A self-healing shrinkage-reducing water reducer and its preparation, recycled aggregate concrete

Abstract

The present invention relates to a self-repairing shrinkage-reducing water reducer and its preparation, and recycled aggregate concrete. The water reducer comprises the following raw material components in parts by weight: 150 to 250 parts of water reducer; 10 to 50 parts of air-entraining agent; 20 to 100 parts of retarder; 50 to 100 parts of alkaline powder; 40 to 120 parts of calcium lactate; 20 to 60 parts of rice husk ash; 50 to 100 parts of dry powder of aerobic alkali-tolerant Bacillus spores; 50 to 100 parts of auxiliary agent; 20 to 80 parts of dispersant; 150 to 200 parts of solvent; 400 to 600 parts of water. The shrinkage-reducing water reducer of the present invention plays a role in optimizing the properties of recycled aggregates, reducing the influence of mud content and old mortar on the workability of recycled concrete, thereby improving the fluidity of concrete, etc.; in addition, aerobic alkali-tolerant Bacillus spores use rice husk ash as a bio-based carrier, which can achieve a good self-repair effect, can effectively fill the cracks and defects in recycled aggregates, bridge the concrete on both sides of the cracks and the fiberglass of recycled fan blades, significantly enhance the bonding force in the crack area, and effectively relieve the stress concentration problem caused by shrinkage stress.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete admixtures, and particularly relates to a self-healing shrinkage-reducing water reducer and its preparation, and recycled aggregate concrete. Background Art

[0002] In the modern construction field, recycled aggregate, as a green and sustainable concrete raw material, has received extensive attention. However, although recycled concrete has the advantages of resource conservation and low-carbon environmental protection, in actual engineering applications, it still faces a series of problems that need to be solved urgently: (1) The porous characteristics of recycled aggregate cause the dry shrinkage problem of recycled concrete. Dry shrinkage is the volume shrinkage phenomenon that occurs during the water evaporation process of concrete, which easily leads to the generation of internal stress in the concrete, thereby triggering the formation of cracks. The existence of cracks not only affects the aesthetics of the building, but also greatly reduces the service life of the concrete and increases the building maintenance cost; (2) The complex composition, high mud content and old mortar content of recycled aggregate result in poor workability of the concrete. After the waste concrete is processed and recycled, the surface of the recycled aggregate often remains hardened cement mortar attached to the aggregate particles, and the mud content is much higher than that of natural aggregate, which will lead to a high water demand, a large dosage of admixture and a large slump loss during the concrete mixing process, thus affecting the workability of recycled concrete.

[0003] At present, adding chemical admixtures is one of the main means to inhibit concrete cracking. For example, adding expansive agents such as superabsorbent resins to compensate for shrinkage, but such products often have a negative impact on the concrete strength. In order to achieve the dual effects of shrinkage reduction and water reduction, scholars at home and abroad have developed a variety of shrinkage-reducing water reducers. For example, Chinese Patent CN201210285006.9 and Chinese Patent CN201510043620.8 introduce polyether shrinkage-reducing groups into the polycarboxylic acid molecular structure to synthesize multifunctional admixtures. However, such admixtures have not really solved the problem of how to balance the water reduction and shrinkage reduction effects. On the other hand, due to the poor characteristics of recycled aggregate, traditional shrinkage-reducing polycarboxylate water reducers cannot effectively control the workability and shrinkage problems of recycled concrete. For recycled concrete, once cracks are generated due to shrinkage or other factors, the new-old interface transition zone and aggregate pores exposed by the cracks will provide rich ion and gas transmission channels, accelerating the deterioration of the concrete. Therefore, for recycled concrete, not only should attention be paid to improving its workability and shrinkage resistance, but also how to repair the cracks after cracking to extend the service life of the concrete structure should be considered. Summary of the Invention

[0004] The object of the present invention is to provide a self-healing shrinkage-reducing water reducer and its preparation method, and recycled aggregate concrete, to reduce the influence of mud content and old mortar on the workability of recycled concrete, fill the cracks and defects in recycled aggregates, alleviate the stress concentration problem caused by shrinkage stress, and improve the survival rate of microorganisms at the same time.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention provides a self-healing shrinkage-reducing water reducer, which comprises the following raw material components in parts by weight: 150-250 parts of water reducer; 10-50 parts of air-entraining agent; 20-100 parts of retarder; 50-100 parts of alkaline powder; 40-120 parts of calcium lactate; 20-60 parts of rice husk ash; 50-100 parts of dry powder of aerobic alkali-resistant Bacillus spores; 50-100 parts of auxiliary agent; 20-80 parts of dispersant; 150-200 parts of solvent; 400-600 parts of water.

[0007] Optionally, the ratio of each raw material is as follows:

[0008] Water reducer: 200 parts;

[0009] Air-entraining agent: 30 parts;

[0010] Retarder: 60 parts;

[0011] Alkaline powder: 75 parts;

[0012] Calcium lactate: 80 parts;

[0013] Rice husk ash: 40 parts;

[0014] Dry powder of aerobic alkali-resistant Bacillus spores: 75 parts;

[0015] Auxiliary agent: 75 parts;

[0016] Dispersant: 50 parts;

[0017] Solvent: 175 parts;

[0018] Water: 500 parts.

[0019] Furthermore, the water reducer is a polycarboxylate superplasticizer, and its water reduction rate is 22%-25%.

[0020] Furthermore, the air-entraining agent is one or several of lignosulfonate, methyltrimethoxysilane or sodium dodecyl sulfate.

[0021] Furthermore, the retarder is one or two of ammonium sulfate and hydroxyethylidene diphosphonic acid.

[0022] Further, the alkaline powder is one or both of sodium hydroxide powder and potassium hydroxide powder.

[0023] Further, the calcium lactate is Ruipu brand calcium lactate, with the molecular formula C6H 10 CaO6, a purity of 99%, in the form of white powder, and is easily soluble in hot water. It can provide nutrients and calcium source for the cells of aerobic alkali-tolerant Bacillus spores.

