CN112939541A - Regenerated dry-mixed composite light aggregate concrete and preparation method thereof - Google Patents

Abstract

The application relates to the field of concrete, and particularly discloses regenerated dry-mixed composite lightweight aggregate concrete and a preparation method thereof. The regenerative dry-mixed composite lightweight aggregate concrete is prepared from the following raw materials in parts by weight: 300 parts of cement 200-plus material, 32-48 parts of blended powder, 45-70 parts of active regenerated micro powder, 40-60 parts of regenerated fine aggregate, 35-70 parts of dry sand, 60-90 parts of hydrophobic polyurethane particles, 20-30 parts of fiber, 5-8 parts of waterproof agent, 7-10 parts of flame retardant, 6-9 parts of water reducing agent, 3-5 parts of early strength agent, 1-3 parts of redispersible latex powder and 80-100 parts of water; the preparation method comprises the following steps: the hydrophobic polyurethane particles and the fire retardant are uniformly mixed with part of cement and water, and then are uniformly mixed with the rest raw materials. The regenerated dry-mixed composite lightweight aggregate concrete can be used as heat-insulating lightweight aggregate concrete and has the advantage of relatively high strength.

Description

Regenerated dry-mixed composite light aggregate concrete and preparation method thereof

Technical Field

The application relates to the field of concrete, in particular to regenerated dry-mixed composite light aggregate concrete and a preparation method thereof.

Background

The lightweight aggregate concrete is also called lightweight concrete, and is prepared by lightweight aggregate, common sand, cement and water. The lightweight aggregate is an aggregate used for the purpose of reducing the mass of concrete and improving the thermal effect, and has a lower apparent density than a conventional aggregate.

In the related technology, waste polyurethane particles are used as light aggregate to prepare concrete, and the prepared dry-mixed light aggregate concrete has the characteristics of light weight, heat preservation and the like, and has good deformation performance, lower elastic modulus, and larger shrinkage and creep under general conditions.

With respect to the related art, the inventors found that concrete to which the polyurethane particles are added has low strength in use.

Disclosure of Invention

In order to improve the strength of the dry-mixed light aggregate concrete, the application provides the regenerated dry-mixed composite light aggregate concrete and the preparation method thereof.

In a first aspect, the application provides a recycled dry-mix composite lightweight aggregate concrete, which adopts the following technical scheme:

the regenerative dry-mixed composite lightweight aggregate concrete comprises the following raw materials in parts by weight: 300 parts of cement 200-plus material, 32-48 parts of blended powder, 45-70 parts of active regenerated micro powder, 40-60 parts of regenerated fine aggregate, 35-70 parts of dry sand, 60-90 parts of hydrophobic polyurethane particles, 20-30 parts of fiber, 5-8 parts of waterproof agent, 7-10 parts of flame retardant, 6-9 parts of water reducing agent, 3-5 parts of early strength agent, 1-3 parts of redispersible latex powder and 80-100 parts of water;

wherein the blending powder comprises the following components in percentage by weight (3-4): (2-3): 1, fly ash, mineral powder and silica fume;

the hydrophobic polyurethane particles are prepared by 40-50ml of polydimethylsiloxane aqueous emulsion with the mass concentration of 0.38-0.42% and 40-50ml of sodium methyl silicate solution with the mass concentration of 4-8% in sequence for carrying out hydrophobic modification on 10-15g of polyurethane particles.

By adopting the technical scheme, the brick-concrete garbage in the construction garbage is made into the active recycled micro powder and the recycled fine aggregate, so that the resource utilization rate of the construction garbage is improved. The surfaces of the polyurethane particles are of porous structures, can absorb water and slurry, and carry out hydrophobic treatment on the polyurethane particles to form a layer of hydrophobic film on the surfaces of the polyurethane particles, so that the absorption of the polyurethane particles on water is reduced, the water absorption rate of a concrete system is reduced, the water-cement ratio is reduced, and the strength of concrete is improved; in addition, the active regenerated micro powder and the blended powder are mixed, so that the particle grading of the powder material is optimized, the gaps in concrete and the gaps on the surface of the polyurethane particles are filled, the porosity of a concrete system is reduced, the compactness of the material system is improved, and the strength stability of the light aggregate concrete is ensured; meanwhile, the silica fume can well reduce the dry density of the test block, the mineral powder has potential hydraulicity and can react with water to generate a substance with a gelling property, the active regenerated micro powder and the regenerated fine aggregate are matched with cement to play a good secondary hydration 'stack effect' to generate a new hydraulicity product, so that the interface strength between the regenerated fine aggregate and cement paste is further improved, and the strength of the light aggregate concrete is promoted.

