Artificial coarse aggregate concrete and preparation method thereof

Abstract

The invention discloses artificial coarse aggregate concrete and a preparation method thereof, and relates to the field of concrete. The preparation method of the artificial coarse aggregate concrete comprises the following steps: mixing waste incineration bottom ash, granulated blast-furnace slag and cement according to a mass ratio of (5-7): (2-4): 1, putting the mixture into a disc granulator, spraying water for granulation, and performing water-saturated maintenance to obtain artificial coarse aggregate; the preparation method comprises the following steps: stirring and mixing cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate according to a mass ratio of (285-550): (449-788): (200-220): (0-1429): (0-1054), pouring the mixture into a compression mold, performing compression for preset time by using a compression stress of 5-15MPa, and curing to obtain artificial coarse aggregate concrete; the use amount of the artificial coarse aggregate is not 0. The artificial coarse aggregate concrete prepared by the preparation method has higher compressive strength and elasticity modulus.

Description

Technical Field

[0001] The invention relates to the field of concrete, and in particular to an artificial coarse aggregate concrete and a preparation method thereof. Background Art

[0002] Concrete is one of the most widely used building materials. Its main components are water, cement and aggregate, of which aggregate accounts for about 65%-80% of the volume of concrete. The production of concrete requires 48 billion tons of natural coarse aggregate every year, but the limited natural coarse aggregate (such as sand and gravel) resources are difficult to meet the huge demand for aggregate. On the other hand, industrial production produces a large amount of solid waste. Direct landfill of industrial solid waste not only occupies land resources, but also causes groundwater pollution. Using solid waste to produce artificial coarse aggregate to replace natural coarse aggregate can not only make resource utilization of solid waste, but also alleviate the shortage of natural coarse aggregate. However, artificial coarse aggregate has the characteristics of high water absorption, high porosity and low compressive strength. In practical applications, it will lead to a decrease in the compressive strength and elastic modulus of concrete, which greatly limits its wide application.

[0003] At present, the performance of artificial coarse aggregate concrete is mainly improved by improving the performance of artificial coarse aggregate and adding fibers to concrete. The use of alkali activation technology and polymer impregnation can improve the performance of artificial coarse aggregate to a certain extent, but it requires the consumption of a large amount of alkali solution and polymer, which is less economical and difficult to apply on a large scale. In addition, some polymers are toxic and potentially harmful to the human body. Although fibers can improve the tensile properties and brittleness of artificial coarse aggregate concrete, they have a poor effect on improving the compressive strength of artificial coarse aggregate concrete, and synthetic fibers may even have a counterproductive effect.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] Based on the above-mentioned deficiencies of the prior art, the object of the present invention is to provide an artificial coarse aggregate concrete and a preparation method thereof, aiming to solve the problem of low compressive strength and elastic modulus of the existing artificial coarse aggregate concrete.

[0006] The technical solution of the present invention is as follows:

[0007] A first aspect of the present invention provides a method for preparing artificial coarse aggregate concrete, comprising the following steps:

[0008] Mixing waste incineration bottom ash, granulated blast furnace slag and cement in a mass ratio of (5-7):(2-4):1 to obtain a mixture;

[0009] The mixed material is put into a disc granulator, and granulated by spraying water to obtain an artificial coarse aggregate blank;

[0010] The artificial coarse aggregate blank is subjected to water-saturated curing to obtain artificial coarse aggregate;

[0011] Cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate are stirred and mixed according to a mass ratio of (285-550):(449-788):(200-220):(0-1429):(0-1054) to obtain concrete slurry; wherein the amount of artificial coarse aggregate is not 0;

[0012] The concrete slurry is poured into a compression mold, compressed for a preset time with a compression stress of 5 to 15 MPa, and solidified to obtain the artificial coarse aggregate concrete.

[0013] Optionally, the mixture is put into a disc granulator and water is sprayed during the granulation process, with the total water consumption being 20% ​​to 22% of the mass of the mixture, for granulation.

[0014] Optionally, the disc granulator has a disc inclination angle of 35 to 55°, a disc diameter of 50 cm, an edge height of 10 cm, and a rotation speed of 30 to 55 rpm;

[0015] The granulation time is 10 to 15 minutes.

[0016] Optionally, the particle size of the artificial coarse aggregate is 4.75-26.5 mm.

[0017] Optionally, when the artificial coarse aggregate passes through a square hole sieve with a pore size of 26.5 mm, a square hole sieve with a pore size of 19.0 mm, a square hole sieve with a pore size of 16.0 mm, a square hole sieve with a pore size of 9.5 mm, and a square hole sieve with a pore size of 4.75 mm, the residue on the sieve is 0%, 5%, 20%, 40%, and 35% of the total mass of the artificial coarse aggregate, respectively.

