Carbide slag-ardealite co-doped foam concrete and preparation method thereof

Abstract

The invention relates to the technical field of foam concrete, in particular to carbide slag-ardealite co-doped foam concrete and a preparation method thereof. The carbide slag-ardealite co-doped foam concrete is prepared from the following raw materials in parts by mass: 320 to 350 parts of ardealite, 10 to 40 parts of carbide slag, 120 to 150 parts of mineral powder, 50 to 80 parts of cement, 5 to 7 parts of water reducing agent, 2 to 5 parts of foaming agent, 0.003 to 0.005 part of sodium aluminate and 210 to 230 parts of water. According to the invention, ardealite is used as a main cementing material, and ardealite is large in stockpiling amount and wide in source, and can be consumed greatly as a roadbed material, so that environmental pollution is reduced, and a low-carbon target is realized; the carbide slag is relatively strong in alkalinity, so that an enough alkaline environment can be provided to promote mineral powder reaction, the utilization rate of solid wastes is remarkably increased, and the cost is further saved; and sodium aluminate is adopted as an exciting agent, so that the alkaline environment is increased, the Al content is increased, and a gel system is promoted to react.

Description

Technical Field

[0001] The present invention relates to the technical field of foamed concrete, and particularly relates to a carbide slag-phosphogypsum compounded foamed concrete and a preparation method thereof. Background Art

[0002] With the rapid development of economic technology, the scale of the construction industry is huge, and the stockpile of solid waste in China is also gradually increasing. Low-carbon and environmental-friendly materials emerge as the times require. Using these industrial solid wastes to prepare foamed concrete can not only achieve low-carbon and environmental protection, reduce environmental problems, but also save costs.

[0003] Phosphogypsum is an industrial waste produced by the wet process in the fertilizer industry. The annual output of phosphogypsum (PG) in the global fertilizer industry is about 150 - 350 million tons. At present, 85 - 90% of PG still remains in landfills untreated, occupying space and polluting the environment. In addition, unprocessed PG contains some pollutants, such as toxic metals. Its use in cementitious materials is severely restricted by its acidity and soluble phosphorus and fluorine. These existences usually result in low activity of PG, so it usually exists in the form of filler in cement-based materials, resulting in insufficient mechanical properties of cement-based materials.

[0004] Subgrade materials are the foundation of road engineering. With the development of China's transportation construction, the demand for subgrade materials is also increasing continuously. Foamed concrete is a new type of subgrade filler. Compared with traditional subgrades, it has the advantages of light weight, convenient construction, less land occupation, and reducing settlement between new and old subgrades. However, traditional foamed concrete mainly uses cement as raw material. Cement is a non-renewable resource and its price is gradually rising. While industrial solid wastes, as resources to be developed, their costs are basically negligible. If industrial solid wastes are used to prepare foamed concrete, it can not only reduce the environmental problems caused by cement production, but also relieve the pressure on the environment caused by industrial solid waste emissions and accumulations, with significant economic and environmental benefits.

[0005] However, phosphogypsum often leads to an extension of the setting time of foamed concrete, and the foam stability time is less than the setting time, ultimately resulting in mold collapse, affecting the performance of foamed concrete. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies existing in the prior art, and to provide a carbide slag-phosphogypsum compounded foamed concrete and a preparation method thereof.

[0007] A carbide slag-phosphogypsum compounded foamed concrete, the raw materials of which by mass include: 320 - 350 parts of phosphogypsum, 10 - 40 parts of carbide slag, 120 - 150 parts of mineral powder, 50 - 80 parts of cement, 5 - 7 parts of water reducing agent, 2 - 5 parts of foaming agent, 0.003 - 0.005 parts of sodium aluminate, and 210 - 230 parts of water.

[0008] Preferably, the phosphogypsum is dark gray, with a particle size of ≤ 0.3 mm and a density of 2.05 - 2.10 g / cm 3 , and a specific surface area of 650 - 680 m 2 / kg.

[0009] Preferably, the carbide slag powder has a particle size of ≤ 20 μm and a density of 2.0 - 2.3 g / cm 3 , and a specific surface area of 710 - 745 m 2 / kg.

[0010] Preferably, the cement is ordinary Portland cement of P·O42.5, with a particle size of ≤ 75 μm and a density of 3.0 - 3.2 g / cm 3 , and a specific surface area of 350 - 360 m 2 / kg.

[0011] Preferably, the mineral powder is of S95 grade, with a particle size of ≤ 70 μm and a density of 3.05 - 3.15 g / cm 3 , and a specific surface area of 425 - 435 m 2 / kg.

