pH-responsive perlite composite concrete and preparation method thereof

Abstract

The application discloses a kind of pH response perlite composite concrete and preparation method thereof, belong to building material field.Preparation the raw materials of the pH response perlite composite concrete include pH response perlite, cement, mineral powder, fine aggregate, coarse aggregate, fly ash, calcium lignosulfonate, the raw materials of preparation the pH response perlite include sodium alginate, methacrylic acid, sodium pyrophosphate, methyl methacrylamide, ammonium persulfate, TEMED, superfine calcium carbonate powder, perlite.The pH response perlite composite concrete prepared by the application not only can improve the compressive strength of concrete and thermal insulation performance, but also can prevent the wall made of perlite concrete from cracking and hollowing, improve the safety of building.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, in particular to a pH-responsive perlite composite concrete and a preparation method thereof. BACKGROUND

[0002] With the improvement of China's economic level and the continuous development of science and technology, the functions of building insulation, sound insulation and the like in China are continuously improved, while meeting the comfort of residents, the building energy consumption problem is increasingly prominent, and the outer wall energy consumption accounts for the largest proportion of building energy consumption, so there are many researches and preparations on outer wall insulation energy-saving materials. The wall insulation energy-saving materials on the building market in China are mainly divided into two categories of organic and inorganic. Organic insulation materials such as molded polystyrene board, phenolic resin board, polyurethane board and the like have the advantages of small thermal conductivity and good insulation energy-saving effect, but the organic insulation materials are easy to burn, have low fire rating, if a fire occurs, the fire will spread rapidly, and toxic smoke will be generated; inorganic insulation materials such as perlite, hollow vitrified microbeads, closed perlite, rock wool, mineral wool, glass wool and the like not only have the advantages of low thermal conductivity and good insulation energy-saving effect, but also are A-grade flame-retardant materials, have good fire safety performance and aging resistance.

[0003] Among them, perlite has the advantages of light weight, high strength, strong fire resistance, high porosity, non-toxicity and harmlessness, and is widely used in the field of building insulation energy-saving materials, and is the main insulation aggregate of inorganic insulation materials. The addition of perlite in cement concrete components can reduce the thermal conductivity of concrete and improve the insulation performance, but the wall made of perlite concrete is easy to crack, on the one hand, the fluffy shape is easy to produce resistance in the process of mixing with mortar, and has poor workability, on the other hand, the high water absorption rate of perlite increases the water demand for preparing perlite concrete, destroys the solidification period of concrete, and greatly reduces the mechanical properties of the dried concrete, which is prone to hollowing and cracking. Wall cracking not only affects the appearance of the wall, causes rework and delays the construction period, and more seriously, affects the building safety and causes the quality to be unqualified. Therefore, it is necessary to develop a new type of perlite composite concrete material, which can be applied in building outer walls to improve the compressive strength and insulation performance, and prevent the insulation wall made of perlite concrete from cracking and hollowing, and improve the safety of the building. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a pH-responsive perlite composite concrete and a preparation method thereof, to solve the problem of easy cracking of the insulation wall prepared by the perlite concrete, to improve the safety of the building, and to improve the compressive strength and insulation performance of the wall.

[0005] The present application solves the above technical problems through the following technical solutions:

[0006] A pH-responsive perlite composite concrete, comprising the following raw materials: pH-responsive perlite, cement, mineral powder, fine aggregate, coarse aggregate, fly ash, calcium lignosulfonate.

[0007] Further, the weight parts of the raw materials are as follows: 48-67 parts of pH-responsive perlite, 25-28 parts of cement, 50-60 parts of mineral powder, 70-80 parts of fine aggregate, 43-52 parts of coarse aggregate, 50-60 parts of fly ash, and 2.2-2.6 parts of calcium lignosulfonate.

[0008] The application also discloses a preparation method of the pH-responsive perlite composite concrete.

[0009] 1) Mortar preparation: water, fine aggregate and coarse aggregate are added into a container and stirred uniformly to form a premix, and the mineral powder and fly ash are added into the premix and stirred uniformly to obtain a mortar;

[0010] 2) Concrete preparation: the mortar is mixed with cement and calcium lignosulfonate, stirred uniformly, and then the pH-responsive perlite is added and stirred again to obtain the pH-responsive perlite composite concrete.