Preferably, the preparation method of the hydrophobic polyurethane particles comprises the following steps:

1) soaking 10-15g of polyurethane particles in 40-50ml of polydimethylsiloxane aqueous emulsion solution with the mass concentration of 0.38-0.42%, soaking for 55-65min under the vacuum condition, filtering and reserving solids, and drying the solids at the constant temperature of 100 ℃ and 110 ℃ to obtain primary modified polyurethane particles;

2) soaking the primary modified polyurethane particles in 40-50ml of methyl sodium silicate solution with the mass concentration of 4-8%, soaking for 55-65min, filtering and reserving solid, and drying the solid at constant temperature of 100-110 ℃ to obtain the hydrophobic polyurethane particles.

By adopting the technical scheme, the polydimethylsiloxane aqueous emulsion forms a layer of breathable and waterproof silicone resin reticular film on the surface of polyurethane particles and the inner walls of pores; sodium methyl cinnamate is passed through with H in the air₂O and CO₂The reaction forms a layer of air-permeable polysiloxane film on the surface of the polyurethane particles, and the films on the two sides are complementary, so that the hydrophobicity of the hydrophobic polyurethane particles is improved. Preferably, in the step 2), the soaking temperature of the primary modified polyurethane particles in the methyl sodium silicate solution is 55-65 ℃.

By adopting the technical scheme, the sodium methyl cinnamate can pass through H in the air at the soaking temperature₂O and CO₂The reaction can form a film on the surface of the polyurethane particle stably and quickly.

Preferably, the hydrophobic polyurethane particles comprise first hydrophobic polyurethane particles and second hydrophobic polyurethane particles, the particle size of the first hydrophobic polyurethane particles is 4-8mm, and the particle size of the second hydrophobic polyurethane particles is 10-16 mm.

Preferably, the weight ratio of the first hydrophobic polyurethane particles to the second hydrophobic polyurethane particles is 1: (0.8-1.1).

By adopting the technical scheme, the hydrophobic polyurethane particles are irregular, the hydrophobic polyurethane particles with different particle sizes are matched with the recycled fine aggregate, the distribution of the aggregate particle sizes in the concrete is optimized, so that the hydrophobic polyurethane particles and the recycled fine aggregate can be matched to build a stable space network structure, and the strength of the concrete is improved.

Preferably, the particle size of the recycled fine aggregate is 0.3-3 mm.

By adopting the technical scheme, the recycled fine aggregate and the waste polyurethane are both in irregular shapes, the performance of the light aggregate concrete can be stabilized only by grading, the particle size of the recycled fine aggregate is optimized, and the recycled fine aggregate is matched with hydrophobic polyurethane particles, so that the dry-mixed composite light aggregate concrete forms stable bulk density, the stability of the performance of the dry-mixed composite light aggregate concrete is further ensured, and the light-mixed composite light aggregate concrete has a certain heat preservation effect.

Preferably, the particle size of the active recycled micro powder is less than 15 μm.

By adopting the technical scheme, the active regenerated micro powder has smaller fineness, can be better dispersed in a cementing material system, and reduces the porosity of the cementing material; meanwhile, the specific surface area of the active regenerated micro powder is increased, the contact area of the active regenerated micro powder and the mixed powder is increased, the secondary hydration superposition effect is enhanced, the hydration activity of a cementing material system is improved, and the concrete strength is favorably improved.

Preferably, the length of the fibers is 4 to 15 mm.

By adopting the technical scheme, the fibers with the length are not easy to tangle and knot in the manufacturing process, are also easy to stir and disperse, are uniformly distributed in the concrete, are distributed disorderly in the concrete to form a three-dimensional network structure, pull and drag aggregates and hydrophobic polyurethane particles in the concrete, enhance the stability of a space network structure formed by lapping the regenerated fine aggregates and the hydrophobic polyurethane particles, and improve the strength of the concrete.

