A concrete containing recycled aggregates and a method for producing the same

Abstract

The application relates to the technical field of concrete, and particularly discloses a concrete containing recycled aggregate, which comprises the following components: water, cement, fly ash, fine sand, modified recycled aggregate, gravel and water reducing agent; and the modification method of the modified recycled aggregate comprises the following steps: 1) preparing a liquid culture medium and a modification liquid; 2) adding heat-loving streptococcus lactis, bacillus subtilis and azotobacter chroococcum to obtain a bacterial suspension; 3) putting the recycled aggregate into the bacterial suspension for soaking, filtering out the recycled aggregate to obtain pretreated recycled aggregate; and 4) culturing the pretreated recycled aggregate at a temperature of 25-30 DEG C and a relative humidity of 80-95% for 7-10 days, and then drying to obtain the modified recycled aggregate; the application has the advantages that the negative influence of the recycled aggregate on the strength of the concrete is reduced, the accumulated waste concrete solid can be better digested, the application is more friendly to the environment, and the environmental pollution can be better reduced.

Description

Technical Field

[0001] The present invention relates to the field of concrete, in particular to concrete containing recycled aggregate and a preparation method thereof. Background Art

[0002] Concrete is a composite material that is made by cementing aggregates into a whole. It mainly includes raw materials such as cement, sand, stone, and water. Sand and stone are aggregates. By adding aggregates, the use of cement can be greatly reduced, which reduces the cost of concrete and improves the physical properties of concrete.

[0003] Usually, aggregates are mainly made of natural sand and stone. However, with the increasing number of concrete buildings, the renewal and iteration of concrete buildings have brought about a large amount of waste concrete solids. Concrete solids are difficult to degrade naturally, and a large amount of waste concrete will cause environmental pollution. In order to make full use of waste concrete, the waste concrete will be crushed and used as recycled aggregate. By partially adding recycled aggregate, the consumption of natural stone can be reduced. At the same time, the accumulation of waste concrete can be reduced, which can reduce costs and environmental pollution, making the application of recycled aggregate more and more extensive.

[0004] However, the main component of recycled aggregate is concrete solid. During the crushing process of concrete solid, the original pores and fine lines will be further expanded under the action of external force, resulting in significantly more cracks on the surface of recycled aggregate than natural crushed stone, making the recycled aggregate have a higher water absorption rate and lower bearing capacity. As a result, after the recycled aggregate is added to the fresh concrete, the strength of the concrete after curing will decrease. The higher the amount of recycled aggregate added, the more obvious the strength decrease. In order to avoid serious impact on the quality of concrete, the existing recycled aggregate can usually only be used in small amounts, making it difficult to fully utilize the recycled aggregate. Therefore, there is still room for improvement. Summary of the Invention

[0005] In order to reduce the negative impact of recycled aggregate on concrete strength, the present application provides concrete containing recycled aggregate and a preparation method thereof.

[0006] In a first aspect, the present application provides a concrete containing recycled aggregate, which adopts the following technical solution:

[0007] A concrete containing recycled aggregate, comprising the following components in parts by mass:

[0008] 153-157 parts water;

[0009] 293-297 parts of cement;

[0010] 40-42 parts of fly ash;

[0011] 750-760 parts of fine sand;

[0012] 600-610 parts of modified recycled aggregate;

[0013] 500-510 parts of crushed stone;

[0014] 2.3-2.4 parts of water reducer;

[0015] The modification method of the modified recycled aggregate is as follows:

[0016] Step 1), preparing liquid culture medium and modifying solution;

[0017] Step 2) adding thermophilic lactic acid streptococci, Bacillus subtilis, and vine nitrogen-fixing bacteria into a liquid culture medium and culturing the culture medium until the OD value is ≥1 to obtain a bacterial suspension;

[0018] Step 3), putting the regenerated aggregate into the bacterial suspension, soaking for 24-48 hours, filtering out the regenerated aggregate, and obtaining pretreated regenerated aggregate;

[0019] Step 4) The pretreated recycled aggregate is cultured at a constant temperature of 25-30° C. and a relative humidity of 80-95% for 7-10 days, and dried to obtain modified recycled aggregate. During the constant temperature culture process, the modified liquid is sprayed onto the surface of the pretreated recycled aggregate to wet the surface of the pretreated recycled aggregate.

[0020] The liquid culture medium is a compound of water, cauliflower juice, cauliflower juice, glucose, corn flour, potassium dihydrogen phosphate, and magnesium sulfate; the modified liquid is a compound of water, cauliflower juice, cauliflower juice, glucose, corn flour, potassium dihydrogen phosphate, magnesium sulfate, and calcium chloride.

[0021] By adopting the above technical solution, the recycled aggregate is placed in a bacterial suspension, so that thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria grow and multiply on the surface and in the gaps of the recycled aggregate to form a biofilm. Then, by spraying a modified liquid, a calcium source and nutrients are provided to the thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria. Through the mutual cooperation of the thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria and the metabolic action of the thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria, calcium carbonate is deposited on the surface and in the gaps of the recycled aggregate. The gaps in the recycled aggregate are filled with calcium carbonate, so that the surface of the recycled aggregate is repaired, the water absorption rate is reduced, and the compressive strength of the recycled aggregate is increased. In addition, the deposition of calcium carbonate on the surface of the recycled aggregate can increase the surface roughness of the recycled aggregate, thereby increasing the bonding strength with cement. Therefore, when a large amount of recycled aggregate is added, it will not have a negative impact on the strength of concrete, and can also improve the strength of the concrete after curing to a certain extent, thereby having high application value.