[0011] Further, the preparation of the pH-responsive perlite is performed by weighing the following raw materials: 10-15 parts of sodium alginate, 4-6 parts of methacrylic acid, 1-2 parts of sodium pyrophosphate, 4-6 parts of methacrylamide, 0.4-0.6 parts of ammonium persulfate, 0.4-0.6 parts of TEMED, 1.5-2.5 parts of ultra-fine calcium carbonate powder and 30-40 parts of perlite.

[0012] Further, the preparation process of the pH-responsive perlite is as follows:

[0013] A, perlite treatment: the perlite is calcined at a temperature of 850-1000 DEG C for 0.8-1 h, and when the temperature of the perlite drops to 100-120 DEG C, 0.9-2 kg of triethoxysilane is sprayed on the perlite, and the perlite is cooled to room temperature;

[0014] B, methacrylic acid treatment: methacrylic acid and deionized water are mixed at a mass ratio of 1:25, and after dissolution, nitrogen gas is introduced at a flow rate of 2 L / min for 10 min, and then methacrylamide with the same mass as the methacrylic acid is added and stirred uniformly;

[0015] C, sodium alginate treatment: sodium alginate and deionized water are mixed at a mass ratio of 1:20, stirred uniformly, sodium pyrophosphate is added, and stirred at 60-70 DEG C for 40-60 min;

[0016] D, Preparation of pH-responsive perlite: the treated perlite, the treated methacrylic acid, the treated sodium alginate, ammonium persulfate, TEMED, and ultra-fine calcium carbonate powder are mixed and stirred uniformly, then vacuum treatment is performed, and the obtained pH-responsive perlite is taken out and irradiated under ultraviolet light for 10-20 min.

[0017] Further, the nitrogen gas is introduced for 10-20 min in the methacrylic acid treatment step, and the flow rate of the nitrogen gas is 2 L / min.

[0018] Further, in the preparation of the pH-responsive perlite, the vacuum treatment is performed as follows: the treated perlite, the treated methacrylic acid, and other raw materials are added to a vacuum cylinder, the vacuum degree is adjusted to 0.05-0.1 MPa, and vacuum treatment is performed for 3-4 h.

[0019] Further, in the preparation of the mortar, the mass ratio of water to cement, fly ash, and mineral powder is 1:(2-2.5).

[0020] Further, in the preparation of the mortar, the fine aggregate is machine-made sand with a particle size of less than 3 mm, and the coarse aggregate is river pebble gravel with a particle size of 5-10 mm.

[0021] Calcination of the perlite at high temperature can expand the pores of the perlite, facilitate the entry of the treated methacrylic acid, the treated sodium alginate, and other raw materials into the internal cavity structure of the perlite to form a composite gel for modification of the perlite, and after calcination of the perlite at high temperature and cooling to a certain temperature, triethoxysilane is sprayed on the perlite to modify the internal pores and surface of the perlite, which is more easily combined with the gel and does not fall off.

[0022] Uniform mixing of sodium pyrophosphate in the sodium alginate raw material can improve the flocculation effect, and sodium pyrophosphate can act together with ammonium persulfate, TEMED, and ultra-fine calcium carbonate powder on sodium alginate and the treated methacrylic acid to promote the formation of the pH-responsive composite gel. When sodium pyrophosphate contacts with ultra-fine calcium carbonate powder, sodium pyrophosphate can also modify ultra-fine calcium carbonate, promote the nucleation of ultra-fine calcium carbonate crystals, and inhibit the growth of the crystals, so that the prepared pH-responsive composite gel has good mechanical properties. The pH-responsive composite gel is combined with the internal or surface of the perlite during the formation process, and finally the gel surface is hardened by ultraviolet irradiation, so that the prepared pH-responsive perlite is more easily and uniformly dispersed in the concrete.