[0024] Further, the rice husk ash is in the form of white powder, with an average particle size of 12.36μm, and the silicon dioxide content ≥ 95%. Its high porosity and high specific surface area make it an ideal biomass carrier, providing space and nucleation points for the growth and metabolism of the cells of aerobic alkali-tolerant Bacillus spores. At the same time, by promoting cement hydration to promote the formation of minerals in the rice husk ash, its high amorphous silicon dioxide content can react with the primary hydration of cement to generate tricalcium silicate (C3S) and dicalcium silicate (C2S), with the molecular formulas 3CaO.SiO2 and 2CaO.SiO2 respectively.

[0025] Further, when the dry powder of the cells of aerobic alkali-tolerant Bacillus spores is mixed and prepared into a water reducer and incorporated into concrete materials, the high-alkaline environment inside the concrete makes the bacteria in a dormant spore state. However, once the concrete cracks and oxygen and water enter, the bacteria resume their metabolic functions, and the bacteria metabolize to produce calcium carbonate precipitation and carbon dioxide.

[0026] The equation for the primary reaction of aerobic alkali-tolerant Bacillus spores using calcium lactate is:

[0027] CaC6H 10 O6 + 6O2 → CaCO3↓ + 5CO2↑ + 5H2O (1)

[0028] Further, the tricalcium silicate (C3S) and dicalcium silicate (C2S) formed by the primary hydration further hydrate to form calcium hydroxide (Ca(OH)2) and calcium silicate hydrate gel (Ca 1.5 SiO 3.5 ·xH2O), and their reaction equations are as follows:

[0029] 2(3CaO.SiO2) + 6H2O → 3CaO.SiO2.3H2O + 3Ca(OH)2 (2)

[0030] 2(2CaO.SiO2) + 4H2O → 3CaO.SiO2.3H2O + Ca(PH)2 (3)

[0031] The calcium silicate hydrate gel can refine the pore structure in the concrete and improve the bonding of the interfacial transition zone.

[0032] Furthermore, the equation for the secondary reaction between the calcium hydroxide and the CO2 generated by the aerobic alkali-resistant Bacillus sp. is as follows:

[0033] CO2 + Ca(OH)2 → CaCO3↓ + H2O (4)

[0034] The calcium carbonate precipitate generated by the aerobic alkali-resistant Bacillus sp. through the primary reaction and the secondary reaction can repair the cracks in the concrete, reduce the crack propagation rate, and improve the crack resistance of the concrete.

[0035] Furthermore, the aerobic alkali-resistant Bacillus sp. will consume harmful substances in the concrete during its growth process, which helps to improve the durability of recycled concrete. These mainly include the following categories:

[0036] (1) Sulfates: The sulfates in the concrete come from the cement and the external environment where the concrete is located. Excessive concentrations of sulfates will cause the erosion and expansion of the concrete, reducing its strength and durability. The aerobic alkali-resistant Bacillus sp. converts sulfates into sulfate compounds through metabolic processes, reducing their damage to the concrete.

[0037] (2) Nitrates: The nitrates in the concrete mainly come from the water, cement in the concrete, and the external environment where the concrete is located. High concentrations of nitrates will cause oxidative corrosion of the concrete, thereby reducing its strength and durability. The aerobic alkali-resistant Bacillus sp. can consume nitrates, reducing their damage to the concrete.

[0038] (3) Alkaline substances: Concrete containing glass fibers will be eroded by alkaline substances (sodium carbonate, calcium oxide) in the environment during long-term use, resulting in a decrease in its strength and durability. The aerobic alkali-resistant Bacillus sp. can absorb and convert alkaline substances, weakening the erosion of glass fibers by reducing the alkaline environment of the system.

[0039] The metabolic, consumption, absorption, and conversion effects of the above-mentioned aerobic alkali-resistant Bacillus sp. help to improve the durability of recycled concrete, and its mechanism of action is as follows:

[0040] (1) Reducing the accumulation of harmful substances: The aerobic alkali-resistant Bacillus sp. consumes harmful substances in the concrete during its growth process, reducing the concentration of harmful substances in the concrete, thereby slowing down the erosion and corrosion rate of the concrete and improving its durability.

[0041] (2) Enhancing the compressive strength of the concrete: The growth metabolites of the aerobic alkali-resistant Bacillus sp. can fill the microscopic pores of the concrete, improving the compactness of the concrete. The compressive strength of the concrete is increased, thereby enhancing its durability.

[0042] (3)Enhance the alkali erosion resistance of glass fiber: Aerobic alkalotolerant Bacillus can absorb and transform the alkaline substances eroded by the outside of the concrete, reducing the alkalinity of the concrete.

[0043] Furthermore, the auxiliary agent is polyvinyl alcohol.

[0044] Furthermore, the dispersant is one or two of sodium n-heptylbenzenesulfonate and silane coupling agent.

[0045] Furthermore, the solvent is one or two of absolute ethanol and dimethylformamide.

[0046] The second technical solution of the present invention provides a preparation method of a self-healing shrinkage-reducing water reducer, including the following steps:

[0047] (1) First, add half of the solvent and water into a reaction vessel equipped with a magnetic stirrer, and start the stirrer;

[0048] (2) Gradually add a water reducer, an air-entraining agent, a retarder, a dispersant and an auxiliary agent into the container, and continuously stir at a temperature of 60 °C for 2-4 h, and the stirring speed is 1200 r / min to ensure uniform mixing;

[0049] (3) Gradually add the dry powder of aerobic alkalotolerant Bacillus, rice husk ash and calcium lactate, as well as the remaining solvent and water, and continuously stir for 2-4 h until all the dry powder of the bacteria is fully dissolved and mixed;

[0050] (4) After the temperature is cooled to room temperature, use an alkaline powder to adjust the pH value of the mixture to maintain its pH within the range of 8.0-10.0;

[0051] (5) Stop the stirrer, put the prepared self-healing shrinkage-reducing water reducer into a sealed container, and store it for use.

[0052] Preferably, the pH value is adjusted to 8.0-10.0 to increase the germination rate of aerobic alkalotolerant Bacillus.

