CN112408829A - Solid waste reclaimed sand and preparation method and application thereof - Google Patents

Abstract

The invention relates to solid waste reclaimed sand and a preparation method and application thereof. The invention creatively mixes the solid waste with the cementing material, the retarder, the plasticizer, the water reducer and the water, and obtains the novel reclaimed sand of the solid waste through a series of treatments, the reclaimed sand has the advantages of small water absorption, low powder content, good fluidity, high strength and high utilization rate of the solid waste, overcomes the defects of the traditional reclaimed sand of the solid waste, and improves the comprehensive performance of the reclaimed sand. The preparation method of the solid waste reclaimed sand related by the invention is simple and easy to operate, and is very suitable for large-scale industrial production.

Description

Solid waste reclaimed sand and preparation method and application thereof

Technical Field

The invention belongs to the technical field of building materials, particularly relates to reclaimed solid waste sand and a preparation method and application thereof, and particularly relates to reclaimed solid waste sand which is low in water absorption rate, low in powder content, high in strength and high in utilization rate of solid waste, and a preparation method and application thereof.

Background

In the field of construction, mortar is a kind of building material whose usage amount is second to that of concrete, and the preparation of mortar needs to use a large amount of traditional river sand, so that natural resources in China are increasingly tense. Due to the irrecoverable damage of sand production to the environment and resources, it is urgent to find corresponding substitute materials. On the other hand, along with the continuous development of society, a large amount of waste is generated in production and life, so that the nation faces huge environmental pressure, and the social demand that solid waste is utilized to produce building materials and is applied to construction engineering is increasingly strong.

In order to achieve the purposes of saving resources and improving the functions of buildings, various novel building materials are developed, and the research and the application of producing the building materials by using various industrial waste residues are wide. At present, people mainly realize the secondary utilization of solid wastes by a mode of preparing recycled aggregates after crushing the solid wastes. The solid waste with the particle size larger than 5mm after being crushed is used as recycled coarse aggregate, and the solid waste with the particle size smaller than or equal to 5mm is used as recycled fine aggregate, namely 'recycled sand'.

CN103864378A discloses a recycled mortar produced by using waste ceramic tiles and a preparation method thereof, wherein the recycled mortar is prepared from the raw materials of cement, waste ceramic tile sand, natural sand and water; wherein, the cement accounts for 15-20%, the waste ceramic tile sand accounts for 20-85%, the natural sand accounts for 0-65%, and the proportion of water in the cement accounts for 120-138%. The invention uses the waste ceramic tiles as aggregates to produce the regenerated mortar, has simple process, rich raw material sources, stable quality, low energy consumption and high efficiency, but still has the defects of larger water absorption rate and higher powder content of the regenerated sand.

CN108658539A discloses a preparation method of compression-resistant recycled mortar, which comprises the steps of weighing 20-30 parts of cement, 100-120 parts of water, 20-30 parts of sand, 50-80 parts of 2-time modified waste concrete and 5-8 parts of urea in sequence, mixing the cement with the water in a mixer, adding the sand, the 2-time modified waste concrete and the urea into the mixer in sequence, mixing and stirring for 30-40min at the temperature of 40-50 ℃ and the rotating speed of 300-400r/min to obtain a blank, carrying out injection molding and vibration molding on the blank, carrying out curing for 1-2 days at room temperature, demoulding to obtain a blank, and carrying out curing for 20-28 days at room temperature to obtain the compression-resistant recycled mortar. The prepared compression-resistant recycled mortar has the characteristics of excellent mechanical property, but still has the defects of larger water absorption of the recycled mortar, higher powder content and pending improvement of the utilization rate of solid wastes.

Therefore, how to improve the defects of large water absorption, high powder content, poor fluidity and insufficient mechanical property of the traditional solid waste reclaimed sand so as to obtain higher comprehensive performance improvement is a problem to be researched and solved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide reclaimed solid waste sand and a preparation method and application thereof, in particular to reclaimed solid waste sand which is low in water absorption rate, low in powder content, high in strength and high in utilization rate of solid waste, and a preparation method and application thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides solid waste reclaimed sand, and raw materials for preparing the solid waste reclaimed sand comprise solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent.

The invention creatively mixes the solid waste with the cementing material, the retarder, the plasticizer, the water reducer and the water, and obtains the novel reclaimed sand of the solid waste through a series of treatments, the reclaimed sand has the advantages of small water absorption, low powder content, good fluidity, high strength and high utilization rate of the solid waste, overcomes the defects of the traditional reclaimed sand of the solid waste, and improves the comprehensive performance of the reclaimed sand.

