CN113387636A

CN113387636A - Preparation method of green environment-friendly recycled concrete

Info

Publication number: CN113387636A
Application number: CN202110524507.7A
Authority: CN
Inventors: 杨双伟; 巩英剑
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-13
Filing date: 2021-05-13
Publication date: 2021-09-14

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of green environment-friendly recycled concrete, which comprises the following steps: s1: crushing and screening the waste concrete to obtain prefabricated body soil particles; s2: putting the prefabricated body soil particles and the waste PET plastics into a heating tank, heating the heating tank, and then separating the prefabricated body soil particles from the plastic liquid by using a metal filter screen to obtain concrete particles; s3: mixing the concrete particles, the plastic particles and the fine aggregate to obtain a first mixture; mixing ordinary portland cement, an air entraining agent, a water reducing agent and a silane coupling agent to obtain a mixture II; s4: adding the mixture II and the mixture I into water in sequence, and fully stirring and mixing to obtain recycled concrete; the preparation method is simple, and the prepared recycled concrete has good mechanical property and impermeability, and is not easy to crack.

Description

Preparation method of green environment-friendly recycled concrete

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of green environment-friendly recycled concrete.

Background

With the rapid development of the construction industry, the urbanization footsteps are faster and faster, meanwhile, the old city is more and more transformed, and a large amount of waste construction waste is generated. Most of the construction wastes in China are not recycled in a scientific mode. Most of construction waste is disposed of as rubbish, piles up in open-air suburbs at will, perhaps takes simple landfill mode to handle, and this kind of processing mode can not carry out the reutilization to construction waste, has reduced the utilization ratio of resource, causes the wasting of resources, and simultaneously, construction waste piles up the region or the easy production of landfill region pollutes, influences environmental quality. Therefore, the construction waste formed by the waste building concrete is crushed into recycled concrete for recycling, so that not only is a large amount of construction waste treated, but also the construction materials are saved. However, in the crushing process of the recycled aggregate, a large number of micro cracks exist in the recycled aggregate due to the external force. Under the condition that the recycled aggregate contains micro cracks and the porosity of the recycled aggregate is high, when the recycled concrete is subjected to the effects of temperature stress and the like after being solidified, the stress inside the recycled concrete is uneven, and the concrete has expansion cracks, so that the compressive strength of the concrete is reduced.

Some technical solutions related to recycled concrete exist in the prior art, for example, chinese patent with application number CN201811500540.0 discloses a modified recycled concrete and a preparation method thereof, and the raw materials of the modified recycled concrete comprise the following components by weight: 190-; 440-460kg/m3 ordinary portland cement; 350-400kg/m3 of natural river sand; 15-20kg/m3 of polycarboxylic acid water reducing agent; 600-620kg/m3 of natural crushed stone; 600-650kg/m3 of modified recycled aggregate; 10-30kg/m3 of alkali modified rubber particles. In the scheme, the recycled aggregate and the rubber particles are modified, the porosity of the recycled aggregate is reduced, and the binding force between the rubber particles and the recycled concrete is improved, so that the mechanical property and the anti-permeability property of the recycled concrete obtained by preparation are improved, but in the actual use process, the pores and cracks in the recycled aggregate are plugged by the nano titanium dioxide, and the pores and cracks existing in the recycled aggregate cannot be fixed and bonded, so that the structural strength of the recycled aggregate is improved in a limited range after the recycled aggregate is modified in the scheme, in addition, in the use process, because the nano titanium dioxide is not completely fixed in the pores and cracks in the recycled aggregate, the cracks close to the surface of the recycled aggregate and the nano titanium dioxide filled in the pores are easy to run off during use, so that the surface layer strength of the recycled aggregate is low, the rubber particles are easy to crack and further influence the mechanical property of the recycled concrete, meanwhile, in the using process, the rubber particles can improve the durability of the recycled concrete to a certain extent, but fillers are not arranged in the rubber particles, so that the rubber particles are easy to deform in the using process and influence the strength of the recycled concrete

Disclosure of Invention

The invention provides a preparation method of green and environment-friendly recycled concrete, which aims to make up the defects of the prior art, solve the problems that when recycled aggregate is used in the recycled concrete, gaps and cracks exist in the recycled aggregate, so that the porosity in the recycled concrete is large, and the recycled concrete is easy to crack, and improve the mechanical property and the impermeability of the prepared recycled concrete.

