Preparation method of slag-ardealite foam concrete

Abstract

The invention relates to the technical field of building concrete, in particular to slag-ardealite foam concrete and a manufacturing method thereof. The slag-ardealite foam concrete comprises the following components in parts by weight: 10-20 parts of ardealite, 75-85 parts of slag powder, 1-5 parts of Portland cement, 1-5 parts of an additive, 3-5 parts of an animal protein foaming agent and 40-60 parts of water. The composite foam stabilizer and the composite early strength agent are used for preparing the foam concrete with excellent pores. By adding the composite foam stabilizer, the stability of foam in the foam concrete can be remarkably improved, and the foam concrete has a better pore structure. The addition of the composite early strength agent can significantly improve the early hydration of the foam concrete, so that the foam concrete is hydrated before the foam surface tension cannot maintain the self weight, and the hydrated part maintains the self weight to avoid the formation of large bubbles in the foam concrete.

Description

Technical Field

[0001] The invention relates to the technical field of building concrete, in particular to slag-phosphogypsum foam concrete and a preparation method thereof. Background Art

[0002] Phosphogypsum is an acidic byproduct of the production of phosphate fertilizers in the phosphorus chemical industry. Most of the phosphogypsum is in powder form, mainly light gray in color. The main component is calcium sulfate dihydrate crystals, and contains a small amount of phosphorus, sulfur, fluorine and other elements; slag is a byproduct of the blast furnace ironmaking process. During the ironmaking process, iron oxide is reduced to metallic iron at high temperatures, and impurities such as silicon dioxide and aluminum oxide in iron ore react with lime to form granular materials with silicates and aluminosilicates as the main components. Excessive accumulation of phosphogypsum and slag will have a great impact on the environment. Phosphogypsum-slag cement is a new type of non-calcined cementitious material. Using it in foamed concrete can not only reduce the amount of cement, but also promote the resource application of industrial solid waste. Summary of the invention

[0003] In view of the problem in the prior art that the foamed concrete is difficult to form or has a poor pore structure due to the long setting time of phosphogypsum-slag cement, the present invention provides a slag-phosphogypsum foamed concrete and a preparation method thereof to solve this problem.

[0004] The present invention is achieved through the following technical solutions: A slag-phosphogypsum foamed concrete comprises the following components in parts by weight: 10-20 parts of phosphogypsum, 75-85 parts of slag powder, 1-5 parts of Portland cement, 1-5 parts of admixture, 3-5 parts of animal protein foaming agent and 40-60 parts of water. Preferably, the original phosphogypsum is pretreated with an alkaline solution, and the pH of the leaching solution after drying is 6.5-8.5 and is sieved. Preferably, the admixture includes the following components in parts by weight: 0.1-0.5 parts of polycarboxylate water reducer, 0.5-3.5 parts of early strength agent, and 0.4-2.5 parts of foam stabilizer.

[0005] More preferably, the early strength agent is one or a combination of attapulgite, bentonite and metakaolin.

[0006] More preferably, the foam stabilizer is one or a combination of sodium succinate sulfonate, nano silicon dioxide, ground phosphogypsum, and ground slag.

[0007] More preferably, the ground phosphogypsum has a specific surface area of ​​700 m 2 / g or more, the ground slag has a specific surface area of ​​500m 2 / g or more; preferably, the specific surface area of ​​the ground phosphogypsum is 720-780m2 / g, the ground slag is S95, and the specific surface area is 720-780m 2 / g.

[0008] Further preferably, the foaming agent is an animal protein foaming agent, which is diluted according to the maximum dilution multiple (40 times) recommended by the merchant when used.

[0009] The method for preparing the slag-phosphogypsum foam concrete comprises the following steps: S1: Mix phosphogypsum, slag powder, cement and admixtures into a mixer, first dry mix, then add water to mix into slurry; S2: prefabricate foam using a foaming machine; S3: adding the prefabricated foam in step S2 to the S1 slurry being stirred, stirring and mixing, making a foamed concrete slurry, pouring it into a test mold, standing and demolding for curing to obtain slag-phosphogypsum foamed concrete.