[0022] The effect of calcium carbonate deposition is better through the combination of thermophilic lactococcus, Bacillus subtilis and brown nitrogen-fixing bacteria. The cooperation of each bacteria can effectively improve the activity of each bacteria and quickly form a biofilm covering the recycled aggregate, thereby achieving a better effect of calcium carbonate deposition on the surface of the recycled aggregate.

[0023] By adding Echeveria juice and Melasma fruit juice to the liquid culture medium and the modified liquid, the activity of thermophilic lactic acid streptococci, Bacillus subtilis and vine nitrogen-fixing bacteria can be well stimulated, so that thermophilic lactic acid streptococci, Bacillus subtilis and vine nitrogen-fixing bacteria can maintain a high activity state for a long time, so that the effect of rapid deposition of calcium carbonate can last longer, the effect of modification of recycled aggregate is better, and the quality of the concrete obtained is higher.

[0024] Preferably, in step 2), the input mass ratio of thermophilic lactic acid streptococcus, Bacillus subtilis, and vinelandia nitrogen-fixing bacteria is 2-3:1-2:1-2.

[0025] By adopting the above technical solution and specifically selecting the mass ratio of thermophilic lactococcus, Bacillus subtilis and vineyard nitrogen-fixing bacteria, the thermophilic lactococcus, Bacillus subtilis and vineyard nitrogen-fixing bacteria can cooperate with each other better, and can deposit calcium carbonate more quickly, so that the effect of using calcium carbonate to repair recycled aggregate is better, and the strength of concrete mixed with modified recycled aggregate is higher.

[0026] Preferably, in the liquid culture medium, the mass ratio of water, echeveria juice, mellea fruit juice, glucose, corn flour, potassium dihydrogen phosphate, and magnesium sulfate is 1000:60-70:50-60:25-35:8-12:0.8-1.2:0.4-0.6.

[0027] By adopting the above technical scheme and specifically selecting the addition amounts of Echeveria juice and Melasma fruit juice, the liquid culture medium can greatly improve the activity of thermophilic lactic acid streptococci, Bacillus subtilis, and vine nitrogen-fixing bacteria, thereby increasing the efficiency of preparing the bacterial suspension, increasing the activity of each bacterium in the prepared bacterial suspension, and achieving a better effect on the modification of recycled aggregates.

[0028] Preferably, in the modified liquid, the mass ratio of water, echeveria juice, mellea fruit juice, glucose, corn flour, potassium dihydrogen phosphate, magnesium sulfate, and calcium chloride is 1000:60-70:50-60:25-35:8-12:0.8-1.2:0.4-0.6:300-400.

[0029] By adopting the above technical scheme, the modified liquid can provide a sufficient calcium source, and with the combination of Echeveria juice and Melasma fruit juice, thermophilic lactic acid streptococci, Bacillus subtilis, and brown nitrogen-fixing bacteria can still maintain a high activity in a high concentration of calcium salt environment, so that the effect of depositing calcium carbonate to modify the recycled aggregate is better.

[0030] Preferably, in step 3), the recycled aggregate is put into the bacterial suspension and soaked for 30-42 hours.

[0031] By adopting the above technical solution and specifically selecting the soaking time, the effect of forming a biofilm on the surface of the recycled aggregate is better, while also saving time, being more efficient, and having higher economic value.

[0032] Preferably, in step 4), the pretreated recycled aggregate is cultured at a constant temperature of 27-29° C. and a relative humidity of 82-88% for 8-9 days.

[0033] By adopting the above technical solution, the modification effect of recycled aggregate is better, the efficiency is higher, time waste is reduced, and it has higher economic value.

[0034] Preferably, in step 4), the modifying liquid is sprayed onto the surface of the pretreated recycled aggregate every 24 hours, and the amount of each spraying is 1-2 liters of modifying liquid per ton of recycled aggregate.

[0035] By adopting the above technical solution and specifically selecting the spraying amount of the modifying liquid, sufficient calcium source and nutrients can be ensured while reducing the waste of the modifying liquid, achieving a better modification effect while better controlling costs and having higher economic value.

[0036] Preferably, in step 4), heating and drying are adopted during drying, and the drying temperature is ≥110°C.

[0037] By adopting the above technical solution, by specifically selecting the drying temperature and utilizing high temperature sterilization, the bacteria can be inactivated while drying, with high efficiency and safety.

[0038] In a second aspect, the present application provides a method for preparing concrete containing recycled aggregate, which adopts the following technical solution:

[0039] A method for preparing concrete containing recycled aggregate comprises the following steps:

[0040] Step 01), cement, fly ash, fine sand, modified recycled aggregate, crushed stone, and water reducing agent are uniformly mixed to obtain a mixture;

[0041] Step 02), adding water to the mixture and mixing evenly to obtain a concrete mixture;

[0042] Step 03), pouring the concrete mixture into a mold, curing, and demoulding to obtain concrete containing recycled aggregate.

[0043] By adopting the above technical solution, the concrete produced is mixed with a large amount of recycled aggregate, which can better digest the accumulated waste concrete solids, is more environmentally friendly, and can better reduce environmental pollution. After adding modified recycled aggregate, the strength of the concrete will be improved to a certain extent. While making full use of waste materials, the quality of the concrete can also be improved. This overcomes the technical defect of the existing recycled aggregate that the performance of the concrete decreases as the amount of mixed increases, and has high economic value.