[0053] Preferably, in step (1), the stirring speed is set to 1000 r / min and the stirring time is 0.5 h.

[0054] Preferably, the sealed container in step (5) should be placed in a vacuum drying environment to reduce the metabolic rate of the dry powder of aerobic alkalotolerant Bacillus.

[0055] For the self-healing shrinkage-reducing water reducer and its preparation method, its shrinkage reduction principle is based on the capillary tension theory. In unit volume of concrete, the cement-based material gradually hydrates, the water in the concrete slowly migrates and is consumed, causing the corresponding humidity inside the hardened cement stone to gradually decrease, and the capillary negative pressure also gradually increases. From the Laplace equation:

[0056] γ·2πr cosθ = -ΔPπr 2 (5)

[0057]

[0058] Among them, ΔP represents the capillary pressure, γ represents the surface tension of the pore solution, θ represents the contact angle of the liquid in contact with the inner wall of the capillary, and r represents the radius of the capillary.

[0059] The self-healing shrinkage-reducing water reducer provided by the present invention can improve the performance of recycled aggregates, thereby reducing the drying shrinkage of concrete. Combining with formula (6), its shrinkage-reducing principle lies in the following three aspects:

[0060] (1) The pH of the shrinkage-reducing water reducer is 8.0 - 10.0. The alkaline water reducer can reduce the surface tension of water, thereby reducing the generation of additional pressure in the capillary. It slows down the rising speed of water in the concrete, reduces the loss of internal water, and thus reduces the shrinkage phenomenon of the concrete. The slower the rising speed of water, the better the humidity inside the concrete can be balanced.

[0061] (2) The chemical components (carboxylates) in the self-healing shrinkage-reducing water reducer can form a gel-like structure with water molecules, thereby increasing the viscosity of the solution, increasing the contact angle, and reducing the additional pressure. By affecting the flow of the liquid in the capillary, it slows down the migration and distribution of water in the concrete, reduces the humidity gradient distribution, and thus reduces the generation of shrinkage cracking.

[0062] (3) The self-healing shrinkage-reducing water reducer contains aerobic alkali-tolerant Bacillus subtilis. These strains are tightly adsorbed by the rice husk ash carrier. Due to osmosis, they gather at the edges of concrete pores and microcracks together with the water reducer. Subsequently, through the metabolic process, they react with Ca(OH)2 to generate calcium carbonate and calcium silicate hydrate gel to refine the pores and cracks. The calcium carbonate precipitation and calcium silicate hydrate gel form aggregates or particles in the capillary, which will block and seal some capillaries. The pores between the capillaries become smaller, making the spatial distribution between the capillaries more uniform, the "effective radius" will increase, and the additional pressure will decrease. This helps to improve the shrinkage resistance of the concrete and reduce the cracking problem, ensuring the durability and safety of the structure.

[0063] The third technical solution of the present invention provides a recycled aggregate concrete, which includes the following raw material components in parts by weight: cement: 300 - 400 parts; recycled coarse aggregate: 860 - 1000 parts; natural sand: 600 - 680 parts; self-healing shrinkage-reducing water reducer: 6 - 10 parts; recycled wind turbine blade glass fiber: 10 - 40 parts; water: 165 - 200 parts.

[0064] Furthermore, the formula of the recycled aggregate concrete is

[0065] Cement: 350 parts;

[0066] Recycled coarse aggregate: 930 parts;

[0067] Natural sand: 640 parts;

[0068] Self-healing shrinkage-reducing water reducer: 8 parts;

[0069] Recycled wind turbine blade glass fiber: 25 parts;

[0070] Water: 183 parts.

[0071] Furthermore, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 12 - 36 μm and a 28-day compressive strength of 46.2 - 53.2 MPa.

[0072] Furthermore, the recycled coarse aggregate adopts a continuous grading of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, with an apparent density of 2300 - 2500 kg / m 3 , a bulk density of 1400 - 1560 kg / m 3 , and a water absorption rate of 2.63% - 4.82%.

[0073] Furthermore, the fineness modulus of the natural sand is 2.2 - 2.8, and the average particle size is 0.20 - 0.50 mm.

[0074] The recycled wind turbine blade glass fiber has a length of 4 - 6 mm and is prepared by cutting, crushing, and screening waste wind turbine blades.

[0075] The fourth technical solution of the present invention provides a preparation method of recycled aggregate concrete, including the following steps:

[0076] (A) Sampling the cement, recycled coarse aggregate, natural sand, and recycled wind turbine blade glass fiber according to the component contents in the ratio, and pouring them into a concrete planetary mixer in sequence for the first stirring to obtain a first mixture;

[0077] (B) Adding 2 / 3 of the water to the first mixture for the second stirring to obtain a second mixture;

[0078] (C) Adding the self-healing shrinkage-reducing water reducer and the remaining 1 / 3 of the water to the second mixture for the third stirring to obtain a newly mixed recycled coarse aggregate concrete mixture;

[0079] (D) The freshly mixed concrete mixture is poured into cube specimens with dimensions of 100 mm×100 mm×100 mm, and then vibrated and compacted on a vibrating table. According to the "Standard Test Method for Mechanical Properties of Ordinary Concrete" (GB / T 50081-2019), after standing at normal temperature for 24 h, the formwork is removed, and then the specimens are cured under standard curing conditions with a temperature of 20°C±2°C and a relative humidity of more than 95% until the specimens reach the specified age, and then performance tests are carried out.

[0080] Preferably, the stirring speed of the first stirring is 100 r / min, and the stirring time is 4 min.

[0081] Preferably, the stirring speed of the second stirring is 120 r / min, and the stirring time is 3 min.

[0082] Preferably, the stirring speed of the third stirring is 80 r / min, and the stirring time is 3 min.

[0083] Compared with the prior art, the present invention has the following advantages:

[0084] (1) Combining the self-repairing microorganisms with the water reducer realizes an integrated design and application method, making the dispersion of the self-repairing microorganisms and the water reducer in the concrete more uniform and stable, thereby improving the overall performance of the effects of the two. By mutually exerting the maximum synergistic effect, the dual optimization of the self-repairing effect and the water-reducing effect is achieved.