[0010] The residual acid and other impurities in the phosphogypsum will significantly slow down the setting time of the slag-phosphogypsum cement paste and have a negative impact on the early strength of the concrete. The present invention pre-treats the phosphogypsum to reduce this negative impact. The addition of cement will increase the alkalinity of the system and dissociate the glassy structure of the slag to make it better dispersed in the system. This is mainly done from two aspects: on the one hand, the dissociated silica and aluminum in the slag will generate hydrated calcium silicate and hydrated calcium aluminate under alkaline conditions; on the other hand, the dissociated silica and aluminum in the slag will react with gypsum to generate hydrated calcium sulfoaluminate, hydrated calcium aluminosilicate and other substances to give it strength. However, the soluble phosphate ions and fluoride ions present in phosphogypsum will react with calcium hydroxide to produce calcium phosphate and calcium fluoride precipitates. These precipitates form a coating on the surface of the particles of this cementitious system, thereby hindering hydration, resulting in a slower setting time and causing the pore structure of the foamed concrete to be poor or even collapse. Although the addition of water reducer can enhance the fluidity of the slurry and thus provide the foam with a better existence environment, it will also delay hydration, which poses a major obstacle to the production of foamed concrete. In view of such problems, the present invention uses sodium succinate sulfonate to reduce the surface tension of water, thereby making it easier to foam. The ground phosphogypsum, slag and nano-silicon dioxide are added to the foaming agent to increase the viscosity of the foam liquid, making it more difficult to remove the liquid in the liquid film, slowing down the speed at which the thickness of the liquid film decreases, and increasing the stability of the foam; on the other hand, the ground phosphogypsum, slag and nano-silicon dioxide are dispersed on the foam wall, and the surface area of ​​the ground material increases, which will accelerate the reaction rate of the material on the foam wall with the surrounding slurry. On this basis, the addition of the early strength agent accelerates the hydration of the slurry, so that before the surface tension of the foam cannot maintain its own weight, the framework generated by hydration replaces the surface tension of the foam to bear the structural self-weight, so that the pore structure of the prepared foam concrete is better.

[0011] The advantages of the present invention are as follows: (1) the slag-phosphogypsum foamed concrete has relatively good performance, a simple and feasible preparation process, is energy-saving and environmentally friendly, has broad market prospects, and is easy to promote; (2) the method of modifying the foaming agent enables the product to achieve performance indicators that are difficult to achieve with a single foaming agent, and the ground material is dispersed on the surface of each bubble wall through high-speed stirring in a foaming machine, which improves the foaming performance on the one hand; on the other hand, the ground material increases the reaction area of ​​the slurry material, thereby improving the hydration of the material on the bubble wall; (3) the slag-phosphogypsum foamed concrete reduces the amount of cement used, improves the utilization rate of phosphogypsum and slag, and turns waste into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Pure paste properties under different cement content (the cement content of a is 1%; the cement content of b is 1%; the cement content of c is 5%; the cement content of d is 10%) Fig. 2 Cox response tracing plot; Figure 3 Mixture model prediction and variance analysis; Figure 4 Test piece production diagram; Figure 5 Sample diagram; Figure 6 Modified foaming agent foaming multiple; Figure 7 Modified foaming agent settling distance; Figure 8 Modified foaming agent water bleeding rate; Fig. 9 Foaming agent performance test sample diagram (a is the foam diagram after real-time filling; b is the foam diagram after one hour); Fig.10 Study on the durability of foaming agent: (a means no foam stabilizer is added; b means foam stabilizer is added; 1 means real-time foam; 2 means 1h foam; 3 means 24h foam; 4 means 48h foam); Fig.11 Example aperture diagram (where af is respectively Example 1-6); Fig.12 Aperture diagrams of examples and comparative examples (where gm is examples 7-9, and np is comparative examples 1-3); Fig.13 Some photos of foam concrete samples. DETAILED DESCRIPTION

[0013] In order to enable those skilled in the art to better understand the present invention and implement it, the present invention is further explained below through specific embodiments and comparative examples combined with pictures, but the embodiments are not intended to limit the present invention.

