Preparation method of recycled aggregate for concrete and full-recycled concrete thereof

Abstract

The application is suitable for the technical field, and provides a preparation method of recycled aggregate and full recycled concrete, and the specific steps are as follows: S1, sorting: removing impurities in waste concrete blocks; S2, waste concrete pretreatment: synchronously performing first-stage crushing, first-stage screening, first-stage washing, second-stage crushing and second-stage washing on the waste concrete blocks and natural stone blocks; S3, multi-stage treatment of waste concrete: performing first-stage iron removal, second-stage screening, second-stage iron removal and third-stage screening on the pretreated recycled aggregate obtained in the step S2; S4, preparation of recycled coarse aggregate: performing first-stage shaping and fourth-stage screening on the 5-31.5mm recycled aggregate obtained in the step S3, so that the 0-5mm recycled aggregate and the final 5-31.5mm recycled coarse aggregate are obtained; S5, preparation of recycled fine aggregate: performing third-stage crushing, fifth-stage screening and third-stage washing on the 0-5mm and 31.5-50mm recycled aggregate obtained in the step S3 and the 0-5mm recycled aggregate obtained in the step S4, so that the final 0-5mm recycled fine aggregate is obtained; the prepared recycled aggregate and full recycled concrete have good performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of recycled aggregate and recycled concrete, and particularly relates to a recycled aggregate for concrete and a preparation method of full recycled concrete of the recycled aggregate. BACKGROUND

[0002] With the rapid development of the construction industry, more and more construction waste is generated. In order to improve the resource utilization of the construction waste, the waste concrete and other construction waste are crushed, screened, washed and the like to form recycled aggregate, which is applied to the concrete to form recycled aggregate concrete. The application of the recycled aggregate concrete effectively solves the problem of waste of construction waste resources.

[0003] In the prior art, the recycled aggregate is usually prepared by treating the waste, but it is difficult to improve the angular shape of the aggregate and peel off the mortar attached to the surface of the recycled aggregate, resulting in poor graininess and low strength of the aggregate, thereby affecting the performance of the recycled concrete.

[0004] Therefore, how to provide a preparation method of a recycled aggregate for concrete and concrete, and produce high-quality recycled aggregate and prepare full recycled concrete with a 100% recycled aggregate replacement rate is a problem to be solved by those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a recycled aggregate for concrete and full recycled concrete, which aims to solve the problems mentioned in the background.

[0006] The present application is implemented as follows: a preparation method of a recycled aggregate for concrete, the specific steps are as follows:

[0007] S1, sorting: removing impurities in the waste concrete block by machine or manually;

[0008] S2, waste concrete pretreatment: synchronously performing primary crushing, primary screening and primary washing on the waste concrete block and the natural stone block, and performing secondary crushing and secondary washing to obtain pretreated 0-50mm recycled aggregate;

[0009] S3, multi-stage treatment of waste concrete: performing primary iron removal, secondary screening, secondary iron removal and tertiary screening on the pretreated recycled aggregate obtained in step S2 to obtain multi-stage treated 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate;

[0010] S4, preparation of recycled coarse aggregate: performing primary shaping and four-stage screening on the 5-31.5mm recycled aggregate obtained in step S3 to obtain 0-5mm recycled aggregate as a screening residue and final 5-31.5mm recycled coarse aggregate;

[0011] S5, recycled fine aggregate preparation: the 0-5mm, 31.5-50mm recycled aggregate obtained in step S3 and the 0-5mm recycled aggregate obtained in step S4 are subjected to three-stage crushing, five-stage screening and three-stage washing to obtain the final 0-5mm recycled fine aggregate.

[0012] Preferably, in step S1, the impurities in the waste concrete blocks are removed by machine or manually, and the specific steps are as follows: using machine or manual sorting to remove plastic, wood, glass, paper, textile and metal impurities in the waste concrete blocks.

[0013] Preferably, in step S2, the waste concrete blocks and natural stone blocks are simultaneously subjected to one-stage crushing, one-stage screening, one-stage washing, two-stage crushing and two-stage washing to obtain the pretreated 0-50mm recycled aggregate, and the specific steps are as follows:

[0014] S21, one-stage crushing: the waste concrete blocks and natural stone blocks are simultaneously fed into the jaw crusher by the loader, and the weight ratio of the waste concrete blocks to the natural stone blocks is 9:1-5:5;

[0015] S22, one-stage screening: the recycled aggregate obtained in step S21 is sent to the roller multifunctional cylindrical screen to separate out the waste concrete blocks and natural stone blocks with a particle size greater than 50mm, the 0-50mm recycled aggregate, the micro powder and the soil;

[0016] S23, one-stage washing: the 0-50mm recycled aggregate is washed and dehydrated in the water wheel washing machine and the dehydration screen to remove the micro powder and the soil in the aggregate;

[0017] S24, two-stage crushing: the waste concrete blocks and natural stone blocks with a particle size greater than 50mm obtained in step S22 are put into the hammer crusher or the impact crusher for two-stage crushing, and the particle size of the discharged material is 0-50mm;

[0018] S25, two-stage washing: the 0-50mm aggregate obtained in step S24 is sequentially washed and dehydrated in the water wheel washing machine and the dehydration screen to remove the micro powder and the soil.