[0018] Optionally, the artificial coarse aggregate blank is placed in water and cured at a temperature of 25° C. for 28 days to obtain the artificial coarse aggregate.

[0019] Optionally, the step of mixing cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate specifically includes:

[0020] Fine aggregate, cement and natural coarse aggregate are dry mixed, then water is added for wet mixing, and finally artificial coarse aggregate is added for mixing.

[0021] Optionally, the preset time is 2 to 10 minutes.

[0022] Optionally, the fine aggregate is at least one of natural river sand, natural sea sand, machine-made sand and sand prepared from industrial waste slag, and the natural coarse aggregate is at least one of granite crushed stone, basalt crushed stone, diabase crushed stone and pebbles.

[0023] A second aspect of the present invention provides an artificial coarse aggregate concrete, wherein the artificial coarse aggregate concrete is prepared by the preparation method of the present invention as described above.

[0024] Beneficial effects: In the present invention, by compressing with a compressive stress of 5 to 15 MPa, water can be squeezed out, the water-cement ratio of artificial coarse aggregate concrete can be reduced, and the compressive strength and elastic modulus of artificial coarse aggregate concrete can be improved. In addition, by compressing with a compressive stress of 5 to 15 MPa, the pores of artificial coarse aggregate concrete can be reduced, and the compressive strength and elastic modulus of artificial coarse aggregate concrete can be improved; by compressing with a compressive stress of 5 to 15 MPa, the stacking skeleton of artificial coarse aggregate can be made denser, the amount of artificial coarse aggregate per unit volume of artificial coarse aggregate concrete can be increased, and the utilization of bulk solid waste can be better realized. In addition, by compressing with a compressive stress of 5 to 15 MPa, the strength of the bonding surface between artificial coarse aggregate and cement mortar can be enhanced, thereby improving the compressive strength and elastic modulus of artificial coarse aggregate concrete. The above aspects work together to improve the compressive strength and elastic modulus of artificial coarse aggregate concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of the assembled compression mold.

[0026] Figure 2 Schematic diagram of the structure for applying compressive stress to the assembled compression mold.

[0027] Figure 3 Graph showing stress-strain test results of concrete in Examples 1-5 and Comparative Example 1.

[0028] Figure 4 Graph showing the compressive strength test results of the concrete in Examples 1-5 and Comparative Example 1.

[0029] Figure 5 Graph showing elastic modulus test results of concrete in Examples 1-5 and Comparative Example 1.

[0030] Figure 6 This is a graph showing the stress-strain test results of the artificial coarse aggregate concrete in Example 6.

[0031] Figure 7 This is a graph showing the compressive strength test results of the artificial coarse aggregate concrete in Example 6.

[0032] Figure 8 This is a graph showing the elastic modulus test results of the artificial coarse aggregate concrete in Example 6.

[0033] Fig. 9This is a graph showing the granulation efficiency of the artificial coarse aggregate in Example 7, Example 8, Example 1 and Comparative Example 2.

[0034] Fig.10 This is a graph showing the cylinder compression strength results of the artificial coarse aggregate in Example 7, Example 8, Example 1 and Comparative Example 2.

[0035] Description of the reference numerals in the accompanying drawings:

[0036] 1. Bottom plate; 2. Hollow loading barrel; 21. First part of loading barrel; 22. Second part of loading barrel; 23. Horizontal outer edge; 3. Cover plate; 31. Flat plate; 32. Protrusion; 4. Fastening bolts; 5. Fixing fasteners; 51. Fastener plate; 52. First bolt; 53. Second bolt; 6. Jack head. DETAILED DESCRIPTION

[0037] The present invention provides an artificial coarse aggregate concrete and a preparation method thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] An embodiment of the present invention provides a method for preparing an artificial coarse aggregate concrete, wherein the method for preparing the artificial coarse aggregate concrete comprises the following steps:

[0040] S1, mixing waste incineration bottom ash, granulated blast furnace slag and cement in a mass ratio of (5-7):(2-4):1 to obtain a mixture;

[0041] S2, putting the mixture into a disc granulator for water spray granulation to obtain an artificial coarse aggregate blank;

[0042] S3, curing the artificial coarse aggregate blank with saturated water to obtain artificial coarse aggregate;

[0043] S4. Cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate are stirred and mixed according to a mass ratio of (285-550):(449-788):(200-220):(0-1429):(0-1054) to obtain concrete slurry; wherein the amount of artificial coarse aggregate is not 0;

[0044] S5, pouring the concrete slurry into a compression mold, compressing it with a compressive stress of 5 to 15 MPa for a preset time, and obtaining the artificial coarse aggregate concrete after curing.