[0012] Preferably, the sodium aluminate is a white powdery solid, soluble in water, of analytical pure (AR) grade, with a melting point of 1800 °C, a particle size of ≤ 50 μm, and a density of 2 g / cm 3 , and a specific surface area of 700 m 2 / kg.

[0013] Preferably, the foaming agent is SC - 4 enhanced composite foaming agent, mainly composed of sodium dodecyl sulfate, with a dilution ratio of 100 times and a sedimentation distance of 4.1 mm after standing in a standard bubble column for 1 h.

[0014] Preferably, the water - reducing agent is polycarboxylate water - reducing agent, with a water - reducing rate of 25 - 40%.

[0015] Preferably, the phosphogypsum is activated phosphogypsum; the activated phosphogypsum is prepared by the following steps: mixing phosphogypsum, aluminum sulfate, and xenotime evenly, drying at 100 - 120 °C for 20 - 30 min, calcining at 240 - 280 °C for 5 - 15 min, cooling to room temperature, and pulverizing.

[0016] The activated phosphogypsum is compounded with phosphogypsum, aluminum sulfate, and xenotime. After calcination, it can not only effectively eliminate the adverse effects of phosphorus on the properties of phosphogypsum, but also effectively remove the organic impurities therein. With the cooperation of rare - earth minerals and aluminum sulfate, it can effectively reduce the setting time of concrete and effectively improve the water resistance. The present invention uses activated phosphogypsum in combination with carbide slag, which can reduce the cement addition amount on the basis of ensuring the compressive strength, and the internal pores are more evenly distributed.

[0017] More preferably, the mass ratio of phosphogypsum, aluminum sulfate, and xenotime is 320 - 350:5 - 15:1 - 3.

[0018] Preferably, the raw materials further include: functionalized sisal fiber; the content of the cementitious material in the raw materials is the sum of the contents of phosphogypsum, carbide slag, mineral powder, and cement, and the mass ratio of the functionalized sisal fiber to the cementitious material is 5 - 10:500 - 620.

[0019] More preferably, the functionalized sisal fiber is prepared by the following steps: Add sisal fiber to an ethanol aqueous solution and ultrasonically treat for 10 - 40 min, add a surfactant thereto and continue ultrasonically treating for 5 - 20 min, add KH750 coupling agent and tetraethyl orthosilicate, adjust the temperature to 60 - 80 °C and continue ultrasonically treating for 1 - 2 h, adjust the pH value of the system to 9 - 10, continue ultrasonically treating for 1 - 2 h, filter, wash, vacuum dry, add to a methanol aqueous solution and stir evenly, add N,N'-methylenebisacrylamide thereto, stir at 50 - 60 °C for 5 - 10 h, add diethylenetriamine and continue stirring for 10 - 20 h, filter, wash, and vacuum dry.

[0020] When sisal fiber is used alone in a concrete system, it is very easy for the fiber bundles to merge and agglomerate. In the present invention, a nano-silica structural layer is deposited on the surface of the sisal fiber, and then a hydrophilic polymer is grafted. This not only effectively improves the dispersion performance of the sisal fiber and effectively ensures the fluidity of the slurry, but also when cured and subjected to an external force, it can effectively absorb and disperse the stress, prevent stress concentration, improve the mechanical properties of the cement, and at the same time, the free water it absorbs plays an internal curing role for the cement, reducing autogenous shrinkage and effectively avoiding the phenomenon of drying collapse.

[0021] The present invention uses a combination of functionalized sisal fiber and activated phosphogypsum. Through experiments, it is found that: compared with non-functionalized sisal fiber, the concrete of the present invention has higher fluidity, higher early strength, effectively increases the shrinkage resistance, and significantly reduces shrinkage.

[0022] More preferably, the mass ratio of sisal fiber, surfactant, KH750 coupling agent, tetraethyl orthosilicate, N,N'-methylenebisacrylamide, and diethylenetriamine is 20 - 40:1 - 2:1 - 3:1 - 5:0.1 - 1:0.01 - 0.5.

[0023] More preferably, the surfactant is cetyltrimethylammonium bromide.

[0024] The preparation method of the above-mentioned carbide slag-phosphogypsum compounded foamed concrete includes the following steps:

[0025] S1. Add a foaming agent to water for dilution, and then foam to obtain foam;

[0026] S2. Stir the phosphogypsum, carbide slag, mineral powder, and cement for 2 - 3 min, add the remaining raw materials and continue stirring for 3 - 4 min to obtain neat cement paste; pour the foam obtained in S1 into the neat cement paste and continue stirring for 2 - 3 min to obtain the carbide slag - phosphogypsum foam concrete mixture.