In a second aspect, the application provides a preparation method of the recycled dry-mixed composite lightweight aggregate concrete, which adopts the following technical scheme:

a preparation method of regenerated dry-mixed composite lightweight aggregate concrete comprises the following steps:

s1, uniformly mixing hydrophobic polyurethane particles, a flame retardant, 80-120 parts of cement and 30-40 parts of water in parts by weight to obtain a mixture A;

and S2, adding the residual cement and other raw materials into the mixture A according to the weight parts, and uniformly stirring to obtain the regenerated dry-mixed composite lightweight aggregate concrete.

By adopting the technical scheme, the hydrophobic polyurethane particles are mixed with cement and the flame retardant, a compact cement protective layer is formed on the surface of the hydrophobic polyurethane particles, the fireproof performance of the polyurethane particles is improved, and meanwhile, the bonding strength of the hydrophobic polyurethane particles and the cement is also improved.

In summary, the present application has the following beneficial effects:

1. because the stable space network structure is formed by overlapping and crosslinking the hydrophobic polyurethane particles and the recycled fine aggregate, the strength of the prepared concrete is between 6.1 and 8.1MPa by cooperating with the gap between the active recycled micro powder and the blended powder filling aggregate, and the strength of the prepared concrete is higher;

2. in the application, hydrophobic polyurethane particles with different particle sizes and recycled fine aggregate are preferably graded to improve the strength of concrete, under the condition of consistent proportion of other raw materials, the strength of the concrete prepared from the hydrophobic polyurethane particles with different particle sizes is 7.2-8.1MPa, and the strength of the concrete prepared from the hydrophobic polyurethane particles with the same particle size is 6.6-6.8 MPa.

Detailed Description

The present application will be described in further detail with reference to examples.

Preparation examples of starting materials and intermediates

Raw materials

The cement is ordinary portland cement;

f II-grade fly ash is adopted as the fly ash;

the mineral powder is S95 grade mineral powder;

the silica fume adopts common micro silica fume;

the active regeneration micro powder is prepared by brick-mixed garbage in construction garbage, and has a particle size of less than 15 μm and a particle size of 16-25 μm;

the recycled fine aggregate is fine aggregate prepared from brick-concrete garbage in the construction garbage, the mud content of the recycled fine aggregate is 5.4 percent, the mud block content is 0.3 percent, the organic matter content meets the requirement, and the void ratio is 0.35 percent;

polypropylene fiber, available from xingtai engineering materials ltd, leuw;

glass fibers, available from tai an hao pine fiber limited;

the waterproof agent is a sodium methylsilicate organosilicon waterproof agent which is purchased from Beijing Xinyi century building materials Co., Ltd;

the flame retardant is magnesium hydroxide flame retardant, and is purchased from Shuanghao Jingmai Co., Ltd;

the water reducing agent is a polycarboxylic acid high-performance water reducing agent which is purchased from Hebei Shengtong building materials science and technology limited company;

the early strength agent model HY-ZQ01, purchased from Beijing Haishite industrialisation concrete additive sales Co., Ltd;

redispersible latex powder available from Hebei Huali chemical Co Ltd;

polydimethylsiloxane aqueous emulsion, available from Qingdao Zhongbao silicon materials science and technology Limited;

sodium methylsilicate, available from chemical Limited, encyclopedia of Jinan, Ji.

Preparation example

Preparation example 1

The preparation method of the hydrophobic polyurethane particle comprises the following steps:

1) soaking 10g of polyurethane particles in 40ml of polydimethylsiloxane aqueous emulsion solution with the mass concentration of 0.38%, soaking for 55min under a vacuum condition, filtering, reserving solid particles, and drying the solid at a constant temperature of 110 ℃ to obtain primary modified polyurethane particles;

2) soaking the primary modified polyurethane particles in 40ml of sodium methyl silicate solution with the mass concentration of 4% for 55min at the soaking temperature of 65 ℃, then filtering and reserving solid particles, and drying the solid at the constant temperature of 100 ℃ to obtain the hydrophobic polyurethane particles.

Preparation examples 2 to 5, which differ from preparation example 1 in the process parameters, are specified in Table 1.

Preparation examples 6 to 8 are different from preparation example 2 in the ratio of raw materials, and are shown in Table 1.

