Anti-freezing renewable concrete and preparation method thereof

Abstract

The invention relates to the field of concrete, and particularly discloses anti-freezing renewable concrete and a preparation method thereof. The anti-freezing renewable concrete is prepared from the following raw material components: 400 to 450 parts of cement; 195 parts of water; 630 to 660 parts of fine aggregate; 1080 to 1120 parts of coarse aggregate; 20 to 25 parts of glass fiber; 10 to 15 parts of polypropylene fiber; 3 to 5 parts of basalt fiber; 10 to 15 parts of a water reducing agent; 8-12 parts of an expanding agent; the fine aggregate comprises 20-30wt% of recycled fine aggregate, the coarse aggregate comprises 40-55wt% of recycled coarse aggregate, the expanding agent is prepared from magnesite, bauxite, dolomite and graphene oxide, and the raw materials are blended to obtain the anti-freezing renewable concrete. The concrete provided by the invention has good anti-freezing capability and mechanical strength, the mass loss rate of 300 freezing and thawing cycles is less than or equal to 0.15%, and the 28d compressive strength is greater than or equal to 76.5 MPa.

Description

Technical Field

[0001] The present application relates to the technical field of concrete, and in particular to an antifreeze renewable concrete and a preparation method thereof. Background Art

[0002] Concrete is a widely used building material in engineering construction, with the advantages of convenient construction and high strength. The mass of aggregate in concrete accounts for about 80wt%. As the use of concrete continues to increase, the large-scale mining of natural aggregates has also had a negative impact on the environment. On the one hand, the raw materials for making concrete are consumed, resulting in damage to the ecological environment; on the other hand, with the development of infrastructure, the speed of replacement of old and new buildings has increased, so a large amount of waste concrete, waste bricks and stones and other construction waste will be generated, which will also cause damage to the environment. Therefore, in order to improve the existing large-scale consumption of non-renewable natural aggregate resources and the accumulation of a large amount of waste aggregates, technicians will screen and crush construction waste to obtain reusable aggregates (recycled aggregates) for the preparation of renewable concrete, which meets the requirements of green development.

[0003] Recycled aggregate refers to the aggregate obtained by disintegrating and dispersing waste concrete into small pieces under the action of external force. Through the process of mechanical crushing, the roughness of the aggregate surface is increased, the angular effect is enhanced, and the particle size of the aggregate is effectively improved, so that the crushed aggregate has a larger mortar bonding force, realizing the regeneration of aggregate. However, due to the mechanical external force damage, the water absorption rate and porosity of the recycled aggregate are much greater than those of the natural aggregate, which makes the concrete mixed with renewable concrete more susceptible to freeze-thaw damage. Under freeze-thaw conditions, the recycled coarse aggregate attached to the mortar will cause the recycled aggregate whose internal water content has reached the critical water saturation to be damaged before the matrix, thereby causing more serious freeze-thaw damage to the entire system. Therefore, the concrete made directly from recycled aggregate has poor frost resistance and durability, which limits the large-scale application of recycled aggregate. Therefore, how to improve the frost resistance and durability of renewable concrete, increase the service life of renewable concrete, and promote the effective use of recycled aggregates still have some problems to be solved. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an antifreeze renewable concrete and a preparation method thereof.

[0005] In the first aspect, the present application provides an antifreeze renewable concrete, the raw materials used include the following components: 400-450 parts of cement; 195 parts of water; 630-660 parts of fine aggregate; 1080-1120 parts of coarse aggregate; 20-25 parts of glass fiber; 10-15 parts of polypropylene fiber; 3-5 parts of basalt fiber; 10-15 parts of water reducer; 8-12 parts of expansion agent; the fine aggregate includes 20-30wt% of recycled fine aggregate, the coarse aggregate includes 40-55wt% of recycled coarse aggregate, and the expansion agent is made of dolomite, bauxite, dolomite and graphene oxide in a weight ratio of 50:(40-45):(20-25):(0.2-1.0).

[0006] By adopting the above technical scheme, the present application adds a certain amount of glass fiber, polypropylene fiber and basalt fiber into the concrete system, utilizes the bridging effect of glass fiber in the concrete system, disperses internal stress concentration and reduces the internal stress of concrete in a freeze-thaw environment, and also utilizes polypropylene fiber to be distributed in the concrete system in a grid shape to inhibit the process of microcracks inside the concrete and improve the internal bonding strength of the concrete. The high modulus and high strength of basalt fiber are utilized to effectively disperse the stress concentration inside the concrete, improve the microstructure of the concrete, reduce the internal porosity, and increase the density of the concrete. The mixing of the three fibers can produce a synergistic effect, improve the brittle failure characteristics of the concrete, and improve the integrity, thereby significantly optimizing the antifreeze ability and mechanical strength of the renewable concrete.