[0044] In summary, this application has the following beneficial effects:

[0045] 1. The present application puts the recycled aggregate into a bacterial suspension, so that thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria grow and reproduce on the surface and in the gaps of the recycled aggregate to form a biofilm, and then provides a calcium source and nutrients for thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria by spraying a modified liquid. Through the cooperation of thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria, and the metabolic action of thermophilic lactic acid streptococci, Bacillus subtilis, and vineyard nitrogen-fixing bacteria, calcium carbonate is deposited on the surface and in the gaps of the recycled aggregate. The gaps of the recycled aggregate are filled with calcium carbonate, so that the surface of the recycled aggregate is repaired, the water absorption rate is reduced, and the compressive strength of the recycled aggregate is increased. In addition, the surface roughness of the recycled aggregate can be increased by depositing calcium carbonate on the surface of the recycled aggregate, thereby increasing the bonding strength with cement. Therefore, when a large amount of recycled aggregate is added, it will not have a negative impact on the strength of the concrete, and can also improve the strength of the concrete after curing to a certain extent, and has high application value.

[0046] 2. In the present application, it is preferred to use thermophilic lactic acid streptococci, Bacillus subtilis, and brown nitrogen-fixing bacteria to deposit calcium carbonate, and the cooperation of each bacterium can effectively improve the activity of each bacterium, and can quickly form a biofilm covering the recycled aggregate, thereby making the effect of calcium carbonate deposition on the surface of the recycled aggregate better.

[0047] 3. In the present application, preferably, by adding Echeveria juice and Melasma fruit juice to the liquid culture medium and the modified liquid, the activity of thermophilic lactic acid streptococci, Bacillus subtilis, and vine nitrogen-fixing bacteria can be well stimulated, so that thermophilic lactic acid streptococci, Bacillus subtilis, and vine nitrogen-fixing bacteria can maintain a high activity state for a long time, so that the effect of rapid deposition of calcium carbonate can last longer, the effect of modified recycled aggregate is better, and the quality of the obtained concrete is higher. DETAILED DESCRIPTION

[0048] The present application is further described in detail below with reference to the embodiments.

[0049] Example 1

[0050] A concrete containing recycled aggregate is prepared from the following components:

[0051] Water, cement, fly ash, fine sand, modified recycled aggregate, crushed stone, water reducing agent.

[0052] Among them, the cement is silicate cement, emollient cement, specification: P.O42.5R.

[0053] Among them, the fly ash is secondary fly ash, which was purchased from Baiyi Mineral Products Processing Plant in Lingshou County.

[0054] The fine sand is river sand, which is commercially available and has a mesh size of 20-40.

[0055] The crushed stone is basalt crushed stone, which is commercially available and has a particle size of 10-15 mm.

[0056] Among them, the water reducer is polycarboxylic acid water reducer, which was purchased from Jinan Quanchi New Materials Co., Ltd.

[0057] Among them, the modified recycled aggregate is made by modifying the recycled aggregate obtained by crushing waste concrete, and the particle size of the modified recycled aggregate is 15-20mm.

[0058] The modification methods of modified recycled aggregates are as follows:

[0059] Step 1) Prepare liquid culture medium and modifying solution as follows:

[0060] Step 1-1), weighing 1000kg water, 60kg echeveria juice, 50kg echeveria juice, 25kg glucose, 8kg corn flour, 0.8kg potassium dihydrogen phosphate, 0.4kg magnesium sulfate, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium; step 1-2), weighing 1000kg water, 60kg echeveria juice, 50kg echeveria juice, 25kg glucose, 8kg corn flour, 0.8kg potassium dihydrogen phosphate, 0.4kg magnesium sulfate, 300kg calcium chloride, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium.

[0061] Step 2) Weigh 1000 kg of liquid culture medium, add 2 g of thermophilic lactococci, 1 g of Bacillus subtilis, and 1 g of vine nitrogen-fixing bacteria into the liquid culture medium, stir continuously at 30 r / min, and culture at a constant temperature of 25-26° C. until the OD value is ≥1 to obtain a bacterial suspension.

[0062] Step 3), weighing 1000 kg of bacterial suspension, then putting 1000 kg of recycled aggregate into the bacterial suspension, keeping the temperature at 25° C., soaking for 24 hours, filtering out the recycled aggregate, and obtaining pretreated recycled aggregate.

[0063] Step 4) The pretreated recycled aggregate was cultured at a constant temperature of 25°C and a relative humidity of 80% for 7 days. During the constant temperature culture process, the modified liquid was sprayed onto the surface of the pretreated recycled aggregate every 24 hours. The spraying amount each time was 1L of modified liquid per 1000kg of recycled aggregate to moisten the surface of the pretreated recycled aggregate. After the constant temperature culture was completed, it was heated to 110°C and dried for 60 minutes to obtain the modified recycled aggregate.

[0064] The stone lotus juice is homemade. Fresh stone lotus is put into a wall breaking machine to crush it, filter it, and take the filtrate to obtain the stone lotus juice.

[0065] The radish juice is homemade. Fresh radish fruits are put into a wall-breaking machine to crush them, filter-pressed, and the filtrate is taken to obtain the radish juice.

[0066] Glucose was obtained from a commercial source with a CAS number of 50-99-7.

[0067] Corn flour was purchased from Xinghua Tiannong Fruit and Vegetable Food Co., Ltd.