The technical scheme adopted by the invention for solving the technical problems is as follows: the invention relates to a preparation method of green environment-friendly recycled concrete, which comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

s1: crushing the waste concrete to obtain particles with the average particle size of 5-30mm, and then washing and air-drying the particles by using water to obtain prefabricated body soil particles;

s2: putting the prefabricated body soil particles into a heating tank, synchronously adding waste PET (polyethylene terephthalate) plastics with the volume equivalent to 1/2 solid particles into the heating tank, heating the heating tank until the waste PET plastics are in a fluid state, keeping the fluid state for 20-30min, separating the prefabricated body soil particles from plastic liquid by using a metal filter screen, and cooling to obtain concrete particles; meanwhile, adding the separated plastic liquid in a fluid state into a granulator to prepare plastic granules with the average grain diameter of 5-15 mm;

s3: putting the concrete particles, the plastic particles and the fine aggregate into a stirrer to be mixed to obtain a mixture I; putting ordinary portland cement, an air entraining agent, a water reducing agent and a silane coupling agent into a stirrer for mixing to obtain a mixture II;

s4: on the basis of the step S3, adding the mixture II and the mixture I into water in sequence, fully stirring in the adding process, and uniformly mixing to obtain the finished product of recycled concrete;

when the concrete is in work, the concrete particles prepared from the waste concrete and the plastic particles prepared from the waste PET plastic are used as recycled aggregates, then the recycled aggregates are filled into the concrete, so that the number of the aggregates used in the conventional concrete can be reduced, the use cost of the concrete is reduced, meanwhile, the aggregates are recycled and prepared from the waste concrete and the waste PET plastic, the aggregates can be recycled, the recycling cost is reduced, the environmental pollution is avoided, meanwhile, the prefabricated body particles prepared by crushing the waste concrete and the waste PET plastic are synchronously put into a heating tank, the waste PET plastic is converted into a fluid state from a solid state through a heating mode, so that the plastic liquid permeates into the prefabricated body particles, gaps and cracks generated by the prefabricated body particles under the action of large external force in the preparation process are sealed, and the porosity of the prepared concrete particles is prevented from being too high, after the silane coupling agent in the recycled concrete is mixed into the concrete, the porosity of the recycled concrete is high, the mechanical property and the durability of the recycled concrete are influenced, the impermeability of the recycled concrete is poor, meanwhile, the silane coupling agent in the recycled concrete can improve the bonding strength between the concrete particles and the surrounding structure in the concrete and reduce the possibility of cracks appearing at the interface between the concrete particles and the surrounding structure after the recycled concrete is subjected to the action of external force because the prefabricated body particles and the waste PET plastic are heated together in the heating tank, so that the mechanical property of the prepared recycled concrete is improved, meanwhile, in the using process, the plastic liquid in a fluid state in the heating tank is separated from the prefabricated body particles and then is sent into a granulator to prepare the plastic particles, and then, the plastic particles are mixed into the recycled concrete, so that the prepared recycled concrete is light in weight and good in heat preservation effect, the impact resistance and wear resistance of the recycled concrete are improved, and the service life of the recycled concrete is prolonged.