[0045] The compressive strength and elastic modulus of concrete can be improved by reducing the water-cement ratio, but this will affect the fluidity of concrete. Therefore, a water reducer needs to be added to increase the fluidity. However, in order to obtain fluidity at a low water-cement ratio, more water reducers need to be added, which increases the cost. In the present invention, no water reducer is needed. The above-mentioned mix ratio is used to obtain a concrete slurry with good fluidity. After pouring, the water can be squeezed out by compressing with a compressive stress of 5 to 15 MPa, thereby reducing the water-cement ratio of the artificial coarse aggregate concrete and improving the compressive strength and elastic modulus of the artificial coarse aggregate concrete. In addition, by compressing with a compressive stress of 5 to 15 MPa, the pores of the artificial coarse aggregate concrete can be reduced, and the compressive strength and elastic modulus of the artificial coarse aggregate concrete can be improved; by compressing with a compressive stress of 5 to 15 MPa, the stacking skeleton of the artificial coarse aggregate can be made denser (because the stacking skeleton of the artificial coarse aggregate has a certain influence on the compressive strength of the concrete, the present invention can make the stacking skeleton of the artificial coarse aggregate denser by applying pressure), and the amount of artificial coarse aggregate per unit volume of the artificial coarse aggregate concrete is increased, so as to better realize the utilization of bulk solid waste. In addition, by compressing with a compressive stress of 5 to 15 MPa, the strength of the bonding surface between the artificial coarse aggregate and the cement mortar can be enhanced, thereby improving the compressive strength and elastic modulus of the artificial coarse aggregate concrete. The above aspects work together to improve the compressive strength and elastic modulus of the artificial coarse aggregate concrete.

[0046] At present, the strength of artificial coarse aggregate concrete is mainly improved from two aspects. First, from the perspective of improving the compressive strength of artificial coarse aggregate, the compressive strength of artificial coarse aggregate can be improved by sintering, alkali solution excitation and increasing cement content. These methods not only consume a lot of energy and funds, but also have very limited improvement effects. The present invention only needs to apply a certain pressure when the concrete is poured to significantly improve the compressive strength and elastic modulus of artificial coarse aggregate concrete. Second, from the perspective of concrete itself, the compressive strength of artificial coarse aggregate concrete can be improved by adding fibers or coating with fiber reinforced composite materials (FRP). Adding fibers can significantly enhance the toughness of artificial coarse aggregate concrete and delay the failure time, but it cannot significantly improve the compressive strength and elastic modulus of artificial coarse aggregate concrete. FRP wrapping can significantly delay the failure time of artificial coarse aggregate concrete, improve compressive strength and improve elastic modulus, but the excellent performance of FRP is expensive and has high construction requirements. The present invention mainly reduces the porosity of artificial coarse aggregate concrete, reduces the water-cement ratio, improves the density of the artificial coarse aggregate stacking skeleton, and enhances the strength of the bonding surface between the artificial coarse aggregate and cement mortar through compression, thereby improving the compressive strength and elastic modulus of the concrete. It does not need to add other materials to the concrete, and the cost is low.

[0047] During the water-jet granulation process, cement, granulated blast furnace slag and waste incineration bottom ash gradually become wet. Due to the intermolecular interaction force, cement particles and granulated blast furnace slag adhere to the coarser waste incineration bottom ash particles. Due to the gelling activity and reaction of cement and granulated blast furnace slag, the waste incineration bottom ash particles are combined and agglomerated to form artificial coarse aggregate. The volcanic ash activity of cement is very high. Hydration occurs during the granulation process. The hydration process will generate Ca(OH)2, providing an alkaline environment. There are some crystalline phases in waste incineration bottom ash, such as K2O·3Al2O3·6SiO2·2H2O (potassium mica), CaMg[SiO4] (orthorhombic olivine), Fe2O3 (hematite) and CaCO3 (calcite). These alkali metal oxides can react chemically with Al2O3 and SiO2 in an alkaline environment and at different curing temperatures to generate a large amount of glass phase inside the artificial coarse aggregate.

[0048] During the granulation process, the amount of water sprayed is relatively small (the total amount of water used is 20% to 22% of the mass of the mixture). The water sprayed is not enough to provide hydration reaction. During the saturated water curing process, the hydration reaction continues to occur inside the artificial coarse aggregate and the reaction is more intense, maintaining the internal alkaline environment. In this alkaline environment, the glass phase gradually depolymerizes, promoting the formation of CSH gel and providing strength. SiO2 and Al2O3 in granulated blast furnace slag will generate CSH gel and CASH gel in the above environment, further filling the pores and improving the strength of artificial coarse aggregate.