[0007] In addition, the present application adds an expansion agent made of magnesite, bauxite, dolomite and graphene oxide, which compensates for the shrinkage of concrete, improves the density of concrete, and improves its anti-seepage performance, thereby effectively improving the overall performance of concrete. The expansion agent of the present application and glass fiber can play a good synergistic effect, can reduce the generation of dynamic elastic modulus when under pressure, and jointly improve the bonding force between coarse aggregate and fine aggregate and cement mortar, and improve the interface bonding strength.

[0008] The present application controls the ratio of each substance and the proportion of recycled aggregate in the aggregate. By compounding multiple substances and producing a synergistic effect, the mechanical strength and antifreeze ability of the renewable concrete are greatly improved while using as much recycled aggregate as possible. Experiments have proved that the mass loss rate of the renewable concrete in the present application does not exceed 0.15% after 300 freeze-thaw cycles (-18°C), and the 28d compressive strength is not less than 76.5MPa, which greatly improves the antifreeze durability of the renewable concrete and increases the service life of the renewable concrete, thereby effectively promoting the utilization of recycled aggregates.

[0009] Preferably, the raw materials used include the following components: 420 parts of cement; 195 parts of water; 655 parts of fine aggregate; 1100 parts of coarse aggregate; 24 parts of glass fiber; 12 parts of polypropylene fiber; 4 parts of basalt fiber; 12 parts of water reducing agent; and 10 parts of expansion agent.

[0010] By adopting the above technical scheme, the present application also strictly controls the ratio of each material, so that the stress distribution in the concrete system is more uniform. Specifically, the glass fiber, polypropylene fiber and basalt fiber under this ratio can form a more stable reinforcement network at the micro level, and the efficiency of the expansion agent under this ratio condition can be maximized, which not only effectively compensates for the shrinkage of the concrete, but also significantly enhances the density of the interface transition zone, thereby comprehensively improving the stability and reliability of the renewable concrete in complex service environments.

[0011] Preferably, the fine aggregate further includes fly ash accounting for 25-30wt%.

[0012] By adopting the above technical scheme, the present application adds fly ash as an active mineral admixture, which can effectively improve the microstructure of concrete, fill pores, reduce internal porosity, and improve density. At the same time, fly ash reacts secondary with cement hydration products to generate more cementitious substances, thereby enhancing the strength and durability of concrete. This improvement measure significantly improves the overall performance of renewable concrete, especially in terms of frost resistance, durability and mechanical strength, without affecting the proportions of other components.

[0013] Preferably, the fine aggregate comprises 25 wt% of recycled fine aggregate, and the coarse aggregate comprises 48 wt% of recycled coarse aggregate.

[0014] By adopting the above technical scheme, the present application accurately controls the proportion of recycled fine aggregate in fine aggregate to 25wt%, and the proportion of recycled coarse aggregate in coarse aggregate to 48wt%, thereby optimizing the ratio of recycled aggregate to natural aggregate. While ensuring a high proportion of recycled aggregate, it avoids excessive negative impact on concrete performance due to the defects of recycled aggregate itself (such as high water absorption and porosity), thereby further enhancing the mechanical strength and frost resistance of concrete.

[0015] Preferably, the expansion agent is made of magnesite, bauxite, dolomite and graphene oxide in a weight ratio of 50:42:23:(0.5-0.8).

[0016] By adopting the above technical scheme, the expansion agent of the present application is composed of magnesite, bauxite, dolomite and graphene oxide in a specific proportion. The formula can effectively compensate for the shrinkage of concrete, improve the density and impermeability of concrete, and graphene oxide can enable the expansion agent to form a more effective interface bond with other components in concrete, promote the hydration process in the system, improve the microstructure of cement mortar, and promote the effective dispersion of cement particles and the formation of hydration products; when the expansion agent and glass fiber work synergistically, the generation of dynamic elastic modulus can be reduced under pressure, the bonding force between coarse aggregate and fine aggregate and cement mortar is enhanced, and the interface bonding strength is improved, thereby significantly improving the overall performance and frost resistance durability of renewable concrete.

[0017] In a second aspect, the present application provides a method for preparing antifreeze renewable concrete, comprising the following steps: mixing coarse aggregate and fine aggregate, stirring evenly, then adding 50wt% of water, stirring evenly, adding cement, glass fiber, basalt fiber and polypropylene fiber, stirring evenly, adding the remaining 50wt% of water, water reducer and expansion agent, and stirring evenly to obtain antifreeze renewable concrete.