Preferably, the raw materials for preparing the reclaimed solid waste sand comprise, by weight, 5-80 parts of solid waste, 10-50 parts of a cementing material, 10-50 parts of water, 0-1 part but not 0 part of a retarder, 0-1 part but not 0 part of a plasticizer, and 0-5 parts but not 0 part of a water reducing agent.

When various preparation raw materials of the reclaimed sand of the solid waste related by the invention are used according to the specific weight proportion, the prepared reclaimed sand has more excellent comprehensive performance in the aspects of water absorption, powder content, fluidity and strength.

The solid waste can be 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts or 80 parts by weight.

The cementing material can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts by weight.

The water may be present in an amount of 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, or the like.

The retarder can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 1 part by weight and the like.

The weight portion of the plasticizer can be 0.1 portion, 0.2 portion, 0.3 portion, 0.4 portion, 0.5 portion, 0.6 portion, 0.7 portion, 0.8 portion, 0.9 portion or 1 portion, etc.

The water reducing agent can be 0.1 part, 0.5 part, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts by weight and the like.

Other unrecited point values in the above numerical ranges can be selected, and are not described in detail herein.

Preferably, the solid waste comprises any one of waste cement, waste mortar, waste concrete, stone powder, waste ceramic tiles or industrial tailings, or a combination of at least two of the same.

The combination of at least two of the above-mentioned materials, such as the combination of waste cement and waste mortar, the combination of waste mortar and waste concrete, the combination of stone powder and waste ceramic tile, etc., any other combination mode can be selected, and it is not repeated here.

Preferably, the particle size of the solid waste is 0-630 μm but not 0, for example, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm or 630 μm, etc., and other values in the above numerical range that are not listed may be selected, and are not described in detail herein.

The solid waste which can be used for the solid waste reclaimed sand has a wide particle size range which can reach 630 mu m at most.

Preferably, the cementing material comprises any one or a combination of at least two of cement, slag powder, fly ash, silica fume, metakaolin or quicklime powder.

The combination of at least two of the above-mentioned materials, such as the combination of cement and slag powder, the combination of fly ash and silica fume, the combination of silica fume and metakaolin, etc., can be selected in any combination manner, and are not described in detail herein.

Preferably, the retarder comprises any one or a combination of at least two of phosphate, metaphosphate, borax, sodium fluorosilicate, citric acid, glucose, sodium gluconate, sucrose, molasses, propylene glycol or glycerol.

The combination of at least two of the above-mentioned compounds, such as the combination of phosphate and metaphosphate, the combination of borax and sodium fluorosilicate, the combination of citric acid and glucose, etc., can be selected in any combination manner, and will not be described in detail herein.

Preferably, the plasticizer comprises any one of sodium humate, starch ether, carboxymethyl cellulose or polyvinyl alcohol or a combination of at least two of them.

The combination of at least two of the above compounds, such as the combination of sodium humate and starch ether, the combination of starch ether and carboxymethyl cellulose, the combination of carboxymethyl cellulose and polyvinyl alcohol, etc., can be selected in any combination manner, and thus, the details are not repeated herein.

Preferably, the water reducing agent comprises any one or a combination of at least two of a lignosulfonate water reducing agent, a naphthalene water reducing agent, a sulfamate water reducing agent, a fatty acid water reducing agent or a polycarboxylic acid water reducing agent.

The combination of the at least two types, for example, the combination of the lignosulfonate water reducing agent and the naphthalene water reducing agent, the combination of the naphthalene water reducing agent and the sulfamate water reducing agent, the combination of the fatty acid water reducing agent and the polycarboxylic acid water reducing agent, and the like, can be selected in any combination manner, and are not repeated herein.

In a second aspect, the present invention provides a method for preparing solid waste reclaimed sand as described above, comprising the steps of:

(1) mixing the solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent to prepare solid waste slurry;

(2) drying the solid waste slurry prepared in the step (1) to prepare dry particles;

(3) and (3) curing the dried particles prepared in the step (2) to obtain the solid waste reclaimed sand.

The preparation method of the solid waste reclaimed sand related by the invention is simple and easy to operate, and is very suitable for large-scale industrial production.

Preferably, the drying in step (2) is spray drying.

Preferably, the water content of the dried particles in step (2) is 0-5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 5%, etc., and other values in the above numerical range that are not listed can be selected, and thus detailed description is omitted.