[0068] Potassium dihydrogen phosphate was commercially available with CAS number: 7778-77-0.

[0069] Magnesium sulfate was commercially available with CAS number: 10034-99-8.

[0070] Calcium chloride was commercially available with CAS number: 10035-04-8.

[0071] Thermophilic lactic acid Streptococcus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D80073.

[0072] Bacillus subtilis was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50713.

[0073] Brown nitrogen-fixing bacteria were purchased from Shanghai Collection of Biotechnology Center with the strain number: SHBCC D81336.

[0074] The preparation method of concrete containing recycled aggregate is as follows:

[0075] Step 01), put 293kg cement, 40kg fly ash, 750kg fine sand, 600kg modified recycled aggregate, 500kg crushed stone, and 2.3kg water reducer into a stirring tank, rotate at 60r / min, stir for 8min, mix evenly, and obtain a mixture.

[0076] Step 02), add 153kg of water to the mixture, rotate at 45r / min, stir for 3min, mix evenly, and obtain a concrete mixture.

[0077] Step 03), pour the concrete mixture into a mold, sprinkle water and cure for 3 days, demould, and statically cure for 28 days to obtain concrete containing recycled aggregate.

[0078] Example 2

[0079] A concrete containing recycled aggregate is prepared from the following components:

[0080] Water, cement, fly ash, fine sand, modified recycled aggregate, crushed stone, water reducing agent.

[0081] Among them, the cement is silicate cement, emollient cement, specification: P.O42.5R.

[0082] Among them, the fly ash is secondary fly ash, which was purchased from Baiyi Mineral Products Processing Plant in Lingshou County.

[0083] The fine sand is river sand, which is commercially available and has a mesh size of 20-40.

[0084] The crushed stone is basalt crushed stone, which is commercially available and has a particle size of 10-15 mm.

[0085] Among them, the water reducer is polycarboxylic acid water reducer, which was purchased from Jinan Quanchi New Materials Co., Ltd.

[0086] Among them, the modified recycled aggregate is made by modifying the recycled aggregate obtained by crushing waste concrete, and the particle size of the modified recycled aggregate is 15-20mm.

[0087] The modification methods of modified recycled aggregates are as follows:

[0088] Step 1) Prepare liquid culture medium and modifying solution as follows:

[0089] Step 1-1), weighing 1000kg water, 62kg echeveria juice, 52kg echeveria juice, 28kg glucose, 9kg corn flour, 0.9kg potassium dihydrogen phosphate, 0.45kg magnesium sulfate, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium; step 1-2), weighing 1000kg water, 62kg echeveria juice, 52kg echeveria juice, 28kg glucose, 9kg corn flour, 0.9kg potassium dihydrogen phosphate, 0.45kg magnesium sulfate, 325kg calcium chloride, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium.

[0090] Step 2) Weigh 1000 kg of liquid culture medium, add 2.25 g of thermophilic lactococci, 1.25 g of Bacillus subtilis, and 1.25 g of vine nitrogen-fixing bacteria into the liquid culture medium, stir continuously at 30 r / min, and culture at a constant temperature of 25-26° C. until the OD value is ≥1 to obtain a bacterial suspension.

[0091] Step 3) Weigh 1000 kg of bacterial suspension, then put 1000 kg of recycled aggregate into the bacterial suspension, keep the temperature at 27° C., soak for 30 hours, filter out the recycled aggregate, and obtain pretreated recycled aggregate.

[0092] Step 4) The pretreated recycled aggregate was cultured at a constant temperature of 27°C and a relative humidity of 82% for 8 days. During the constant temperature culture process, the modified liquid was sprayed onto the surface of the pretreated recycled aggregate every 24 hours. The spraying amount each time was 1.25L of modified liquid per 1000kg of recycled aggregate to moisten the surface of the pretreated recycled aggregate. After the constant temperature culture was completed, it was heated to 110°C and dried for 60 minutes to obtain the modified recycled aggregate.

[0093] The stone lotus juice is homemade. Fresh stone lotus is put into a wall breaking machine to crush it, filter it, and take the filtrate to obtain the stone lotus juice.

[0094] The radish juice is homemade. Fresh radish fruits are put into a wall-breaking machine to crush them, filter-pressed, and the filtrate is taken to obtain the radish juice.

[0095] Glucose was obtained from a commercial source with a CAS number of 50-99-7.

[0096] Corn flour was purchased from Xinghua Tiannong Fruit and Vegetable Food Co., Ltd.

[0097] Potassium dihydrogen phosphate was commercially available with CAS number: 7778-77-0.

[0098] Magnesium sulfate was commercially available with CAS number: 10034-99-8.

[0099] Calcium chloride was commercially available with CAS number: 10035-04-8.

[0100] Thermophilic lactic acid Streptococcus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D80073.

[0101] Bacillus subtilis was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50713.

[0102] Brown nitrogen-fixing bacteria were purchased from Shanghai Collection of Biotechnology Center with the strain number: SHBCC D81336.

[0103] The preparation method of concrete containing recycled aggregate is as follows:

[0104] Step 01), 294kg cement, 40.5kg fly ash, 752kg fine sand, 602kg modified recycled aggregate, 502kg crushed stone, and 2.32kg water reducer are put into a stirring tank at a speed of 60r / min, stirred for 8min, and mixed evenly to obtain a mixture.

[0105] Step 02), add 154kg of water to the mixture, rotate at 45r / min, stir for 3min, mix evenly, and obtain a concrete mixture.