[0085] (2) By optimizing the treatment of the recycled aggregate, the self-repairing shrinkage-reducing water reducer effectively improves the performance of the recycled aggregate. The recycled aggregate usually affects the workability of the concrete due to reasons such as residual hardened cement mortar attached to the particles and high mud content. The introduction of this shrinkage-reducing water reducer can reduce the influence of the mud content and old mortar on the fluidity of the concrete, and reduce the viscosity of the concrete during the construction process, thereby improving the workability of the concrete.

[0086] (3) The introduction of aerobic alkali-tolerant Bacillus subtilis in the self-repairing shrinkage-reducing water reducer enables the microorganisms to grow and metabolize in the concrete cracks and react with calcium hydroxide in the cement to form calcium carbonate, filling the cracks and defects inside the concrete. In addition, during the preparation of the recycled wind turbine blade glass fiber, it is prepared by cutting, crushing and screening, and its surface is often uneven, showing pores, notches and cracks of different degrees. The aerobic alkali-tolerant Bacillus subtilis will produce an aggregation effect due to the increased contact area of the broken parts of the glass fiber, and induce calcium carbonate deposition through its metabolic activities, thereby filling these defects. At the same time, the calcium carbonate deposition can also bridge the concrete and glass fiber on both sides of the crack, enhancing the bonding force in the crack area.

[0087] (4) Aerobic alkali-tolerant Bacillus usually requires to survive and maintain a certain activity in concrete to exert its effects. Binding the bacterial cells to the water-reducing agent can provide a better protection and nutritional environment required by the bacterial cells, maintain the survival rate and activity of the bacterial cells, and achieve long-term self-healing effects in concrete. This self-healing effect can effectively alleviate the stress concentration problem caused by drying shrinkage, thereby reducing the risk of crack generation and improving the durability and service life of concrete.

[0088] (5) Recycled concrete is prone to drying shrinkage during the drying process, which leads to internal stress concentration and crack generation. The anti-shrinkage water-reducing agent provided by the present invention successfully reduces the rising speed of water in concrete by adjusting the formula and introducing the capillary tension theory. The alkaline water-reducing agent in its composition can reduce the surface tension of water, thereby slowing down the migration speed of water and effectively alleviating the drying shrinkage problem of concrete.

[0089] (6) The self-healing anti-shrinkage water-reducing agent provided by the present invention not only solves the performance problems of recycled aggregate concrete, but also has advantages in terms of environmental protection and sustainability. The application of recycled aggregates can effectively reduce the demand for natural resources and reduce environmental pressure. At the same time, the research and development and application of the self-healing anti-shrinkage water-reducing agent provide technical support for the popularization of recycled aggregate concrete. By improving the quality and performance of recycled aggregate concrete, it helps to promote the development of sustainable buildings and green buildings and provides an innovative solution for the future application of building materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 It is a schematic diagram of the action mechanism of the self-healing anti-shrinkage water-reducing agent.

[0091] Figure 2 It is an electron micrograph of self-healing microbially induced calcium carbonate precipitation in Example 1 under 10,000-fold electron microscope.

[0092] Figure 3 It is a schematic diagram of the preparation process of the self-healing anti-shrinkage water-reducing agent provided by the present invention;

[0093] Figure 4 It is a schematic diagram of the preparation process of the recycled aggregate concrete provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0094] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0095] The raw material sources in the described embodiments are shown in Table 1.

[0096] Table 1 Raw Material Sources in the Embodiments

[0097]

[0098]

[0099] For the remaining raw materials or processing techniques without special instructions, it indicates that they are all conventional commercially available raw materials or conventional processing techniques in this field.

[0100] Example 1

[0101] (1) Preparation of a self-healing shrinkage-reducing water reducer, which is compounded from the following raw materials in parts by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of dry powder of aerobic alkali-tolerant Bacillus spores; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0102] Specifically, the preparation steps of a self-healing shrinkage-reducing water reducer are as follows: ① First, add half of the solvent and water into a reaction vessel equipped with a magnetic stirrer, start the stirrer and set the stirring speed to 1000 r / min, and stir for 0.5 h; ② Gradually add the water reducer, air-entraining agent, retarder, dispersant and auxiliary agent into the vessel, and continuously stir at a temperature of 60 °C for 2 - 4 h, with a stirring speed of 1200 r / min to ensure uniform mixing; ③ Gradually add the dry powder of aerobic alkali-tolerant Bacillus spores, rice husk ash and calcium lactate, as well as the remaining solvent and water, and continuously stir for 2 - 4 h until all the dry powder of spores is fully dissolved and mixed; ④ After the temperature is cooled to room temperature, use the alkaline powder to adjust the pH value of the mixture to maintain it within the range of 8.0 - 10.0; ⑤ Stop the stirrer, put the prepared self-healing shrinkage-reducing water reducer into a sealed container, and place it in a vacuum drying environment for storage for use.

[0103] (2) A preparation method of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer, in parts by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self-healing shrinkage-reducing water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0104] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, and adopts a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, with an apparent density of 2396.0 kg / m 3, the bulk density is 1477.0 kg / m 3 , the water absorption rate is 2.92%; the fineness modulus of natural sand is 2.4, and the average particle size is 0.24 mm; the length of the recycled wind turbine blade glass fiber is 4 - 6 mm, which is prepared by cutting, crushing and screening waste wind turbine blades; the water is tap water supplied by the laboratory.