Preferably, the curing in step (3) is performed at a temperature of 5-80 ℃, e.g., 5 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃, and the like, and at a humidity of 70% or more, e.g., 70%, 75%, 80%, 85%, 90%, 95% or 100%, and the like, for a period of 1-28 days, e.g., 1 day, 5 days, 8 days, 10 days, 12 days, 15 days, 18 days, 20 days, 22 days, 25 days or 28 days, and the like, and other non-listed points in the above ranges of values can be selected, and are not repeated herein.

As a preferred technical scheme of the invention, the preparation method of the solid waste reclaimed sand specifically comprises the following steps:

(1) mixing the solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent according to the parts by weight to prepare solid waste slurry;

(2) spray drying the solid waste slurry prepared in the step (1) to prepare dry particles with the water content of 0-5%;

(3) and (3) curing the dried particles prepared in the step (2) for 1-28 days in an environment with the temperature of 5-80 ℃ and the humidity of more than 70% to obtain the solid waste reclaimed sand.

In a third aspect, the invention provides an application of the solid waste reclaimed sand in preparing building materials.

Compared with the prior art, the invention has the following beneficial effects:

the invention creatively mixes the solid waste with the cementing material, the retarder, the plasticizer, the water reducer and the water, and obtains the novel reclaimed sand of the solid waste through a series of treatments, the reclaimed sand has the advantages of small water absorption, low powder content, good fluidity, high strength and high utilization rate of the solid waste, overcomes the defects of the traditional reclaimed sand of the solid waste, and improves the comprehensive performance of the reclaimed sand. The preparation method of the solid waste reclaimed sand related by the invention is simple and easy to operate, and is very suitable for large-scale industrial production.

Detailed Description

To further illustrate the technical means and effects of the present invention, the following further describes the technical solution of the present invention with reference to the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

Example 1

The embodiment provides solid waste reclaimed sand which comprises the following components in parts by weight: 30 parts of waste concrete, 30 parts of stone powder, 15 parts of cement, 16 parts of fly ash, 0.2 part of retarder, 0.2 part of plasticizer, 1 part of water reducing agent and 40 parts of water. Wherein the cement is P.II 52.5R ordinary portland cement; the fly ash is F-class I-grade fly ash; the retarder is sodium gluconate; the plasticizer is carboxymethyl cellulose; the water reducing agent is a polycarboxylic acid water reducing agent.

The preparation method comprises the following steps:

(1) adding the solid waste, the cementing material, the water, the retarder, the plasticizer and the water reducing agent into a stirrer according to the weight parts, and mixing and stirring for 10min to prepare solid waste slurry;

(2) spray drying the solid waste slurry prepared in the step (1) to prepare dry particles with the water content of 2.8%;

(3) and (3) curing the dried particles prepared in the step (2) for 28 days in an environment with the temperature of 25 ℃ and the humidity of 90% to obtain the solid waste reclaimed sand.

Example 2

The embodiment provides solid waste reclaimed sand which comprises the following components in parts by weight: 80 parts of waste ceramic tile, 15 parts of cement, 5 parts of slag powder, 8 parts of silica fume, 0.2 part of retarder, 0.2 part of plasticizer, 1.2 parts of water reducing agent and 33 parts of water. Wherein the cement is P.O 42.5R ordinary portland cement; the slag powder is S95 slag powder; the silica fume is 28d silica fume with the activity index of 122 percent; the retarder is sodium gluconate; the plasticizer is polyvinyl alcohol; the water reducing agent is lignosulfonate water reducing agent.

The preparation method comprises the following steps:

(1) adding the solid waste, the cementing material, the water, the retarder, the plasticizer and the water reducing agent into a stirrer according to the weight parts, and mixing and stirring for 30min to prepare solid waste slurry;

(2) spray drying the solid waste slurry prepared in the step (1) to prepare dry particles with the water content of 3.7%;

(3) and (3) curing the dried particles prepared in the step (2) for 28 days in an environment with the temperature of 60 ℃ and the humidity of 99% to obtain the solid waste reclaimed sand.