[0023] The pH response perlite is wrapped by the pH response composite gel inside and on the surface of the pores, which not only changes the fluffy appearance of the perlite to weaken the resistance of the perlite and mortar during stirring, improves the workability, and makes the perlite highly and durably combined with the concrete, but also slowly expands the pH response composite gel inside and outside the perlite in the alkaline environment of the concrete when the concrete is solidified, so that the composite gel can fully fill the pores inside the pH response perlite after the concrete is dried, reduces the water absorption of the perlite, and thus reduces the water demand for preparing the perlite concrete and the water absorption of the concrete from the air in the later period, and can prevent the cracks and hollowing caused by the evaporation of water in the perlite concrete after drying.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The pH response perlite composite concrete prepared by the application can improve the compressive strength and thermal insulation performance when applied to the outer wall building, can prevent the cracks and hollowing of the wall body prepared by the perlite concrete, improves the stability and safety of the building, avoids rework and delays the construction period, and improves the durability of the building. DETAILED DESCRIPTION

[0026] The application will be described in detail below with reference to specific embodiments.

[0027] Embodiment 1

[0028] In order to prepare the pH response perlite composite concrete, the pH response perlite needs to be prepared first, and the following raw materials are weighed: 10 kg of sodium alginate, 4 kg of methacrylic acid, 1 kg of sodium pyrophosphate, 4 kg of methacrylamide, 0.4 kg of ammonium persulfate, 0.4 kg of TEMED, 1.5 kg of superfine calcium carbonate powder, and 30 kg of perlite.

[0029] The preparation process of the pH response perlite is as follows:

[0030] A, perlite treatment: calcine the perlite at a temperature of 850 DEG C for 0.8 h, and spray 0.9 kg of triethoxysilane on the perlite when the temperature of the perlite drops to 100 DEG C, and cool to room temperature;

[0031] B, methacrylic acid treatment: mix the methacrylic acid and deionized water at a mass ratio of 1:25, dissolve, and then pass nitrogen gas at a flow rate of 2 L / min for 10 min, then add the same amount of methacrylamide as the methacrylic acid and stir uniformly;

[0032] C, sodium alginate treatment: mix the sodium alginate and deionized water at a mass ratio of 1:20, stir uniformly, add sodium pyrophosphate, and stir at 60 DEG C for 40 min.

[0033] D, pH-responsive perlite preparation: the treated perlite, treated methacrylic acid, treated sodium alginate, ammonium persulfate, TEMED, ultra-fine calcium carbonate powder are mixed and stirred uniformly, added into a vacuum cylinder, the vacuum degree is adjusted to 0.05 MPa by a vacuum pump, vacuum treatment for 3 h, taken out, irradiated under ultraviolet light with a wavelength of 300 nm for 10 min to obtain the pH-responsive perlite.

[0034] The prepared pH-responsive perlite can be used to prepare pH-responsive perlite composite concrete. If it is necessary to increase the mass of the prepared pH-responsive perlite, the raw materials are increased in proportion.

[0035] The raw materials of the pH-responsive perlite composite concrete are weighed: 240 kg of pH-responsive perlite, 125 kg of cement, 250 kg of mineral powder, 250 kg of water, 350 kg of fine aggregate, 215 kg of coarse aggregate, 250 kg of fly ash, and 11 kg of calcium lignosulfonate. The fine aggregate is machine-made sand with a particle size of less than 3 mm, and the coarse aggregate is river pebble gravel with a particle size of 5-10 mm.

[0036] The process of preparing the concrete is as follows:

[0037] 1) Mortar preparation: the coarse aggregate and fine aggregate are sieved and used, water, sieved fine aggregate and coarse aggregate are added to a container, stirred uniformly to form a premix, mineral powder and fly ash are added to the premix, stirred uniformly to obtain a mortar;

[0038] 2) Concrete preparation: the mortar is mixed with cement and calcium lignosulfonate, stirred uniformly, the pH-responsive perlite is added, stirred again uniformly to obtain the pH-responsive perlite composite concrete.