[0018] By adopting the above technical scheme, the preparation method of the present application utilizes the method of pre-mixing coarse aggregate and fine aggregate and adding water in steps, ensuring the initial uniform contact between aggregate and water, avoiding the phenomenon of local over-wetting or over-drying of materials caused by one-time water addition, and then adding cement and three kinds of fibers and stirring, so that the fibers can be fully dispersed in the concrete system, and play their respective strengthening and toughening effects, especially the bridging effect of glass fiber, the micro-crack inhibition effect of polypropylene fiber and the stress dispersion effect of basalt fiber are maximized, and finally the remaining water, water reducer and expansion agent are added for further stirring, ensuring the full integration of the components, especially the expansion agent can effectively compensate for the shrinkage of concrete, improve the overall density and impermeability. The preparation method is simple and efficient, which helps to greatly improve the mechanical strength and antifreeze durability of renewable concrete.

[0019] Preferably, the swelling agent is prepared by the following method: I. freeze-drying graphene oxide and dispersing it in isopropanol to obtain a GO-IPA dispersion for standby use; II. mixing magnesite, bauxite and dolomite, calcining at a temperature of 850-1050°C for 50-70min, cooling to 750-800°C and continuing to calcine for 50-60min to obtain a base material; III. dispersing the base material in step II in isopropanol for activation, then adding the GO-IPA dispersion, stirring for 20-25h, filtering to obtain a solid substance, and drying to obtain a swelling agent.

[0020] By adopting the above technical solution, the present application firstly performs high temperature calcination treatment on the mineral raw materials (magnesite, bauxite and dolomite) to enhance the activity of the materials, and at the same time further optimizes the microstructure of the expansion agent by utilizing the characteristics of graphene oxide. This improvement enables the expansion agent to better play the role of compensating shrinkage in the concrete system, improve the density and impermeability of the concrete, and thus greatly improve the overall performance and antifreeze durability of the renewable concrete.

[0021] Preferably, the recycled coarse aggregate and recycled fine aggregate are prepared by the following method: crushing the waste concrete, immersing it in a sodium silicate solution with a concentration of 5-8wt%, leaving it to stand for 2-4h, filtering, washing, drying, and then irradiating it with microwaves for 200-250s at a power of 2.0-3.0kW, and sieving according to particle size to obtain the recycled coarse aggregate and recycled fine aggregate.

[0022] Preferably, the power of the microwave irradiation is 2.8 kW and the time is 220 s.

[0023] Preferably, the concentration of the sodium silicate solution is 6wt%, and the standing time is 3h.

[0024] By adopting the above technical solution, the present application crushes the waste concrete and then irradiates it with microwaves, strictly controls the power and time, removes the residual waste mortar solidified material on the surface of the recycled aggregate, and then immerses it in a sodium silicate solution and allows it to stand, strictly controls the concentration of the sodium silicate solution and the standing time, so that a dense protective film is formed on the surface of the recycled aggregate, effectively reducing the pores and cracks inside the aggregate and improving its bonding strength with cement mortar. This method significantly improves the quality of the recycled aggregate and reduces the water absorption rate, thereby improving the frost resistance durability and overall performance of the renewable concrete.

[0025] In summary, this application has the following beneficial technical effects: 1. The antifreeze renewable concrete of the present application contains glass fiber, polypropylene fiber and basalt fiber. The above three fibers can effectively disperse the internal stress concentration of concrete, inhibit the generation and expansion of micro cracks, and significantly improve the antifreeze ability and mechanical strength of renewable concrete; 2. The present application uses an expansion agent made of magnesite, bauxite, dolomite and graphene oxide, which effectively compensates for the shrinkage of concrete, enhances the density and interface bonding strength, thereby greatly improving the anti-permeability and overall performance; the present application also pre-treats the recycled aggregate to improve its bonding strength with cement mortar and reduce water absorption; 3. The preparation method of the present application is simple and efficient, which helps to significantly improve the mechanical strength and antifreeze durability of renewable concrete. DETAILED DESCRIPTION