[0027] S3. Pour the carbide slag - phosphogypsum foam concrete mixture obtained in S2 into a mold, cure it naturally for 44 - 52 h, and then demold it for standard curing.

[0028] Preferably, in S1, the total time for foaming treatment and foam collection ≤ 2 min.

[0029] Preferably, in S3, the pouring height must be 1 - 2 cm higher than the mold.

[0030] Preferably, in S3, the standard curing temperature is 20 ± 2°C and the humidity is not less than 95%.

[0031] Beneficial effects:

[0032] In the present invention, phosphogypsum is used as the main cementitious material. Based on the large stockpile and wide source of phosphogypsum, it can be consumed in large quantities as a subgrade material, reducing environmental pollution and achieving the low - carbon goal. The cement - mineral powder - phosphogypsum system is activated with a suitable activator to reduce the cement dosage; while carbide slag, as a by - product of acetylene production by hydrolysis of calcium carbide, has strong alkalinity and can provide a sufficient alkaline environment to promote the reaction of mineral powder, significantly increasing the utilization rate of solid waste and further saving costs; and sodium aluminate is used as an activator, which is first dissolved in water to form [Al(OH)4] - monomers, which not only increase the alkaline environment but also increase the Al content, promoting the reaction of the cementitious system. Description of the drawings

[0033] Figure 1 It is a comparison chart of the wet apparent density and fluidity of the carbide slag - phosphogypsum foam concrete obtained in Examples 1 - 4 and Comparative Examples 1 - 2.

[0034] Figure 2 It is a comparison chart of the setting time and compressive strength of the carbide slag - phosphogypsum foam concrete obtained in Examples 1 - 4 and Comparative Examples 1 - 2.

[0035] Figure 3 It is a comparison chart of the water absorption rate and water softening coefficient of the carbide slag - phosphogypsum foam concrete obtained in Examples 1 - 4 and Comparative Examples 1 - 2.

[0036] Figure 4 It is a comparison chart of the fluidity and 28 - day drying shrinkage rate of the carbide slag - phosphogypsum foam concrete obtained in Examples 3, 5 - 6 and Comparative Examples 3 - 4.

[0037] Figure 5The comparison chart of the setting time of the carbide slag-phosphogypsum foam concrete obtained in Example 3, Examples 5-6 and Comparative Examples 3-4.

[0038] Figure 6 The comparison chart of the compressive strength of the carbide slag-phosphogypsum foam concrete obtained in Example 3, Examples 5-6 and Comparative Examples 3-4.

[0039] Figure 7 The comparison chart of the water absorption rate and water softening coefficient of the carbide slag-phosphogypsum foam concrete obtained in Example 3, Examples 5-6 and Comparative Examples 3-4. Detailed implementation manners

[0040] The present invention will be further explained below with reference to specific embodiments.

[0041] The cement used below is P·O42.5 cement produced by Zhucheng Jiuqi Building Materials Co., Ltd., with a density of 3.1 g / cm 3 , and a specific surface area of 358 m 2 / kg.

[0042] The mineral powder used below is S95-grade mineral powder produced by Gongyi Longze Water Purification Materials Co., Ltd., with a density of 3.10 g / cm 3 , and a specific surface area of 429 m 2 / kg.

[0043] The phosphogypsum used below is the original phosphogypsum from the storage yard of Anhui Sierte Industry Co., Ltd. In the laboratory, it is crushed, dried and passed through a 60-mesh (0.3 mm) stainless steel square hole sieve, with a density of 2.09 g / cm 3 , and a moisture content of 18%.

[0044] The carbide slag powder used below comes from Sichuan Jinlu Resin Co., Ltd., with a density of 2.2 g / cm 3 , and a specific surface area of 720 m 2 / kg.

[0045] The foaming agent used below is the SC-4 enhanced composite foaming agent produced by Guangdong Shoucheng Construction Technology Co., Ltd., with the main component being sodium dodecyl sulfate, a dilution ratio of 100 times, and meeting the performance indicators of the foaming agent determined by CJJ / T177-2012 "Technical Specification for Filled Engineering with Bubble Mixed Lightweight Soil".

[0046] The sodium aluminate used below is produced by Shanghai Macklin Biochemical Technology Co., Ltd., with an analytical pure (AR) grade, a melting point of 1800 °C, and is a white powdery solid.