[0105] Specifically, the preparation steps of a recycled coarse aggregate concrete added with a self - repairing anti - shrinkage water - reducing agent are as follows: ① Sample cement, recycled coarse aggregate, natural sand and recycled wind turbine blade glass fiber according to the component content in the ratio, and pour them into a concrete planetary mixer in sequence for the first stirring. The stirring speed is 100 r / min, and the stirring time is 4 min to obtain the first mixture; ② Add 2 / 3 of the water to the first mixture for the second stirring. The stirring speed is 120 r / min, and the stirring time is 3 min to obtain the second mixture; ③ Add the self - repairing anti - shrinkage water - reducing agent and the remaining 1 / 3 of the water to the second mixture for the third stirring. The stirring speed is 80 r / min, and the stirring time is 3 min to obtain a newly - mixed recycled coarse aggregate concrete mixture; ④ Pour the newly - mixed concrete mixture into 100 mm×100 mm×100 mm cube specimens, and then vibrate and compact them on a vibrating table. According to the "Standard Test Method for Mechanical Properties of Ordinary Concrete" (GB / T 50081 - 2019), after standing at room temperature for 24 h, remove the formwork, and then cure under the standard curing conditions of a temperature of 20℃±2℃ and a relative humidity of more than 95% until the specimens reach the specified age for performance testing.

[0106] Example 2

[0107] (1) The preparation of a self - repairing anti - shrinkage water - reducing agent is compounded from the following raw materials by weight: 200 parts of water - reducing agent; 30 parts of air - entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1 - hydroxyethylidene - 1,1 - diphosphonic acid); 75 parts of alkaline powder (potassium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of aerobic alkali - resistant bacillus cell dry powder; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n - heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0108] Specifically, the preparation of a self - repairing anti - shrinkage water - reducing agent is carried out with reference to the steps of Example 1.

[0109] (2) A preparation method of a recycled coarse aggregate concrete added with a self - repairing anti - shrinkage water - reducing agent, by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self - repairing anti - shrinkage water - reducing agent; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0110] Among them, the cement is P.O 42.5 ordinary Portland cement with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , a bulk density of 1477.0 kg / m 3 , a water absorption rate of 2.92%; the fineness modulus of the natural sand is 2.4 and the average particle size is 0.24 mm; the length of the recycled wind turbine blade glass fiber is 4 - 6 mm, which is prepared by cutting, crushing, and screening waste wind turbine blades; the water is tap water supplied by the laboratory.

[0111] Specifically, the preparation of a recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0112] Example 3

[0113] (1) Preparation of a self-healing shrinkage-reducing water reducer, which is compounded from the following raw materials in parts by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 20 parts of rice husk ash; 75 parts of aerobic alkali-resistant Bacillus spore dry powder; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0114] Specifically, the preparation of a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0115] (2) A preparation method of a recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer, in parts by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self-healing shrinkage-reducing water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0116] Among them, the cement is P.O 42.5 ordinary Portland cement with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , a bulk density of 1477.0 kg / m 3, the water absorption rate was 2.92%; the fineness modulus of natural sand was 2.4, and the average particle size was 0.24 mm; the length of the recycled wind turbine blade glass fiber was 4 - 6 mm, which was prepared by cutting, crushing, and screening waste wind turbine blades; the water was tap water supplied by the laboratory.

[0117] Specifically, the preparation of recycled coarse aggregate concrete with a self - repairing shrinkage - reducing water - reducing agent was carried out according to the steps of Example 1.

[0118] Example 4

[0119] (1) The preparation of a self - repairing shrinkage - reducing water - reducing agent was compounded from the following raw materials by weight: 200 parts of water - reducing agent; 30 parts of air - entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1 - hydroxyethylidene - 1,1 - diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 50 parts of dry powder of aerobic alkali - resistant Bacillus sphaericus; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n - heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0120] Specifically, the preparation of a self - repairing shrinkage - reducing water - reducing agent was carried out according to the steps of Example 1.

[0121] (2) The preparation method of recycled coarse aggregate concrete with a self - repairing shrinkage - reducing water - reducing agent, by weight, included the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self - repairing shrinkage - reducing water - reducing agent; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0122] Among them, the cement was P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28 - day compressive strength of 47.4 MPa; the recycled coarse aggregate was crushed stone formed from construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , a bulk density of 1477.0 kg / m 3 , the water absorption rate was 2.92%; the fineness modulus of natural sand was 2.4, and the average particle size was 0.24 mm; the length of the recycled wind turbine blade glass fiber was 4 - 6 mm, which was prepared by cutting, crushing, and screening waste wind turbine blades; the water was tap water supplied by the laboratory.

[0123] Specifically, the preparation of recycled coarse aggregate concrete with a self - repairing shrinkage - reducing water - reducing agent was carried out according to the steps of Example 1.

[0124] Example 5

[0125] (1) Preparation of a self-healing shrinkage-reducing water reducer, which is compounded from the following raw materials in parts by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 100 parts of dry powder of aerobic alkali-resistant Bacillus spores; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (absolute ethanol); 500 parts of water.

[0126] Specifically, the preparation of a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0127] (2) A preparation method of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer, in parts by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self-healing shrinkage-reducing water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0128] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , a bulk density of 1477.0 kg / m 3 , and a water absorption rate of 2.92%; the fineness modulus of natural sand is 2.4, and the average particle size is 0.24 mm; the length of the recycled wind turbine blade glass fiber is 4 - 6 mm, which is prepared by cutting, crushing, and screening waste wind turbine blades; the water is tap water supplied by the laboratory.

[0129] Specifically, the preparation of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0130] Example 6

[0131] (1) Preparation of a self-healing shrinkage-reducing water reducer, which is compounded from the following raw materials in parts by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 40 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of dry powder of aerobic alkali-resistant Bacillus spores; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (absolute ethanol); 500 parts of water.

[0132] Specifically, the preparation of a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0133] (2) A preparation method of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer, by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self-healing shrinkage-reducing water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0134] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , a bulk density of 1477.0 kg / m 3 , and a water absorption rate of 2.92%; the fineness modulus of natural sand is 2.4, and the average particle size is 0.24 mm; the length of the recycled wind turbine blade glass fiber is 4 - 6 mm, which is prepared by cutting, crushing, and screening waste wind turbine blades; the water is tap water supplied by the laboratory.