[0019] Preferably, in step S3, the pretreated 0-50mm recycled aggregate obtained in step S2 is subjected to one-stage iron removal, two-stage screening, two-stage iron removal and three-stage screening to obtain the multi-stage treated 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate, and the specific steps are as follows:

[0020] S31, one-stage iron removal: the 0-50mm recycled aggregate obtained in steps S23 and S25 is removed by the iron absorption device to remove the metal impurities.

[0021] S32, secondary screening: the 0-50mm recycled aggregate obtained in step S31 is put into a dust-free sieve to remove the fine powder and soil in the aggregate, and the 0-50mm recycled aggregate is obtained after screening;

[0022] S33, secondary iron removal: the 0-50mm recycled aggregate obtained in step S32 is passed through an iron absorption device to remove metal impurities;

[0023] S34, tertiary screening: the 0-50mm recycled aggregate obtained in step S33 is put into a vibrating screen to obtain multi-stage treated 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate after screening;

[0024] Preferably, in step S4, the 5-31.5mm recycled aggregate obtained in step S3 is subjected to primary shaping and four-stage screening to obtain the 0-5mm recycled aggregate and the final 5-31.5mm recycled coarse aggregate, and the specific steps are as follows:

[0025] S41, primary shaping: the 5-31.5mm coarse aggregate obtained in step S34 is put into a disc grinder for grinding and shaping to obtain the 0-31.5mm aggregate after shaping;

[0026] S42, four-stage screening: the 0-31.5mm aggregate obtained in step S41 is put into a vibrating screen to obtain the 0-5mm recycled aggregate and the final 5-31.5mm recycled coarse aggregate.

[0027] Preferably, in step S5, the 0-5mm, 31.5-50mm recycled aggregate obtained in step S3 and the 0-5mm recycled aggregate obtained in step S4 are subjected to three-stage crushing, five-stage screening and three-stage washing to obtain the final 0-5mm recycled fine aggregate, and the specific steps are as follows:

[0028] S51, three-stage crushing: the 31.5-50mm recycled aggregate obtained in step S34 is put into an impact sand making machine to obtain the 0-5mm recycled aggregate after crushing;

[0029] S52, five-stage screening: the 0-5mm recycled aggregate obtained in step S51 is put into a vibrating screen to remove the fine powder and soil in the aggregate;

[0030] S53, three-stage washing: the 0-5mm recycled aggregate obtained in steps S42 and S52 is sequentially washed and dehydrated by a water wheel washing machine and a dehydration screen to remove the fine powder and soil, and the final 0-5mm recycled fine aggregate is obtained.

[0031] The present application mixes and crushes the natural stone block with higher hardness and the waste concrete by using the above steps, the natural aggregate and the recycled aggregate hit, collide and rub with each other in the production process, the old mortar attached to the surface of the recycled aggregate can be removed, and the edges and corners of the recycled aggregate are polished, and the recycled coarse aggregate obtained has good particle shape, low needle and flake content, low old mortar content and small crushing index.

[0032] Preferably, the approximate calculation formula of the attached old mortar content of the recycled coarse aggregate produced by the recycled aggregate preparation method given by the present application is:

[0033] m a =A-0.48w+0.05w 2

[0034] In the formula, m a is the old mortar content of the recycled coarse aggregate, A is the attached old mortar content of the recycled coarse aggregate produced when no natural stone block is put into step S21, and w is the proportion of the natural stone block put into step S21.

[0035] Preferably, the approximate calculation formula of the needle and flake particle content of the recycled coarse aggregate produced by the recycled aggregate preparation method given by the present application is:

[0036] m b =B-0.14w-0.11w 2

[0037] In the formula, m b is the needle and flake particle content of the recycled coarse aggregate, B is the needle and flake particle content of the recycled coarse aggregate produced when no natural stone block is put into step S21, and w is the proportion of the natural stone block put into step S21.

[0038] By using the above steps, the present application produces the recycled aggregate with low micro powder content, low mud block content, low impurity content and high aggregate quality through multi-stage crushing, screening, flushing and iron removal in the production process.