[0049] Artificial coarse aggregate plays the role of skeleton support in concrete. Artificial coarse aggregate with larger particle size interlocks with each other, providing the main strength and stability for concrete. Cement paste wraps around the surface of artificial coarse aggregate and fills its gaps. Artificial coarse aggregate and cement paste jointly bear external forces through mechanical bite. When concrete is under pressure, artificial coarse aggregate can also effectively disperse stress and prevent the cement paste from being damaged prematurely. Artificial coarse aggregate with rough surface and multi-angle has stronger bonding with cement paste and can better play a reinforcing role. The excess slag in artificial coarse aggregate can react with calcium hydroxide produced during cement hydration to form a dense gel network structure, which makes up for the defects in the interface transition zone and improves the overall strength of concrete.

[0050] In step S1, the mass ratio of the waste incineration bottom ash, granulated blast furnace slag and cement is (5-7):(2-4):1, for example, it can be 5:2:1, 5:3:1, 5:4:1, 6:2:1, 6:3:1, 6:4:1, 7:2:1, 7:3:1 or 7:4:1, etc.

[0051] The main chemical components of the waste incineration bottom ash, granulated blast furnace slag and cement in the present invention are SiO2, Fe2O3, Al2O3 and CaO. SiO2, Fe2O3, Al2O3 and CaO are the main components that affect the volcanic ash activity in hydraulic cementitious materials. Although there are a certain amount of SiO2 and CaO in the waste incineration bottom ash, the active components in both are relatively small, especially the active part in SiO2 only accounts for 10%-20%, so the volcanic ash activity of the waste incineration bottom ash is poor and the gel performance is poor. In order to use a large amount of waste incineration bottom ash, its proportion in artificial coarse aggregate is 50-70%. A high proportion of waste incineration bottom ash will have a greater negative impact on the performance of artificial coarse aggregate, so it is necessary to add some cementitious materials with good volcanic ash reaction activity. Although cement is a cementitious material with good volcanic ash reaction activity, cement production requires a large amount of energy consumption and emits a large amount of carbon dioxide, so the amount of cement should be reduced as much as possible. Granulated blast furnace slag is a waste produced in the industrial production process, which contains a large amount of SiO2 and CaO, and the active components can reach almost 100%. Therefore, adding 20% ​​to 40% granulated blast furnace slag and 10% cement can make up for the lack of activity of the bottom ash from waste incineration and ensure that the artificial coarse aggregate has good performance.

[0052] In step S2, in some embodiments, the disc inclination angle of the disc granulator is 35-55° (for example, 35°, 40°, 45° or 55°, etc.), the disc diameter is 50 cm, the edge height is 10 cm, and the rotation speed is 30-55 rpm (for example, 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm or 55 rpm, etc.);

[0053] The granulation time is 10 to 15 minutes, for example, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes.

[0054] In step S2, after water spray granulation, the granules are sieved to obtain an artificial coarse aggregate blank with a particle size of 4.75 to 26.5 mm. In step S3, the particle size of the artificial coarse aggregate is 4.75 to 26.5 mm.

[0055] In some specific embodiments, when the artificial coarse aggregate passes through a square hole sieve with a pore size of 26.5 mm, a square hole sieve with a pore size of 19.0 mm, a square hole sieve with a pore size of 16.0 mm, a square hole sieve with a pore size of 9.5 mm, and a square hole sieve with a pore size of 4.75 mm, the residue on the sieve is 0%, 5%, 20%, 40%, and 35% of the total mass of the artificial coarse aggregate, respectively.

[0056] In step S3, in some embodiments, the artificial coarse aggregate blank is placed in water and cured at a temperature of 25° C. for 28 days to obtain the artificial coarse aggregate.

[0057] In step S4, in some embodiments, the mass ratio of cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate is (285.71-550):(449.89-787.93):(200-220):(0-1428.59):(0-1053.8). In some specific embodiments, the mass ratio of cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate is 450:589.23:202.5:(0-961.28):(177.27-886.36), for example, it can be 450:589.23:202.5:961.28:177.27, 450:589.23:202.5:720.96:354.55, 450:589.23:202.5:480.64:531.82 or 450:589.23:202.5:240.32:709.09, etc.

[0058] In some embodiments, the step of mixing cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate specifically includes:

[0059] Fine aggregate, cement and natural coarse aggregate are dry-mixed (speed is 30-50rpm, time is 5-10min), then water is added for wet mixing (speed is 30-50rpm, time is 2-5min), and finally artificial coarse aggregate is added for stirring and mixing (speed is 30-50rpm, time is 2-5min).