[0026] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: Graphene oxide was purchased from Zhongke Leiming Technology Co., Ltd., with a diameter of 0.5-3 μm and a thickness of 0.55-1.2 nm; Magnesite was purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.; Bauxite was purchased from Jianshi Mineral Powder Factory in Lingshou County with a purity of 80%; Dolomite was purchased from Erping Mineral Products Processing Plant in Lingshou County; Cement was purchased from Jinyu Zhenxing Environmental Protection Technology Co., Ltd., model P.O42.5; The water reducer was purchased from Wuhan Runxingyuan Technology Co., Ltd., model QSC-polycarboxylate water reducer B; Glass fiber was purchased from Taian Haoda New Materials Co., Ltd., with a fiber diameter of 9-13 μm and an elastic modulus of 8 GPa; Polypropylene fiber was purchased from Shandong Jinyi Building Materials Co., Ltd. with a fiber diameter of 2 mm, a porosity of 0.06, and a fiber length of 300 mm; Basalt fiber was purchased from Shandong Tongying New Materials Co., Ltd., with a fiber diameter of 7-25um, an elastic modulus of 35GPa, and a tensile strength of 700MPa; Quartz sand was purchased from Nanyang Hengsheng Quartz Sand Filter Material Co., Ltd. with a particle size of 19 μm and an apparent density of 1.75 g / cm 3 , model is medium sand in zone II; The Yellow River sediment was purchased from Lingshou County Haoyu Trading Co., Ltd. with a particle size of 2.5-3.9 mm and an apparent density of 1.5 g / cm 3 ; The ceramsite was purchased from Lingshou County Ruojia Mineral Products Co., Ltd., with a particle size of 5-16 mm and a moisture content of 0.1%; The quartz stone was purchased from Nanyang Hengsheng Quartz Sand Filter Material Co., Ltd., with an apparent density of 2730kg / m 3 The particle size range is 4.75-16 mm; fly ash was purchased from Shijiazhuang Zed Mineral Products Co., Ltd., with a particle size of 44 μm, a hardness of 6.2 HB, and a density of 1.3 g / cm 3 , model is Class F-Class II.

[0027] The present application is further described in detail below in conjunction with embodiments and comparative examples.

[0028] Preparation Example 1.1 The preparation method of the expansion agent comprises the following steps: I. Disperse 20 g of graphene oxide in water and freeze it with liquid nitrogen, put it in a freeze drying oven and dry it for 24 h, then disperse it in isopropanol, break it into small pieces with an ultrasonic cleaner, and disperse it for 1.5 h to obtain a GO-IPA dispersion for later use; II. Mix 5 kg of magnesite, 4 kg of bauxite and 2.5 kg of dolomite, calcine at 1050° C. for 50 min, cool to 800° C. and continue calcining for 50 min to obtain a base material; III. Disperse all the base materials obtained in step II in isopropanol and perform ultrasonic treatment for 30 minutes to activate the base materials. Then add all the GO-IPA dispersion and stir for 25 hours. Filter to obtain solid matter, dry at 50°C for 5 hours, and crush through a 200-mesh sieve to obtain a swelling agent.

[0029] Preparation Example 1.2 The preparation method of the expansion agent comprises the following steps: I. Disperse 100 g of graphene oxide in water and freeze it with liquid nitrogen, put it in a freeze drying oven and dry it for 24 h, then disperse it in isopropanol, break it into small pieces with an ultrasonic cleaner, and disperse it for 1.5 h to obtain a GO-IPA dispersion for standby use; II. 5 kg of magnesite, 4.5 kg of bauxite and 2 kg of dolomite were mixed, calcined at 850° C. for 70 min, cooled to 750° C. and then calcined for 70 min to obtain a base material; III. Disperse all the base materials obtained in step II in isopropanol and perform ultrasonic treatment for 30 minutes to activate the base materials. Then add all the GO-IPA dispersion and stir for 20 hours. Filter to obtain solid matter, dry at 50°C for 5 hours, and crush through a 200-mesh sieve to obtain a swelling agent.

[0030] Preparation Example 1.3 The preparation method of the expanding agent is different from that of Preparation Example 1.1 in that: in step I, the amount of graphene oxide used is 50 g, in step II, the amount of bauxite used is 4.2 kg, and the amount of dolomite used is 2.3 kg, and the rest is the same as Preparation Example 1.1.

[0031] Preparation Example 1.4 The preparation method of the expanding agent is different from that of Preparation Example 1.1 in that: in step I, the amount of graphene oxide used is 80 g, in step II, the amount of bauxite used is 4.2 kg, and the amount of dolomite used is 2.3 kg, and the rest is the same as Preparation Example 1.1.

[0032] Comparative Preparation Example 1 5 kg of magnesite, 4 kg of bauxite and 2.5 kg of dolomite were mixed, calcined at 1050°C for 50 min, cooled to 800°C and continued to calcine for 50 min, crushed through a 200-mesh sieve to obtain a product.

[0033] Comparative Preparation Example 2.1 The difference from Preparation Example 1.1 is that in step I, the amount of graphene oxide used is 10 g, and the rest is the same as Preparation Example 1.1.

[0034] Comparative Preparation Example 2.2 The difference from Preparation Example 1.1 is that in step I, the amount of graphene oxide used is 120 g, and the rest is the same as Preparation Example 1.1.