[0047] The water reducer used below is the polycarboxylate superplasticizer produced by Jiangsu Bote, with a water reduction rate of 30%.

[0048] The water used below meets the requirements of JGJ 63-2006 "Standard for Water Used in Concrete".

[0049] Example 1

[0050] A kind of foam concrete with compound admixture of carbide slag and phosphogypsum, its raw materials by mass include: 10 parts of carbide slag, 80 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water reducer, 2 parts of foaming agent and 220 parts of water.

[0051] The preparation method of the above-mentioned foam concrete with compound admixture of carbide slag and phosphogypsum includes the following steps;

[0052] S1. Dry-mix and stir the cementitious materials for 2 min, add water, water reducer and sodium aluminate and continue to stir for 3 min to obtain uniform concrete slurry;

[0053] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, use the foaming agent to foam, and collect an appropriate amount of foam, and this process is carried out within 2 min;

[0054] S3. Pour the collected foam into the concrete slurry, continue to stir for 2 min to obtain a uniform mixture of carbide slag-phosphogypsum foam concrete, pour it into a 100mm×100mm×100mm iron mold. To prevent mold collapse, the pouring height must be 1-2 cm higher than the mold, cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and put it into a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0055] Example 2

[0056] A kind of foam concrete with compound admixture of carbide slag and phosphogypsum, its raw materials by mass include: 20 parts of carbide slag, 70 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water reducer, 2 parts of foaming agent and 220 parts of water.

[0057] The preparation method of the above-mentioned foam concrete with compound admixture of carbide slag and phosphogypsum includes the following steps;

[0058] S1. Dry-mix and stir the cementitious materials for 3 min, add water, water reducer and sodium aluminate and continue to stir for 4 min to obtain uniform concrete slurry;

[0059] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, use the foaming agent to foam, and collect an appropriate amount of foam, and this process is carried out within 2 min;

[0060] S3. Pour the collected foam into the neat cement paste, and continue stirring for 3 min to obtain a uniform carbide slag - phosphogypsum foam concrete mixture. Pour it into an iron mold of 100 mm×100 mm×100 mm. To prevent the mold from collapsing, the pouring height must be 1 - 2 cm higher than the mold. Cover it with a plastic film and cure it naturally for 2 d. Scrape the surface flat and demold it, then put it into a standard curing box for standard curing until the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0061] Example 3

[0062] A carbide slag - phosphogypsum compound - doped foam concrete, the raw materials of which by mass include: 30 parts of carbide slag, 60 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0063] The preparation method of the above - mentioned carbide slag - phosphogypsum compound - doped foam concrete includes the following steps;

[0064] S1. Dry - mix and stir the cementitious materials for 2.5 min, add water, water - reducing agent and sodium aluminate and continue stirring for 3.5 min to obtain a uniform concrete neat paste;

[0065] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir it evenly, use the foaming agent to foam, and collect an appropriate amount of foam. This process is carried out within 2 min;

[0066] S3. Pour the collected foam into the concrete neat paste, and continue stirring for 2.5 min to obtain a uniform carbide slag - phosphogypsum foam concrete mixture. Pour it into an iron mold of 100 mm×100 mm×100 mm. To prevent the mold from collapsing, the pouring height must be 1 - 2 cm higher than the mold. Cover it with a plastic film and cure it naturally for 2 d. Scrape the surface flat and demold it, then put it into a standard curing box for standard curing until the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0067] Example 4

[0068] A carbide slag - phosphogypsum compound - doped foam concrete, the raw materials of which by mass include: 40 parts of carbide slag, 50 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0069] The preparation method of the above - mentioned carbide slag - phosphogypsum compound - doped foam concrete includes the following steps;

[0070] S1. Dry - mix and stir the cementitious materials for 2.5 min, add water, water - reducing agent and sodium aluminate and continue stirring for 3.5 min to obtain a uniform concrete neat paste;

[0071] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, foam using the foaming agent, and collect an appropriate amount of foam. This process is carried out within 2 minutes.

[0072] S3. Pour the collected foam into the neat cement paste, continue stirring for 2.5 minutes to obtain a uniform carbide slag - phosphogypsum foam concrete mixture, pour it into an iron mold of 100mm×100mm×100mm. To prevent mold collapse, the pouring height must be 1 - 2 cm higher than the mold. Cover it with a plastic film for natural curing for 2 days, scrape the surface flat for demolding, and place it in a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0073] Comparative Example 1

[0074] A carbide slag - phosphogypsum compound - doped foam concrete, the raw materials of which by mass include: 0 parts of carbide slag, 90 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0075] The preparation method of the above - mentioned phosphogypsum foam concrete includes the following steps;

[0076] S1. Dry - mix and stir the cementitious materials for 2.5 minutes, add water, water - reducing agent and sodium aluminate and continue stirring for 3.5 minutes to obtain a uniform concrete neat paste;

[0077] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, foam using the foaming agent, and collect an appropriate amount of foam. This process is carried out within 2 minutes.