[0135] Specifically, the preparation of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0136] Example 7

[0137] (1) A preparation of a self-healing shrinkage-reducing water reducer is compounded from the following raw materials by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of aerobic alkali-tolerant Bacillus spore powder; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0138] Specifically, the preparation of a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0139] (2) A preparation method of recycled coarse aggregate concrete added with a self-healing shrinkage-reducing water reducer, by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 6 parts of self-healing shrinkage-reducing water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0140] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , and a bulk density of 1477.0 kg / m 3 , and a water absorption rate of 2.92%; the fineness modulus of the natural sand is 2.4, and the average particle size is 0.24 mm; the recycled wind turbine blade glass fiber has a length of 4 - 6 mm and is prepared by cutting, crushing and screening waste wind turbine blades; the water is tap water supplied by the laboratory.

[0141] Specifically, the preparation of the recycled coarse aggregate concrete added with the self-healing anti-shrinkage water reducer is carried out according to the steps of Example 1.

[0142] Example 8

[0143] (1) Preparation of a self-healing anti-shrinkage water reducer, which is compounded from the following raw materials in parts by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of aerobic alkali-tolerant Bacillus spore powder; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0144] Specifically, the preparation of a self-healing anti-shrinkage water reducer is carried out according to the steps of Example 1.

[0145] (2) Preparation method of recycled coarse aggregate concrete added with self-healing anti-shrinkage water reducer, in parts by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 10 parts of self-healing anti-shrinkage water reducer; 25 parts of recycled wind turbine blade glass fiber; 183 parts of water.

[0146] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, an apparent density of 2396.0 kg / m 3 , and a bulk density of 1477.0 kg / m 3, the water absorption rate is 2.92%; the fineness modulus of natural sand is 2.4, and the average particle size is 0.24 mm; the glass fiber length of the recycled fan blade is 4 - 6 mm, which is prepared by cutting, crushing and screening waste fan blades; the water is tap water supplied by the laboratory.

[0147] Specifically, the preparation of recycled coarse aggregate concrete added with self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0148] Example 9

[0149] (1) Preparation of a self-healing shrinkage-reducing water reducer, which is compounded from the following raw materials by weight: 200 parts of water reducer; 30 parts of air-entraining agent (sodium dodecyl sulfate); 60 parts of retarder (1-hydroxyethylidene-1,1-diphosphonic acid); 75 parts of alkaline powder (sodium hydroxide); 80 parts of calcium lactate; 40 parts of rice husk ash; 75 parts of aerobic alkali-tolerant Bacillus spore powder; 75 parts of auxiliary agent (polyvinyl alcohol); 50 parts of dispersant (sodium n-heptylbenzenesulfonate); 175 parts of solvent (anhydrous ethanol); 500 parts of water.

[0150] Specifically, the preparation of a self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0151] (2) Preparation method of recycled coarse aggregate concrete added with self-healing shrinkage-reducing water reducer, by weight, includes the following components: 350 parts of cement; 930 parts of recycled coarse aggregate; 640 parts of sand; 8 parts of self-healing shrinkage-reducing water reducer; 15 parts of recycled fan blade glass fiber; 183 parts of water.

[0152] Among them, the cement is P.O 42.5 ordinary Portland cement, with an average particle size of 14.77 μm and a 28-day compressive strength of 47.4 MPa; the recycled coarse aggregate is the crushed stone formed by construction and demolition waste, with a continuous gradation of (5 mm - 10 mm):(10 mm - 16 mm):(16 mm - 25 mm) = 1:3:6, apparent density of 2396.0 kg / m 3 , bulk density of 1477.0 kg / m 3 , the water absorption rate is 2.92%; the fineness modulus of natural sand is 2.4, and the average particle size is 0.24 mm; the glass fiber length of the recycled fan blade is 4 - 6 mm, which is prepared by cutting, crushing and screening waste fan blades; the water is tap water supplied by the laboratory.

[0153] Specifically, the preparation of recycled coarse aggregate concrete added with self-healing shrinkage-reducing water reducer is carried out according to the steps of Example 1.

[0154] Comparative Example 1:

[0155] Compared with Example 1, most of them are the same, except that the addition of the alkaline powder is omitted.

[0156] Comparative Example 2:

[0157] Compared with Example 1, most of them are the same, except that the addition of the dry powder of aerobic alkaliphilic Bacillus is omitted.

[0158] Comparative Example 3:

[0159] Compared with Example 1, most of them are the same, except that the dry powder of aerobic alkaliphilic Bacillus is replaced with an equal mass of Bacillus kochii (CN106045400B).

[0160] Comparative Example 4:

[0161] Compared with Example 1, most of them are the same, except that the addition of calcium lactate is omitted.

[0162] Comparative Example 5:

[0163] Compared with Example 1, most of them are the same, except that calcium lactate is replaced with an equal mass of calcium acetate.

[0164] Comparative Example 6:

[0165] Compared with Example 1, most of them are the same, except that the addition of rice husk ash is omitted.

[0166] Comparative Example 7:

[0167] Compared with Example 1, most of them are the same, except that the addition of rice husk ash is omitted during the preparation of the water reducing agent, but an equal mass of rice husk ash as in Example 1 is added separately during the preparation of the concrete.

[0168] Comparative Example 8

[0169] Compared with Example 1, most of them are the same, except that rice husk ash is replaced with an equal mass of fly ash.

[0170] Comparative Example 9

[0171] Compared with Example 1, most of them are the same, except that the preparation of the self-healing anti-shrinkage water reducing agent is omitted, and the self-healing anti-shrinkage water reducing agent is replaced with PCA-9 series polycarboxylate superplasticizer during the preparation of the recycled coarse aggregate concrete.

[0172] Comparative Example 10

[0173] Compared with Example 1, most of them are the same, except that the addition of recycled wind turbine blade glass fiber is omitted.

[0174] The properties of the prepared recycled coarse aggregate concrete were tested, including the following property test methods:

[0175] (1) Working performance test: The method specified in GB / T 50080-2016 was adopted, and the results are shown in Table 2.

[0176] (2) Mechanical property test: The method specified in GB / T 50081-2019 was adopted, and the results are shown in Table 2.