[0039] Example 2:

[0040] To prepare the pH-responsive perlite composite concrete, the pH-responsive perlite needs to be prepared first. The following raw materials are weighed: 12.5 kg of sodium alginate, 5 kg of methacrylic acid, 1.5 kg of sodium pyrophosphate, 5 kg of methacrylamide, 0.5 kg of ammonium persulfate, 0.5 kg of TEMED, 2 kg of ultra-fine calcium carbonate powder, and 35 kg of perlite.

[0041] The preparation process of the pH-responsive perlite is as follows:

[0042] A, perlite treatment: the perlite is calcined at a temperature of 925℃ for 0.9 h, when the temperature of the perlite drops to 110℃, 1.4 kg of triethoxysilane is sprayed on the perlite, and cooled to room temperature;

[0043] B, methacrylic acid treatment: methacrylic acid and deionized water were mixed in a mass ratio of 1:25, dissolved and then nitrogen was introduced at a flow rate of 2 L / min for 15 min, the same mass of methacrylamide as the methacrylic acid was added and stirred uniformly, and then used;

[0044] C, sodium alginate treatment: sodium alginate and deionized water were mixed in a mass ratio of 1:20, stirred uniformly, sodium pyrophosphate was added, stirred at 65°C for 50 min, and then used;

[0045] D, pH-responsive perlite preparation: the treated perlite, treated methacrylic acid, treated sodium alginate, ammonium persulfate, TEMED, and ultra-fine calcium carbonate powder were mixed and stirred uniformly, then placed in a vacuum cylinder, the vacuum degree was adjusted to 0.08 MPa using a vacuum pump, vacuum treatment was performed for 3.5 h, then removed, and irradiated under ultraviolet light with a wavelength of 300 nm for 15 min to obtain the pH-responsive perlite.

[0046] The prepared pH-responsive perlite can be used to prepare pH-responsive perlite composite concrete, and if it is necessary to increase the mass of the prepared pH-responsive perlite, the raw materials are increased in proportion.

[0047] The raw materials for preparing the pH-responsive perlite composite concrete were weighed: 290 kg of pH-responsive perlite, 135 kg of cement, 275 kg of mineral powder, 310 kg of water, 375 kg of fine aggregate, 240 kg of coarse aggregate, 275 kg of fly ash, and 12 kg of calcium lignosulfonate, wherein the fine aggregate was machine-made sand with a particle size of less than 3 mm, and the coarse aggregate was river pebble gravel with a particle size of 5-10 mm.

[0048] The process of preparing the concrete was the same as that of Example 1.

[0049] Example 3:

[0050] To prepare the pH-responsive perlite composite concrete, the pH-responsive perlite needs to be prepared first, and the following raw materials were weighed: 15 kg of sodium alginate, 6 kg of methacrylic acid, 2 kg of sodium pyrophosphate, 6 kg of methacrylamide, 0.6 kg of ammonium persulfate, 0.6 kg of TEMED, 2.5 kg of ultra-fine calcium carbonate powder, and 40 kg of perlite.

[0051] The preparation process of the pH-responsive perlite is as follows:

[0052] A, perlite treatment: the perlite was calcined at a temperature of 1000°C for 1 h, and when the temperature of the perlite dropped to 120°C, 2 kg of triethoxysilane was sprayed onto the perlite, and then cooled to room temperature;

[0053] B. Methacrylic acid treatment: Mix methacrylic acid and deionized water at a mass ratio of 1:25. After dissolution, introduce nitrogen at a flow rate of 2 L / min for 20 minutes. Add methacrylamide of the same mass as methacrylic acid, stir evenly, and set aside.

[0054] C. Sodium alginate treatment: Mix sodium alginate and deionized water in a mass ratio of 1:20, stir evenly, add sodium pyrophosphate, stir at 70°C for 60 minutes, and set aside;

[0055] D. Preparation of pH-responsive perlite: The treated perlite was mixed with treated methacrylic acid, treated sodium alginate, ammonium persulfate, TEMED, and ultrafine calcium carbonate powder, stirred evenly, and added to a vacuum cylinder. The vacuum degree was adjusted to 0.1 MPa using a vacuum pump. The mixture was vacuum treated for 4 hours, taken out, and irradiated with ultraviolet light at a wavelength of 300 nm for 20 minutes to obtain pH-responsive perlite.