Example 3

The embodiment provides solid waste reclaimed sand which comprises the following components in parts by weight: 20 parts of waste mortar, 40 parts of waste concrete, 10 parts of waste ceramic tiles, 35 parts of cement, 5 parts of fly ash, 8 parts of metakaolin, 0.45 part of retarder, 0.38 part of plasticizer, 1.33 parts of water reducer and 38 parts of water. Wherein the cement is P.II 42.5R ordinary portland cement; the fly ash is C-class I-grade fly ash; the metakaolin is the metakaolin with 28d activity index of 108 percent; the retarder is propylene glycol; the plasticizer is starch ether; the water reducing agent is a polycarboxylic acid water reducing agent.

The preparation method comprises the following steps:

(1) adding the solid waste, the cementing material, the water, the retarder, the plasticizer and the water reducing agent into a stirrer according to the weight parts, and mixing and stirring for 20min to prepare solid waste slurry;

(2) spray drying the solid waste slurry prepared in the step (1) to prepare dry particles with the water content of 2.2%;

(3) and (3) curing the dried particles prepared in the step (2) for 14 days in an environment with the temperature of 25 ℃ and the humidity of 80% to obtain the solid waste reclaimed sand.

Example 4

This example provides a solid waste reclaimed sand, the composition of which differs from that of example 1 only in that: 45 parts of waste concrete and 45 parts of stone powder, and other components and the using amount are kept unchanged. And the preparation method is the same as that of example 1.

Example 5

This example provides a solid waste reclaimed sand, the composition of which differs from that of example 1 only in that: 30 parts of cement, 30 parts of fly ash, and other components and the using amount are kept unchanged. And the preparation method is the same as that of example 1.

Example 6

This example provides a method for preparing reclaimed sand from solid waste, which is different from example 1 only in the following composition: 60 parts of water, and other components and the using amount are kept unchanged. And the preparation method is the same as that of example 1.

The water consumption is too high in the embodiment, so that the prepared solid waste slurry has too high fluidity, and the solid waste is easy to settle in the slurry, is separated from the slurry and cannot be formed by spray drying.

Comparative example 1

This comparative example provides a solid waste reclaimed sand whose composition differs from that of example 1 only in that: the retarder component is not contained, and other components and the using amount are kept unchanged. And the preparation method is the same as that of example 1.

Comparative example 2

This comparative example provides a solid waste reclaimed sand whose composition differs from that of example 1 only in that: no plasticizer component is contained, and other components and the use amount are kept unchanged. And the preparation method is the same as that of example 1.

Comparative example 3

This comparative example provides a method for preparing reclaimed sand from solid waste, the composition of which differs from that of example 1 only in that: does not contain water reducing agent components, and other components and the using amount are kept unchanged. And the preparation method is the same as that of example 1.

The comparative example cannot prepare solid waste slurry with proper fluidity and cannot be molded due to lack of the water reducing agent component.

Performance evaluation:

the fineness modulus and apparent density (kg/m) of the reclaimed sands obtained in examples 1 to 5 and comparative examples 1 to 2 were measured according to the method in "recycled Fine aggregates for concrete and mortar" GB/T25176-2010³) Bulk density (kg/m)³) Water demand ratio, mortar strength ratio and crush index value.

Water demand ratio: the ratio of the water consumption of the tested mortar prepared from the reclaimed sand to the water consumption of the reference mortar when the tested mortar reaches a certain fluidity. The strength ratio of the mortar: the ratio of the compressive strength of the tested mortar test piece prepared from the reclaimed sand to that of the reference mortar test piece. Crush index value: the reclaimed sand with a certain grain diameter is loaded into a steel die, and a certain pressure is applied. After the test is finished, part of the regenerated sand is reduced in particle size due to pressure damage, the regenerated sand in the steel die is collected and sieved, and the proportion of the mass of the sand damaged due to pressure in the whole is measured to be the crushing index value. For reclaimed sand, the smaller the water demand ratio, the better; the higher the mortar strength ratio, the better; the lower the crush index value, the better.

The results are shown in Table 1.

TABLE 1

As can be seen from the data in Table 1:

the solid waste reclaimed sand related by the invention has the advantages of low water absorption, low powder content, good fluidity, high strength and high solid waste utilization rate, overcomes the defects of the traditional solid waste reclaimed sand, and improves the comprehensive performance of the reclaimed sand. The addition of the retarder, the water reducer and the plasticizer in the reclaimed sand is very necessary, and the quality proportion of the raw materials can also obviously influence the performance of the reclaimed sand.

Comparative examples 1 and 4 show that: in example 4, the total amount of the waste concrete and the stone powder is too high, which results in a decrease in the proportion of the cementitious material in the reclaimed sand, and the waste concrete and the stone powder lack the reinforcing effect of the cementitious material, which results in a decrease in the mortar strength ratio of the reclaimed sand produced and an increase in the crushing index value.