[0039] Preferably, when the natural stone block put into step S2 is granite, and the mass proportion of the granite is 30% to 50%, the quality of the recycled aggregate produced by the method is as follows:

[0040] The 0-5mm recycled fine aggregate has a particle gradation of 2-zone medium sand, a micro powder content of <7%, a mud block content of <2%, a crushing index of <20%, an apparent density of >2450kg / m 3 , a bulk density of >1350kg / m 3 , a porosity of <45%, and the overall performance reaches the standard of type II recycled fine aggregate specified in GB / T25176. When the original strength of the waste concrete is high and the impurity content is low, the recycled fine aggregate can reach the standard of type I recycled fine aggregate specified in GB / T25176.

[0041] 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle flake content is <10%, the crushing index is <18%, and the apparent density is >2450kg / m 3 , the porosity is <45%, and the overall performance meets the II type recycled coarse aggregate standard specified in GB / T 25177. When the original strength of the waste concrete is higher and the impurity content is less, the I type recycled coarse aggregate standard specified in GB / T 25177 can be reached.

[0042] Preferably, when the natural stone blocks put in step S2 are quartzite, and the mass ratio of quartzite is 30%-50%, the quality of the aggregate produced by the method is as follows:

[0043] 0-5mm recycled fine aggregate: the particle size distribution is 2-zone medium sand, the powder content is <7%, the mud content is <2%, the crushing index is <22%, and the apparent density is >2400kg / m 3 , the bulk density is >1320kg / m 3 , the porosity is <47%, and the overall performance meets the II type recycled fine aggregate standard specified in GB / T 25176. When the original strength of the waste concrete is higher and the impurity content is less, the I type recycled fine aggregate standard specified in GB / T 25176 can be reached.

[0044] 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle flake content is <10%, the crushing index is <20%, and the apparent density is >2430kg / m 3 , the porosity is <47%, and the overall performance meets the II type recycled coarse aggregate standard specified in GB / T 25177. When the original strength of the waste concrete is higher and the impurity content is less, the I type recycled coarse aggregate standard specified in GB / T 25177 can be reached.

[0045] Preferably, when the natural stone blocks put in step S2 are limestone, and the mass ratio of limestone is 30%-50%, the quality of the aggregate produced by the method is as follows:

[0046] 0-5mm recycled fine aggregate: the particle size distribution is 2-zone medium sand, the powder content is <7%, the mud content is <2%, the crushing index is <25%, and the apparent density is >2350kg / m 3 , the bulk density is >1300kg / m 3, porosity < 48%, the overall performance reaches the II type recycled fine aggregate standard stipulated in GB / T25176. When the original strength of the waste concrete is higher and the impurity content is less, the I type recycled fine aggregate standard stipulated in GB / T25176 can be reached.

[0047] 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the micro powder content is < 2%, the mud content is < 0.7%, the water absorption is < 5%, the needle flake content is < 10%, the crushing index is < 20%, and the apparent density is > 2400kg / m 3 , porosity < 50%, the overall performance reaches the II type recycled coarse aggregate standard stipulated in GB / T 25177. When the original strength of the waste concrete is higher and the impurity content is less, the I type recycled coarse aggregate standard stipulated in GB / T 25177 can be reached.

[0048] A full recycled concrete made of the recycled aggregate produced according to the method given in the application comprises the following components in weight parts: cement 210-450 parts, fly ash 0-110 parts, slag powder 0-160 parts, recycled coarse aggregate 930-1250 parts, recycled fine aggregate 660-950 parts, water 150-210 parts, and water reducing agent 2.5-7.0 parts. The cement is P·O42.5 ordinary portland cement, the fly ash is F type I or II grade fly ash, the water reducing agent is one or any combination of polycarboxylic acid water reducing agent, naphthalene water reducing agent or amino water reducing agent, and the water reduction rate is greater than 25%.

[0049] A full recycled concrete preparation method made of the recycled aggregate produced according to the method given in the application, and the specific steps are as follows:

[0050] S100, the cement, fly ash, slag powder, recycled coarse aggregate and recycled fine aggregate are mixed and stirred for 15-45s to obtain material A;

[0051] S200, the water and the water reducing agent are mixed and stirred uniformly, and then are mixed with the material A obtained in step S100 and stirred for 90-180s, to obtain the concrete.

[0052] Compared with the prior art, the beneficial effects of the application include at least one of the following:

[0053] (1) The recycled aggregate obtained by the production method has good particle shape, low needle flake content, low old mortar content and small crushing index, and the strength of the recycled aggregate is equivalent to that of pure natural aggregate.

[0054] (2) The production process of the recycled aggregate production method is simple, has high automation degree, low energy consumption and high economic benefit.

[0055] (3) The recycled aggregate produced by the method can replace natural aggregate to prepare green recycled concrete with a high replacement rate, and has a wide range of applications.