[0056] The pH responsive perlite prepared above can be used to prepare pH responsive perlite composite concrete. If the mass of the prepared pH responsive perlite needs to be increased, the raw materials can be increased proportionally.

[0057] The raw materials of pH-responsive perlite composite concrete were weighed as follows: 335 kg pH-responsive perlite, 140 kg cement, 300 kg mineral powder, 370 kg water, 400 kg fine aggregate, 260 kg coarse aggregate, 300 kg fly ash, and 13 kg calcium lignin sulfonate. The fine aggregate was machine-made sand with a particle size of less than 3 mm, and the coarse aggregate was river pebble gravel with a particle size of 5-10 mm.

[0058] The process of preparing concrete is the same as that in Example 2.

[0059] Comparative Example 1:

[0060] The concrete of Comparative Example 1 is compared with the concrete of Example 3. The main difference is that the perlite treatment step in Comparative Example 1 does not include methacrylic acid treatment. The specific preparation method and raw material ratio of the modified perlite used in the comparative example are as follows:

[0061] Weigh the raw materials: 15 kg sodium alginate, 2 kg sodium pyrophosphate, 2.5 kg ultrafine calcium carbonate powder, and 40 kg perlite.

[0062] The preparation process is as follows:

[0063] A. Perlite treatment: Calcine the perlite at 1000°C for 1 hour. When the temperature of the perlite drops to 120°C, spray 2 kg of triethoxysilane on the perlite and cool it to room temperature.

[0064] B, sodium alginate treatment: sodium alginate and deionized water were mixed in a mass ratio of 1:20, stirred uniformly, sodium pyrophosphate was added, stirred at 70°C for 60 min, and used;

[0065] C, preparation of sodium alginate gel composite perlite: the treated perlite, treated sodium alginate and superfine calcium carbonate powder were mixed and stirred uniformly, added into a vacuum cylinder, the vacuum degree was adjusted to 0.1 MPa, vacuum treatment for 4 h, taken out, irradiated under ultraviolet light with a wavelength of 300 nm for 20 min, and modified perlite was obtained.

[0066] The modified perlite prepared above can be used to prepare perlite composite concrete. If it is necessary to increase the mass of the prepared perlite, the raw materials are increased in proportion.

[0067] The other raw materials for preparing concrete and the mass of the raw materials are the same as in Example 3, and the process for preparing concrete is also the same as in Example 3.

[0068] Comparative Example 2:

[0069] The concrete of Comparative Example 2 is compared with the concrete of Example 3, and the main difference is that there is no sodium alginate treatment in the perlite treatment step of Comparative Example 2. The specific preparation method and raw material ratio of the modified perlite used in Comparative Example 2 are as follows:

[0070] The raw materials were weighed: 6 kg of methacrylic acid, 6 kg of methacrylamide, 0.6 kg of ammonium persulfate, 0.6 kg of TEMED, and 40 kg of perlite.

[0071] The preparation process is as follows:

[0072] A, perlite treatment: the perlite was calcined at a temperature of 1000°C for 1 h, and when the temperature of the perlite dropped to 120°C, 2 kg of triethoxysilane was sprayed on the perlite, and it was cooled to room temperature;

[0073] B, methacrylic acid treatment: methacrylic acid and deionized water were mixed in a mass ratio of 1:25, after dissolution, nitrogen gas was introduced at a flow rate of 2 L / min for 30 min, the same mass of methacrylamide as the methacrylic acid was added and stirred uniformly, and used;

[0074] C, preparation of methacrylic acid gel composite perlite: the treated perlite, treated methacrylic acid, ammonium persulfate and TEMED were mixed and stirred uniformly, added into a vacuum cylinder, the vacuum degree was adjusted to 0.1 MPa, vacuum treatment for 4 h, taken out, irradiated under ultraviolet light with a wavelength of 300 nm for 20 min, and modified perlite was obtained.

[0075] The other raw materials for preparing concrete and the mass of the raw materials are the same as in Example 3, and the process for preparing concrete is also the same as in Example 3.