[0177] (3) Shrinkage rate performance test: The method specified in the published journal paper (Paper name: Preparation of plastic retention - shrinkage reducing polycarboxylate superplasticizer by bulk polymerization; Authors: Sun Zhenping, Zhang Jianfeng, Wang Jiafeng) was used to test the concrete shrinkage rate, and the results are shown in Table 3.

[0178] (4) The self - repair performance was characterized by the average crack healing rate and the average crack repair width (D t ). When the self - repairing concrete was cured under standard conditions for 28 days, the mechanical property test was carried out on each group of concrete cube specimens according to the method specified in GB / T 50081-2019. Each group of tests included three cube specimens. Then, the remaining self - repairing recycled concrete was loaded step by step to obtain an apparent complete crack pattern. Then, 1 crack observation point was set at an interval of 1 cm along the crack direction on the tested concrete cube specimens and marked. Cracks with width ranges of 0 - 0.5 mm, 0.5 - 1.0 mm, and about 1.0 - 1.5 mm were set, and about 10 cracks were selected in each range. The repair results were characterized by the crack width repair rate within each width range. Then, it was placed in water for immersion curing, and the crack healing situation was observed at 7 days, 14 days, and 28 days of repair respectively. The results are shown in Table 4. The calculation formulas for the average crack healing rate (H (p，t) ) and the average crack repair width (Dt) are as follows:

[0179]

[0180]

[0181] Where: h (0，i) is the crack repair width value of the monitoring point at 0 days of curing within the range of 0 - 0.5 mm, in mm; h (t，i) is the crack repair width value of the monitoring point at t days of curing within the range of 0 - 0.5 mm, in mm; h (0，j) is the crack repair width value of the monitoring point at 0 days of curing within the range of 0.5 - 1.0 mm, in mm; h (t,j) is the crack repair width value of the monitoring point at t days of curing within the range of 0.5 - 1.0 mm, in mm; h (0k) is the crack repair width value of the monitoring point at 0 days of curing within the range of 1.0 - 1.5 mm, in mm; h (t，k)The crack repair width value at the monitoring point when curing for t days within the range of 1.0 - 1.5 mm, in mm. N i , N j , N k The number of crack widths within the ranges of 0 - 0.5 mm, 0.5 - 1.0 mm, and 1.0 - 1.5 mm. The values taken in the present invention are all 10.

[0182] Table 2 Workability and 28 - day compressive strength of fresh concrete mixtures in Examples 1 - 9 and Comparative Examples 1 - 10

[0183]

[0184]

[0185] Table 2 shows the test results of the workability and mechanical properties of recycled aggregate concrete in Examples 1 - 9 and Comparative Examples 1 - 10, including the initial slump and spread, 1 - h slump and spread, and 28 - day compressive strength of the concrete. The results show that due to the use of the self - repairing shrinkage - reducing water - reducing agent, the initial slump and spread of Example 1 reached 235 mm and 615 mm respectively, and the use of the retarder effectively extended the initial setting time of the fresh recycled concrete. After 1 h, the concrete only reduced the slump and spread by 12.8% and 14.6% respectively; meanwhile, the 28 - day compressive strength of Example 1 reached the highest value of 68.6 MPa.

[0186] Table 3 Shrinkage rates of recycled coarse aggregate concrete in Examples 1 - 9 and Comparative Examples 1 - 10 at different curing ages

[0187]

[0188]

[0189] Table 4 Average crack healing rate and crack repair width of recycled coarse aggregate concrete in Examples 1 - 9 and Comparative Examples 1 - 10

[0190]

[0191]

[0192] Tables 3 and 4 show the shrinkage resistance and crack healing performance of the recycled aggregate concrete of Examples 1 to 9 and Comparative Examples 1 to 10, including shrinkage rate, average crack healing rate and crack repair width at 7 days, 14 days and 28 days. The results show that due to the alkaline environment of the pore solution, the large viscosity and contact angle, the self-repair effect of microorganisms and the good bonding effect of the recycled wind turbine blade glass fiber, the hardened recycled concrete in Example 1 showed the smallest shrinkage rate at 7 to 28 days, and the average crack healing rate reached 99.85% on the 28th day, indicating that its shrinkage resistance and crack repair performance are the best.

[0193] According to the working performance, compressive strength, shrinkage rate and self-repairing performance of fresh concrete in the examples and comparative examples, it is observed that the self-repairing anti-shrinkage water-reducing agent used in Example 1 can significantly improve the working performance and shrinkage performance of recycled aggregate concrete, thereby enhancing its compressive strength and crack self-repairing performance. Specifically, compared with Example 1, the solubility of potassium hydroxide in Example 2 is lower in water, and the slow increase in pH value is not enough to provide a sufficient alkaline environment for the dormancy of microorganisms; Example 3 reduces the amount of rice husk ash, which is not conducive to the nucleation effect and microbial growth; Examples 4 and 5 change the amount of aerobic alkali-resistant Bacillus cells, and too little or too much cell will have an adverse effect on the dispersion or survival rate of microorganisms; Example 6 reduces the amount of calcium lactate, and the reduction of nutrients is not conducive to the growth and metabolism of microorganisms; In general, Examples 2 to 6 do not provide a suitable living environment and nutrients for self-repairing microorganisms, resulting in the inability of microorganisms to achieve good growth and play their repair and improvement role. Examples 7 and 8 changed the amount of water reducer, which destroyed the balance between water reducer and admixtures such as air entraining agent and retarder, which was not conducive to the function of other admixtures; at the same time, compared with Example 7, the increase in the amount of water reducer will have an adverse effect on the mechanical properties and shrinkage properties of concrete, but the increase in the number of self-repairing microorganisms will improve the self-repairing properties of cracks to a certain extent. Example 9 reduced the amount of glass fiber used in the regenerative fan blades, weakened the anti-shrinkage and crack repair properties of concrete, which is mainly because the damaged glass fiber on the surface provides a place for the metabolic activities of microorganisms, and the reduction in the amount of fiber will lead to a decrease in the metabolic site, a decrease in the generated calcium carbonate precipitation, and a decrease in the bonding strength of the system. Comparative Examples 1 to 10 omit or replace the raw materials of the self-repairing anti-shrinkage water agent described in the present invention, so they cannot achieve satisfactory practical application effects.