[0060] Because low-strength artificial coarse aggregate is easily broken by the mixer during dry mixing, the fine aggregate, cement and natural coarse aggregate are first dry-mixed, then water is added for wet mixing, and finally the artificial coarse aggregate is added for stirring and mixing.

[0061] In some embodiments, the fine aggregate is at least one of natural river sand, natural sea sand, machine-made sand and sand prepared from industrial waste slag, but is not limited thereto; the natural coarse aggregate is at least one of granite crushed stone, basalt crushed stone, diabase crushed stone and pebbles, but is not limited thereto.

[0062] In step S5, in some embodiments, the preset time is 2 to 10 minutes, for example, it can be 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0063] In some embodiments, the compression mold is an iron compression mold, which can effectively restrict the lateral deformation of the concrete slurry when it is compressed, so that a greater compressive stress can be applied to achieve the best effect.

[0064] In some embodiments, Figure 1 and Figure 2 As shown, the compression mold includes the following components:

[0065] Bottom plate 1;

[0066] A hollow charging barrel 2, wherein the hollow charging barrel 2 can be movably connected to the bottom plate 1 (or the hollow charging barrel can be detachably connected to the bottom plate);

[0067] The cover plate 3 can be movably connected to the hollow charging barrel 2 (or the cover plate can be detachably connected to the charging barrel, specifically by bolts), the cover plate comprises a flat portion 31 and a protrusion 32 located on the flat portion (the flat portion and the protrusion can be integrally formed to form the cover plate), the protrusion 32 can enter into the hollow charging barrel 2 and can slide in the hollow charging barrel 2, and when in a preset position, the cover plate and the charging barrel can be locked by tightening bolts 4.

[0068] In some embodiments, the hollow charging barrel 2 is a detachable split structure. Specifically, the hollow charging barrel 2 is composed of two parts in the radial direction, namely, a first charging barrel part 21 and a second charging barrel part 22. After the first charging barrel part and the second charging barrel part are butt-jointed, they can be fixed by bolts to form a hollow charging barrel.

[0069] When used, first install the compression mold, specifically, set the hollow charging cylinder on the bottom plate, fix the two, and enclose a cavity, then pour the concrete slurry into the cavity, and then cover the cover plate 3 so that the flat plate portion is located on the side away from the concrete slurry, and then place the pressure head 6 of the jack in the center of the flat plate portion 31 of the cover plate (such as Figure 2 As shown in the figure, after applying pressure, the protruding part of the cover plate slides into the charging barrel, and the cover plate as a whole moves downward for a certain distance. When the cover plate no longer moves downward, the cover plate is locked on the charging barrel by tightening bolts 4 (this can prevent the concrete slurry from rebounding, because the unhardened concrete slurry after compression will rebound and affect the compression effect. The compression mold can maintain the compression state of the concrete slurry before hardening until the mold is removed by locking the cover plate). After curing for 24 hours, the cover plate, the charging barrel and the bottom plate are disassembled to obtain artificial coarse aggregate concrete.

[0070] In some embodiments, a horizontal outer edge 23 extends outward from the bottom of the charging barrel.

[0071] In some embodiments, the compression mold further includes a fixing fastener 5, and the fixing fastener 5 includes:

[0072] A first bolt 52 (having a head and a screw connected to the head, wherein the diameter of the head is greater than the diameter of the screw);

[0073] A second bolt 53 (having a head and a screw connected to the head, wherein the diameter of the head is greater than the diameter of the screw);

[0074] A fastener plate 51 is provided with a through hole in the middle position of the fastener plate 51, the aperture of which is larger than the screw diameter of the first bolt 52 and smaller than the head diameter of the first bolt 52; a threaded through hole is provided at the end position of one end of the fastener plate 51, the thread of which matches the second bolt 53; the first bolt 52 is fixedly connected to the base plate after passing through the through hole in the middle position of the fastener plate 51.

[0075] The first bolt may also be a supporting part, which includes a head and a rod connected to the head (head diameter>through hole diameter in the middle of the fastener plate>rod diameter), the rod passes through the through hole in the middle of the fastener plate and is welded to the base plate.

[0076] In specific applications, since the current fastener plate can move along the second bolt, it cannot play the role of fixing the bottom plate and the charging barrel. Therefore, when the bottom plate and the charging barrel need to be fixed, the second bolt 53 is screwed into the threaded through hole of the fastener plate 51, and the end of the fastener plate 51 provided with the threaded through hole is constantly lifted, and the other end of the fastener plate 51 away from the threaded through hole continuously applies pressure to the horizontal outer edge 23 extending from the bottom of the charging barrel. When the other end of the fastener plate 51 away from the threaded through hole applies sufficient pressure to the horizontal outer edge 23 extending from the bottom of the charging barrel, the bottom end of the screw of the second bolt 53 is against the bottom plate 1 (the bottom plate 1 is not provided with a threaded hole matching the second bolt, and the second bolt is not screwed into the bottom plate), so that the charging barrel and the bottom plate are fixed.