[0106] Step 03), pour the concrete mixture into a mold, sprinkle water and cure for 3 days, demould, and statically cure for 28 days to obtain concrete containing recycled aggregate.

[0107] Example 3

[0108] A concrete containing recycled aggregate is prepared from the following components:

[0109] Water, cement, fly ash, fine sand, modified recycled aggregate, crushed stone, water reducing agent.

[0110] Among them, the cement is silicate cement, emollient cement, specification: P.O42.5R.

[0111] Among them, the fly ash is secondary fly ash, which was purchased from Baiyi Mineral Products Processing Plant in Lingshou County.

[0112] The fine sand is river sand, which is commercially available and has a mesh size of 20-40.

[0113] The crushed stone is basalt crushed stone, which is commercially available and has a particle size of 10-15 mm.

[0114] Among them, the water reducer is polycarboxylic acid water reducer, which was purchased from Jinan Quanchi New Materials Co., Ltd.

[0115] Among them, the modified recycled aggregate is made by modifying the recycled aggregate obtained by crushing waste concrete, and the particle size of the modified recycled aggregate is 15-20mm.

[0116] The modification methods of modified recycled aggregates are as follows:

[0117] Step 1) Prepare liquid culture medium and modifying solution as follows:

[0118] Step 1-1), weighing 1000kg water, 65kg echeveria juice, 55kg echeveria juice, 30kg glucose, 10kg corn flour, 1kg potassium dihydrogen phosphate, 0.5kg magnesium sulfate, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium; step 1-2), weighing 1000kg water, 65kg echeveria juice, 55kg echeveria juice, 30kg glucose, 10kg corn flour, 1kg potassium dihydrogen phosphate, 0.5kg magnesium sulfate, 350kg calcium chloride, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium.

[0119] Step 2) Weigh 1000 kg of liquid culture medium, add 2.5 g of thermophilic lactic acid streptococci, 1.5 g of Bacillus subtilis, and 1.5 g of vine nitrogen-fixing bacteria into the liquid culture medium, stir continuously at 30 r / min, and culture at a constant temperature of 25-26° C. until the OD value is ≥1 to obtain a bacterial suspension.

[0120] Step 3) Weigh 1000 kg of bacterial suspension, then put 1000 kg of recycled aggregate into the bacterial suspension, keep the temperature at 28° C., soak for 36 hours, filter out the recycled aggregate, and obtain pretreated recycled aggregate.

[0121] Step 4) The pretreated recycled aggregate was cultured at a constant temperature of 28°C and a relative humidity of 85% for 8.5 days. During the constant temperature culture process, the modified liquid was sprayed onto the surface of the pretreated recycled aggregate every 24 hours. The spraying amount each time was 1.5L of modified liquid per 1000kg of recycled aggregate to moisten the surface of the pretreated recycled aggregate. After the constant temperature culture was completed, it was heated to 110°C and dried for 60 minutes to obtain the modified recycled aggregate.

[0122] The stone lotus juice is homemade. Fresh stone lotus is put into a wall breaking machine to crush it, filter it, and take the filtrate to obtain the stone lotus juice.

[0123] The radish juice is homemade. Fresh radish fruits are put into a wall-breaking machine to crush them, filter-pressed, and the filtrate is taken to obtain the radish juice.

[0124] Glucose was obtained from a commercial source with a CAS number of 50-99-7.

[0125] Corn flour was purchased from Xinghua Tiannong Fruit and Vegetable Food Co., Ltd.

[0126] Potassium dihydrogen phosphate was commercially available with CAS number: 7778-77-0.

[0127] Magnesium sulfate was commercially available with CAS number: 10034-99-8.

[0128] Calcium chloride was commercially available with CAS number: 10035-04-8.

[0129] Thermophilic lactic acid Streptococcus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D80073.

[0130] Bacillus subtilis was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50713.

[0131] Brown nitrogen-fixing bacteria were purchased from Shanghai Collection of Biotechnology Center with the strain number: SHBCC D81336.

[0132] The preparation method of concrete containing recycled aggregate is as follows:

[0133] Step 01), 295kg cement, 41kg fly ash, 755kg fine sand, 605kg modified recycled aggregate, 505kg crushed stone, and 2.35kg water reducer are put into a stirring tank at a speed of 60r / min, stirred for 8min, and mixed evenly to obtain a mixture.

[0134] Step 02), add 155kg of water to the mixture, rotate at 45r / min, stir for 3min, mix evenly, and obtain a concrete mixture.

[0135] Step 03), pour the concrete mixture into a mold, sprinkle water and cure for 3 days, demould, and statically cure for 28 days to obtain concrete containing recycled aggregate.

[0136] Example 4

[0137] A concrete containing recycled aggregate is prepared from the following components:

[0138] Water, cement, fly ash, fine sand, modified recycled aggregate, crushed stone, water reducing agent.

[0139] Among them, the cement is silicate cement, emollient cement, specification: P.O42.5R.

[0140] Among them, the fly ash is secondary fly ash, which was purchased from Baiyi Mineral Products Processing Plant in Lingshou County.

[0141] The fine sand is river sand, which is commercially available and has a mesh size of 20-40.

[0142] The crushed stone is basalt crushed stone, which is commercially available and has a particle size of 10-15 mm.

[0143] Among them, the water reducer is polycarboxylic acid water reducer, which was purchased from Jinan Quanchi New Materials Co., Ltd.