[0035] Comparative Preparation Example 3.1 The difference from Preparation Example 1.1 is that in step II, bauxite is removed and the amount of dolomite used is 9 kg. The rest is the same as Preparation Example 1.1.

[0036] Comparative Preparation Example 3.2 The difference from Preparation Example 1.1 is that in step II, dolomite is removed, the amount of dolomite used is 7.5 kg, and the rest is the same as Preparation Example 1.1.

[0037] Example 1.1 A method for preparing antifreeze renewable concrete comprises the following steps: S1. crushing the waste concrete, irradiating it with microwaves at a power of 3.0 kW for 200 seconds, then immersing it in a sodium silicate solution with a concentration of 8 wt% and letting it stand for 2 hours, filtering, washing, and drying it in a ventilated and illuminated place, and sieving it according to the particle size to obtain recycled coarse aggregate with a particle size of less than 4.75 mm and continuously graded recycled fine aggregate with particle sizes of 5-10 mm, 10-16 mm, 16-20 mm, and 20-25 mm; S2. Coarse aggregate and fine aggregate were mixed and stirred for 60 seconds, followed by adding 50 wt% of water and stirring for 60 seconds, adding cement, glass fiber, basalt fiber and polypropylene fiber, stirring for 30 seconds, adding the remaining 50 wt% of water, water reducer and the expansive agent prepared in Preparation Example 1.1, and stirring for 120 seconds to obtain antifreeze renewable concrete. The specific amounts of each component are shown in Table 1.

[0038] Example 1.2 A method for preparing antifreeze renewable concrete comprises the following steps: S1. crushing the waste concrete, irradiating it with microwaves for 250 seconds at a power of 2.0 kW, then immersing it in a sodium silicate solution with a concentration of 5 wt% and letting it stand for 4 hours, filtering, washing, and drying it in a ventilated and illuminated place, and sieving it according to the particle size to obtain recycled coarse aggregate with a particle size of less than 4.75 mm and continuously graded recycled fine aggregate with particle sizes of 5-10 mm, 10-16 mm, 16-20 mm and 20-25 mm respectively; S2. Mix the coarse aggregate and the fine aggregate, stir for 60 seconds, then add 50wt% of water, stir for 60 seconds, add cement, glass fiber, basalt fiber and polypropylene fiber, stir for 30 seconds, add the remaining 50wt% of water, water reducer and the expansive agent prepared in Preparation Example 1.2, stir for 120 seconds to obtain antifreeze renewable concrete. The specific amount of each component is shown in Table 1.

[0039] Example 1.3 A method for preparing antifreeze renewable concrete comprises the following steps: S1. crushing the waste concrete, irradiating it with microwaves at a power of 3.0 kW for 200 seconds, then immersing it in a sodium silicate solution with a concentration of 8 wt% and letting it stand for 2 hours, filtering, washing, and drying it in a ventilated and illuminated place, and sieving it according to the particle size to obtain recycled coarse aggregate with a particle size of less than 4.75 mm and continuously graded recycled fine aggregate with particle sizes of 5-10 mm, 10-16 mm, 16-20 mm, and 20-25 mm; S2. Coarse aggregate and fine aggregate were mixed and stirred for 60 seconds, followed by adding 50 wt% of water and stirring for 60 seconds, adding cement, glass fiber, basalt fiber and polypropylene fiber, stirring for 30 seconds, adding the remaining 50 wt% of water, water reducer and the expansive agent prepared in Preparation Example 1.1, and stirring for 120 seconds to obtain antifreeze renewable concrete. The specific amounts of each component are shown in Table 1.

[0040] Table 1 Amount of each component in Examples 1.1-1.3 (kg) Example 2.1 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step S1, the power of microwave irradiation is 2.5 kW and the time is 240 s, and the rest is the same as Example 1.3.

[0041] Example 2.2 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step S1, the power of microwave irradiation is 2.8 kW and the time is 220 s, and the rest is the same as Example 1.3.

[0042] Example 3.1 A method for preparing antifreeze renewable concrete, which is different from Example 2.2 in that: in step S1, the concentration of the sodium silicate solution is 7wt%, the standing time is 3h, and the rest is the same as Example 2.2.

[0043] Example 3.2 A method for preparing antifreeze renewable concrete, which is different from Example 2.2 in that: in step S1, the concentration of the sodium silicate solution is 6wt%, the standing time is 3h, and the rest is the same as Example 2.2.

[0044] Example 4.1 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step II, the fine aggregate also includes fly ash accounting for 30wt%, the amount of recycled fine aggregate is 131kg, the amount of fly ash is 196.5kg, the amount of quartz sand is 163.8kg, and the amount of Yellow River silt is 168.7kg, and the rest is the same as Example 1.3.