TABLE 1 formulations and Process parameters for preparation examples 1-8

Examples

Example 1

A regenerated dry-mixed composite lightweight aggregate concrete is prepared by the following steps:

s1, adding 90kg of hydrophobic polyurethane particles, 7kg of flame retardant, 120kg of cement and 30kg of water into a stirring tank, and uniformly mixing to obtain a mixture A;

s2, 80kg of cement, 24kg of fly ash, 16kg of mineral powder, 8kg of silica fume, 45kg of active regenerated micro powder, 60kg of regenerated fine aggregate, 35kg of dry sand, 20kg of polypropylene fiber, 8kg of waterproof agent, 6kg of water reducing agent, 5kg of early strength agent, 1kg of redispersible emulsion powder and 50kg of water;

wherein the hydrophobic polyurethane particles are from preparation example 1, and the hydrophobic polyurethane particles comprise 60kg of first hydrophobic polyurethane particles with a particle size of 4-8mm and 30kg of second hydrophobic polyurethane particles with a particle size of 10-16mm, i.e. the weight ratio of the first hydrophobic polyurethane particles to the second hydrophobic polyurethane particles is 1: 0.5; the particle size of the recycled fine aggregate is 0.3-3 mm; the regenerated active micro powder particles are less than 15 mu m; the length of the polypropylene fiber is 4-15 mm.

Examples 2 to 6 differ from example 1 in that: the proportions of the raw materials are different and are detailed in table 2.

Example 7 differs from example 2 in that the polypropylene fibers are replaced by equal amounts of glass fibers.

TABLE 2 examples 1-7 raw material ratios (kg)

Examples 8-14 differ from example 2 in that the hydrophobic polyurethane particles of examples 8-14 were obtained from preparation examples 2-8, respectively.

Examples 15-18 differ from example 2 in the ratio of first hydrophobic polyurethane particles to second hydrophobic polyurethane particles, as detailed in table 3.

TABLE 3 particle size distribution Table (kg) for hydrophobic polyurethanes of examples 2 and 15-18

	Example 2	Example 15	Example 16	Example 17	Example 18
						First hydrophobic polyurethane particles	50	37.5	30	0	75
Second hydrophobic polyurethane particles	25	37.5	45	75	0

Example 19 differs from example 2 in that the recycled fine aggregate has a particle size of 1.5 to 4.5 mm.

Example 20 differs from example 2 in that the particle size of the active recycled micropowder is 16 to 25 μm.

Example 21 differs from example 2 in that the polypropylene fibres have a length of 15-25 mm.

Comparative example

Comparative example 1

The polyurethane particle light aggregate concrete produced by corridor, Youding, energy-saving technology limited company.

Comparative example 2

In contrast to example 2, the hydrophobic polyurethane particles were replaced by the same amount of conventional polyurethane particles.

Comparative example 3

In contrast to example 2, the active recycled micropowder was replaced by an equal amount of blended powder.

Comparative example 4

In contrast to example 2, the recycled fine aggregate was replaced with an equal amount of dry sand.

Comparative example 5

In contrast to example 2, the blended powder was replaced by an equal amount of regenerated active micropowder.

Performance test

Detection method

Concrete is prepared according to the methods in examples 1-21 and comparative examples 1-5 respectively, the concrete is cured for 28 days in the same curing step, and the compression strength of the concrete is measured according to the standard of the test method for the mechanical properties of common concrete (GB/T50081-2002); then, according to the technical specification of lightweight aggregate concrete (JGJ50-2002), the thermal conductivity and water absorption of the concrete are measured, and the detection results are shown in Table 4.