[0014] Materials used in Examples and Comparative Examples 1Powdered materials The ordinary Portland cement, phosphogypsum, attapulgite, bentonite, metakaolin and slag used are powdered materials. The ordinary Portland cement is Huaxing P·O42.5, the phosphogypsum is taken from Hubei Yihua Group Co., Ltd., the slag is purchased from Hubei Tengkuo Construction Engineering Co., Ltd., the metakaolin is purchased online from Longda Chemical, the attapulgite is purchased online from Xincheng Mineral Products, and the bentonite is purchased from Nanjing Sijia Runtu Processing Co., Ltd. The phosphogypsum is pretreated with an alkaline solution, and the pH of the leaching solution after drying is 6.5-8.5. The specific surface area of ​​the ground phosphogypsum is 720-780m 2 / g. The specific surface area of ​​ground slag is 720-780m 2 / g. The main components of the powdered materials are shown in Tables 1 to 6.

[0015] Table 1 Main chemical components of ordinary Portland cement (wt / %)

[0016] Table 2 Main chemical components of phosphogypsum (wt / %)

[0017] Table 3 Main chemical components of attapulgite (wt / %)

[0018] Table 4 Main chemical components of bentonite (wt / %)

[0019] Table 5 Main chemical components of metakaolin (wt / %)

[0020] Table 6 Main chemical components of slag (wt / %)

[0021] 2 Liquid Materials The animal protein foaming agent used in this application is a yellow-brown liquid, the main component of which is animal keratin. The base material used for foaming is purchased online from Chengxin Plastics; the nano-silicon dioxide used in this application is a nano-silicon solution, 50% alkaline, purchased online from Guangzhou Changhao Chemical Co., Ltd. Polycarboxylate water reducer is purchased online from Shanghai Chemical Wholesale and Retail. Example and comparative example formulation design Figure 1 For the performance study of slag-cement, Figure 1It can be seen that the slag-phosphogypsum cement system without foaming has better performance under the conditions of cement content of 1%~5% and slag content of 75%~85%. In order to further optimize the dosage ratio, Minitab was used to uniformly design the optimal interval of the dosage, and the design results are shown in Table 7. The phosphogypsum, slag, ordinary Portland cement and water used in the test were taken in proportion, put into a blender and dry-mixed, and water was added to stir to form a slurry. The slurry was poured into the test mold at 1 / 3 of the height and shaken. The slurry was continued to be added to 2 / 3 of the height of the test mold and shaken. The slurry was continued to be added to 1-2mm above the test mold and continued to shake. It was scraped flat with a scraper saw, wrapped in plastic wrap and placed in a curing box until the surface hardened. The excess part of the test mold was scraped flat with a scraper, and the prepared pure slurry test block was obtained by demolding. The pure slurry test block was wrapped in plastic wrap and placed in a standard curing box for curing until 28 days, and then taken out for strength testing. The 28-day strength data was imported into Minitab, and the response tracking results are shown in Figure 2 , model credibility and strength variance analysis see Figure 3 .from Figure 2 It can be seen that as the cement content increases, its strength decreases, and its dosage is linearly related to strength; the dosage of phosphogypsum and slag is not linearly related to strength; the optimal ratio of the system is the intersection of each response line, that is, the optimal dosage is 77.5% slag, 19.5% phosphogypsum, and 3% cement. R-sq (R 2 ) value, the better the model fit. Figure 3 It can be seen that the R 2 Reached 93.42%, R 2 The prediction reached 78.45%, indicating that the reliability of the optimal formula obtained by the model is very high. Figure 4 and Figure 5 Diagram showing specimen preparation and specimen demoulding.

[0022] Dilute the animal protein foaming agent according to the dilution ratio, weigh one or more materials used in the foam stabilizer according to the ratio and add them to the foaming agent, add the mixed liquid into the foaming machine for foaming, and study the performance of the foaming agent for foamed concrete according to the test method in standard JG / T 266-2011 "Foamed Concrete". The modified results of animal protein foaming agent are shown in Figure 6 , Figure 7 and Figure 8 The dosage of the admixtures in the figure is based on the dosage of animal protein foaming agent. Figure 6 It can be seen that compared with the blank sample, with the increase of the amount of ground phosphogypsum, ground slag powder and nano-silica, the foaming multiple of the foaming agent gradually decreases, and the addition of sodium succinate sulfonate increases the foaming multiple. Figure 7 and Figure 8 It can be seen that the dosage of 0.4% and 0.6% can have a positive effect on the foam. Fig. 9 This is the foaming agent test chart. Fig.10 For the durability diagram of the foaming agent, Fig.10 It can be seen that the foam condition of the component with added foam stabilizer (0.4% ground phosphogypsum + 0.6% ground slag + 0.4% nano-silicon solution + 0.4% sodium succinate sulfonate) after 48 hours is better than that without adding. Table 7 Number of parts by mass of each substance in uniform design (parts)