[0045] Example 4.2 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step II, the fine aggregate also includes fly ash accounting for 25wt%, the amount of recycled fine aggregate is 131kg, the amount of fly ash is 163.75kg, the amount of quartz sand is 180.15kg, and the amount of Yellow River silt is 180.1kg, and the rest is the same as Example 1.3.

[0046] Example 5.1 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step II, the amount of recycled fine aggregate is 163.75 kg, the total amount of fine aggregate and the weight ratio of quartz sand to Yellow River silt remain unchanged, the amount of recycled coarse aggregate is 528 kg, the total amount of coarse aggregate and the weight ratio of ceramsite and quartz stone remain unchanged, and the rest are the same as Example 1.3.

[0047] Example 5.2 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step II, the amount of recycled fine aggregate is 144.1 kg, the total amount of fine aggregate and the weight ratio of quartz sand to Yellow River silt remain unchanged, the amount of recycled coarse aggregate is 550 kg, the total amount of coarse aggregate and the weight ratio of ceramsite and quartz stone remain unchanged, and the rest are the same as Example 1.3.

[0048] Example 5.3 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that: in step II, the amount of recycled fine aggregate is 183.4 kg, the total amount of fine aggregate and the weight ratio of quartz sand to Yellow River silt remain unchanged, the amount of recycled coarse aggregate is 495 kg, the total amount of coarse aggregate and the weight ratio of ceramsite and quartz stone remain unchanged, and the rest are the same as Example 1.3.

[0049] Example 6.1 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that the expansive agent prepared in Preparation Example 1.1 in step I is replaced by the expansive agent prepared in Preparation Example 1.3, and the rest is the same as Example 1.3.

[0050] Example 6.2 A method for preparing antifreeze renewable concrete, which is different from Example 1.3 in that the expansive agent prepared in Preparation Example 1.1 in step I is replaced by the expansive agent prepared in Preparation Example 1.4, and the rest is the same as Example 1.3.

[0051] Comparative Example 1.1 The difference from Example 1.3 is that the expansion agent prepared in Preparation Example 1.1 in step I is replaced by the product prepared in Comparative Preparation Example 1, and the rest is the same as Example 1.3.

[0052] Comparative Example 1.2-1.5 The difference from Example 1.3 is that the expansion agent prepared in Preparation Example 1.1 in step I is replaced by the expansion agents prepared in Comparative Preparation Examples 2.1-3.2 respectively, and the rest is the same as Example 1.3.

[0053] Comparative Example 2.1 The difference from Example 1.3 is that in step II, the glass fiber is removed, the amount of polypropylene fiber used is 30 kg, the amount of basalt fiber used is 10 kg, and the rest is the same as Example 1.3.

[0054] Comparative Example 2.2 The difference from Example 1.3 is that in step II, the polypropylene fiber is removed, the amount of glass fiber used is 34.3 kg, the amount of basalt fiber used is 5.7 kg, and the rest is the same as Example 1.3.

[0055] Comparative Example 2.3 The difference from Example 1.3 is that in step II, basalt fiber is removed, the amount of glass fiber used is 26.7 kg, the amount of polypropylene fiber used is 13.3 kg, and the rest is the same as Example 1.3.

[0056] Performance Testing 1. First, the slurry of the antifreeze regenerable concrete prepared in the embodiment and the comparative example was made into a cube with a side length of 150 mm as a concrete specimen, and each group of concrete specimens had 3 pieces. The concrete specimens were cured for 28 days, and then their 28d compressive strength (MPa) was tested. The average value of each group of 3 test pieces is recorded in Table 2; 2. The slurry of the antifreeze regenerable concrete prepared in the embodiment and the comparative example was made into concrete specimens with a size of 100 mm × 100 mm × 500 mm, each group of concrete specimens had 3 pieces, and the concrete specimens were cured for 28 days. According to the test method in JTGE30-2005 "Test Procedure for Cement and Cement Concrete for Highway Engineering", the test was carried out. The antifreeze performance of the concrete was tested using a rapid freezing tester, and the freeze-thaw cycle was repeated 300 times; wherein, one freeze-thaw cycle took 2-5 h, and the freeze-thaw temperature was -18 ° C. The average mass loss of each group of 3 test pieces is recorded in Table 2.