TABLE 4 Performance test results

	Compressive strength (MPa)	Coefficient of thermal conductivity (W/m. k)	Water absorption (%)
				Example 1	7.0	0.29	18.4
Example 2	7.2	0.28	18.2
				Example 3	6.9	0.29	18.3
Example 4	6.6	0.30	18.7
				Example 5	6.3	0.31	18.6
Example 6	6.5	0.30	18.9
				Example 7	7.0	0.28	18.3
Example 8	7.4	0.26	18.1
				Example 9	7.2	0.27	18.2
Example 10	6.7	0.29	18.7
				Example 11	6.8	0.30	18.5
Example 12	7.5	0.28	18.0
				Example 13	7.8	0.25	17.7
Example 14	7.4	0.27	17.9
				Example 15	8.1	0.23	17.5
Example 16	7.7	0.26	17.2
				Example 17	6.8	0.29	19.5
Example 18	6.6	0.27	19.3
				Example 19	6.1	0.33	19.7
Example 20	6.3	0.31	20.0
				Example 21	6.7	0.30	19.5
Comparative example 1	5.0	0.36	21.7
				Comparative example 2	4.9	0.38	22.5
Comparative example 3	5.6	0.34	20.6
				Comparative example 4	4.8	0.33	21.8
Comparative example 5	5.3	0.35	20.7

By combining examples 1-21 with comparative example 1 and table 4, it can be seen that the compressive strength of the concrete prepared in examples 1-21 is higher than that of the concrete prepared in comparative example 1, the thermal conductivity of the concrete prepared in examples 1-21 is lower than that of the concrete prepared in comparative example 1, and the water absorption of the concrete prepared in examples 1-21 is higher than that of the concrete prepared in comparative example 1, which indicates that the compressive strength, the thermal insulation performance and the like of the concrete prepared in the application are better than those of the concrete prepared in comparative example 1, and the overall performance of the concrete prepared in the application is better.

By combining example 2 with comparative example 2 and table 4, it can be seen that the compressive strength and the thermal insulation performance of the concrete in example 2 are better than those of comparative example 2, and the water absorption rate of example 2 is much lower than that of comparative example 2, probably because the polyurethane particles after hydrophobic treatment reduce the absorption of moisture, thereby reducing the moisture absorption of the concrete system, reducing the water-cement ratio and improving the concrete strength.

By combining the example 2 with the comparative examples 3 and 5 and combining the table 4, it can be seen that the compressive strength and the thermal insulation performance of the concrete in the example 2 are superior to those of the comparative examples 3 and 5, which shows that the blending of the active regenerated micro powder and the blended powder optimizes the powder material gradation in the concrete, improves the compactness of the material system and is beneficial to improving the strength of the concrete.

By combining the example 2 and the comparative example 4 and combining the table 4, it can be seen that the compressive strength and the thermal insulation performance of the concrete in the example 2 are better than those of the comparative example 4, which indicates that the hydrophobic polyurethane particles and the recycled fine aggregate are overlapped and crosslinked to form a stable spatial network structure, and the two exert the combined action to improve the strength of the concrete.

By combining the concrete of the embodiment 2 and the embodiments 4 to 5 and combining the table 1, it can be seen that the compressive strength of the concrete of the embodiment 2 is higher than that of the concrete of the embodiments 4 to 5, which indicates that the hydrophobic polyurethane particles and the recycled fine aggregate are overlapped and crosslinked to form a stable spatial network structure, the strength of the concrete is improved, and the proportioning relationship between the hydrophobic polyurethane particles and the recycled light aggregate influences the strength of the concrete.

By combining the embodiment 2 and the embodiment 6 and combining the table 4, it can be seen that the compressive strength of the concrete in the embodiment 2 is higher than that of the concrete in the embodiment 6, which shows that the blending of the active regenerated micro powder and the blended powder optimizes the powder material gradation in the concrete, improves the compactness of the material system, ensures the stable strength of the lightweight aggregate concrete, and the proportion relationship among the fly ash, the mineral powder and the silica fume in the blended powder affects the strength of the concrete.

Combining example 2 with example 7, and combining table 4, it can be seen that the concrete performance in example 2 is equivalent to that in example 7, which indicates that the kind of fiber has little influence on the concrete performance in the present application.

The better performance of the concrete prepared in example 13, as seen by combining example 2 with examples 8-14, and table 4, demonstrates that the formulation and process for preparing hydrophobic concrete in example 7 are better and the soaking temperature of the sodium methylsilicate solution has some effect on the hydrophobic polyurethane particles.

By combining the example 2 with the examples 15 to 18 and combining the table 4, it can be seen that the concrete prepared in the example 15 has better performance, the hydrophobic polyurethane particles with different particle sizes are doped, the grading between the hydrophobic polyurethane particles and the recycled hydrophilic aggregate is optimized, and the concrete strength is favorably improved.