[0144] Among them, the modified recycled aggregate is made by modifying the recycled aggregate obtained by crushing waste concrete, and the particle size of the modified recycled aggregate is 15-20mm.

[0145] The modification methods of modified recycled aggregates are as follows:

[0146] Step 1) Prepare liquid culture medium and modifying solution as follows:

[0147] Step 1-1), weighing 1000kg water, 67kg echeveria juice, 57kg echeveria juice, 32kg glucose, 11kg corn flour, 1.1kg potassium dihydrogen phosphate, 0.55kg magnesium sulfate, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium; step 1-2), weighing 1000kg water, 67kg echeveria juice, 57kg echeveria juice, 32kg glucose, 11kg corn flour, 1.1kg potassium dihydrogen phosphate, 0.55kg magnesium sulfate, 375kg calcium chloride, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium.

[0148] Step 2) Weigh 1000 kg of liquid culture medium, add 2.75 g of thermophilic lactic acid streptococci, 1.75 g of Bacillus subtilis, and 1.75 g of vine nitrogen-fixing bacteria into the liquid culture medium, stir continuously at 30 r / min, and culture at a constant temperature of 25-26° C. until the OD value is ≥1 to obtain a bacterial suspension.

[0149] Step 3), weighing 1000 kg of bacterial suspension, then putting 1000 kg of recycled aggregate into the bacterial suspension, keeping the temperature at 29° C., soaking for 42 hours, filtering out the recycled aggregate, and obtaining pretreated recycled aggregate.

[0150] Step 4) The pretreated recycled aggregate was cultured at a constant temperature of 29°C and a relative humidity of 88% for 9 days. During the constant temperature culture process, the modified liquid was sprayed onto the surface of the pretreated recycled aggregate every 24 hours. The spraying amount each time was 1.75L of modified liquid per 1000kg of recycled aggregate to moisten the surface of the pretreated recycled aggregate. After the constant temperature culture was completed, it was heated to 110°C and dried for 60 minutes to obtain the modified recycled aggregate.

[0151] The stone lotus juice is homemade. Fresh stone lotus is put into a wall breaking machine to crush it, filter it, and take the filtrate to obtain the stone lotus juice.

[0152] The radish juice is homemade. Fresh radish fruits are put into a wall-breaking machine to crush them, filter-pressed, and the filtrate is taken to obtain the radish juice.

[0153] Glucose was obtained from a commercial source with a CAS number of 50-99-7.

[0154] Corn flour was purchased from Xinghua Tiannong Fruit and Vegetable Food Co., Ltd.

[0155] Potassium dihydrogen phosphate was commercially available with CAS number: 7778-77-0.

[0156] Magnesium sulfate was commercially available with CAS number: 10034-99-8.

[0157] Calcium chloride was commercially available with CAS number: 10035-04-8.

[0158] Thermophilic lactic acid Streptococcus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D80073.

[0159] Bacillus subtilis was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50713.

[0160] Brown nitrogen-fixing bacteria were purchased from Shanghai Collection of Biotechnology Center with the strain number: SHBCC D81336.

[0161] The preparation method of concrete containing recycled aggregate is as follows:

[0162] Step 01), 296kg cement, 41.5kg fly ash, 758kg fine sand, 608kg modified recycled aggregate, 508kg crushed stone, and 2.38kg water reducer are put into a stirring tank at a speed of 60r / min, stirred for 8min, and mixed evenly to obtain a mixture.

[0163] Step 02), add 156kg of water to the mixture, rotate at 45r / min, stir for 3min, mix evenly, and obtain a concrete mixture.

[0164] Step 03), pour the concrete mixture into a mold, sprinkle water and cure for 3 days, demould, and statically cure for 28 days to obtain concrete containing recycled aggregate.

[0165] Example 5

[0166] A concrete containing recycled aggregate is prepared from the following components:

[0167] Water, cement, fly ash, fine sand, modified recycled aggregate, crushed stone, water reducing agent.

[0168] Among them, the cement is silicate cement, emollient cement, specification: P.O42.5R.

[0169] Among them, the fly ash is secondary fly ash, which was purchased from Baiyi Mineral Products Processing Plant in Lingshou County.

[0170] The fine sand is river sand, which is commercially available and has a mesh size of 20-40.

[0171] The crushed stone is basalt crushed stone, which is commercially available and has a particle size of 10-15 mm.

[0172] Among them, the water reducer is polycarboxylic acid water reducer, which was purchased from Jinan Quanchi New Materials Co., Ltd.

[0173] Among them, the modified recycled aggregate is made by modifying the recycled aggregate obtained by crushing waste concrete, and the particle size of the modified recycled aggregate is 15-20mm.

[0174] The modification methods of modified recycled aggregates are as follows:

[0175] Step 1) Prepare liquid culture medium and modifying solution as follows:

[0176] Step 1-1), weighing 1000kg water, 70kg echeveria juice, 60kg echeveria juice, 35kg glucose, 12kg corn flour, 1.2kg potassium dihydrogen phosphate, 0.6kg magnesium sulfate, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium; step 1-2), weighing 1000kg water, 70kg echeveria juice, 60kg echeveria juice, 35kg glucose, 12kg corn flour, 1.2kg potassium dihydrogen phosphate, 0.6kg magnesium sulfate, 400kg calcium chloride, rotating speed 120r / min, stirring for 10min, stirring evenly to obtain a liquid culture medium.