Preferably, in the step S2, the heating tank is kept sealed during the heating process, and the pressure in the heating tank is not equal to the pressure in the outside; in the heating process, periodically pumping air from the heating tank and inflating air into the heating tank; when the heating tank is filled with gas, the filled gas is carbon dioxide;

when the concrete heating tank works, a large number of fine gaps and cracks exist in concrete particles obtained by crushing waste concrete, so that the interior of the heating tank is periodically pumped or inflated in the heating process, the pressure in the heating tank is continuously changed between positive pressure and negative pressure, meanwhile, gas existing in the gaps and the cracks in the concrete particles can be effectively discharged through the change of the pressure in the heating tank, plastic liquid in a fluid state can conveniently permeate into the gaps and the cracks in the concrete particles, the impermeability of prepared recycled concrete is improved, meanwhile, in the use process, the strength of the concrete particles can be improved to a certain degree through the plastic liquid permeating into the interior of the concrete particles, and the concrete particles are prevented from cracking due to the gaps and the cracks in the concrete particles in the use process, influence the mechanical properties of recycled concrete, simultaneously, at the heating in-process, fill carbon dioxide gas in the heating jar, reduce the oxygen content in the heating jar, avoid in the heating process, PET plastic liquid is quick to be oxidized, influences the normal performance of plastics.

Preferably, the plastic grains at least comprise three grains with different grain diameters, and the grain diameters of the grains are respectively 5mm, 10mm and 15 mm; the proportion occupied by the particles with different particle sizes in the plastic particles is equal; the concrete particles at least comprise three particles with different particle sizes, and the particle sizes of the particles are respectively 5-10mm, 10-20mm and 20-30 mm; the proportion occupied by the particles with different particle sizes in the concrete particles is equal;

during operation, the recycled aggregates consisting of the concrete particles and the plastic particles are graded with each other by controlling the particle sizes of the concrete particles and the plastic particles, so that after the recycled aggregates are added into the recycled concrete, the recycled aggregates can be embedded with each other, the contact tightness between the recycled aggregates is improved, the gap structure in the recycled concrete is improved, the compactness of the recycled concrete is higher, the mechanical property of the prepared recycled concrete is further improved, the compressive strength, the flexural strength and the impermeability of the recycled concrete are improved, and meanwhile, in the use process, the plastic particles and the concrete particles are uniformly distributed in the recycled concrete by controlling the particle sizes of the concrete particles and the plastic particles, so that the problem that the performance of the recycled concrete is influenced due to the nonuniform distribution of the recycled aggregates in the recycled concrete is avoided.

Preferably, the surface of the plastic grains is provided with a groove; the convex parts on the concrete particles are embedded into the grooves on the surfaces of the plastic particles; in the granulation process of the plastic granules, a groove with a cross section in a specified shape is obtained by controlling the shape of a die hole on the granulator; the cross section of the groove is any one of a triangle, a semicircle and a square;

in the during operation, because the concrete grain obtains after through the discarded concrete breakage, therefore, there is convex edges and corners in the surface of concrete grain, after sneaking into recycled concrete with the recycled aggregate, convex edges and corners embedding on the concrete grain surface is in the slot on the plastics surface, thereby promote the combination stability between the two after concrete grain and plastic grain gradation, avoid in the use, the recycled aggregate in the recycled concrete appears the possibility of offset, promote the performance of recycled concrete, and simultaneously, in the use, through protruding edges and corners on the concrete grain and the cooperation between the slot on the plastic grain surface, can further reduce the space in the recycled concrete, thereby promote the impervious performance of the recycled concrete that the preparation obtained.