By combining example 2 with example 19 and table 4, it can be seen that the concrete prepared in example 2 has better performance, which indicates that the particle size of the recycled aggregate affects the grading effect between the recycled aggregate and the hydrophobic polyurethane particles, thereby affecting the strength of the concrete.

By combining the example 2 and the example 20 and combining the table 4, the concrete prepared in the example 2 has better performance, which shows that the active regenerated micro powder with smaller particle size can be better dispersed in a cementing material system and reduce the porosity of the cementing material; meanwhile, the contact area of the active regenerated micro powder and the blended powder is increased, the secondary hydration superposition effect is enhanced, the hydration activity of a cementing material system is improved, and the concrete strength is favorably improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (9)

1. The regenerated dry-mixed composite lightweight aggregate concrete is characterized by being prepared from the following raw materials in parts by weight: 300 parts of cement 200-plus material, 32-48 parts of blended powder, 45-70 parts of active regenerated micro powder, 40-60 parts of regenerated fine aggregate, 35-70 parts of dry sand, 60-90 parts of hydrophobic polyurethane particles, 20-30 parts of fiber, 5-8 parts of waterproof agent, 7-10 parts of flame retardant, 6-9 parts of water reducing agent, 3-5 parts of early strength agent, 1-3 parts of redispersible latex powder and 80-100 parts of water;

wherein the blending powder comprises the following components in percentage by weight (3-4): (2-3): 1, fly ash, mineral powder and silica fume;

the hydrophobic polyurethane particles are prepared by 40-50ml of polydimethylsiloxane aqueous emulsion with the mass concentration of 0.38-0.42% and 40-50ml of sodium methyl silicate solution with the mass concentration of 4-8% in sequence for carrying out hydrophobic modification on 10-15g of polyurethane particles.

2. The recycled dry-mix composite lightweight aggregate concrete according to claim 1, wherein: the preparation method of the hydrophobic polyurethane particles comprises the following steps:

1) soaking 10-15g of polyurethane particles in 40-50ml of polydimethylsiloxane aqueous emulsion solution with the mass concentration of 0.38-0.42%, soaking for 55-65min under the vacuum condition, filtering and reserving solids, and drying the solids at the constant temperature of 100 ℃ and 110 ℃ to obtain primary modified polyurethane particles;

2) soaking the primary modified polyurethane particles in 40-50ml of methyl sodium silicate solution with the mass concentration of 4-8%, soaking for 55-65min, filtering and reserving solid, and drying the solid at constant temperature of 100-110 ℃ to obtain the hydrophobic polyurethane particles.

3. The recycled dry-mix composite lightweight aggregate concrete according to claim 2, wherein: in the step 2), the soaking temperature of the primary modified polyurethane particles in the methyl sodium silicate solution is 55-65 ℃.

4. The recycled dry-mix composite lightweight aggregate concrete according to claim 1, wherein: the hydrophobic polyurethane particles comprise first hydrophobic polyurethane particles and second hydrophobic polyurethane particles, the particle size of the first hydrophobic polyurethane particles is 4-8mm, and the particle size of the second hydrophobic polyurethane particles is 10-16 mm.

5. The recycled dry-mix composite lightweight aggregate concrete according to claim 4, wherein: the weight ratio of the first hydrophobic polyurethane particles to the second hydrophobic polyurethane particles is 1: (0.8-1.1).

6. The recycled dry-mix composite lightweight aggregate concrete according to claim 1, wherein: the particle size of the recycled fine aggregate is 0.3-3 mm.

7. The recycled dry-mix composite lightweight aggregate concrete according to claim 1, wherein: the particle size of the active regenerated micro powder is less than 15 mu m.

8. The recycled dry-mix composite lightweight aggregate concrete according to claim 1, wherein: the length of the fiber is 4-15 mm.

9. A method for preparing the recycled dry-mix composite lightweight aggregate concrete as claimed in any one of claims 1 to 8, which is characterized in that: the method comprises the following steps:

s1, uniformly mixing hydrophobic polyurethane particles, a flame retardant, 80-120 parts of cement and 30-40 parts of water in parts by weight to obtain a mixture A;

and S2, adding the residual cement and other raw materials into the mixture A according to the weight parts, and uniformly stirring to obtain the regenerated dry-mixed composite lightweight aggregate concrete.