A large-volume concrete based on construction waste and its preparation method

Abstract

The present invention discloses a mass concrete based on construction waste. The components and their dosages include: 100 - 300 kg / m of cement 3 , 50 - 180 kg / m of concrete admixture 3 , 30 - 100 kg / m of recycled waste slurry powder 3 , 800 - 1100 kg / m of sand 3 , 1400 - 2000 kg / m of recycled coarse aggregate 3 , 140 - 160 kg / m of water 3 , 2.3 - 5.8 kg / m of composite modifier 3 , 2 - 8 kg / m of water reducer 3 ; wherein, the recycled coarse aggregate is obtained by crushing and surface strengthening construction waste with high-pressure water jet; the recycled waste slurry powder is obtained by ultrafine grinding of the waste slurry residue of the remaining liquid phase collected after high-pressure water crushing of construction waste. The present invention can achieve zero emission in the process of resource utilization of construction waste. The obtained mass concrete has the advantages of low hydration heat, high strength, small shrinkage, etc., and has significant economic and environmental benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a mass concrete based on construction waste and a preparation method thereof. Background Art

[0002] Mass concrete refers to a concrete structure with a minimum cross-sectional dimension of more than 1 m, which has the characteristics of thick structure, large shape, large amount of concrete, complex engineering conditions and high construction technical requirements. During the hardening period of mass concrete, on the one hand, a large amount of hydration heat will be released during the cement hydration process, making the structural member have the characteristic of "thermal expansion"; on the other hand, the concrete has the characteristic of "shrinkage" when it hardens. The result of the interaction of the two will directly damage the concrete structure and cause cracks in the structure. If the control measures are improper and the temperature stress exceeds the tensile limit value that the concrete can bear, cracks are likely to occur. At present, the temperature control measures for mass concrete mainly start from problems such as reducing the temperature of the raw materials entering the mold, and methods such as cooling water pipes are used in construction, but usually the problem of internal temperature rise of large volume cannot be fundamentally solved.

[0003] In addition, at the present stage, the treatment method of construction waste is usually the mechanical crushing method to form recycled aggregates. This method has problems such as large dust in the production process and poor performance of recycled aggregates. Therefore, it is particularly necessary to further develop a mass concrete with excellent performance, which can fully recycle construction waste and has better environmental protection benefits. Summary of the Invention

[0004] The main purpose of the present invention is to provide a mass concrete based on construction waste in view of the problems and deficiencies existing in the prior art, which can achieve zero emissions in the process of resource utilization of construction waste, and the obtained mass concrete has low hydration heat, small shrinkage and excellent performance; and the involved preparation method is relatively simple, the cost is relatively low, and it has significant economic and environmental benefits and is suitable for popularization and application.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A mass concrete based on construction waste, the components and their dosages include: cement 100 - 300 kg / m 3 , concrete admixture 50 - 180 kg / m 3 , recycled waste slurry powder 30 - 100 kg / m 3 , sand 800 - 1100 kg / m 3 , recycled coarse aggregate 1400 - 2000 kg / m 3 , water 140 - 160 kg / m 3 , composite modifier 2.3 - 5.8 kg / m 3 , water reducer 2 - 8 kg / m 3Among them, the recycled coarse aggregate is obtained by crushing construction waste with high-pressure water jet to obtain recycled crushed aggregate, and then through surface strengthening treatment; the recycled waste slurry powder is obtained by ultra-fine grinding of the waste slurry residue of the remaining liquid phase part collected after crushing construction waste with high-pressure water jet; the composite modifier is obtained by reacting with lignin, sodium sulfate, lime milk, polyethylene glycol, cellulose fiber and alkali solution as the main raw materials.

[0007] In the above solution, the construction waste is waste concrete.

[0008] In the above solution, the water pressure of the high-pressure water jet is 10 - 30 MPa.

[0009] In the above solution, the strengthening treatment step includes: first, mixing water and surface strengthening material evenly to prepare a slurry of the surface strengthening material (the mass ratio of water to surface strengthening material is 1:0.7 - 1), and then using it to perform slurry coating treatment on the recycled coarse aggregate.