Preferably, an ultrasonic vibration mechanism is arranged in the heating tank used in the step S2 to ultrasonically stir the material in the heating tank; after the waste PET plastic in the heating tank becomes a fluid state, starting an ultrasonic vibration mechanism arranged in the heating tank;

in the step S2, carbon nanofibers are added into the heating tank; the nano carbon fibers comprise two types, namely a first fiber and a second fiber; the diameter of the first fiber is 100-120nm, and the length of the first fiber is 50-100 um; the diameter of the second fiber is 0.1-0.2um, and the length is 2-5 mm;

during operation, the first fibers added into the nano carbon fibers in the heating tank can synchronously permeate into gaps and cracks inside concrete particles along with the plastic liquid in a fluid state under the stirring of the ultrasonic vibration mechanism to generate a reinforcing effect on the concrete particles, so that after the concrete particles are added into the recycled concrete, the possibility of cracking can be generated after the concrete particles are subjected to an external force action in the use process, the mechanical property of the recycled concrete obtained through preparation is improved, meanwhile, the first fibers are remained on the surfaces of the cooled concrete particles, the surface roughness of the concrete particles can be effectively increased, the bonding strength between the concrete particles and the recycled concrete is improved, the mechanical property of the recycled concrete is improved, and meanwhile, in the preparation process, the gaps inside the concrete particles can be further promoted through the vibration and the stirring of the ultrasonic vibration mechanism, The bubbles in the cracks are discharged, the viscosity of the plastic liquid in a fluid state is reduced to be higher, the adverse effect on the bubble discharge process is avoided, meanwhile, in the preparation process, the second fibers added into the nano carbon fibers in the heating tank can be uniformly mixed into the plastic liquid under the stirring of the ultrasonic vibration mechanism, the possibility that the second fibers are gathered in the plastic liquid is reduced, meanwhile, in the use process, the second fibers mixed into the plastic granules can effectively improve the strength of the plastic granules, the plastic granules are prevented from being greatly deformed when being subjected to external force after being mixed into recycled concrete, the strength of the recycled concrete is reduced, even the recycled concrete is cracked, the normal use of the recycled concrete is influenced, meanwhile, in the preparation process of the plastic granules, the second fibers protrude to the surfaces of the plastic granules, and the surface roughness of the plastic granules is improved, and then make the combination between plastic pellet and the recycled concrete inseparabler, reduce the space size and the quantity in the recycled concrete, promote the mechanical properties and the impervious performance of recycled concrete.

Preferably, when the prefabricated body soil particles are prepared by crushing waste concrete, the waste concrete is crushed for multiple times until the prefabricated body soil particles with the quantity meeting the requirement are obtained; in the preparation process of the prefabricated body soil particles, after waste concrete is crushed for one time, the crushed product is sieved for multiple times to obtain prefabricated body soil particles of 5-10mm, 10-20mm and 20-30 mm;

during operation, through breaking many times for the preparation speed and the preparation efficiency of prefabricated body soil grain, and at every turn broken back, carry out a lot of screening to the result after the breakage, thereby at broken once back, obtain the prefabricated body soil grain of different particle diameters, avoid continuously carrying out the breakage to abandonment concrete, the particle diameter that leads to the prefabricated body soil grain that obtains after the breakage is less, can not satisfy the requirement, simultaneously, reduces and lasts the crushing in-process, the energy of consumption, reduction in production cost.

The invention has the following beneficial effects:

1. the invention relates to a method for preparing green environment-friendly recycled concrete, which comprises the steps of arranging concrete granules and plastic granules, preparing the concrete granules by using waste concrete, synchronously putting the concrete granules and waste PET plastic into a heating tank, heating to convert the waste PET plastic into a fluid state from a solid state, further enabling plastic liquid to permeate into gaps and cracks inside the concrete granules and block the gaps and cracks, thereby reducing the porosity of the prepared recycled concrete, improving the mechanical property and the impermeability of the prepared recycled concrete, simultaneously, after synchronously heating the concrete granules and the waste PET plastic, wrapping a plastic layer on the surface of the cooled concrete granules, improving the surface roughness of the concrete granules to a certain degree, improving the bonding strength of the concrete granules and other materials in the recycled concrete, and further enabling the mechanical property of the prepared recycled concrete to be better, meanwhile, in the preparation process, the plastic liquid in a fluid state is sent into a granulator to finish the preparation of plastic granules, and the energy consumption in the preparation process of the plastic granules is reduced.