[0078] S3. Pour the collected foam into the concrete neat paste, continue stirring for 2.5 minutes to obtain a uniform phosphogypsum foam concrete mixture, pour it into an iron mold of 100mm×100mm×100mm. To prevent mold collapse, the pouring height must be 1 - 2 cm higher than the mold. Cover it with a plastic film for natural curing for 2 days, scrape the surface flat for demolding, and place it in a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0079] Comparative Example 2

[0080] A carbide slag - phosphogypsum compound - doped foam concrete, the raw materials of which by mass include: 90 parts of carbide slag, 0 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of phosphogypsum, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0081] The preparation method of the above-mentioned carbide slag-phosphogypsum compound admixture foam concrete includes the following steps;

[0082] S1. Dry-mix and stir the cementitious materials for 2.5 min, add water, water reducer and sodium aluminate, and continue to stir for 3.5 min to obtain a uniform concrete paste;

[0083] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, foam using the foaming agent, and collect an appropriate amount of foam. This process is carried out within 2 min;

[0084] S3. Pour the collected foam into the concrete paste, continue to stir for 2.5 min to obtain a uniform carbide slag-phosphogypsum foam concrete mixture, pour it into a 100 mm×100 mm×100 mm iron mold. To prevent mold collapse, the pouring height must be 1-2 cm higher than the mold. Cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and place it in a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0085] Test the properties of the carbide slag-phosphogypsum foam concrete obtained in the above Examples 1-4 and Comparative Examples 1-2. The results are as Figures 1-3 shown.

[0086] It can be seen from Examples 1-4 that with the increase in the dosage of carbide slag powder, the wet apparent density of the carbide slag-phosphogypsum compound admixture foam concrete gradually increases, the fluidity decreases significantly, the setting time becomes shorter, the compressive strength decreases slowly, the water absorption rate decreases, and the water resistance improves.

[0087] It can be seen from Comparative Example 1 and Comparative Example 2 that the foam concrete without carbide slag powder has a longer setting time, a larger flow value, a significantly higher compressive strength, and a higher water absorption rate than the foam concrete without cement.

[0088] The incorporated carbide slag powder has a negative impact on the cementitious system, which is related to its hydration ability. Since the carbide slag powder is not easily soluble, with the increase in the dosage, the undissolved carbide slag powder exists in the system and releases a large amount of calcium hydroxide during hydration. The generated gel wraps the mineral powder and phosphogypsum, preventing further hydration and resulting in a decrease in strength; the carbide slag powder has a strong alkalinity, and the hydration products hydrate faster in an alkaline environment, and the setting time also speeds up, making the paste more viscous and resulting in a decrease in fluidity; the specific surface area of the carbide slag powder is higher than that of cement. When replacing part of the cement, the wet apparent density of the foam concrete is large, and the pore distribution inside the concrete is more uniform.

[0089] In summary, when the fluidity and water softening coefficient meet the requirements (fluidity is 160 - 200 mm, water resistance coefficient > 0.8), the compressive strength of Example 2 is higher than that of Example 3. Considering that the strength requirement for subgrade filling is not high and the water softening coefficient meets the specification requirements, in order to dispose of solid waste in large quantities, Example 3 is more suitable.

[0090] Example 5

[0091] A carbide slag - phosphogypsum compound - doped foamed concrete, the raw materials of which include by mass: 30 parts of carbide slag, 60 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 340 parts of activated phosphogypsum, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0092] The activated phosphogypsum is prepared by the following steps: Mix 340 parts of phosphogypsum, 10 parts of aluminum sulfate and 2 parts of xenotime evenly by mass, dry at a temperature of 110°C for 25 min, send it into a calcining kiln at a temperature of 260°C for calcining for 10 min, cool to room temperature, and pulverize.