[0010] In the above solution, the surface strengthening material can be selected from clay or a mixture of cement and silica fume; the introduced surface strengthening material can effectively block the cracks on the surface of the recycled aggregate and can reduce the linear expansion coefficient of the recycled coarse aggregate.

[0011] In the above solution, the particle size of the recycled coarse aggregate is 5 - 20 mm, 5 - 25 mm or 5 - 31.5 mm.

[0012] In the above solution, during the ultra-fine grinding treatment, the vibration frequency of the grinding mill used is 40 - 60 Hz; the time is 1 - 4 h; the average diameter D50 of the obtained recycled waste slurry powder is 0.1 - 10 μm.

[0013] Furthermore, a grinding aid and an activity activator are introduced during the ultra-fine grinding treatment.

[0014] In the above solution, the grinding aid can be selected from one or several of diethanol monoisopropanolamine, triethanolamine, triisopropanolamine, etc.

[0015] In the above solution, the activity activator is an inorganic salt activator, and specifically can be selected from one or several of sodium sulfate, sodium chloride, ferric chloride, etc.

[0016] In the above solution, the specific preparation steps of the recycled waste slurry powder include: crushing waste concrete with high-pressure water jet, separating and separating the recycled crushed aggregate, and then introducing the remaining waste slurry into a sedimentation tank for sedimentation; adding a grinding aid and an activity activator to the sedimented waste slurry residue, and performing ultra-fine grinding treatment to obtain the recycled waste slurry powder.

[0017] In the above solution, the dosage of the grinding aid is 0.02 - 0.05% of the mass of the waste slurry residue; the dosage of the activity activator is 0.02 - 0.05% of the mass of the waste slurry residue.

[0018] In the above solution, the cement can be selected as ordinary Portland cement, etc.

[0019] In the above solution, the admixture can be selected from one or several of fly ash, ground granulated blast-furnace slag, silica fume, etc.

[0020] In the above solution, the fineness modulus of the sand is 2.6 - 2.9, and the mud content is less than 2%.

[0021] In the above solution, the raw materials and their weight parts in the composite modifier include: 1 part of lignin (relative molecular weight 100 - 500), 0.5 - 1 part of sodium sulfate, 0.5 - 1 part of lime milk, 10 - 20 parts of polyethylene glycol (relative molecular weight 1600 - 6000), 10 - 30 parts of cellulose fiber, and 50 - 80 parts of alkali solution.

[0022] Further, the alkali solution can be selected as sodium hydroxide solution, etc., and its pH value is 12 - 13.

[0023] In the above solution, the specific preparation steps of the composite modifier include:

[0024] 1) Dissolve 1 part of lignin, 0.5 - 1 part of sodium sulfate, and 0.5 - 1 part of lime milk completely in 50 - 80 parts of alkali solution, and mix evenly;

[0025] 2) Put the obtained mixed solution into a reaction kettle and react at a high temperature of 160 - 180 °C for 4 - 6 h. After standing at room temperature, add 10 - 30 parts of cellulose fiber and 10 - 20 parts of polyethylene glycol, mix evenly, and then evaporate and dry to obtain a solid mixture, that is, the composite modifier.

[0026] In the above solution, the water reducer is a polycarboxylate water reducer, and its water reduction rate is more than 25%.

[0027] The preparation method of the above-mentioned mass concrete based on construction waste includes the following steps:

[0028] 1) Weigh each raw material according to the proportion, and each component and its content include: cement 100 - 300 kg / m 3 , admixture 50 - 180 kg / m 3 , recycled waste slurry powder 30 - 100 kg / m 3 , sand 800 - 1100 kg / m 3 , recycled coarse aggregate 1400 - 2000 kg / m 3 , water 140 - 160 kg / m 3, composite modifier: 2.3 - 5.8 kg / m 3 , water reducing agent: 2 - 8 kg / m 3 ;

[0029] 2) Mix the weighed cement, admixture, recycled waste slurry powder, sand, recycled coarse aggregate, and composite modifier evenly.

[0030] 3) Then add the weighed water reducing agent and water and conduct stirring treatment until all raw materials are fully and evenly mixed, thus obtaining the mass concrete.

[0031] In the above solution, the stirring treatment time is 2 minutes or more.