[0056] (4) The method can recycle waste concrete and reduce the land resources occupied by waste concrete landfill.

[0057] (5) The method realizes 100% replacement of natural aggregate with recycled aggregate, reduces natural sandstone mining, protects the ecological environment, and has significant social, environmental and economic benefits.

[0058] (6) The method has simple and efficient process, no special requirements for equipment, and basically consistent operation method with ordinary commercial concrete, and is convenient for industrialized and large-scale production. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0060] The specific implementation of the present application will be described in detail below with specific examples.

[0061] A method for preparing recycled aggregate for concrete, comprising the following steps:

[0062] S1, sorting: using a machine or manual sorting method to remove plastic, wood, glass, paper, textiles and metal impurities in the waste concrete blocks;

[0063] S2, waste concrete pretreatment: synchronously pretreating the waste concrete blocks and natural stone blocks by primary crushing, primary screening, primary washing, secondary crushing and secondary washing to obtain 0-50mm recycled aggregate, and the specific steps include:

[0064] S21, primary crushing: using a loader to simultaneously feed the waste concrete blocks and natural stone blocks (such as magma rock, metamorphic rock, sedimentary rock, etc.) into a jaw crusher, the ratio of the waste concrete blocks to the natural stone blocks is 9:1-5:5, and the particle size of the discharged material is 0-100mm;

[0065] S22, primary screening: feeding the recycled aggregate obtained in step S21 into a roller multifunctional cylindrical screen to separate out the waste concrete blocks and natural stone blocks with a particle size greater than 50mm, the 0-50mm recycled aggregate, the micro powder and the soil;

[0066] S23, primary washing: the 0-50 mm aggregate is put into a water wheel washing machine and a dehydration screen to remove the powder and soil in the aggregate;

[0067] S24, secondary crushing: the waste concrete blocks and natural stone blocks with a particle size greater than 50 mm obtained in step S22 are put into a hammer crusher or an impact crusher for secondary crushing, and the particle size of the output is 0-50 mm;

[0068] S25, secondary washing: the 0-50 mm aggregate obtained in step S24 is sequentially washed and dehydrated by a water wheel washing machine and a dehydration screen to remove the powder and soil.

[0069] S3, multi-stage treatment of waste concrete: the pretreated recycled aggregate obtained in step S2 is subjected to primary iron removal, secondary screening, secondary iron removal, and tertiary screening to obtain 0-5 mm, 5-31.5 mm, and 31.5-50 mm recycled aggregates after multi-stage treatment, and the specific steps include:

[0070] S31, primary iron removal: the 0-50 mm recycled aggregate obtained in steps S23 and S25 is subjected to iron absorption to remove metal impurities.

[0071] S32, secondary screening: the 0-50 mm recycled aggregate obtained in step S31 is put into a dust-free screen to remove the powder and soil in the aggregate, and 0-50 mm recycled aggregate is obtained after screening;

[0072] S33, secondary iron removal: the 0-50 mm recycled aggregate obtained in step S32 is subjected to iron absorption to remove metal impurities.

[0073] S34, tertiary screening: the 0-50 mm recycled aggregate obtained in step S33 is put into a vibrating screen, and after screening, 0-5 mm, 5-31.5 mm, and 31.5-50 mm recycled aggregates after multi-stage treatment are obtained;

[0074] S4, preparation of recycled coarse aggregate: the 5-31.5 mm recycled aggregate obtained in step S3 is subjected to primary shaping and four-stage screening to obtain 0-5 mm recycled aggregate as a screen residue and 5-31.5 mm recycled coarse aggregate as a final product, and the specific steps include:

[0075] S41, primary shaping: the 5-31.5 mm coarse aggregate obtained in step S34 is put into a disc grinder for grinding and shaping to obtain 0-31.5 mm aggregate after shaping;

[0076] S42, four-stage screening: the 0-31.5 mm aggregate obtained in step S41 is put into a vibrating screen to obtain 0-5 mm recycled aggregate as a screen residue and 5-31.5 mm recycled coarse aggregate as a final product;

[0077] S5, preparation of recycled fine aggregate: the 0-5mm, 31.5-50mm recycled aggregate obtained in step S3 and the 0-5mm recycled aggregate obtained in step S4 are subjected to three-stage crushing, five-stage screening and three-stage washing to obtain the final 0-5mm recycled fine aggregate, and the specific steps include:

[0078] S51, three-stage crushing: the 31.5-50mm recycled aggregate obtained in step S34 is put into an impact sand making machine, and after crushing, 0-5mm recycled aggregate is obtained;

[0079] S52, five-stage screening: the 0-5mm recycled aggregate obtained in step S51 is put into a vibrating screen to remove the powder and soil in the aggregate.