[0093] The preparation method of the above - mentioned carbide slag - phosphogypsum compound - doped foamed concrete includes the following steps;

[0094] S1. Dry - mix and stir the cementitious materials for 2.5 min, add water, water - reducing agent and sodium aluminate and continue to stir for 3.5 min to obtain a uniform concrete slurry;

[0095] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, foam using the foaming agent, and collect an appropriate amount of foam, and this process is carried out within 2 min;

[0096] S3. Pour the collected foam into the concrete slurry, continue to stir for 2.5 min to obtain a uniform carbide slag - phosphogypsum foamed concrete mixture, pour it into an iron mold of 100 mm × 100 mm × 100 mm. To prevent mold collapse, the pouring height must be 1 - 2 cm higher than the mold, cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and put it into a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20 ± 2°C and a humidity of not less than 95%.

[0097] Example 6

[0098] A carbide slag - phosphogypsum compound - doped foamed concrete, the raw materials of which include by mass: 30 parts of carbide slag, 55 parts of cement, 0.003 parts of sodium aluminate, 140 parts of mineral powder, 335 parts of activated phosphogypsum, 10 parts of functionalized sisal fiber, 5 parts of water - reducing agent, 2 parts of foaming agent and 220 parts of water.

[0099] Activated phosphogypsum is prepared by the following steps: Mix 340 parts of phosphogypsum, 10 parts of aluminum sulfate, and 2 parts of xenotime evenly by mass, dry at 110 °C for 25 min, send it into a calcination kiln at 260 °C and calcine for 10 min, cool to room temperature, and pulverize.

[0100] Functionalized sisal fiber is prepared by the following steps: Add 30 parts of sisal fiber by mass to 80 parts of an ethanol aqueous solution with a mass fraction of 50%, perform ultrasonic treatment for 25 min at an ultrasonic frequency of 9 kHz, add 1.5 parts of cetyltrimethylammonium bromide thereto and continue ultrasonic treatment for 15 min, add 2 parts of KH750 coupling agent and 3 parts of tetraethyl orthosilicate, adjust the temperature to 70 °C and continue ultrasonic treatment for 1.5 h, dropwise add ammonia water to adjust the pH value of the system to 9 - 10, continue ultrasonic treatment for 1.5 h, filter, wash, vacuum dry, add it to 45 parts of a methanol aqueous solution with a mass fraction of 70% and stir evenly, add 0.5 part of N,N’-methylenebisacrylamide thereto, stir at 55 °C for 8 h, add 0.03 part of diethylenetriamine and continue stirring for 15 h, filter, wash, and vacuum dry.

[0101] The preparation method of the above-mentioned foam concrete with compound admixture of carbide slag and phosphogypsum includes the following steps;

[0102] S1. Dry-mix and stir the cementitious materials for 2.5 min, add the functionalized sisal fiber, water, water reducer, and sodium aluminate and continue stirring for 3.5 min to obtain a uniform concrete paste;

[0103] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, use the foaming agent to foam, and collect an appropriate amount of foam, which is carried out within 2 min;

[0104] S3. Pour the collected foam into the concrete paste, continue stirring for 2.5 min to obtain a uniform foam concrete mixture of carbide slag and phosphogypsum, pour it into an iron mold of 100 mm × 100 mm × 100 mm. To prevent mold collapse, the pouring height must be 1 - 2 cm higher than the mold, cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and place it in a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20 ± 2 °C and a humidity of not less than 95%.

[0105] Comparative Example 3

[0106] A foam concrete with compound admixture of carbide slag and phosphogypsum, its raw materials by mass include: 30 parts of carbide slag, 55 parts of cement, 0.003 part of sodium aluminate, 140 parts of mineral powder, 335 parts of activated phosphogypsum, 10 parts of functionalized sisal fiber, 5 parts of water reducer, 2 parts of foaming agent, and 220 parts of water.

[0107] The activated phosphogypsum is prepared by the following steps: Mix 340 parts of phosphogypsum and 12 parts of aluminum sulfate evenly by mass, dry at 110 °C for 25 min, send it into a calcination furnace at 260 °C for calcination for 10 min, cool to room temperature, and crush.

[0108] The functionalized sisal fiber is prepared by the following steps: Add 30 parts of sisal fiber by mass to 80 parts of an ethanol aqueous solution with a mass fraction of 50%, perform ultrasonic treatment for 25 min, with an ultrasonic frequency of 9 kHz, add 1.5 parts of cetyltrimethylammonium bromide thereto and continue ultrasonic treatment for 15 min, add 2 parts of KH750 coupling agent and 3 parts of tetraethyl orthosilicate, adjust the temperature to 70 °C and continue ultrasonic treatment for 1.5 h, dropwise add ammonia water to adjust the pH value of the system to 9 - 10, continue ultrasonic treatment for 1.5 h, filter, wash, dry in vacuum, add it to 45 parts of a methanol aqueous solution with a mass fraction of 70% and stir evenly, add 0.5 part of N,N'-methylenebisacrylamide thereto, stir at 55 °C for 8 h, add 0.03 part of diethylenetriamine and continue stirring for 15 h, filter, wash, and dry in vacuum.