[0076] Comparative Example 3:

[0077] Comparative Example 3 is compared with Example 3, the main difference is that there is no methylacrylic acid treatment step and sodium alginate treatment step in the perlite treatment step in Comparative Example 3, and the preparation method of the modified perlite used in Comparative Example 3 is as follows:

[0078] Perlite treatment: calcine the perlite at a temperature of 1000℃ for 1h, spray 2kg of triethoxysilane on the perlite when the temperature of the perlite drops to 120℃, and cool to room temperature;

[0079] The other raw materials for preparing the concrete and the mass of the raw materials are the same as those in Example 3, and the process for preparing the concrete is the same as that in Example 3.

[0080] Comparative Example 4:

[0081] The concrete of Comparative Example 4 is compared with the concrete of Example 3, the main difference is that no perlite is used in Comparative Example 4, and the prepared concrete is ordinary concrete, the raw materials include cement, mineral powder, fine aggregate, coarse aggregate, fly ash, calcium lignosulfonate, the mass of each raw material is the same as that in Example 3, and the steps in Example 3 are still followed to first prepare a mortar, and then add the remaining raw materials to stir uniformly to prepare an ordinary concrete.

[0082] The performance of the concrete prepared in Examples 1-3 and Comparative Examples 1-4 is detected, the thermal conductivity and the compressive strength of the concrete are tested according to the method specified in GBT50081-2019, in addition, the concrete prepared in Examples 1-3 and Comparative Examples 1-4 is respectively cast in a mold of 100cm×100cm×24cm to prepare three cubic samples, the number of cracks with a crack width of more than 1mm, a depth of more than 2cm and a length of more than 2cm in the samples at 24 months is tested by ultrasonic flaw detection technology, and the average value of the crack numbers of the three samples is taken.

[0083] The obtained data is shown in Table 1:

[0084] Table 1

[0085]

[0086] Analysis of experimental data:

[0087] (1) The concrete prepared in Examples 1-3 and Comparative Examples 1-3 has lower thermal conductivity and higher compressive strength compared with the ordinary concrete prepared in Comparative Example 4, which shows that the use of perlite can improve the thermal insulation performance and compressive strength of the concrete.

[0088] (2) Compared with the comparative examples 1-3, the thermal conductivity of the examples 1-3 is lower than that of the comparative examples 1-3, and the compressive strength is higher than that of the comparative examples 1-3, which indicates that the treatment method of the present application can improve the thermal insulation performance and the compressive strength of the perlite concrete, wherein the comparative example 1 is not treated with methacrylic acid compared with example 3, the comparative example 2 is not treated with sodium alginate compared with example 3, the comparative example 3 is not treated with methacrylic acid and sodium alginate compared with example 3, the thermal insulation performance and the compressive strength of the comparative examples 1-3 are worse than that of example 3, which can indicate that the perlite treated with the methacrylic acid and sodium alginate disclosed in the present application and applied to the concrete can significantly improve the thermal insulation performance and the compressive strength of the concrete, and achieve the purpose of thermal insulation, energy saving, and improving the stability and safety of the building.

[0089] (3) Compared with the ordinary concrete block sample prepared in the comparative example 4, the block sample prepared in the comparative example 3 has lower thermal conductivity and more cracks, which indicates that the wall made of the perlite concrete is more thermal insulation than the wall made of the ordinary concrete, but is more prone to cracking.

[0090] (4) Compared with the comparative examples 1-3, the crack number of the examples 1-3 is lower than that of the comparative examples 1-3, which indicates that the treatment method of the present application can prevent the wall made of the perlite concrete from cracking. Among them, the comparative example 1 is not treated with methacrylic acid compared with example 3, the comparative example 2 is not treated with sodium alginate compared with example 3, the comparative example 3 is not treated with methacrylic acid and sodium alginate compared with example 3, the crack number of the comparative examples 1-3 is more than that of example 3, which can indicate that the perlite treated with the methacrylic acid and sodium alginate disclosed in the present application and applied to the concrete can effectively prevent the wall made of the perlite concrete from cracking, and improve the safety and durability of the building.