[0032] The technical principle of the present invention is as follows:

[0033] 1) The present invention first proposes to recycle aggregates by means of high-pressure water jets, and further conduct surface strengthening treatment or ultrafine grinding treatment to obtain recycled aggregates and recycled waste powder. Among them:

[0034] During the preparation process of the recycled waste slurry powder, the aggregate particles therein can play the role of micro-grinding media, promoting the ultra-fine treatment of cement hydration products; at the same time, through ultra-fine treatment and activation treatment, the pozzolanic activity of the obtained recycled waste slurry powder can be effectively improved, and the micro-aggregate effect can be exerted. The pozzolanic reaction can generate hydrated product C-S-H gel, which has the potential of C-S-H gel crystal seed early strength agent. At the same time, the C-S-H gel structure is dense, and the porosity is significantly reduced. Therefore, the migration of early-stage moisture in concrete can be reduced, the shrinkage of concrete can be reduced, and thus cracking can be reduced. In addition, the pozzolanic activity of the recycled waste slurry powder mainly occurs in the later stage, and the early hydration heat is relatively low, which can effectively reduce the temperature and the rising rate of the internal temperature of mass concrete in the early stage, reduce the temperature difference between the inside and outside of the mass concrete, and reduce the cracking caused by temperature stress.

[0035] The recycled coarse aggregate treated with surface strengthening materials can effectively reduce the linear expansion coefficient of the recycled coarse aggregate, thereby reducing the overall linear expansion coefficient of the mass concrete, and further reducing problems such as cracking caused by temperature stress; the water absorption rate of the recycled coarse aggregate treated with surface strengthening treatment according to the present invention is relatively low, which can improve the workability of concrete; and when the later-stage concrete is in a long-term dry shrinkage environment, the coarse aggregate with a small water absorption rate has less evaporation of internal moisture. Due to the lack of relatively large porosity in itself and other reasons, its ability to restrain the dry shrinkage of concrete is relatively good, making the later-stage dry shrinkage rate smaller.

[0036] 2) The compound modifier is an organic compound with both hydrophilic and hydrophobic groups, an ionizable charged hydrophilic group. The hydrophobic group adsorbs on the surface of cement and waste powder materials, having good dispersibility. The hydrophilic group carboxyl groups point to the aqueous solution and repel each other, thus exerting a good dispersing effect and reducing the water consumption. In addition, after forming a covering film on the cement particles, it can extend the coagulation process, thereby reducing the rate of heat release during cement hydration, avoiding early concentrated heat release, reducing the temperature difference between the inside and outside of mass concrete, and giving sufficient time for mass concrete to dissipate heat, reducing the risk of cracking. Moreover, the compound modifier contains sulfate components that can stimulate the pozzolanic activity of recycled waste slurry powder to produce calcium silicate hydrate. In addition, the polyethylene glycol in the compound modifier has the function of phase change energy storage, being uniformly dispersed inside the cement stone. It can absorb the heat released during cement hydration in the early stage of cement hydration, thus reducing the temperature inside the concrete. The polyethylene glycol in the compound modifier undergoes a lapping reaction with cellulose fibers in an alkaline environment. On the one hand, the cellulose fibers undergoing the lapping reaction can be dispersed in the concrete, improving the crack resistance of mass concrete. On the other hand, it can further enhance the heat adsorption capacity inside the cement stone.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1) The present invention can achieve 100% recycling of construction waste; adopting the method of high-pressure water jet to prepare recycled aggregate and recycled waste powder materials, the preparation process is pollution-free and dust-free, the recycled aggregate particles are complete, and the treated recycled aggregate and recycled waste powder materials can be efficiently applied in mass concrete;

[0039] 2) The mass concrete obtained by the present invention can take into account good workability, mechanical properties, crack resistance, etc., and at the same time has significant economic and environmental benefits, and is suitable for popularization and application. Specific embodiments

[0040] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in combination with embodiments. 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.

[0041] In the following embodiments, the cement used is P·O42.5 ordinary Portland cement; the fly ash is Class F Grade II fly ash; the blast furnace slag powder is S95 grade blast furnace slag powder.

[0042] The recycled coarse aggregate is an aggregate with well-graded continuous gradation.