[0080] S53, three-stage washing: the 0-5mm recycled aggregate obtained in steps S42 and S52 is sequentially washed and dehydrated by a water wheel washing machine and a dehydration screen to remove the powder and soil, and the final 0-5mm recycled fine aggregate is obtained.

[0081] As a preferred embodiment of the present application, a certain proportion of natural stone blocks with higher hardness (such as magmatic rocks like granite, metamorphic rocks like quartzite, and sedimentary rocks like limestone) are put into step S21, and the natural aggregate obtained by crushing the natural stone blocks is used to mechanically strengthen the recycled aggregate, that is, the natural aggregate and the recycled aggregate collide and rub against each other in the subsequent process to remove the old mortar with low strength attached to the surface of the recycled aggregate, and at the same time, the edges and corners of the recycled aggregate are polished to improve the performance of the recycled aggregate.

[0082] As a preferred embodiment of the present application, when no natural stone blocks are put into step S21, only a batch of recycled aggregate is produced from waste concrete, and the high-temperature heat treatment method is used to measure that the attached old mortar content A is 34.75%. When the natural limestone blocks with a mass ratio w=30% are put into step S21, and mixed with 70% waste concrete to produce a batch of recycled aggregate, the high-temperature heat treatment method is used to measure that the attached old mortar content is 21.09%. The attached old mortar content m is approximately calculated by the following formula: a :

[0083] m a = A-0.49w+0.06w 2 = 34.75%-0.49x0.3+0.06x0.3 2 = 20.59%

[0084] The calculated value and the experimental value differ by 0.5%.

[0085] When the natural stone blocks with a mass ratio w=50% are put into step S21, a batch of recycled aggregate is produced by mixing and crushing the waste concrete with a mass ratio of 50%, and the attached old mortar content is 12.39% measured by high-temperature heat treatment. The attached old mortar content m is approximately calculated by the following formula a is:

[0086] m a =A-0.49w+0.06w 2 =34.75%-0.49*0.5+0.06*0.5 2 =11.75%

[0087] The difference between the calculated value and the experimental value is 0.64%.

[0088] As a preferred embodiment of the present application, when the natural stone blocks are not put into step S21, a batch of recycled aggregate is produced by only using the waste concrete, and the needle and flake particle content B is 10.2% measured according to the needle and flake particle content test method specified in GB / T14685. When the natural stone blocks with a mass ratio w=30% are put into step S21, a batch of recycled aggregate is produced by mixing and crushing the waste concrete with a mass ratio of 70%, and the needle and flake particle content is 4.8% measured according to the needle and flake particle content test method specified in GB / T14685. The needle and flake particle content m is approximately calculated by the following formula b is:

[0089] m b =B-0.14w-0.11w 2 =10.2%-0.14*0.3-0.11*0.3 2 =5.01%

[0090] The difference between the calculated value and the experimental value is 0.21%.

[0091] When the natural stone blocks with a mass ratio w=50% are put into step S21, a batch of recycled aggregate is produced by mixing and crushing the waste concrete with a mass ratio of 50%, and the needle and flake particle content is 0.3% measured according to the needle and flake particle content test method specified in GB / T14685. The needle and flake particle content m is approximately calculated by the following formula b is:

[0092] m b =B-0.14w-0.11w 2 =10.2%-0.14*0.5-0.11*0.5 2 =0.45%

[0093] The difference between the calculated value and the experimental value is 0.15%.

[0094] As another preferred embodiment of the present application, when the natural granite stone blocks with a mass ratio of 50% are put into step S21, the quality of the aggregate produced by the method is as follows:

[0095] 0-5mm recycled fine aggregate: the particle size distribution is 2-zone medium sand, the micro powder content is <7%, the mud content is <2%, the crushing index is <20%, the apparent density is >2450kg / m 3 , the bulk density is >1350kg / m 3 , the porosity is <45%, and the overall performance meets the II-class recycled fine aggregate standard specified in GB / T25176. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled fine aggregate standard specified in GB / T25176 can be met.

[0096] 5-31.5mm recycled coarse aggregate: the particle size distribution meets the 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle and flake content is <10%, the crushing index is <18%, the apparent density is >2450kg / m 3 , the porosity is <45%, and the overall performance meets the II-class recycled coarse aggregate standard specified in GB / T 25177. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled coarse aggregate standard specified in GB / T 25177 can be met.

[0097] As another preferred embodiment of the present application, when the natural quartzite stone blocks with a mass ratio of 50% are put into step S21, the quality of the aggregate produced by the method is as follows:

[0098] 0-5mm recycled fine aggregate: the particle size distribution is 2-zone medium sand, the micro powder content is <7%, the mud content is <2%, the crushing index is <22%, the apparent density is >2400kg / m 3 , the bulk density is >1320kg / m 3 , the porosity is <47%, and the overall performance meets the II-class recycled fine aggregate standard specified in GB / T25176. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled fine aggregate standard specified in GB / T25176 can be met.

