion speed, promoting the progress of the hydration reaction, thus resulting in the shortening of the setting time of recycled high-strength gypsum.

[0117] Comparative Example 5

[0118] The difference between this comparative example and Example 4 is only that: when preparing recycled high-strength gypsum, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well salt gypsum was 98:2, and the water consumption was 23.8 kg; the rest were the same as in Example 4.

[0119] The neat paste material for the compressive strength test of the masonry bricks in this comparative example was tested in accordance with the standard of GB / T 25183-2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks". After testing, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example were as follows: the compressive strength (4h) was 21.3 MPa, the fluidity (bucket lifting method) was 161 mm, the initial setting time was 12 min, and the final setting time was 18 min.

[0120] The above results show that: the proportion of waste ordinary paper-faced gypsum and anhydrous well salt gypsum is too large. Due to the large specific surface area of waste ordinary paper-faced gypsum, more calcium ion and sulfate exchange sites are provided, shortening the ion diffusion path and accelerating the diffusion rate, promoting the hydration reaction, and thus shortening the setting time of the recycled high-strength gypsum.

[0121] Comparative Example 6

[0122] The difference between this comparative example and Example 4 is only that: when preparing the recycled high-strength gypsum, the mass ratio of waste ordinary paper-faced gypsum to anhydrous well salt gypsum is 20:80, and the water consumption is 13 kg; the rest are the same as Example 4.

[0123] The neat paste material for the compressive strength test of the masonry bricks in this comparative example was tested in accordance with the standard of GB / T 25183-2010 "Neat Paste Material for Compressive Strength Test of Masonry Bricks". After testing, the basic properties of the neat paste material for the compressive strength test of the masonry bricks in this comparative example were as follows: the compressive strength (4h) was 10.5 MPa, the fluidity (bucket lifting method) was 164 mm, the initial setting time was 23 min, and the final setting time was 34 min.

[0124] The above results show that: the proportion of waste ordinary paper-faced gypsum and anhydrous well salt gypsum is too small. The calcium ions and sulfates provided by waste ordinary paper-faced gypsum are less, making it difficult for anhydrous well salt gypsum to transform into α high-strength gypsum during the salt solution treatment process, resulting in too low strength of the neat paste material for the compressive strength test of the masonry bricks and unable to meet the use requirements.

[0125] Comparative Example 7

[0126] The difference between this comparative example and Example 2 is only that: when preparing the recycled high-strength gypsum, waste gypsum products that do not require the addition of a setting retarder during the preparation process are used to replace the waste ordinary paper-faced gypsum in Example 2, and the water consumption is 23 kg; the rest are the same as Example 2.

[0127] Among them, the waste gypsum products were prepared by simulating the following method: building gypsum and water were mixed evenly (the mass ratio of building gypsum to water was 0.6), formed, and fully cured to obtain gypsum products (using these gypsum products to replace the waste ordinary paper-faced gypsum in Example 2).

[0128] The neat cementitious material for the compressive strength test of masonry bricks in this comparative example was tested in accordance with the standard of GB / T 25183-2010 "Neat Cementitious Material for Compressive Strength Test of Masonry Bricks". After testing, the basic properties of the neat cementitious material for the compressive strength test of masonry bricks in this comparative example were as follows: the compressive strength (4h) was 17.8 MPa, the fluidity (bucket-lifting method) was 164 mm, the initial setting time was 15 min, and the final setting time was 24 min.

[0129] The above results show that: the water requirement of the neat cementitious material in this comparative example has increased significantly compared with that in Example 2, resulting in a decrease in the compressive strength of the neat cementitious material in this comparative example and failing to meet the usage requirements. The waste ordinary paper gypsum in Example 2 played a role in reducing the water requirement of the neat cementitious material.

[0130] In summary, when the neat cementitious materials for the compressive strength test of masonry bricks obtained from the above examples and comparative examples were added to water and used for the compressive strength test of masonry bricks, the neat cementitious materials for the compressive strength test of masonry bricks in the examples could all meet the requirements of the standard of GB / T25183-2010 "Neat Cementitious Material for Compressive Strength Test of Masonry Bricks" for neat cementitious materials; and after being detected by the HD-2001 low-background multi-channel gamma spectrometer, their internal exposure index and external exposure index were both less than 1 (the internal exposure index of the neat cementitious materials for the compressive strength test of masonry bricks in Examples 1-8 was about 0.21, and the external exposure index was about 0.18). By comparing Example 2 and Comparative Example 1, it was found that if the proportion of building gypsum in the main material was too high, the strength of the neat cementitious material would be reduced, making it difficult to meet the requirements of the standard for the performance of the neat cementitious material for the compressive strength test of masonry bricks; by comparing Example 2 and Comparative Example 2, it was found that if the proportion of high-strength gypsum in the main material was too high, the setting time of the neat cementitious material would be prolonged and the strength would increase, making it difficult to meet the requirements of the standard for the setting time and strength of the neat cementitious material.