[0043] The sand used is medium sand with hard particles and good gradation. It is required to be natural clean medium sand with a particle size less than 4.75 mm, a fineness modulus of 2.6 - 2.8, and a mud content less than 2%.

[0044] The water reducer is a polycarboxylate water reducer with a water reduction rate of 25%.

[0045] In the following examples, the waste concrete used was taken from the waste concrete after the demolition of a certain old house building, and its concrete strength grade was C30.

[0046] Example 1

[0047] A mass concrete based on construction waste, and its preparation method includes the following steps:

[0048] 1) Preparation of recycled coarse aggregate and recycled waste slurry powder;

[0049] Collect waste concrete, use high-pressure water jet to crush the waste concrete, collect the obtained recycled crushed aggregate, and perform screening to obtain 5-20 mm continuously graded aggregate; then add it to the cement slurry (mixed evenly by cement, silica fume and water according to the mass ratio of 1:0.3:0.5) for slurry coating treatment, and place it for 28 days to obtain recycled coarse aggregate;

[0050] The waste slurry obtained from the crushing treatment is flushed into the sedimentation tank for sedimentation, collect the waste slurry residue in the sedimentation tank, then take 1 part (by weight, the same below) of the waste slurry residue, add 0.0003 part of grinding aid and 0.0003 part of activity activator to it, and grind for 2 h (the grinding vibration frequency of the grinder is 50 Hz) to obtain recycled waste slurry powder with a D50 of 2.42 μm;

[0051] 2) Preparation of composite modifier;

[0052] Dissolve 50 g of wheat straw lignin, 50 g of sodium sulfate, and 50 g of lime milk completely in 2500 g of sodium hydroxide solution (pH value 13); put the obtained mixed solution into the reaction kettle and react at 180 °C for 6 h, after standing at room temperature, add 1000 g of cellulose fiber and 800 g of polyethylene glycol, mix evenly, and then perform evaporation and drying to obtain a solid mixture, that is, the composite modifier;

[0053] 3) Weigh each raw material in the mass concrete according to the ratio, and each component and its content are: cement 200 kg / m 3 , fly ash 180 kg / m 3 , recycled waste slurry powder 30 kg / m 3 , sand 900 kg / m 3 , recycled coarse aggregate 1500 kg / m 3 , water 150 kg / m 3 , composite modifier 2.8 kg / m 3 , water reducer 7 kg / m 3 ;

[0054] 4) Weigh the cement, admixture (fly ash), recycled waste slurry powder, sand, recycled coarse aggregate, and composite modifier, and add them to a mixer to mix evenly; then add the weighed water reducer and water, and stir for 5 minutes until all raw materials are fully and evenly mixed, thus obtaining the mass concrete.

[0055] Example 2

[0056] A mass concrete based on construction waste, and its preparation method includes the following steps:

[0057] 1) Preparation of recycled coarse aggregate and recycled waste slurry powder;

[0058] Collect waste concrete, use high-pressure water jet to crush the waste concrete, collect the obtained recycled crushed aggregate, and perform screening to obtain aggregate with a continuous gradation of 5 - 20 mm; then add it to the cement slurry (prepared by mixing cement, silica fume, and water in a mass ratio of 1:0.3:0.5) for slurry coating treatment, and leave it for 28 days to obtain recycled coarse aggregate;

[0059] The waste slurry obtained from the crushing treatment is flushed into a sedimentation tank for sedimentation. Collect the waste slurry residue in the sedimentation tank. Then, take 1 part of the waste slurry residue, add 0.0003 parts of triethanolamine and 0.0003 parts of sodium sulfate to it, and grind for 3 hours (the grinding vibration frequency of the grinder is 50 Hz) to obtain recycled waste slurry powder with a D50 of 0.36 μm;

[0060] 2) Preparation of composite modifier;

[0061] Dissolve 50 g of wheat straw lignin, 50 g of sodium sulfate, and 50 g of lime milk completely in 2500 g of sodium hydroxide solution (pH value 13); put the obtained mixed solution into a reaction kettle and react at a high temperature of 180 °C for 6 hours. After leaving it at room temperature, add 1000 g of cellulose fiber and 800 g of polyethylene glycol, mix evenly, and then perform evaporation and drying to obtain a solid mixture, thus obtaining the composite modifier;