[0077] Compared with directly fixing the charging barrel and the bottom plate with bolts, the fixing fasteners used in the present invention can not only prevent the bolt holes of the bottom plate from being blocked, but also leave a certain gap between the charging barrel and the bottom plate, which is more conducive to water outflow during compression.

[0078] A second aspect of the present invention provides an artificial coarse aggregate concrete, wherein the artificial coarse aggregate concrete is prepared by the preparation method of the present invention as described above.

[0079] The present invention will be further described below by means of specific examples.

[0080] The main chemical components of the waste incineration bottom ash, granulated blast furnace slag and cement (i.e., ordinary Portland cement) used in the following examples and comparative examples are shown in Table 1.

[0081] Table 1. Main chemical components of waste incineration bottom ash, granulated blast furnace slag and cement

[0082]

[0083] The natural coarse aggregate used in the following examples and comparative examples is granite crushed stone, and the fine aggregate is natural river sand. The physical properties of the natural coarse aggregate and the artificial coarse aggregate are shown in Table 2.

[0084] Table 2. Physical properties of coarse aggregate

[0085]

[0086]

[0087] The particle size distribution of natural coarse aggregate and artificial coarse aggregate in the following examples is shown in Table 3.

[0088] Table 3. Particle gradation of natural coarse aggregate and artificial coarse aggregate

[0089]

[0090] The mix ratios of concrete in the following examples and comparative examples are shown in Table 4.

[0091] Table 4, mix ratio of concrete in each embodiment and comparative example

[0092]

[0093]

[0094] Example 1

[0095] This embodiment provides a method for preparing artificial coarse aggregate concrete, comprising the following steps:

[0096] Mixing waste incineration bottom ash, granulated blast furnace slag and cement in a mass ratio of 7:2:1 to obtain a mixture;

[0097] The mixture is put into a disc granulator (the disc inclination angle of the disc granulator is 45°, the disc diameter is 50 cm, the edge height is 10 cm, and the rotation speed is 45 rpm), and water is sprayed during the granulation process, and the total water consumption is 20% of the mass of the mixture. After granulation for 10 minutes and hardening for 24 hours, the mixture is sieved to obtain an artificial coarse aggregate blank with a particle size of 4.75 to 26.5 mm;

[0098] The artificial coarse aggregate blank is placed in tap water (the tap water covers the artificial coarse aggregate blank), and the artificial coarse aggregate is cured at a temperature of 25° C. for 28 days to obtain the artificial coarse aggregate;

[0099] According to the mix ratio of concrete in Example 1 in Table 4, fine aggregate, cement and natural coarse aggregate were mixed and dry-mixed (speed of 50 rpm, time of 5 min), then water was poured in for wet mixing (speed of 50 rpm, time of 2 min), and finally artificial coarse aggregate was poured in for mixing (speed of 50 rpm, time of 2 min), and then poured into a compression mold (such as Figure 1 As shown in the figure, a hydraulic jack is used to compress the concrete for 120 seconds with compressive stresses of 0 MPa and 15 MPa, respectively. After curing for 24 hours, the formwork is removed, and the obtained artificial coarse aggregate concrete is recorded as R20P0 (corresponding to 0 MPa compressive stress) and R20P15 (corresponding to 15 MPa compressive stress), respectively.

[0100] Example 2

[0101] This embodiment provides a method for preparing an artificial coarse aggregate concrete, which is different from Embodiment 1 only in that the mix ratio of concrete in Embodiment 2 in Table 4 is adopted, and the obtained artificial coarse aggregate concretes are respectively recorded as R40P0 (corresponding to 0 MPa compressive stress) and R40P15 (corresponding to 15 MPa compressive stress).

[0102] Example 3

[0103] This embodiment provides a method for preparing an artificial coarse aggregate concrete, which is different from Embodiment 1 only in that the mix ratio of concrete in Embodiment 3 in Table 4 is adopted, and the obtained artificial coarse aggregate concretes are respectively recorded as R60P0 (corresponding to 0 MPa compressive stress) and R60P15 (corresponding to 15 MPa compressive stress).

[0104] Example 4

[0105] This embodiment provides a method for preparing an artificial coarse aggregate concrete, which is different from Embodiment 1 only in that the mix ratio of concrete in Embodiment 4 in Table 4 is adopted, and the obtained artificial coarse aggregate concretes are respectively recorded as R80P0 (corresponding to 0 MPa compressive stress) and R80P15 (corresponding to 15 MPa compressive stress).