[0099] 5-31.5mm recycled coarse aggregate: the particle size distribution meets the 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle and flake content is <10%, the crushing index is <20%, the apparent density is >2430kg / m 3 , the porosity is <47%, and the overall performance meets the II-class recycled coarse aggregate standard specified in GB / T 25177. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled coarse aggregate standard specified in GB / T 25177 can be met.

[0100] As another preferred embodiment of the present application, when the natural limestone blocks with a mass ratio of 50% are put into step S21, the quality of the aggregate produced by the method is as follows:

[0101] 0-5mm recycled fine aggregate: the particle size distribution is 2-zone medium sand, the micro powder content is <7%, the mud content is <2%, the crushing index is <25%, the apparent density is >2350kg / m 3 , the bulk density is >1300kg / m 3 , the porosity is <48%, and the overall performance meets the II-class recycled fine aggregate standard specified in GB / T25176. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled fine aggregate standard specified in GB / T25176 can be met.

[0102] 5-31.5mm recycled coarse aggregate: the particle size distribution meets the 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle and flake content is <10%, the crushing index is <20%, and the apparent density is >2400kg / m 3 , the porosity is <50%, and the overall performance meets the II-class recycled coarse aggregate standard specified in GB / T 25177. When the original strength of the waste concrete is high and the impurity content is low, the I-class recycled coarse aggregate standard specified in GB / T 25177 can be met.

[0103] A kind of green recycled concrete is prepared by the recycled aggregate obtained by the preparation method provided by the present application, and the preparation method comprises the following steps:

[0104] (1) The performance index of recycled coarse aggregate is detected according to GB / T25177, and the recycled coarse aggregate for preparing recycled concrete needs to meet the requirements of I-class or II-class aggregate;

[0105] (2) The performance index of recycled fine aggregate is detected according to GB / T25176, and the recycled fine aggregate for preparing recycled concrete needs to meet the requirements of I-class or II-class aggregate;

[0106] (3) The mixing proportion of full recycled concrete is as shown in Table 1:

[0107] Table 1 Full recycled concrete mixing proportion

[0108]

[0109]

[0110] Among them, the cement is P·O42.5 ordinary portland cement, the fly ash is F-class I-grade fly ash, and the water reducing agent is polycarboxylic acid water reducing agent. According to the data provided by the manufacturer, the tax reduction rate is 30%.

[0111] (4) The full recycled concrete mixing methods of the first group, the second group, the third group and the fourth group are as follows:

[0112] 1) Cement, fly ash, recycled coarse aggregate and recycled fine aggregate are mixed and stirred for 15-45s (preferably 30s) to obtain material A;

[0113] 2) Water and water reducing agent are mixed and stirred uniformly, and then mixed with the material A obtained in step 1) and stirred for 90-180s (preferably 120s) to obtain the full recycled concrete.

[0114] The performance test methods of the full recycled concrete of each group prepared above are as follows:

[0115] The immediate slump and 30min slump of the full recycled concrete mixture of each group are determined according to GB / T50080 "Standard Test Methods for Properties of Ordinary Concrete Mixtures".

[0116] According to GB / T 50081 "Standard Test Methods for Physical and Mechanical Properties of Concrete", two groups of 150mmx150mmx150mm cubic standard test blocks are prepared for each group of mix proportion, and the compressive strength of each group of test blocks after 7-day and 28-day curing is determined.

[0117] The slump and compressive strength determination results of the concrete of each group above are shown in Table 2:

[0118] Table 2: Compressive strength and slump determination results of each group of full recycled concrete mix proportion (Mpa)

[0119] Group First group Second group Third group Fourth group Initial slump (mm) 200 210 205 200 30 min slump (mm) 180 185 185 180 7-day compressive strength (Mpa) 21.7 26.9 32.3 36.4 28-day compressive strength (Mpa) 28.6 34.9 40.5 45.5

[0120] As can be seen from the results in Table 2, the fluidity of each group of full recycled concrete is good, which can meet the requirements of conventional construction. The compressive strengths of the first group to the fourth group of mix proportion reach C20, C25, C30 and C35 respectively.