[0194] In summary, the self-repairing anti-shrinkage water-reducing agent provided by the present invention reduces the usage of polycarboxylate water-reducing agent, has significant economic and environmental benefits, and helps to promote the wider application of recycled aggregates in the construction field.

[0195] The above description of the embodiments is provided to enable those of ordinary skill in the art to understand and use the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention as disclosed should fall within the protection scope of the present invention.

Claims

1. A self-healing anti-shrinkage water reducer, characterized in that, Comprising the following raw material components in parts by weight: Water reducing agent: 150 - 250 parts; Air entraining agent: 10 - 50 parts; Retarding agent: 20 - 100 parts; Alkaline powder: 50 - 100 parts; Calcium lactate: 40 - 120 parts; Rice husk ash: 20 - 60 parts; Dry powder of aerobic alkali - resistant Bacillus spores: 50 - 100 parts; Auxiliary agent: 50 - 100 parts; Dispersant: 20 - 80 parts; Solvent: 150 - 200 parts; Water: 400 - 600 parts; The air entraining agent is one or more of lignosulfonate, methyltrimethoxysilane or sodium dodecyl sulfate; the retarding agent is one or two of ammonium sulfate and hydroxyethylidene diphosphonic acid; The alkaline powder is one or two of sodium hydroxide powder or potassium hydroxide powder; The auxiliary agent is polyvinyl alcohol; The dispersant is one or two of sodium n - heptylbenzenesulfonate and silane coupling agent; This water reducing agent is prepared through the following steps: (1) First, in a reaction vessel equipped with a magnetic stirrer, add half of the solvent and water, start the stirrer and set the stirring speed to 1000 r / min, and stir for 0.5 h; (2) Gradually add the water reducing agent, air entraining agent, retarding agent, dispersant and auxiliary agent into the container, and continuously stir at a temperature of 60 °C for 2 - 4 h, with a stirring speed of 1200 r / min to ensure uniform mixing; (3) Gradually add the dry powder of aerobic alkali - resistant Bacillus spores, rice husk ash and calcium lactate, as well as the remaining solvent and water, and continuously stir for 2 - 4 h until all the dry powder of the spores is fully dissolved and mixed; (4) After the temperature is cooled to room temperature, use the alkaline powder to adjust the pH value of the mixture to maintain the pH within the range of 8.0 - 10.0; (5) Stop the stirrer, fill the prepared self - repairing anti - shrinkage water reducing agent into a sealed container, and place it in a vacuum drying environment for storage for use.

2. The self-healing anti-shrinkage water reducing agent according to claim 1, wherein The solvent is one or two of anhydrous ethanol and dimethylformamide.

3. The preparation method of a self - repairing anti - shrinkage water reducing agent as described in claim 1 or 2, comprising the following steps: (1) First, in a reaction vessel equipped with a magnetic stirrer, add half of the solvent and water, start the stirrer and set the stirring speed to 1000 r / min, and stir for 0.5 h; (2) Gradually add the water reducing agent, air entraining agent, retarding agent, dispersant and auxiliary agent into the container, and continuously stir at a temperature of 60 °C for 2 - 4 h, with a stirring speed of 1200 r / min to ensure uniform mixing; (3) Gradually add the dry powder of aerobic alkali - resistant Bacillus spores, rice husk ash and calcium lactate, as well as the remaining solvent and water, and continuously stir for 2 - 4 h until all the dry powder of the spores is fully dissolved and mixed; (4) After the temperature is cooled to room temperature, use the alkaline powder to adjust the pH value of the mixture to maintain the pH within the range of 8.0 - 10.0; (5) Stop the stirrer, fill the prepared self - repairing anti - shrinkage water reducing agent into a sealed container, and place it in a vacuum drying environment for storage for use.

4. A recycled aggregate concrete, characterized in that, Comprising the following raw material components in parts by weight: Cement: 300 - 400 parts; Recycled coarse aggregate: 860 - 1000 parts; Natural sand: 600 - 680 parts; Self-healing anti-shrinkage water reducer according to claim 1 or 2: 6-10 parts; Recycled fan blade glass fiber: 10-40 parts; Water: 165-200 parts.

5. The recycled aggregate concrete according to claim 4, wherein The cement is P.O 42.5 ordinary Portland cement with an average particle size of 12-36 μm and a 28-day compressive strength of 46.2-53.2 MPa; The recycled coarse aggregate adopts a continuous gradation of (5mm - 10mm):(10mm - 16mm):(16mm - 25mm) = 1:3:6, and its apparent density is 2300 - 2500 kg / m 3 , and the bulk density is 1400 - 1560 kg / m 3 , and the water absorption rate is 2.63% - 4.82%; The fineness modulus of the natural sand is 2.2-2.8, and the average particle size is 0.20-0.50 mm; The recycled fan blade glass fiber has a length of 4-6 mm and is prepared by cutting, crushing and screening waste fan blades.

6. The preparation method of recycled aggregate concrete according to claim 4, characterized in that It includes the following steps: (A) Sampling the cement, recycled coarse aggregate, natural sand and recycled fan blade glass fiber according to the component contents in the ratio, and sequentially pouring them into a concrete planetary mixer for the first stirring to obtain a first mixture; (B) Adding 2 / 3 of the water to the first mixture for the second stirring to obtain a second mixture; (C) Adding the self-healing anti-shrinkage water reducer and the remaining 1 / 3 of the water to the second mixture for the third stirring to obtain a newly mixed concrete mixture of recycled aggregate; (D) Pouring the newly mixed concrete mixture into a cube specimen of 100 mm×100 mm×100 mm, then vibrating and compacting it on a vibrating table, demolding it after standing at normal temperature for 24 h, and then curing it under standard curing conditions of a temperature of 20°C±2°C and a relative humidity of more than 95% until the test block reaches the specified age and then conducting performance tests.

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