[0106] Example 5

[0107] This embodiment provides a method for preparing an artificial coarse aggregate concrete, which is different from Embodiment 1 only in that the mix ratio of concrete in Embodiment 5 in Table 4 is adopted, and the obtained artificial coarse aggregate concretes are respectively recorded as R100P0 (corresponding to 0 MPa compressive stress) and R100P15 (corresponding to 15 MPa compressive stress).

[0108] Comparative Example 1

[0109] This comparative example provides a method for preparing natural coarse aggregate concrete, which differs from Example 1 only in that the mix ratio of concrete in Comparative Example 1 in Table 4 is adopted, and the obtained concretes are respectively recorded as R0P0 (corresponding to 0 MPa compressive stress) and R0P15 (corresponding to 15 MPa compressive stress).

[0110] test:

[0111] (1) The concrete in Examples 1-5 and Comparative Example 1 was subjected to stress-strain tests. The results are as follows: Figure 3 shown.

[0112] (2) The compressive strength and elastic modulus of the concrete in Examples 1-5 and Comparative Example 1 were tested, and the results are shown in Table 5 (wherein the compressive strength improvement rate is the compressive strength improvement rate of the concrete when a compressive stress of 15 MPa is applied relative to that of a compressive stress of 0 MPa; the elastic modulus improvement rate is the elastic modulus improvement rate of the concrete when a compressive stress of 15 MPa is applied relative to that of a compressive stress of 0 MPa) and Figure 4 (Ordinary pouring refers to concrete poured under 0MPa compressive stress, and compression pouring refers to concrete poured under 15MPa compressive stress) and Figure 5 shown.

[0113] Table 5. Compressive strength and elastic modulus results

[0114]

[0115]

[0116] Example 6

[0117] This embodiment provides a method for preparing artificial coarse aggregate concrete, comprising the following steps:

[0118] According to the mix ratio of concrete in Example 5 in Table 4, fine aggregate, cement and natural coarse aggregate were mixed and dry stirred (rotation speed of 50 rpm, time of 5 min), then water was poured in for wet mixing (rotation speed of 50 rpm, time of 2 min), and finally artificial coarse aggregate was poured in for stirring (rotation speed of 50 rpm, time of 2 min), and then poured into a compression mold, and compressed for 120 s with a hydraulic jack using a compressive stress of 0 MPa, 5 MPa, 10 MPa, and 15 MPa, respectively. After curing for 24 h, the mold was removed, and the obtained artificial coarse aggregate concretes were recorded as R100P0 (corresponding to 0 MPa compressive stress), R100P5 (corresponding to 5 MPa compressive stress), R100P10 (corresponding to 10 MPa compressive stress), and R100P15 (corresponding to 15 MPa compressive stress), respectively.

[0119] The artificial coarse aggregate concrete in Example 6 was subjected to stress-strain test. The results are as follows: Figure 6 shown.

[0120] The compressive strength and elastic modulus of the artificial coarse aggregate concrete in Example 6 were tested. The results are shown in Table 6 and Figure 7 as well as Figure 8 shown.

[0121] Table 6. Compressive strength and elastic modulus results of artificial coarse aggregate concrete in Example 6

[0122]

[0123] From the above results, it can be seen that applying a certain pressure during the preparation process of artificial coarse aggregate concrete can significantly improve the compressive strength and elastic modulus of artificial coarse aggregate, and compared with natural coarse aggregate concrete, the compressive strength and elastic modulus of the artificial coarse aggregate concrete in the present invention are more significantly improved after applying pressure during the preparation process.

[0124] Example 7

[0125] This embodiment provides a method for preparing artificial coarse aggregate, which is different from the method for preparing artificial coarse aggregate in Example 1 only in that:

[0126] The waste incineration bottom ash, granulated blast furnace slag and cement are mixed in a mass ratio of 5:4:1 to obtain a mixture.

[0127] Example 8

[0128] This embodiment provides a method for preparing artificial coarse aggregate, which is different from the method for preparing artificial coarse aggregate in Example 1 only in that:

[0129] The waste incineration bottom ash, granulated blast furnace slag and cement are mixed in a mass ratio of 6:3:1 to obtain a mixture.

[0130] Comparative Example 2

[0131] This comparative example provides a method for preparing an artificial coarse aggregate, which differs from the method for preparing an artificial coarse aggregate in Example 1 only in that:

[0132] The waste incineration bottom ash, granulated blast furnace slag and cement are mixed in a mass ratio of 8:1:1 to obtain a mixture.