[0121] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing recycled aggregates for concrete, characterized by, The specific steps are as follows: S1, sorting: removing impurities in the waste concrete block by machine or manual method; S2, waste concrete pretreatment: synchronously crushing, screening, washing, crushing and washing the waste concrete block and the natural stone block to obtain the pretreated 0-50mm recycled aggregate; In step S2, the waste concrete block and the natural stone block are synchronously crushed, screened, washed, crushed and washed to obtain the pretreated 0-50mm recycled aggregate, and the specific steps are as follows: S21, primary crushing: the waste concrete block and the natural stone block are simultaneously put into the jaw crusher by the loader, and the weight ratio of the waste concrete block to the natural stone block is 9:1-5:5; S22, primary screening: the recycled aggregate obtained in step S21 is sent into the roller multifunctional cylindrical screen to separate the waste concrete block and the natural stone block with a particle size greater than 50mm, the 0-50mm recycled aggregate, the micro powder and the soil; S23, primary washing: the 0-50mm recycled aggregate is washed and dehydrated by the water wheel washing machine and the dehydration screen to remove the micro powder and the soil; S24, secondary crushing: the waste concrete block and the natural stone block with a particle size greater than 50mm obtained in step S22 are put into the hammer crusher or the impact crusher for secondary crushing, and the particle size of the discharged material is 0-50mm; S25, secondary washing: the 0-50mm aggregate obtained in step S24 is sequentially washed and dehydrated by the water wheel washing machine and the dehydration screen to remove the micro powder and the soil; S3, multi-stage treatment of waste concrete: the pretreated recycled aggregate obtained in step S2 is subjected to primary iron removal, secondary screening, secondary iron removal and tertiary screening to obtain the 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate after multi-stage treatment; S4, preparation of recycled coarse aggregate: the 5-31.5mm recycled aggregate obtained in step S3 is subjected to primary shaping and four-stage screening to obtain the 0-5mm recycled aggregate as the screen residue and the final 5-31.5mm recycled coarse aggregate; S5, preparation of recycled fine aggregate: the 0-5mm, 31.5-50mm recycled aggregate obtained in step S3 and the 0-5mm recycled aggregate obtained in step S4 are subjected to three-stage crushing, five-stage screening and three-stage washing to obtain the final 0-5mm recycled fine aggregate.

2. A method of producing recycled aggregates for concrete according to claim 1, characterized in that, In step S1, the impurities in the waste concrete block are removed by machine or manual method, and the specific steps are as follows: the plastic, wood, glass, paper, textile and metal impurities in the waste concrete block are removed by machine or manual sorting method.

3. A method of producing recycled aggregates for concrete according to claim 1, characterized in that, In step S3, the pretreated 0-50mm recycled aggregate obtained in step S2 is subjected to primary iron removal, secondary screening, secondary iron removal and tertiary screening to obtain the 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate after multi-stage treatment, and the specific steps are as follows: S31, primary iron removal: the 0-50mm recycled aggregate obtained in steps S23 and S25 is removed by the iron absorption device to remove the metal impurities; S32, secondary screening: the 0-50mm recycled aggregate obtained in step S31 is put into a dust-free sieve to remove the fine powder and soil in the aggregate, and after screening, the 0-50mm recycled aggregate is obtained; S33, secondary iron removal: the 0-50mm recycled aggregate obtained in step S32 is passed through an iron absorption device to remove metal impurities; S34, tertiary screening: the 0-50mm recycled aggregate obtained in step S33 is put into a vibrating screen, and after screening, the 0-5mm, 5-31.5mm and 31.5-50mm recycled aggregate after multi-stage processing is obtained.

4. The method for preparing recycled aggregate for concrete according to claim 1, characterized in that, In step S4, the 5-31.5mm recycled aggregate obtained in step S3 is subjected to primary shaping and four-stage screening to obtain the 0-5mm recycled aggregate and the final 5-31.5mm recycled coarse aggregate, and the specific steps are as follows: S41, primary shaping: the 5-31.5mm coarse aggregate obtained in step S34 is put into a disc grinder for grinding and shaping to obtain the 0-31.5mm aggregate after shaping; S42, four-stage screening: the 0-31.5mm aggregate obtained in step S41 is put into a vibrating screen to obtain the 0-5mm recycled aggregate and the final 5-31.5mm recycled coarse aggregate.

5. The method for preparing recycled aggregate for concrete according to claim 1, characterized in that, In step S5, the 0-5mm, 31.5-50mm recycled aggregate obtained in step S3 and the 0-5mm recycled aggregate obtained in step S4 are subjected to three-stage crushing, five-stage screening and three-stage washing to obtain the final 0-5mm recycled fine aggregate, and the specific steps are as follows: S51, three-stage crushing: the 31.5-50mm recycled aggregate obtained in step S34 is put into an impact sand making machine, and after crushing, the 0-5mm recycled aggregate is obtained; S52, five-stage screening: the 0-5mm recycled aggregate obtained in step S51 is put into a vibrating screen to remove the fine powder and soil in the aggregate; S53, three-stage washing: the 0-5mm recycled aggregate obtained in steps S42 and S52 is sequentially washed and dehydrated by a water wheel washing machine and a dehydration screen to remove the fine powder and soil, and the final 0-5mm recycled fine aggregate is obtained.