[0062] 3) Weigh each raw material in the mass concrete according to the ratio. Each component and its content are as follows: cement 180 kg / m 3 , fly ash 150 kg / m 3 , recycled waste slurry powder 60 kg / m 3 , sand 980 kg / m 3 , recycled coarse aggregate 1680 kg / m 3 , water 160 kg / m 3 , composite modifier 2.4 kg / m 3 , water reducer 2.8 kg / m 3 ;

[0063] 4) Weigh the cement, admixture (fly ash), recycled waste slurry powder, sand, recycled coarse aggregate, and composite modifier, and add them to a mixer to mix evenly; then add the weighed water reducer and water, and stir for 5 minutes until all raw materials are fully and evenly mixed, thus obtaining the mass concrete.

[0064] Example 3

[0065] A mass concrete based on construction waste, and its preparation method includes the following steps:

[0066] 1) Preparation of recycled coarse aggregate and recycled waste slurry powder;

[0067] Collect waste concrete, use high-pressure water jet to crush the waste concrete, collect the obtained recycled crushed aggregate, and perform screening to obtain an aggregate with a continuous gradation of 5 - 20 mm; then add it to the cement slurry (prepared by mixing cement, silica fume, and water in a mass ratio of 1:0.3:0.5) for slurry coating treatment, and place it for 28 days to obtain the recycled coarse aggregate;

[0068] The waste slurry obtained from the crushing treatment is flushed into a sedimentation tank for sedimentation. Collect 1 part (by weight, the same below) of the waste slurry residue in the liquid phase state in the sedimentation tank, then add 0.0003 parts of grinding aid and 0.0003 parts of activity activator to it, and grind for 3 hours (the grinding vibration frequency of the grinder is 50 Hz) to obtain recycled waste slurry powder with a D50 of 0.36 μm;

[0069] 2) Preparation of composite modifier;

[0070] Completely dissolve 50 g of wheat straw lignin, 50 g of sodium sulfate, and 50 g of lime milk in 2500 g of sodium hydroxide solution (pH value 13); put the obtained mixed solution into a reaction kettle and react at a high temperature of 180 °C for 6 hours. After returning to room temperature, add 1000 g of cellulose fiber and 800 g of polyethylene glycol, mix evenly, and then perform evaporation and drying to obtain a solid mixture, which is the composite modifier;

[0071] 3) Weigh each raw material in the mass concrete according to the ratio. The components and their contents are as follows: cement 250 kg / m 3 , fly ash 75 kg / m 3 , recycled waste slurry powder 75 kg / m 3 , sand 880 kg / m 3 , recycled coarse aggregate 1680 kg / m 3 , water 150 kg / m 3 , composite modifier 2.24 kg / m 3 , water reducer 7 kg / m 3 ;

[0072] 4) Weigh the cement, admixture (fly ash), recycled waste slurry powder, sand, recycled coarse aggregate, and compound modifier, and add them to a mixer to mix evenly; then add the weighed water reducer and water, and stir for 5 minutes until all raw materials are fully and evenly mixed, thus obtaining the mass concrete.

[0073] Comparative Example 1

[0074] A mass concrete, the preparation method of which is substantially the same as that of Example 1, except that the mixing ratio used is: cement 200 kg / m 3 , fly ash 180 kg / m 3 , recycled waste slurry powder 30 kg / m 3 , sand 900 kg / m 3 , recycled coarse aggregate 1500 kg / m 3 , water 150 kg / m 3 , water reducer 7 kg / m 3 .

[0075] Comparative Example 2

[0076] A mass concrete, the preparation method of which is substantially the same as that of Example 1, except that the mixing ratio used is: cement 180 kg / m 3 , fly ash 150 kg / m 3 , recycled waste slurry powder 60 kg / m 3 , sand 980 kg / m 3 , recycled coarse aggregate 1680 kg / m 3 , water 160 kg / m 3 , compound modifier 2.4 kg / m 3 , water reducer 2.8 kg / m 3 ; wherein the coarse aggregate is natural gravel with a continuous gradation of particle sizes of 5 - 20 mm.