[0057] Table 2 Performance test table Group 28d compressive strength (MPa) Freeze-thaw cycle mass loss rate % Example 1.1 76.5 0.15 Example 1.2 76.6 0.15 Example 1.3 77.2 0.12 Example 2.1 77.2 0.13 Example 2.2 77.4 0.10 Example 3.1 77.3 0.11 Example 3.2 77.5 0.07 Example 4.1 79.6 0.09 Example 4.2 79.8 0.08 Example 5.1 78.8 0.11 Example 5.2 77.1 0.12 Example 5.3 77.4 0.13 Example 6.1 77.8 0.09 Example 6.2 77.6 0.09 Comparative Example 1.1 76.3 0.39 Comparative Example 1.2 76.8 0.28 Comparative Example 1.3 76.5 0.31 Comparative Example 1.4 77.1 0.24 Comparative Example 1.5 77.0 0.21 Comparative Example 2.1 74.3 0.33 Comparative Example 2.2 75.0 0.27 Comparative Example 2.3 74.8 0.31 Data Analysis: It can be seen from Table 2 that the 28d compressive strength of the renewable concrete of Examples 1.1-1.2 is 76.5-76.6 MPa, and the mass loss rate after 300 freeze-thaw cycles is 0.15%, which proves that the present application greatly improves the mechanical strength and antifreeze ability of the renewable concrete by compounding multiple substances and producing a synergistic effect while using recycled aggregates as much as possible. The obtained renewable concrete has excellent antifreeze durability and long service life, and can effectively promote the utilization of recycled aggregates.

[0058] The renewable concrete of Example 1.3 has a higher 28d compressive strength and a lower mass loss rate after 300 freeze-thaw cycles, which proves that the present application strictly controls the ratio of each material to make the stress distribution in the concrete system more uniform. The glass fiber, polypropylene fiber and basalt fiber under this ratio can form a more stable reinforcement network at the micro level. The efficiency of the expansive agent under this ratio can also be maximized, which not only effectively compensates for the shrinkage of the concrete, but also significantly enhances the density of the interface transition zone, thereby comprehensively improving the stability and reliability of the renewable concrete in a complex service environment.

[0059] The parameters of the microwave irradiation treatment in Examples 2.1-2.2 are different from those in Example 1.3. The results show that the renewable concrete obtained in Example 2.2 has a higher 28d compressive strength and a lower mass loss rate after 300 freeze-thaw cycles, which proves that the present application removes the residual waste mortar solids on the surface of the recycled aggregate by strictly controlling the power and time, thereby improving the quality of the recycled aggregate and reducing the water absorption rate, thereby improving the frost resistance, durability and overall performance of the renewable concrete.

[0060] The sodium silicate solution concentrations and standing times of Examples 3.1-3.2 are different from those of Example 2.2. The results show that the mass loss rate of the renewable concrete obtained in Example 3.2 after 300 freeze-thaw cycles is lower, which proves that the present application forms a dense protective film on the surface of the recycled aggregate by strictly controlling the concentration of the sodium silicate solution and the standing time, effectively reducing the pores and cracks inside the aggregate and improving its bonding strength with the cement mortar.

[0061] In Examples 4.1-4.2, fly ash is further mixed into the system on the basis of Example 1.3. The results show that the renewable concrete obtained in Examples 4.1-4.2 has higher 28d compressive strength and lower mass loss rate after 300 freeze-thaw cycles, which proves that the addition of fly ash as an active mineral admixture in this application can effectively improve the microstructure of concrete, fill pores, reduce internal porosity, and increase density. At the same time, fly ash reacts secondary with cement hydration products to generate more cementitious substances, thereby enhancing the strength and durability of concrete. This improvement measure significantly improves the overall performance of the renewable concrete, especially in terms of frost resistance, durability and mechanical strength, without affecting the proportions of other components.

[0062] Examples 5.1-5.3 adjust the amount of recycled aggregate added on the basis of Example 1.3. The results show that the renewable concrete obtained in Example 5.1 has a higher 28d compressive strength and a lower mass loss rate after 300 freeze-thaw cycles, which proves that the present application accurately controls the proportion of recycled fine aggregate in fine aggregate to 25wt%, and the proportion of recycled coarse aggregate in coarse aggregate to 48wt%, optimizes the ratio of recycled aggregate to natural aggregate, and while ensuring a high proportion of recycled aggregate, avoids excessive negative impact on concrete performance due to defects in the recycled aggregate itself, further enhancing the mechanical strength and frost resistance of the concrete.

[0063] Examples 6.1-6.2 replace the expansive agent obtained by different material ratios on the basis of Example 1.3. The results show that the 28d compressive strength of the renewable concrete obtained in Examples 6.1-6.2 is improved, and the mass loss rate after 300 freeze-thaw cycles is reduced, which proves that the present application further controls the weight ratio of magnesite, bauxite, dolomite and graphene oxide to effectively compensate for the shrinkage of concrete, improve the density and impermeability of concrete, promote the hydration process in the system, improve the microstructure of cement mortar, and promote the effective dispersion of cement particles and the formation of hydration products.