[0133] The granulation efficiency results of the artificial coarse aggregate in Example 7, Example 8, Example 1, and Comparative Example 2 are as follows: Fig. 9 As shown, the granulation efficiency is the ratio of the weight of the artificial coarse aggregate with a particle size of 4.75-20 mm to the total weight of the feed (ie the total mass of the mixture). It can be seen that the granulation efficiency of the artificial coarse aggregate in Comparative Example 2 is significantly reduced.

[0134] The cylinder compressive strength of the artificial coarse aggregate in Example 7, Example 8, Example 1 and Comparative Example 2 (the cylinder compressive strength is tested according to "Light Aggregate and Its Test Method" GB-T 17431.2-2010) is as follows: Fig.10 It can be seen that the cylinder compression strength of the artificial coarse aggregate in Comparative Example 2 is significantly lower than that of the artificial coarse aggregate in Example 7, Example 8 and Example 1.

[0135] Unlike natural coarse aggregate, artificial coarse aggregate has lower strength and is more sensitive to compression pressure when preparing concrete. Excessive compressive stress may damage artificial coarse aggregate, thereby reducing the compressive strength of artificial coarse aggregate concrete. In practical applications, production efficiency is also a key consideration. If the granulation efficiency is too low, the production efficiency will be reduced. Although the cylinder compression strength and granulation efficiency of the artificial coarse aggregate in Examples 7 and 8 are slightly higher than those of the artificial coarse aggregate in Example 1, from the perspective of treating waste incineration bottom ash, the preparation method of artificial coarse aggregate in Example 1 can make more use of waste incineration bottom ash, and the granulation efficiency and cylinder compression strength are less reduced. Therefore, the ratio of waste incineration bottom ash, granulated blast furnace slag and cement in artificial coarse aggregate is preferably 7:2:1.

[0136] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing artificial coarse aggregate concrete, characterized in that: The steps include: Mixing waste incineration bottom ash, granulated blast furnace slag and cement in a mass ratio of (5-7):(2-4):1 to obtain a mixture; The mixed material is put into a disc granulator, and granulated by spraying water to obtain an artificial coarse aggregate blank; The artificial coarse aggregate blank is subjected to water-saturated curing to obtain artificial coarse aggregate; Cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate are stirred and mixed according to a mass ratio of (285-550):(449-788):(200-220):(0-1429):(0-1054) to obtain concrete slurry; wherein the amount of artificial coarse aggregate is not 0; The concrete slurry is poured into a compression mold, compressed for a preset time with a compression stress of 5 to 15 MPa, and solidified to obtain the artificial coarse aggregate concrete.

2. The preparation method according to claim 1, characterized in that: The mixed material is put into a disc granulator, and water is sprayed during the granulation process, with the total water consumption being 20% ​​to 22% of the mass of the mixed material, to carry out granulation.

3. The preparation method according to claim 1, characterized in that: The disc granulator has a disc inclination angle of 35 to 55°, a disc diameter of 50 cm, an edge height of 10 cm, and a rotation speed of 30 to 55 rpm; The granulation time is 10 to 15 minutes.

4. The preparation method according to claim 1, characterized in that: The particle size of the artificial coarse aggregate is 4.75-26.5 mm.

5. The preparation method according to claim 1, characterized in that: When the artificial coarse aggregate passes through a square hole sieve with a hole diameter of 26.5 mm, a square hole sieve with a hole diameter of 19.0 mm, a square hole sieve with a hole diameter of 16.0 mm, a square hole sieve with a hole diameter of 9.5 mm and a square hole sieve with a hole diameter of 4.75 mm in sequence, the residues on the sieves are 0%, 5%, 20%, 40% and 35% of the total mass of the artificial coarse aggregate respectively.

6. The preparation method according to claim 1, characterized in that: The artificial coarse aggregate blank is placed in water and cured at a temperature of 25° C. for 28 days to obtain artificial coarse aggregate.

7. The preparation method according to claim 1, characterized in that: The steps of mixing cement, fine aggregate, water, natural coarse aggregate and artificial coarse aggregate specifically include: Fine aggregate, cement and natural coarse aggregate are dry mixed, then water is added for wet mixing, and finally artificial coarse aggregate is added for mixing.

8. The preparation method according to claim 1, characterized in that: The preset time is 2 to 10 minutes.

9. The preparation method according to claim 1, characterized in that: The fine aggregate is at least one of natural river sand, natural sea sand, machine-made sand and sand prepared from industrial waste residues, and the natural coarse aggregate is at least one of granite crushed stone, basalt crushed stone, diabase crushed stone and pebbles.

10. An artificial coarse aggregate concrete, characterized in that: The artificial coarse aggregate concrete is prepared by the preparation method according to any one of claims 1 to 9.

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