[0091] The above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the purpose and scope of the present application, and all modifications and equivalent replacements should be included in the scope of the claims of the present application. The technical, shape and structure parts not described in detail in the present application are all known technologies.

Claims

1. A pH-responsive perlite composite concrete, characterized in that: The raw materials include: pH-responsive perlite, cement, mineral powder, fine aggregate, coarse aggregate, fly ash, and calcium lignin sulfonate; The pH-responsive perlite is prepared by weighing the following raw materials in parts by weight: 10-15 parts of sodium alginate, 4-6 parts of methacrylic acid, 1-2 parts of sodium pyrophosphate, 4-6 parts of methacrylamide, 0.4-0.6 parts of ammonium persulfate, 0.4-0.6 parts of TEMED, 1.5-2.5 parts of ultrafine calcium carbonate powder, and 30-40 parts of perlite; The preparation process of the pH responsive perlite is as follows: A. Perlite treatment: calcine the perlite at 850-1000℃ for 0.8-1h. When the temperature of the perlite drops to 100-120℃, spray 0.9-2kg triethoxysilane on the perlite and cool it to room temperature. B. Methacrylic acid treatment: Mix methacrylic acid and deionized water in a mass ratio of 1:25, and after dissolving, introduce nitrogen. Then add methacrylamide of the same mass as methacrylic acid, stir evenly, and set aside. C. Sodium alginate treatment: Mix sodium alginate and deionized water in a mass ratio of 1:20, stir evenly, add sodium pyrophosphate, stir at 60-70°C for 40-60 minutes, and set aside; D. Preparation of pH-responsive perlite: The treated perlite is mixed with treated methacrylic acid, treated sodium alginate, ammonium persulfate, TEMED, and ultrafine calcium carbonate powder, and stirred evenly. The mixture is then vacuum-treated, taken out, and irradiated under ultraviolet light for 10-20 minutes to obtain pH-responsive perlite.

2. A pH-responsive perlite composite concrete according to claim 1, characterized in that: The weight proportions of the raw materials are: 48-67 parts of pH-responsive perlite, 25-28 parts of cement, 50-60 parts of mineral powder, 70-80 parts of fine aggregate, 43-52 parts of coarse aggregate, 50-60 parts of fly ash, and 2.2-2.6 parts of calcium lignin sulfonate.

3. A method for preparing pH-responsive perlite composite concrete according to claim 1, characterized in that: The following steps are involved: 1) Mortar preparation: Add water, fine aggregate and coarse aggregate into a container and stir evenly to form a premix. Add mineral powder and fly ash to the premix and stir evenly to obtain mortar. 2) Concrete preparation: mortar, cement, and calcium lignin sulfonate were mixed and stirred evenly. pH-responsive perlite was added and stirred evenly again to obtain pH-responsive perlite composite concrete.

4. The method for preparing a pH-responsive perlite composite concrete according to claim 3, wherein: The time for introducing nitrogen in the methacrylic acid treatment step is 10-20 minutes, and the flow rate of the nitrogen is 2 L / min.

5. The method for preparing a pH-responsive perlite composite concrete according to claim 4, wherein: The specific operation of the vacuum treatment in the pH-responsive perlite preparation step is as follows: the treated perlite is mixed and stirred evenly with the treated methacrylic acid, the treated sodium alginate, ammonium persulfate, TEMED, and ultrafine calcium carbonate powder, and the mixture is added to a vacuum cylinder, the vacuum degree is adjusted to 0.05-0.1 MPa, and the vacuum treatment is performed for 3-4 hours.

6. The method for preparing a pH-responsive perlite composite concrete according to claim 5, wherein: In the mortar preparation step, the total mass ratio of water to cement, fly ash and mineral powder is 1:(2-2.5).

7. The method for preparing a pH-responsive perlite composite concrete according to claim 6, wherein: In the mortar preparation step, the fine aggregate is machine-made sand with a particle size of less than 3 mm, and the coarse aggregate is river pebble gravel with a particle size of 5-10 mm.

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