2. The invention relates to a method for preparing green environment-friendly recycled concrete, which is characterized in that carbon fibers are arranged, first fibers and second fibers with different lengths are added in the preparation process, the first fibers with shorter lengths in the first fibers and the second fibers penetrate into gaps and cracks in concrete granules under the action of ultrasonic stirring, the structural strength of the concrete granules is improved under the action of the first fibers, the strength of the concrete granules is close to that of natural aggregate, the mechanical property of the prepared recycled concrete is improved, meanwhile, the first fibers are fixed inside the concrete granules under the action of the plastic liquid penetrating into the gaps and cracks, the first fibers which enter the concrete granules are prevented from losing during use and influencing the strength of the concrete granules, and meanwhile, the second fibers synchronously added in the use process can be subjected to ultrasonic stirring, the homogeneous mixing is to the plastic liquid in to the evenly distributed has the second fibre in the plastic pellet that makes through the plastic liquid preparation, improve the structural strength of plastic pellet, in reducing the use, the plastic pellet appears the possibility of warping, the mechanical properties that makes the recycled concrete that obtains of preparation is better, simultaneously, in the use, mix into the second fibre in the plastic liquid, after the plastic pellet is prepared into to the plastic pellet at the plastic liquid, can make the surface roughness of plastic pellet, promote the bonding strength of plastic pellet and other materials of recycled concrete.

Drawings

The invention will be further explained with reference to the drawings.

FIG. 1 is a flow chart of a production process of the present invention;

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

As shown in figure 1, the green and environment-friendly recycled concrete preparation method provided by the invention comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

In an embodiment of the present invention, in the step S2, the heating tank is kept sealed during the heating process, and the pressure in the heating tank is not equal to the pressure in the outside; in the heating process, periodically pumping air from the heating tank and inflating air into the heating tank; when the heating tank is filled with gas, the filled gas is carbon dioxide;

As an embodiment of the invention, the plastic granules at least comprise three granules with different grain diameters, and the grain diameters of the granules are respectively 5mm, 10mm and 15 mm; the proportion occupied by the particles with different particle sizes in the plastic particles is equal; the concrete particles at least comprise three particles with different particle sizes, and the particle sizes of the particles are respectively 5-10mm, 10-20mm and 20-30 mm; the proportion occupied by the particles with different particle sizes in the concrete particles is equal;

As an embodiment of the invention, the surface of the plastic grains is provided with grooves; the convex parts on the concrete particles are embedded into the grooves on the surfaces of the plastic particles; in the granulation process of the plastic granules, a groove with a cross section in a specified shape is obtained by controlling the shape of a die hole on the granulator; the cross section of the groove is any one of a triangle, a semicircle and a square;

As an embodiment of the present invention, the heating tank used in the step S2 is provided with an ultrasonic vibration mechanism for ultrasonically stirring the material inside the heating tank; after the waste PET plastic in the heating tank becomes a fluid state, starting an ultrasonic vibration mechanism arranged in the heating tank;

As an embodiment of the present invention, when the precast body soil particles are prepared by crushing waste concrete, the waste concrete is crushed for a plurality of times until the precast body soil particles with the required number are obtained; in the preparation process of the prefabricated body soil particles, after waste concrete is crushed for one time, the crushed product is sieved for multiple times to obtain prefabricated body soil particles of 5-10mm, 10-20mm and 20-30 mm;