[0109] The preparation method of the above-mentioned carbide slag-phosphogypsum compound admixture foam concrete includes the following steps;

[0110] S1. Dry-mix and stir the cementitious materials for 2.5 min, add the functionalized sisal fiber, water, water reducer, and sodium aluminate and continue stirring for 3.5 min to obtain a uniform concrete paste;

[0111] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming liquid, stir evenly, use the foaming agent to foam, and collect an appropriate amount of foam, which is carried out within 2 min;

[0112] S3. Pour the collected foam into the concrete paste, continue stirring for 2.5 min to obtain a uniform carbide slag-phosphogypsum foam concrete mixture, pour it into an iron mold of 100 mm×100 mm×100 mm. To prevent mold collapse, the pouring height must be 1 - 2 cm higher than the mold, cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and put it into a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2 °C and a humidity of not less than 95%.

[0113] Comparative Example 4

[0114] A carbide slag-phosphogypsum compound admixture foam concrete, the raw materials of which by mass include: 30 parts of carbide slag, 55 parts of cement, 0.003 part of sodium aluminate, 140 parts of mineral powder, 335 parts of activated phosphogypsum, 10 parts of sisal fiber, 5 parts of water reducer, 2 parts of foaming agent, and 220 parts of water.

[0115] Activated phosphogypsum is prepared by the following steps: Mix 340 parts of phosphogypsum, 10 parts of aluminum sulfate, and 2 parts of xenotime evenly by mass, dry at 110°C for 25 min, send it into a calcination furnace at 260°C for calcination for 10 min, cool to room temperature, and crush.

[0116] The preparation method of the above-mentioned carbide slag-phosphogypsum composite foam concrete includes the following steps;

[0117] S1. Dry-mix and stir the cementitious materials for 2.5 min, add sisal fiber, water, water reducer, and sodium aluminate, and continue to stir for 3.5 min to obtain uniform concrete slurry;

[0118] S2. Dilute the foaming agent and water at a ratio of 1:100 to obtain a foaming solution, stir evenly, foam using the foaming agent, and collect an appropriate amount of foam. This process is carried out within 2 min;

[0119] S3. Pour the collected foam into the concrete slurry, continue to stir for 2.5 min to obtain a uniform carbide slag-phosphogypsum foam concrete mixture, pour it into an iron mold of 100 mm×100 mm×100 mm. To prevent mold collapse, the pouring height must be 1-2 cm higher than the mold. Cover it with a plastic film for natural curing for 2 d, scrape the surface flat for demolding, and put it into a standard curing box for standard curing to the specified age. Among them, the standard curing process is a curing temperature of 20±2°C and a humidity of not less than 95%.

[0120] Test the properties of the carbide slag-phosphogypsum foam concrete obtained in Examples 3, 5-6 and Comparative Examples 3-4 above. The results are as Figures 4-7 shown.

[0121] There was no significant difference in water absorption between groups (P>0.05). The fluidity, compressive strength, and water softening coefficient of the carbide slag-phosphogypsum foam concrete obtained in Example 6 were the highest, superior to other groups (P<0.05); while the 28-day dry shrinkage rate and setting time were the smallest, superior to other groups (P<0.05).

[0122] The applicant believes that: Since the present invention uses phosphogypsum compounded with aluminum sulfate and xenotime, after calcination, it can not only effectively eliminate the adverse effects of phosphorus on the properties of phosphogypsum, but also effectively remove the organic impurities therein. In combination with rare earth minerals and aluminum sulfate, it can effectively reduce the setting time of concrete and effectively improve the water resistance. The present invention uses activated phosphogypsum in combination with carbide slag, which can reduce the amount of cement added while ensuring the compressive strength, and the internal pores are more evenly distributed. At the same time, the present invention deposits a nano-silica structural layer on the surface of sisal fiber and then grafts a hydrophilic polymer, which can not only effectively improve the dispersion performance of sisal fiber and effectively ensure the fluidity of the slurry, but also, when subjected to external forces after curing, effectively absorb and disperse the stress, prevent stress concentration, improve the mechanical properties of cement, and at the same time, the free water absorbed by it plays an internal curing role for cement, reducing autogenous shrinkage and effectively avoiding the phenomenon of dry slump; further compounding functionalized sisal fiber with activated phosphogypsum makes the concrete of the present invention have higher fluidity, higher early strength, effectively increases the shrinkage resistance and significantly reduces the shrinkage.