[0064] Comparative Examples 1.1-1.5 replaced the expansive agents obtained with different material ratios on the basis of Example 1.3. The results showed that the 28d compressive strength of the obtained renewable concrete was reduced, and the mass loss rate after 300 freeze-thaw cycles was greatly improved, which proved that the expansive agent of the present application compensated for the shrinkage of the concrete, improved the density and impermeability of the concrete, and had a good synergistic effect with the glass fiber. When under pressure, it can reduce the generation of dynamic elastic modulus, and jointly improve the bonding force between coarse aggregate and fine aggregate and cement mortar, and improve the interface bonding strength.

[0065] Comparative Examples 2.1-2.3 removed a certain type of fiber respectively. The results showed that the 28d compressive strength of the obtained renewable concrete was reduced, and the mass loss rate after 300 freeze-thaw cycles was increased, proving that the three fiber blends in the present application can produce a synergistic effect, improve the brittle failure characteristics of concrete, and improve its integrity, thereby significantly optimizing the antifreeze ability and mechanical strength of the renewable concrete.

[0066] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A frost-proof renewable concrete, characterized in that: The raw materials used include the following components: 400-450 parts of cement; Water 195 parts; 630-660 parts of fine aggregate; Coarse aggregate 1080-1120 parts; Glass fiber 20-25 parts; 10-15 parts of polypropylene fiber; 3-5 parts of basalt fiber; 10-15 parts of water reducing agent; 8-12 parts of expansion agent; The fine aggregate comprises 20-30wt% of recycled fine aggregate, the coarse aggregate comprises 40-55wt% of recycled coarse aggregate, and the expansion agent is prepared from magnesite, bauxite, dolomite and graphene oxide in a weight ratio of 50: (40-45): (20-25): (0.2-1.0).

2. The antifreeze recyclable concrete according to claim 1, characterized in that: The raw materials used include the following components: 420 parts of cement; Water 195 parts; 655 parts of fine aggregate; 1100 parts of coarse aggregate; Glass fiber 24 parts; Polypropylene fiber 12 parts; 4 parts of basalt fiber; 12 parts of water reducing agent; 10 parts of expansion agent.

3. The antifreeze recyclable concrete according to claim 1, characterized in that: The fine aggregate also includes fly ash accounting for 25-30wt%.

4. The antifreeze recyclable concrete according to claim 1, characterized in that: The fine aggregate includes 25 wt% of recycled fine aggregate, and the coarse aggregate includes 48 wt% of recycled coarse aggregate.

5. The antifreeze recyclable concrete according to claim 1, characterized in that: The expansion agent is prepared from magnesite, bauxite, dolomite and graphene oxide in a weight ratio of 50:42:23:(0.5-0.8).

6. A method for preparing the antifreeze renewable concrete according to claim 1, characterized in that: The following steps are involved: The coarse aggregate and the fine aggregate are mixed and stirred evenly, then 50wt% of water is added and stirred evenly, cement, glass fiber, basalt fiber and polypropylene fiber are added and stirred evenly, and then the remaining 50wt% of water, water reducing agent and expansion agent are added and stirred evenly to obtain antifreeze renewable concrete.

7. The method for preparing antifreeze recyclable concrete according to claim 6, characterized in that: The expansion agent is prepared by the following method: The graphene oxide is freeze-dried and then dispersed in isopropanol to obtain a GO-IPA dispersion for later use; Mix magnesite, bauxite and dolomite, calcine at 850-1050°C for 50-70min, cool to 750-800°C and continue calcining for 50-60min to obtain a base material; The base material in step II is dispersed in isopropanol for activation, and then the GO-IPA dispersion is added, stirred for 20-25 hours, filtered to obtain a solid substance, and dried to obtain a swelling agent.

8. The method for preparing antifreeze renewable concrete according to claim 6, characterized in that: The recycled coarse aggregate and recycled fine aggregate are prepared by the following method: The waste concrete is crushed, subjected to microwave irradiation for 200-250s at a power of 2.0-3.0kW, then immersed in a sodium silicate solution with a concentration of 5-8wt% and allowed to stand for 2-4h, filtered, washed, dried, and sieved according to particle size to obtain recycled coarse aggregate and recycled fine aggregate.

9. The method for preparing antifreeze renewable concrete according to claim 8, characterized in that: The power of the microwave irradiation was 2.8 kW and the time was 220 s.

10. The method for preparing antifreeze renewable concrete according to claim 8, characterized in that: The concentration of the sodium silicate solution is 6wt%, and the standing time is 3h.

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