[0131] The present invention uses construction waste gypsum and salt gypsum to prepare the neat cementitious material for the compressive strength test of masonry bricks, which can greatly reduce the accumulation of construction waste gypsum and salt gypsum, reduce environmental pollution, and at the same time reduce the cost of the neat cementitious material for the compressive strength test of masonry bricks.

[0132] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A neat cementitious material for testing the compressive strength of masonry bricks, characterized in that, By weight parts, the neat paste material for the compressive strength test of the masonry brick includes the following raw materials: 45 - 55 parts of high-strength gypsum powder, 5 - 15 parts of building gypsum powder, 40 - 50 parts of sand, 0 - 0.3 parts of water reducing agent, and 0 - 0.2 parts of coagulant accelerator; The high-strength gypsum powder is a mixture of natural high-strength gypsum powder and recycled high-strength gypsum powder; The recycled high-strength gypsum powder is obtained by treating waste ordinary paper-faced gypsum and anhydrous well-mined salt gypsum with a salt solution.

2. The neat cement material for the compressive strength test of the masonry wall brick according to claim 1, wherein, In the salt solution, the concentration of ethylenediaminetetraacetic acid is 0.18% - 0.22%, and the pH is 4 - 6; The mass ratio of the waste ordinary paper-faced gypsum to the anhydrous well-mined salt gypsum is (90 - 95):(5 - 10). In the mixed solution of the salt solution, waste ordinary paper-faced gypsum and salt gypsum, the concentration of sodium chloride is 14% - 16%; The temperature for the treatment with the salt solution is 100 - 110 °C, and the treatment time is 3.0 - 3.5 h.

3. The neat cement material for the compressive strength test of masonry bricks according to claim 2, characterized in that, The mass ratio of the natural high-strength gypsum powder to the recycled high-strength gypsum powder is (8.5 - 9.5):1; The natural high-strength gypsum powder is natural high-strength gypsum powder of α40 and / or α50 grade; 4. The neat cement material for the compressive strength test of the masonry wall brick according to claim 1, characterized in that, The building gypsum powder includes natural building gypsum powder and recycled building gypsum powder; The recycled building gypsum powder is obtained by drying, ball milling and calcining waste gypsum.

5. The neat cement material for the compressive strength test of masonry bricks as described in claim 4, characterized in that, The temperature for the calcination is 160 - 170 °C, and the calcination time is 2 - 4 h; The natural building gypsum powder is natural building gypsum of 3.0 grade and / or 4.0 grade; The mass ratio of the natural building gypsum powder to the recycled building gypsum powder is (3.5 - 4.5):

1.

6. The neat cement material for the compressive strength test of the masonry wall bricks as described in claim 1, wherein, The sand is at least one of river sand, machine-made sand and standard sand; or, The sand is a mixed sand composed of river sand and recycled construction waste sand; the recycled construction waste sand is recycled aggregate made from waste concrete through crushing and screening; Preferably, in the mixed sand, the mass ratio of the river sand to the recycled construction waste sand is (3.5 - 4.5):1; More preferably, the sand is fine sand with a nominal maximum particle size less than 1.18 mm.

7. The neat cement material for the compressive strength test of the masonry wall bricks as described in claim 1, wherein, The water reducing agent is polycarboxylate water reducing agent and / or amino sulfonic acid water reducing agent; Preferably, the water reducing agent is a mixture of polycarboxylate water reducing agent and amino sulfonic acid water reducing agent, and the mass ratio of the polycarboxylate water reducing agent to the amino sulfonic acid water reducing agent is (4.5 - 5.5):

1.

8. The neat cement material for the compressive strength test of the masonry wall bricks as described in claim 1, wherein, The coagulant accelerator is potassium sulfate or sodium sulfate; or, The coagulant accelerator is a mixed coagulant accelerator including potassium sulfate and potassium bisulfate; Preferably, in the mixed coagulant accelerator, the mass ratio of potassium sulfate to potassium bisulfate is (0.9 - 1.1):

1.

9. The preparation method of the neat paste material for the compressive strength test of the masonry wall brick according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1. Preparation of the admixture solution: Add the water reducing agent and the coagulant accelerator into water, stir evenly to obtain the admixture solution; Step 2. Powder mixing: Mix the high-strength gypsum powder and the building gypsum powder evenly to obtain powder; Step 3. Add the powder into the admixture solution, stir for 1.0 - 1.5 min, then add the sand and stir evenly to obtain the neat paste material for the compressive strength test of the masonry brick.

10. The preparation method of the neat cement material for the compressive strength test of the masonry wall brick according to claim 9, characterized in that, The amount of water used is 15%-30% of the total amount of the high-strength gypsum powder, building gypsum powder and sand.