[0023] Examples and comparative examples formulations and performance A slag-phosphogypsum foamed concrete with better performance is composed of the following components by weight: 77.5 parts of slag, 19.5 parts of phosphogypsum, 3 parts of cement, 3 parts of animal protein foaming agent, and 0.3 parts of polycarboxylate water reducer. Other components are shown in Table 8. Its main properties after 28 days are shown in Table 9.

[0024] Table 8 Mass fractions of other components in Examples and Comparative Examples (parts)

[0025] Table 9 Main properties of examples and comparative examples

[0026] According to Table 8, Table 9 and Figure 11-13 By comparing Examples 1-2 with Comparative Example 1, it can be seen that the addition of the early strength agent greatly improves the setting time of the foamed concrete; by comparing Examples 1-6, it can be seen that the composite early strength agent has a stronger improvement effect on the setting time of the foamed concrete than a single one; by comparing Examples 6-9 with Comparative Example 3, it can be seen that the addition of the foam stabilizer improves the dry density and compressive strength of the foamed concrete, and the improvement effect of the composite foam stabilizer is better than that of the single foam stabilizer; the addition of the early strength agent and the foam stabilizer makes the pore structure of the foamed concrete better. In summary, the foam stabilizing method and early strength means in this application have a good promoting effect on the foamed concrete in this application, especially in terms of performance and pore structure.

[0027] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions described in the claims, including equivalent replacement solutions of the technical features in the technical solutions described in the claims.

Claims

1. A slag-phosphogypsum foamed concrete, characterized in that: The slag-phosphogypsum foamed concrete includes the following components in parts by weight: 10-20 parts of phosphogypsum, 75-85 parts of slag powder, 1-5 parts of Portland cement, 1-5 parts of admixture, 3-5 parts of animal protein foaming agent, and 40-60 parts of water.

2. The slag-phosphogypsum foamed concrete according to claim 1, characterized in that: The original phosphogypsum is pretreated with an alkaline solution, and the pH of the leaching solution after drying is 6.5-8.5 and is sieved.

3. The slag-phosphogypsum foamed concrete according to claim 1, characterized in that: The admixture includes the following components in parts by weight: 0.1-0.5 parts of polycarboxylic acid water reducer, 0.5-3.5 parts of early strength agent, and 0.4-2.5 parts of foam stabilizer.

4. The slag-phosphogypsum foamed concrete according to claim 3, characterized in that: The early strength agent is one or a combination of attapulgite, bentonite and metakaolin.

5. The slag-phosphogypsum foamed concrete according to claim 3, characterized in that: The foam stabilizer is one or a combination of sodium succinate sulfonate, nano silicon dioxide, ground phosphogypsum, and ground slag.

6. The slag-phosphogypsum foamed concrete according to claim 5, characterized in that: The specific surface area of ​​ground phosphogypsum is 700m 2 / g or more, the ground slag has a specific surface area of ​​500m 2 / g or more; preferably, the specific surface area of ​​the ground phosphogypsum is 720-780m 2 / g, the ground slag is S95, and the specific surface area is 720-780m 2 / g.

7. The slag-phosphogypsum foamed concrete according to claim 1, characterized in that: The foaming agent is an animal protein foaming agent, which is diluted according to the recommended maximum dilution multiple when used.

8. The slag-phosphogypsum foamed concrete with better performance as described in claims 1-7, characterized in that: The production process includes the following steps: S1: Mix phosphogypsum, slag powder, cement and admixtures into a mixer, first dry mix, then add water to mix into slurry; S2: prefabricate foam using a foaming machine; S3: adding the prefabricated foam in step S2 to the S1 slurry being stirred, stirring and mixing, making a foamed concrete slurry, pouring it into a test mold, standing and demolding for curing to obtain slag-phosphogypsum foamed concrete.

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