The specific working process is as follows:

during operation, concrete grains prepared from waste concrete and plastic grains prepared from waste PET plastics are used as recycled aggregates, then the recycled aggregates are filled into the concrete, meanwhile, prefabricated body soil grains prepared from the crushed waste concrete and the waste PET plastics are synchronously put into a heating tank, the waste PET plastics are converted from a solid state into a fluid state through a heating mode, plastic liquid is permeated into the prefabricated body soil grains, gaps and cracks in the prefabricated body soil grains are sealed, meanwhile, plastic liquid in the fluid state in the heating tank is separated from the prefabricated body soil grains and then sent into a granulator to prepare plastic grains, and then the plastic grains are mixed into the recycled concrete; in the heating process, the interior of the heating tank is periodically pumped or inflated to ensure that the pressure in the heating tank is constantly changed between positive pressure and negative pressure, and gas existing in gaps and cracks in the soil particles of the prefabricated body is discharged, so that the plastic liquid in a fluid state can conveniently permeate into the gaps and cracks in the soil particles of the prefabricated body; the recycled aggregate composed of the concrete particles and the plastic particles is mutually graded by controlling the particle sizes of the concrete particles and the plastic particles, so that the gap structure in the recycled concrete is improved, and the compactness of the recycled concrete is higher; after the recycled aggregate is mixed into recycled concrete, the convex edges and corners on the surface of the concrete particles are embedded into the grooves on the surface of the plastic, and the combination stability of the concrete particles and the plastic particles after grading is better; the first fibers added into the carbon nanofibers in the heating tank can synchronously permeate into gaps and cracks inside the prefabricated body soil particles along with the plastic liquid in a fluid state under the stirring of the ultrasonic vibration mechanism, meanwhile, after the prefabricated body soil particles are cooled, the first fibers are remained on the surface, the surface roughness of the concrete particles is increased, the bonding strength between the concrete particles and recycled concrete is improved, meanwhile, the second fibers added into the carbon nanofibers in the heating tank can be uniformly mixed into the plastic liquid under the stirring of the ultrasonic vibration mechanism, and the strength of the prepared plastic particles is improved.

In order to verify the practical use effect of the recycled concrete prepared by the present invention, the following experiment was made.

Experiment group one: the preparation method of the green environment-friendly recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

in the step S2, the heating tank is kept sealed during the heating process, and the pressure in the heating tank is not equal to the pressure in the outside; in the heating process, periodically pumping air from the heating tank and inflating air into the heating tank; when the heating tank is filled with gas, the filled gas is carbon dioxide;

the plastic grains at least comprise three grains with different grain diameters, and the grain diameters of the grains are respectively 5mm, 10mm and 15 mm; the proportion occupied by the particles with different particle sizes in the plastic particles is equal; the concrete particles at least comprise three particles with different particle sizes, and the particle sizes of the particles are respectively 5-10mm, 10-20mm and 20-30 mm; the proportion occupied by the particles with different particle sizes in the concrete particles is equal;

grooves are formed in the surfaces of the plastic particles; the convex parts on the concrete particles are embedded into the grooves on the surfaces of the plastic particles; in the granulation process of the plastic granules, a groove with a cross section in a specified shape is obtained by controlling the shape of a die hole on the granulator; the cross section of the groove is any one of a triangle, a semicircle and a square;

an ultrasonic vibration mechanism is configured in the heating tank used in the step S2, and materials in the heating tank are ultrasonically stirred; after the waste PET plastic in the heating tank becomes a fluid state, starting an ultrasonic vibration mechanism arranged in the heating tank;

when the prefabricated body soil particles are prepared by crushing waste concrete, crushing the waste concrete for multiple times until the prefabricated body soil particles with the quantity meeting the requirement are obtained; in the preparation process of the prefabricated body soil particles, after waste concrete is crushed for one time, the crushed product is sieved for multiple times to obtain the prefabricated body soil particles with the sizes of 5-10mm, 10-20mm and 20-30 mm.