[0123] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

Claims

1. A carbide slag-phosphogypsum compound admixture foam concrete, characterized in that, Its raw materials by mass include: 320 - 350 parts of phosphogypsum, 10 - 40 parts of carbide slag, 120 - 150 parts of ore powder, 50 - 80 parts of cement, 5 - 7 parts of water reducing agent, 2 - 5 parts of foaming agent, 0.003 - 0.005 parts of sodium aluminate, and 210 - 230 parts of water.

2. The carbide slag-phosphogypsum compound admixture foam concrete according to claim 1, characterized in that, The particle size of phosphogypsum is ≤ 0.3 mm, and its density is 2.05 - 2.10 g / cm 3 , and its specific surface area is 650 - 680 m 2 / kg; the particle size of carbide slag powder is ≤ 20 μm, and its density is 2.0 - 2.3 g / cm 3 , and its specific surface area is 710 - 745 m 2 / kg.

3. The carbide slag-phosphogypsum compound admixture foamed concrete according to claim 1, characterized in that, The cement is ordinary Portland cement of P·O42.

5.

4. The carbide slag-phosphogypsum compound admixture foam concrete according to claim 1, characterized in that, The water reducing agent is polycarboxylate water reducing agent, and its water reducing rate is 25 - 40%.

5. The carbide slag-phosphogypsum compound admixture foam concrete according to claim 1, characterized in that, The phosphogypsum is activated phosphogypsum; the activated phosphogypsum is prepared by the following steps: Mix phosphogypsum, aluminum sulfate, and xenotime evenly, dry at 100 - 120°C for 20 - 30 min, calcine at 240 - 280°C for 5 - 15 min, cool to room temperature, and pulverize.

6. The carbide slag-phosphogypsum compound admixture foamed concrete according to claim 5, characterized in that The mass ratio of phosphogypsum, aluminum sulfate, and xenotime is 320 - 350:5 - 15:1 - 3.

7. The carbide slag-phosphogypsum compound-doped foamed concrete according to claim 1, characterized in that, Its raw materials also include: functionalized sisal fiber; the content of the cementitious material in the raw materials is the sum of the contents of phosphogypsum, carbide slag, ore powder, and cement, and the mass ratio of the functionalized sisal fiber to the cementitious material is 5 - 10:500 - 620.

8. The carbide slag-phosphogypsum compound admixture foam concrete according to claim 7, characterized in that, The functionalized sisal fiber is prepared by the following steps: Add sisal fiber into an ethanol aqueous solution and ultrasonically treat for 10 - 40 min, add a surfactant and continue ultrasonically treat for 5 - 20 min, add KH750 coupling agent and tetraethyl orthosilicate, adjust the temperature to 60 - 80°C and continue ultrasonically treat for 1 - 2 h, adjust the pH value of the system to 9 - 10, continue ultrasonically treat for 1 - 2 h, filter, wash, vacuum dry, add into a methanol aqueous solution and stir evenly, add N,N’-methylenebisacrylamide, stir at 50 - 60°C for 5 - 10 h, add diethylenetriamine and continue stirring for 10 - 20 h, filter, wash, and vacuum dry.

9. The carbide slag-phosphogypsum compound admixture foam concrete according to claim 8, characterized in that, The mass ratio of sisal fiber, surfactant, KH750 coupling agent, tetraethyl orthosilicate, N,N’-methylenebisacrylamide, and diethylenetriamine is 20 - 40:1 - 2:1 - 3:1 - 5:0.1 - 1:0.01 - 0.

5.

10. A carbide slag-phosphogypsum compound admixture foam concrete according to any one of claims 1-9, characterized in that, It includes the following steps: S1. Add the foaming agent into water for dilution, and then foam to obtain foam. S2. Stir phosphogypsum, carbide slag, ore powder, and cement for 2 - 3 min, add the remaining raw materials and continue stirring for 3 - 4 min to obtain concrete paste; Pour the foam obtained in S1 into the concrete paste and continue stirring for 2 - 3 min to obtain a carbide slag - phosphogypsum foam concrete mixture. S3. Pour the carbide slag - phosphogypsum foam concrete mixture obtained in S2 into a mold, cure naturally for 44 - 52 h, and then demold for standard curing.

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