[0077] Comparative Example 3

[0078] A mass concrete, the preparation method of which is substantially the same as that of Example 1, except that the mixing ratio used is: cement 230 kg / m 3 , fly ash 180 kg / m 3 , sand 900 kg / m 3 , recycled coarse aggregate 1500 kg / m 3 , water 150 kg / m 3 , compound modifier 2.8 kg / m 3 , water reducer 7 kg / m 3 .

[0079] Comparative Example 4

[0080] A large-volume concrete, the preparation method of which is substantially the same as that of Example 2, except that:

[0081] 1) The preparation process of the composite modifier includes: completely dissolving 50 g of wheat straw lignin, 50 g of sodium sulfate, and 50 g of lime milk in 2500 g of sodium hydroxide solution with a pH of 13; putting the obtained mixed solution into a reaction kettle and reacting at a high temperature of 180 °C for 6 h, then performing evaporation and drying to obtain a solid mixture, i.e., the composite modifier;

[0082] 2) The components and their contents in the large-volume concrete are: cement 180 kg / m 3 , fly ash 150 kg / m 3 , recycled waste slurry powder 60 kg / m 3 , sand 980 kg / m 3 , recycled coarse aggregate 1680 kg / m 3 , water 160 kg / m 3 , composite modifier 2.4 kg / m 3 , water reducer 2.8 kg / m 3 .

[0083] The large-volume concretes prepared in Examples 1-3 and Comparative Examples 1-3 were respectively tested for workability, mechanical properties, shrinkage properties, and temperature conditions at different parts. The test results of slump, internal temperature at 24 h, maximum internal and external temperature difference, compressive strength at 28 d, compressive strength at 90 d, autogenous shrinkage rate at 28 d, etc. are shown in Table 1 respectively.

[0084] Table 1 Test results of large-volume concrete performance

[0085]

[0086] Comparative analysis of the test results found that:

[0087] Comparing and analyzing the test results of Example 1 and Comparative Example 1, it can be seen that: the incorporation of the composite modifier described in the present invention can significantly improve the workability of the concrete; reduce the internal temperature and the maximum internal and external temperature difference of the concrete; improve the strength of the concrete; and at the same time can effectively reduce the shrinkage of the concrete.

[0088] By comparing and analyzing the test results of Example 1 and Comparative Example 2, it can be seen that: the use of the recycled coarse aggregate described in the present invention can improve the slump of concrete. This is because the natural aggregate contains a certain amount of mud content, and the water absorption rate of the recycled coarse aggregate after surface strengthening treatment is relatively low, thus improving the workability of concrete; it can significantly reduce the shrinkage of concrete, which is related to its relatively low linear expansion coefficient. In addition, the water absorption rate of the recycled coarse aggregate after surface strengthening treatment is relatively low, thus improving the workability of concrete; and when the concrete is in a long-term dry shrinkage environment in the later stage, the coarse aggregate with a small water absorption rate has less evaporation of internal moisture. Due to the absence of relatively large porosity in its own interior and other reasons, its ability to restrain the dry shrinkage of concrete is relatively good, making the dry shrinkage rate in the later stage smaller.

[0089] By comparing and analyzing the test results of Example 1 and Comparative Example 3, it can be seen that: the incorporation of the recycled waste slurry described in the present invention will slightly reduce the slump of concrete, which may be because the water absorption of the recycled waste slurry powder is higher than that of cement and fly ash; it can effectively reduce the internal temperature of concrete and the maximum temperature difference between the inside and outside, which is related to its relatively low early hydration heat; it will reduce the early strength of concrete to a certain extent, but can improve the later strength, which is related to the fact that the pozzolanic activity of the recycled waste slurry plays a major role in the later stage; at the same time, it can significantly reduce the shrinkage of concrete, which is because the C-S-H gel structure of its hydration products is dense, the porosity is significantly reduced, and the migration of early moisture in concrete is reduced, thereby reducing the shrinkage of concrete.