Experiment group two: the preparation method of the green environment-friendly recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

s2: putting the waste PET plastic into a heating tank, heating the heating tank until the waste PET plastic is in a fluid state, and then adding plastic liquid in the fluid state into a granulator to prepare plastic granules with the average particle size of 5-15 mm; putting the prefabricated body soil particles into a heating tank, heating the heating tank, keeping the heating temperature to be the same as the temperature when the waste PET plastics are converted into a fluid state for 20-30min, taking out the prefabricated body soil particles from the heating tank, and cooling to obtain concrete particles;

in the step S2, the same operation is performed for the heating tank into which the waste PET plastic is charged and the heating tank into which the preform soil particles are charged; the heating tank is kept sealed in the heating process, and the pressure in the heating tank is not equal to the pressure in the outside; in the heating process, periodically pumping air from the heating tank and inflating air into the heating tank; when the heating tank is filled with gas, the filled gas is carbon dioxide;

in the step S2, the carbon nanofibers are added to a heating tank in which the waste PET plastic is put; the nano carbon fibers comprise two types, namely a first fiber and a second fiber; the diameter of the first fiber is 100-120nm, and the length of the first fiber is 50-100 um; the diameter of the second fiber is 0.1-0.2um, and the length is 2-5 mm;

Experiment group three: the preparation method of the green environment-friendly recycled concrete is provided, and the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

Experiment group four: the preparation method of the green environment-friendly recycled concrete is provided, and the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

in the step S2, carbon nanofibers are added into the heating tank; the nano carbon fiber is a first fiber, the diameter of the first fiber is 100-120nm, and the length of the first fiber is 50-100 um;

Experiment group five: the preparation method of the green environment-friendly recycled concrete is provided, and the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

in the step S2, carbon nanofibers are added into the heating tank; the nano carbon fiber is a second fiber; the diameter of the second fiber is 0.1-0.2um, and the length is 2-5 mm;

Experiment group six: the preparation method of the green environment-friendly recycled concrete is provided, and the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

s2: putting the prefabricated body soil particles into a heating tank, synchronously adding waste PET (polyethylene terephthalate) plastics with the volume equivalent to 1/2 solid particles into the heating tank, heating the heating tank until the waste PET plastics are in a fluid state, keeping the fluid state for 20-30min, separating the prefabricated body soil particles from plastic liquid by using a metal filter screen, and cooling to obtain concrete particles; meanwhile, adding the separated plastic liquid in a fluid state into a granulator to prepare plastic granules with the average grain diameter of 5-30 mm;

the plastic grains at least comprise three grains with different grain diameters, and the grain diameters of the grains are respectively 5-10mm, 10-20mm and 20-30mm, and the proportion occupied by the grains with different grain diameters in the plastic grains is equal; the concrete particles at least comprise three particles with different particle sizes, and the particle sizes of the particles are respectively 5-10mm, 10-20mm and 20-30 mm; the proportion occupied by the particles with different particle sizes in the concrete particles is equal;

Experimental group seven: the preparation method of the green environment-friendly recycled concrete is provided, and the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

And numbering the recycled concrete prepared in the experimental groups I to seven according to the sequence to obtain samples I to seven, selecting a part of common recycled concrete sold in the market, sending the samples I to seven and the common recycled concrete to a concrete third-party detection mechanism, and detecting the mechanical properties and the impermeability of the samples I to seven and the recycled concrete. The test results for each sample are reported in the table. The experiments were performed in triplicate and the results of the three experiments are shown in the table below.

Wherein, the anti-permeability performance test standard is as follows: GB/T50082-2009 Standard test methods for the long-term performance and the durability of ordinary concrete; the mechanical property test standard is as follows: GB/T50081-2016 Standard test method for mechanical Properties of general concrete.