Comparative examples 1 and 5 show that: in example 5, the total amount of cement and fly ash is too high, and the prepared dry particles are easy to crack in the curing process, so that the strength ratio of the reclaimed sand to the mortar is reduced due to cracks, and the water demand ratio and the crushing index value are obviously increased.

Comparative example 1 and comparative example 1 show that: comparative example 1 lacks a retarder component, resulting in accelerated hydration hardening of the cement during spray drying under the influence of high temperatures. The reclaimed sand is not fully maintained under the condition of sufficient humidity, so the strength is not high; in addition, the external environment is dry, so that cracks are generated on the surface of the reclaimed sand, and further the strength of the reclaimed sand is damaged.

Comparative example 1 and comparative example 2 show that: comparative example 2 lacks the plasticizer component, resulting in the formation of a large number of drying cracks on the surface of the dried particles, a decrease in the reclaimed sand mortar strength ratio, and a significant increase in the water demand ratio, the crush index value.

The applicant states that the invention is illustrated by the above examples to a solid waste reclaimed sand of the invention and a preparation method and application thereof, but the invention is not limited to the above examples, that is, the invention is not necessarily dependent on the above examples to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

Claims (10)

1. The solid waste reclaimed sand is characterized in that raw materials for preparing the solid waste reclaimed sand comprise solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent.

2. The solid waste reclaimed sand according to claim 1, wherein the raw materials for preparing the solid waste reclaimed sand comprise, by weight, 5 to 80 parts of solid waste, 10 to 50 parts of a cementing material, 10 to 50 parts of water, 0 to 1 part but not 0 part of a retarder, 0 to 1 part but not 0 part of a plasticizer, and 0 to 5 parts but not 0 part of a water reducing agent;

preferably, the solid waste comprises any one or a combination of at least two of waste cement, waste mortar, waste concrete, stone powder, waste ceramic bricks or industrial tailings;

preferably, the particle size of the solid waste is 0 to 630 μm excluding 0.

3. The solid waste reclaimed sand of claim 1 or 2, wherein the cementitious material comprises any one of cement, slag powder, fly ash, silica fume, metakaolin, or quicklime powder, or a combination of at least two thereof.

4. The solid waste reclaimed sand of any of claims 1-3, wherein the retarder comprises any one of or a combination of at least two of phosphate, metaphosphate, borax, sodium fluorosilicate, citric acid, glucose, sodium gluconate, sucrose, molasses, propylene glycol, or glycerol.

5. The solid waste reclaimed sand of any of claims 1 to 4, wherein the plasticizer comprises any one of sodium humate, starch ether, carboxymethyl cellulose or polyvinyl alcohol or a combination of at least two thereof.

6. The solid waste reclaimed sand of any one of claims 1 to 5, wherein the water reducer comprises any one of a lignosulfonate water reducer, a naphthalene based water reducer, a sulfamate water reducer, a fatty acid water reducer or a polycarboxylic acid water reducer, or a combination of at least two thereof.

7. The method for preparing solid waste reclaimed sand according to any one of claims 1 to 6, wherein the method comprises the following steps:

(1) mixing the solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent to prepare solid waste slurry;

(2) drying the solid waste slurry prepared in the step (1) to prepare dry particles;

(3) and (3) curing the dried particles prepared in the step (2) to obtain the solid waste reclaimed sand.

8. The method for preparing solid waste reclaimed sand according to claim 7, wherein the drying in the step (2) is spray drying;

preferably, the water content of the dried particles in the step (2) is 0-5%;

preferably, the curing temperature in the step (3) is 5-80 ℃, the humidity is more than 70%, and the curing time is 1-28 days.

9. The method for preparing solid waste reclaimed sand according to claim 7 or 8, wherein the method specifically comprises the following steps:

(1) mixing the solid waste, a cementing material, water, a retarder, a plasticizer and a water reducing agent according to the parts by weight to prepare solid waste slurry;

(2) spray drying the solid waste slurry prepared in the step (1) to prepare dry particles with the water content of 0-5%;

(3) and (3) curing the dried particles prepared in the step (2) for 1-28 days in an environment with the temperature of 5-80 ℃ and the humidity of more than 70% to obtain the solid waste reclaimed sand.

10. Use of the solid waste reclaimed sand of any one of claims 1 to 6 in the preparation of a building material.