[0177] Step 2) Weigh 1000 kg of liquid culture medium, add 3 g of thermophilic lactic acid streptococci, 2 g of Bacillus subtilis, and 2 g of vine nitrogen-fixing bacteria into the liquid culture medium, stir continuously at 30 r / min, and culture at a constant temperature of 25-26° C. until the OD value is ≥1 to obtain a bacterial suspension.

[0178] Step 3), weighing 1000 kg of bacterial suspension, then putting 1000 kg of recycled aggregate into the bacterial suspension, keeping the temperature at 30° C., soaking for 48 hours, filtering out the recycled aggregate, and obtaining pretreated recycled aggregate.

[0179] Step 4) The pretreated recycled aggregate was cultured at a constant temperature of 30°C and a relative humidity of 95% for 10 days. During the constant temperature culture process, the modified liquid was sprayed onto the surface of the pretreated recycled aggregate every 24 hours. The spraying amount each time was 2L of modified liquid per 1000kg of recycled aggregate to moisten the surface of the pretreated recycled aggregate. After the constant temperature culture was completed, it was heated to 110°C and dried for 60 minutes to obtain the modified recycled aggregate.

[0180] The stone lotus juice is homemade. Fresh stone lotus is put into a wall breaking machine to crush it, filter it, and take the filtrate to obtain the stone lotus juice.

[0181] The radish juice is homemade. Fresh radish fruits are put into a wall-breaking machine to crush them, filter-pressed, and the filtrate is taken to obtain the radish juice.

[0182] Glucose was obtained from a commercial source with a CAS number of 50-99-7.

[0183] Corn flour was purchased from Xinghua Tiannong Fruit and Vegetable Food Co., Ltd.

[0184] Potassium dihydrogen phosphate was commercially available with CAS number: 7778-77-0.

[0185] Magnesium sulfate was commercially available with CAS number: 10034-99-8.

[0186] Calcium chloride was commercially available with CAS number: 10035-04-8.

[0187] Thermophilic lactic acid Streptococcus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D80073.

[0188] Bacillus subtilis was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50713.

[0189] Brown nitrogen-fixing bacteria were purchased from Shanghai Collection of Biotechnology Center with the strain number: SHBCC D81336.

[0190] The preparation method of concrete containing recycled aggregate is as follows:

[0191] Step 01), 297kg cement, 42kg fly ash, 760kg fine sand, 610kg modified recycled aggregate, 510kg crushed stone, and 2.4kg water reducer are put into a stirring tank at a speed of 60r / min, stirred for 8min, and mixed evenly to obtain a mixture.

[0192] Step 02), add 157kg of water to the mixture, rotate at 45r / min, stir for 3min, mix evenly, and obtain a concrete mixture.

[0193] Step 03), pour the concrete mixture into a mold, sprinkle water and cure for 3 days, demould, and statically cure for 28 days to obtain concrete containing recycled aggregate.

[0194] Comparative Example 1

[0195] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0196] In the modification method of the modified recycled aggregate, an equal amount of Desulfovibrio fructosolicus is used to replace Streptococcus thermophilus.

[0197] Desulfovibrio fructosporus was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D51438.

[0198] Comparative Example 2

[0199] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0200] In the modification method of the modified recycled aggregate, Bacillus pasteurianus is used to replace Bacillus subtilis in equal amounts.

[0201] Bacillus pasteurianus was purchased from Shanghai Biotechnology Collection Center with the strain number: ATCC 11859.

[0202] Comparative Example 3

[0203] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0204] In the modification method of the modified recycled aggregate, an equal amount of spherical Lysinibacillus is used to replace the brown nitrogen-fixing bacteria.

[0205] Lysinibacillus sphaeroides was purchased from Shanghai Biotechnology Collection Center with the strain number: SHBCC D50450.

[0206] Comparative Example 4

[0207] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0208] In the modification method of the modified recycled aggregate, an equal amount of lettuce juice is used to replace the echeveria juice.

[0209] Lettuce juice is homemade. Fresh lettuce is put into a wall breaking machine for crushing, and the filtrate is filtered to obtain lettuce juice.

[0210] Comparative Example 5

[0211] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0212] In the modification method of the modified recycled aggregate, carrot juice was used to replace the groundnut juice in equal amount.

[0213] The carrot juice is homemade. Fresh carrots are put into a wall-breaking machine for crushing, and the filtrate is filtered to obtain carrot juice.

[0214] Comparative Example 6

[0215] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0216] In the modification method of the modified recycled aggregate, water is used to replace the juice of Echeveria sinensis and the juice of Dioscorea oleifera in equal amounts.

[0217] Comparative Example 7

[0218] A concrete containing recycled aggregate, compared with Example 3, differs only in that:

[0219] Use crushed stone to replace the modified recycled aggregate in equal amounts.

[0220] Experiment 1

[0221] According to GB / T50081-2019 “Standard for Test Methods for Physical and Mechanical Properties of Concrete”, the 7d compressive strength and 28d compressive strength of the samples prepared from the concrete mixtures of each embodiment and comparative example were tested.

[0222] Experiment 2

[0223] The slump of the concrete mixtures prepared in each embodiment and comparative example was tested according to GBT50080-2016 “Standard for Test Methods of Performance of Ordinary Concrete Mixtures”.

[0224] The specific test data of Experiment 1-2 are shown in Table 1.