[0090] By comparing Example 2 and Comparative Example 4, it can be seen that: the composite modifier obtained in the present invention has a more obvious improvement on the performance of mass concrete. This is because polyethylene glycol in the composite modifier has the function of phase change energy storage and is uniformly dispersed inside the cement stone. It can absorb the heat released by cement hydration in the early stage of cement hydration, thereby reducing the internal temperature of concrete. Polyethylene glycol in the composite modifier undergoes a lapping reaction with cellulose fibers in an alkaline environment. On the one hand, the cellulose fibers that have undergone the lapping reaction can be dispersed in the concrete, improving the crack resistance of mass concrete; on the other hand, it enhances the adsorption capacity for the heat inside the cement stone.

[0091] The above embodiments are only for clearly illustrating the examples and are not a limitation on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Therefore, the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A mass concrete based on construction waste, characterized in that The components and their dosages include: 100 - 300 kg / m of cement 3 , 50 - 180 kg / m of concrete admixture 3 , 30 - 100 kg / m of recycled waste slurry powder 3 , 800 - 1100 kg / m of sand 3 , 1400 - 2000 kg / m of recycled coarse aggregate 3 , 140 - 160 kg / m of water 3 , 2.3 - 5.8 kg / m of composite modifier 3 , 2 - 8 kg / m of water reducer 3 ; among them, the recycled coarse aggregate is obtained by crushing construction waste with high-pressure water jet to obtain recycled crushed particles and then performing surface strengthening treatment; the recycled waste slurry powder is obtained by ultrafine grinding of the waste slurry residue of the remaining liquid phase part collected after crushing construction waste with high-pressure water jet; the composite modifier is obtained by reacting with lignin, sodium sulfate, lime milk, polyethylene glycol, cellulose fiber and alkali solution as the main raw materials; The strengthening treatment steps include: mixing water and the surface strengthening material evenly to prepare a slurry of the surface strengthening material, and then using it to carry out slurry coating treatment on the recycled coarse aggregate; The specific preparation steps of the composite modifier include: 1) completely dissolving 1 part of lignin, 0.5 - 1 part of sodium sulfate, and 0.5 - 1 part of lime milk in 50 - 80 parts of alkali solution and mixing evenly; 2) putting the obtained mixed solution into a reaction kettle and reacting at a high temperature of 160 - 180 °C for 4 - 6 h. After being placed at room temperature, adding 10 - 30 parts of cellulose fiber and 10 - 20 parts of polyethylene glycol, mixing evenly, and then carrying out evaporation and drying to obtain a solid mixture, that is, the composite modifier.

2. The mass concrete according to claim 1, characterized in that The surface strengthening material is clay, or a mixture of cement and silica fume.

3. The mass concrete according to claim 1, characterized in that The particle size of the recycled coarse aggregate is 5 - 20 mm, 5 - 25 mm, or 5 - 31.5 mm.

4. The mass concrete according to claim 1, characterized in that During the ultra-fine grinding treatment process, the grinding vibration frequency of the grinding mill used is 40 - 60 Hz, and the time is 1 - 4 h; the average diameter D50 of the obtained recycled waste slurry powder is 0.1 - 10 μm.

5. The mass concrete according to claim 1, characterized in that A grinding aid and an activity activator are introduced during the ultra-fine grinding treatment process.

6. The mass concrete according to claim 1, characterized in that The cement is ordinary Portland cement; the admixture is one or more of fly ash, slag powder, and silica fume; the fineness modulus of the sand is 2.6 - 2.9, and the mud content is less than 2%.

7. The preparation method of the mass concrete based on construction waste according to any one of claims 1 to 6, characterized in that It includes the following steps: 1) Weigh each raw material proportionally. Each component and its content include: 100 - 300 kg / m of cement 3 , 50 - 180 kg / m of admixture 3 , 30 - 100 kg / m of recycled waste slurry powder 3 , 800 - 1100 kg / m of sand 3 , 1400 - 2000 kg / m of recycled coarse aggregate 3 , 140 - 160 kg / m of water 3 , 2.3 - 5.8 kg / m of composite modifier 3 , 2 - 8 kg / m of water reducer 3 ; 2) Mix the weighed cement, concrete admixture, recycled waste slurry powder, sand, recycled coarse aggregate, and composite modifier evenly; 3) Then add the weighed water reducer and water and stir and mix them evenly to obtain the mass concrete.

Images