TABLE 1

From the experimental data recorded in table 1, by comparing the samples one to seven with the common recycled concrete, it can be found that the mechanical properties and the impermeability of the recycled concrete prepared by completely adopting the preparation process of the invention and the recycled concrete prepared by adopting part of the preparation process of the invention are higher than those of the common recycled concrete in data, therefore, the preparation process of the invention has certain advantages compared with the common preparation process, and is worth being popularized and used; meanwhile, after the samples two to seven are respectively compared with the sample one, the mechanical property and the impermeability of the recycled concrete prepared by the complete process are clearly obtained through experimental data, and the data of the mechanical property and the impermeability of the recycled concrete prepared by the complete process are generally higher than those of the recycled concrete prepared by partial processes of the invention, so that the complete process is adopted to prepare the recycled concrete in the production process, and the problem that the mechanical property and the impermeability of the prepared recycled concrete are reduced and the use of the recycled concrete is influenced due to the simplified and omitted process steps in the production process is avoided.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A preparation method of green environment-friendly recycled concrete is characterized by comprising the following steps: the recycled concrete comprises the following components in parts by weight: 75-80 parts of ordinary portland cement, 85-95 parts of recycled aggregate, 20-25 parts of fine aggregate, 8-10 parts of fly ash, 2-4 parts of air entraining agent, 1-2 parts of water reducing agent, 1-3 parts of silane coupling agent and 35-45 parts of water; the fine aggregate is natural river sand; the recycled aggregate comprises plastic grains and concrete grains, and the ratio of the plastic grains to the concrete grains is 1: 2; the plastic granules are obtained by re-granulating waste PET plastic; the concrete particles are prepared by crushing waste concrete;

the preparation method comprises the following steps:

s4: and on the basis of the step S3, adding the mixture II and the mixture I into water in sequence, fully stirring in the adding process, and uniformly mixing to obtain the finished product of the recycled concrete.

2. The method for preparing green environment-friendly recycled concrete according to claim 1, characterized in that: in the step S2, the heating tank is kept sealed during the heating process, and the pressure in the heating tank is not equal to the pressure in the outside; in the heating process, periodically pumping air from the heating tank and inflating air into the heating tank; when the heating tank is filled with gas, the filled gas is carbon dioxide.

3. The method for preparing green environment-friendly recycled concrete according to claim 1, characterized in that: the plastic grains at least comprise three grains with different grain diameters, and the grain diameters of the grains are respectively 5mm, 10mm and 15 mm; the proportion occupied by the particles with different particle sizes in the plastic particles is equal; the concrete particles at least comprise three particles with different particle sizes, and the particle sizes of the particles are respectively 5-10mm, 10-20mm and 20-30 mm; the proportion occupied by the particles with different particle diameters in the concrete particles is equal.

4. The method for preparing green environment-friendly recycled concrete according to claim 1, characterized in that: grooves are formed in the surfaces of the plastic particles; the convex parts on the concrete particles are embedded into the grooves on the surfaces of the plastic particles; in the granulation process of the plastic granules, a groove with a cross section in a specified shape is obtained by controlling the shape of a die hole on the granulator; the cross section of the groove is any one of a triangle, a semicircle and a square.

5. The method for preparing green environment-friendly recycled concrete according to claim 2, characterized in that: an ultrasonic vibration mechanism is configured in the heating tank used in the step S2, and materials in the heating tank are ultrasonically stirred; after the waste PET plastic in the heating tank becomes a fluid state, starting an ultrasonic vibration mechanism arranged in the heating tank;

in the step S2, carbon nanofibers are added into the heating tank; the nano carbon fibers comprise two types, namely a first fiber and a second fiber; the diameter of the first fiber is 100-120nm, and the length of the first fiber is 50-100 um; the diameter of the second fiber is 0.1-0.2um, and the length is 2-5 mm.

6. The method for preparing green environment-friendly recycled concrete according to claim 3, characterized in that: when the prefabricated body soil particles are prepared by crushing waste concrete, crushing the waste concrete for multiple times until the prefabricated body soil particles with the quantity meeting the requirement are obtained; in the preparation process of the prefabricated body soil particles, after waste concrete is crushed for one time, the crushed product is sieved for multiple times to obtain the prefabricated body soil particles with the sizes of 5-10mm, 10-20mm and 20-30 mm.