[0225] Table 1

[0226] 7d compressive strength / Mpa 28d compressive strength / Mpa Example 1 34.6 46.1 Example 2 34.9 46.3 Example 3 35.0 46.4 Example 4 35.2 46.6 Example 5 35.1 46.5 Comparative Example 1 31.5 41.8 Comparative Example 2 31.1 41.2 Comparative Example 3 31.8 42.1 Comparative Example 4 33.1 43.9 Comparative Example 5 33.0 43.7 Comparative Example 6 332.2 42.7 Comparative Example 7 34.0 45.1

[0227] According to the comparison of the data of each embodiment and comparative example 7 in Table 1, it can be seen that the compressive strength of each embodiment is higher than that of each comparative example. It can be seen that after the recycled aggregate is modified by adopting a special process in each embodiment, the compressive strength of the concrete prepared by adding a large amount of modified recycled aggregate does not decrease, and the strength of the concrete is improved to a certain extent.

[0228] According to the data comparison in Table 1, the compressive strength of each embodiment is significantly higher than that of Comparative Examples 1-6. It can be seen that the bacterial suspension formed by the combination of thermophilic Streptococcus, Bacillus subtilis, and brown nitrogen-fixing bacteria has a better modification effect on the recycled aggregate in the presence of a modifying liquid containing Echeveria juice and Melissa officinalis juice. However, Comparative Examples 1-3 destroy the composite system of thermophilic Streptococcus, Bacillus subtilis, and brown nitrogen-fixing bacteria, resulting in a decrease in the effect of calcium carbonate deposition, thereby reducing the strength of the recycled aggregate and further reducing the strength of the prepared concrete. The strength is lower than that of Comparative Example 7 using pure natural crushed stone. Comparative Examples 4-6 replace Echeveria juice and Melissa officinalis juice, and the effect of improving the activity of thermophilic Streptococcus, Bacillus subtilis, and brown nitrogen-fixing bacteria is reduced, resulting in a decrease in the efficiency of calcium carbonate deposition, thereby reducing the strength of the recycled aggregate and further reducing the strength of the prepared concrete.

[0229] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A concrete containing recycled aggregate, characterized in that: The composition includes the following parts by weight: 153-157 parts water; 293-297 parts of cement; 40-42 parts of fly ash; 750-760 parts of fine sand; 600-610 parts of modified recycled aggregate; 500-510 parts of crushed stone; 2.3-2.4 parts of water reducer; The modification method of the modified recycled aggregate is as follows: Step 1), preparing liquid culture medium and modifying solution; Step 2), adding thermophilic lactic acid streptococci, Bacillus subtilis, and vine nitrogen-fixing bacteria into the liquid culture medium, and culturing until the OD value is ≥1 to obtain a bacterial suspension; Step 3), the recycled aggregate is put into the bacterial suspension, soaked for 24-48 hours, and the recycled aggregate is filtered out to obtain pretreated recycled aggregate; Step 4), the pretreated recycled aggregate is cultured at a constant temperature of 25-30°C and a relative humidity of 80-95% for 7-10 days, and dried to obtain modified recycled aggregate. During the constant temperature culture process, the modified liquid is sprayed onto the surface of the pretreated recycled aggregate to moisten the surface of the pretreated recycled aggregate; The liquid culture medium is a mixture of water, echeveria juice, radix schizonepetae juice, glucose, corn flour, potassium dihydrogen phosphate, and magnesium sulfate; The modified liquid is a mixture of water, echeveria juice, radix schizonepetae juice, glucose, corn flour, potassium dihydrogen phosphate, magnesium sulfate and calcium chloride; In the step 2), the input mass ratio of thermophilic lactic acid streptococcus, Bacillus subtilis, and vine nitrogen-fixing bacteria is 2-3:1-2:1-2.

2. The concrete containing recycled aggregate according to claim 1, characterized in that: In the liquid culture medium, the mass ratio of water, echeveria juice, mellea fruit juice, glucose, corn flour, potassium dihydrogen phosphate, and magnesium sulfate is 1000:60-70:50-60:25-35:8-12:0.8-1.2:0.4-0.

6.

3. The concrete containing recycled aggregate according to claim 2, characterized in that: In the modified liquid, the mass ratio of water, caesalpinia fruit juice, mellea fruit juice, glucose, corn flour, potassium dihydrogen phosphate, magnesium sulfate and calcium chloride is 1000:60-70:50-60:25-35:8-12:0.8-1.2:0.4-0.6:300-400.

4. The concrete containing recycled aggregate according to claim 1, characterized in that: In step 3), the recycled aggregate is put into the bacterial suspension and soaked for 30-42 hours.

5. The concrete containing recycled aggregate according to claim 1, characterized in that: In the step 4), the pretreated recycled aggregate is cultured at a constant temperature of 27-29° C. and a relative humidity of 82-88% for 8-9 days.

6. The concrete containing recycled aggregate according to claim 1, characterized in that: In the step 4), the modifying liquid is sprayed onto the surface of the pretreated recycled aggregate every 24 hours, and the spraying amount each time is 1-2 liters of modifying liquid per 1 ton of recycled aggregate.

7. The concrete containing recycled aggregate according to claim 1, characterized in that: In the step 4), heating and drying are adopted during drying, and the drying temperature is ≥110°C.

8. A method for preparing concrete containing recycled aggregate according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 01), cement, fly ash, fine sand, modified recycled aggregate, crushed stone, and water reducing agent are uniformly mixed to obtain a mixture; Step 02), adding water to the mixture and mixing evenly to obtain a concrete mixture; Step 03) pour the concrete mixture into a mold, cure it, and demould it to obtain concrete containing recycled aggregate.