6. A method of producing recycled aggregates for concrete as claimed in claim 1, wherein: The content of the attached old mortar of the recycled coarse aggregate can be approximately calculated by formula (1): m a = A - 0.49w + 0.06w 2 (1) In the formula, m a is the old mortar content of the recycled coarse aggregate, A is the attached old mortar content of the recycled coarse aggregate produced when no natural stone blocks are fed in step S21, and w is the mass proportion of the natural stone blocks fed in step S21 to the total amount fed.

7. A method of producing recycled aggregates for concrete according to claim 1, characterized in that: The content of the needle-like particles of the recycled coarse aggregate can be approximately calculated by formula (2): m b = B - 0.14w - 0.11w 2 (2) In the formula, m b is the needle and flake particle content of the recycled coarse aggregate, B is the needle and flake particle content of the recycled coarse aggregate produced when no natural stone is put into step S21, and w is the mass proportion of the natural stone put into step S21 to the total amount of input.

8. The method for preparing recycled aggregate for concrete according to claim 1, characterized in that, When the natural stone blocks put in step S2 are granite, and the mass ratio of granite is 30%-50%, the quality of the recycled aggregate produced by this method is as follows: 0~5mm recycled fine aggregate: particle gradation is 2-zone medium sand, micro powder content <7%, mud content <2%, crushing index <20%, apparent density >2450kg / m 3 , bulk density >1350kg / m 3 , porosity <45%, overall performance reaches the standard of type II recycled fine aggregate specified in GB / T25176; 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle flake content is <10%, the crushing index is <18%, and the apparent density is >2450kg / m 3 , the porosity is <45%, and the overall performance meets the II type recycled coarse aggregate standard specified in GB / T 25177.

9. A method for preparing recycled aggregate for concrete according to claim 1, characterized in that, When the natural stone blocks put in step S2 are quartzite, and the mass ratio of quartzite is 30%-50%, the quality of the recycled aggregate produced by this method is as follows: 0~5mm recycled fine aggregate: particle gradation is 2-zone medium sand, micro powder content <7%, mud content <2%, crushing index <22%, apparent density >2400kg / m 3 , bulk density >1320kg / m 3 , porosity <47%, overall performance reaches the standard of type II recycled fine aggregate specified in GB / T25176; 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle flake content is <10%, the crushing index is <20%, and the apparent density is >2430kg / m 3 , the porosity is <47%, and the overall performance meets the II type recycled coarse aggregate standard specified in GB / T 25177.

10. A method for preparing recycled aggregate for concrete according to claim 1, characterized in that, When the natural stone blocks put in step S2 are limestone, and the mass ratio of limestone is 30%-50%, the quality of the recycled aggregate produced by this method is as follows: 0~5mm recycled fine aggregate: particle gradation is 2-zone medium sand, micro powder content <7%, mud content <2%, crushing index <25%, apparent density >2350kg / m 3 , bulk density >1300kg / m 3 , porosity <48%, overall performance reaches the standard of type II recycled fine aggregate specified in GB / T25176; 5-31.5mm recycled coarse aggregate: the particle size distribution meets 5-31.5mm continuous particle size, the micro powder content is <2%, the mud content is <0.7%, the water absorption is <5%, the needle flake content is <10%, the crushing index is <20%, the apparent density is >2400kg / m 3 , the porosity is <50%, and the overall performance meets the II type recycled coarse aggregate standard specified in GB / T 25177.

11. A full recycled concrete made of recycled aggregates prepared by the method according to any one of claims 1 to 6, characterized in that, The cement 210-450 parts, fly ash 0-110 parts, slag powder 0-160 parts, recycled coarse aggregate 930-1250 parts, recycled fine aggregate 660-950 parts, water 150-210 parts, water reducing agent 2.5-7.0 parts, the cement adopts P.O42.5 ordinary portland cement, the fly ash adopts F class I or II grade fly ash, the water reducing agent adopts one or any combination of polycarboxylic acid water reducing agent, naphthalene water reducing agent or amino water reducing agent, and the water reducing rate is greater than 25%.

12. A method of producing the fully recycled concrete as claimed in claim 11, characterized in that, The specific steps are as follows: S100, the cement, fly ash, slag powder, recycled coarse aggregate, recycled fine aggregate are mixed and stirred for 15-45s to obtain material A; S200, water and water reducing agent are mixed and stirred uniformly, and are mixed with the material A obtained in step S100, and are stirred for 90-180s to obtain the full recycled concrete.

Images