CN114656217B - Impervious high-durability large-volume concrete and preparation method thereof - Google Patents

Abstract

The application relates to the technical field of concrete, in particular to impervious high-durability mass concrete which comprises the following raw materials in parts by weight: 150-180 parts of cement, 820-840 parts of stone, 60-80 parts of coarse sand, 30-50 parts of fine sand, 10-15 parts of fly ash, 5-15 parts of mixed fiber, 2-10 parts of hydrophobic microspheres, 0.5-0.8 part of water reducer, 0.3-0.6 part of air entraining agent and 150-170 parts of water; the preparation method of the hydrophobic microspheres comprises the following steps: s1, adding 2-3 parts by weight of methacrylate, 7-9 parts by weight of styrene, 0.3-0.6 part by weight of methacrylic acid and 0.05-0.07 part by weight of double-end-vinyl polydimethylsiloxane into DMF, stirring until the two parts are dissolved, adding an initiator, heating for reaction, then dropwise adding divinylbenzene, trivinylbenzene or trivinylsilane, and continuing to react to obtain a mixed solution; s2, carrying out solid-liquid separation on the mixed solution to obtain hydrophobic microspheres; it has the advantage of improving the impermeability of concrete.

Description

Impervious high-durability large-volume concrete and preparation method thereof

Technical Field

The application relates to the technical field of concrete, in particular to impervious high-durability large-volume concrete and a preparation method thereof.

Background

Concrete is one of the most important civil engineering materials of the present generation. The artificial stone is prepared by a cementing material, granular aggregate (also called aggregate), water, an additive and an admixture which are added if necessary according to a certain proportion, and is formed by uniformly stirring, compacting, forming, curing and hardening. The concrete has the characteristics of rich raw materials, low price and simple production process, so that the consumption of the concrete is increased more and more. Meanwhile, the concrete also has the characteristics of high compressive strength, good durability, wide strength grade range and the like. These characteristics make it very widely used, not only in various civil engineering, that is shipbuilding, machinery industry, ocean development, geothermal engineering, etc., but also concrete is an important material.

However, the microstructure of the cement paste adjacent to the large-particle aggregate in the concrete is usually greatly different from that of the cement paste or mortar body in the system, namely an interface transition region, and due to the interface transition region, different numbers of pores and microcracks exist in the concrete. When the concrete is influenced by the external environment, the micro cracks are easy to expand and combine with the pores, so that the impermeability of the concrete is reduced, and the durability is seriously influenced.

Disclosure of Invention

In order to improve the impermeability of concrete, the application provides an impermeability high-durability mass concrete and a preparation method thereof.

In a first aspect, the present application provides an impervious high-durability mass concrete, which adopts the following technical scheme:

the impervious high-durability large-volume concrete comprises the following raw materials in parts by weight: 180 parts of cement, 840 parts of pebble 820, 60-80 parts of coarse sand, 30-50 parts of fine sand, 10-15 parts of fly ash, 5-15 parts of mixed fiber, 2-10 parts of hydrophobic microspheres, 0.5-0.8 part of water reducer, 0.3-0.6 part of air entraining agent and 170 parts of water 150;

the preparation method of the hydrophobic microspheres comprises the following steps:

s1, adding 2-3 parts by weight of methacrylate, 7-9 styrene, 0.3-0.6 part by weight of methacrylic acid and 0.5-0.7 part by weight of double-ended vinyl polydimethylsiloxane into 40-50 parts by weight of DMF under the atmosphere of nitrogen, stirring until the methacrylic acid, the 7-9 styrene, the 0.3-0.6 part by weight of methacrylic acid and the 0.5-0.7 part by weight of double-ended vinyl polydimethylsiloxane are dissolved, adding 0.07-0.08 part by weight of initiator, heating to 70-80 ℃, stirring for reaction for 3-5h, then dropwise adding 0.1-0.15 part by weight of divinylbenzene, trivinylbenzene or trivinylsilane, and then continuously stirring for reaction for 12-15h to obtain a mixed solution;

and S2, carrying out solid-liquid separation on the mixed liquid obtained in the S1, washing the obtained solid, and drying to obtain the hydrophobic microspheres.

By adopting the technical scheme, the comprehensive performance of the concrete is better through the grading effect of the raw materials; the hydrophobic microspheres can fill micropores in concrete in the anti-permeability effect, and can block water permeation due to the hydrophobic property of the hydrophobic microspheres; the fly ash can also fill the micropores in the concrete, so that the permeation of water by utilizing the connectivity of the micropores can be slowed down to a certain degree; the mixed fiber can destroy the connectivity of micropores in concrete; therefore, the three raw materials are mutually cooperated through respective functions, so that the impermeability of the concrete is greatly improved, and the durability of the concrete is improved; in the preparation of the hydrophobic microspheres, a small amount of divinylbenzene, trivinylbenzene or trivinylsilane is dripped as a crosslinking agent after reaction for a period of time, so that the microspheres with low internal crosslinking density, polysiloxane with the effect of improving flexibility and high surface crosslinking density are formed, and the prepared hydrophobic microspheres have elastic deformation performance. The microspheres obtained in this way can deform under the action of external force, when microcracks appear and the external force becomes smaller or disappears, the deformed microspheres recover to be spherical to form filling, and the hydrophobic effect on the surfaces of the microspheres also causes that water cannot easily pass through the microcracks. Thereby greatly improving the impermeability of the concrete.

Preferably, the method comprises the following steps: the addition amount of the hydrophobic microspheres is 5-8 parts by weight.

By adopting the technical scheme, when the addition amount of the hydrophobic microspheres is 5-8 parts by weight, the water seepage height of the prepared concrete is below 1.2mm, the impermeability of the concrete is excellent, and when the addition amount of the hydrophobic microspheres is further increased, the reduction range of the water seepage height is low, and comprehensively considered, the excellent addition amount of the hydrophobic microspheres is 5-8 parts by weight.

Preferably, the method comprises the following steps: the initiator is azobisisobutyronitrile or azobisisoheptonitrile.

By adopting the technical scheme, when the initiator is azobisisobutyronitrile or azobisisoheptonitrile, stable free radicals can be generated, and the free radical polymerization can be stably carried out.

Preferably, the method comprises the following steps: the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

Preferably, the method comprises the following steps: the mixed fiber comprises the following raw materials in parts by weight: 20-30 parts of polypropylene fiber and 10-20 parts of carbon fiber.

By adopting the technical scheme, the composite fiber, the polypropylene fiber and the carbon fiber can play respective excellent roles, so that a three-dimensional network structure is formed in concrete, the concrete is not easy to crack, and the composite fiber, the fly ash and the hydrophobic microspheres act together, so that the impermeability of the concrete is further improved.

Preferably, the method comprises the following steps: the length of the polypropylene fiber is 2-4cm, and the length of the carbon fiber is 1-3 cm.

Preferably, the method comprises the following steps: the residue of the 45 mu m square-hole sieve of the fly ash is less than or equal to 7 percent.

In a second aspect, the present application provides a method for preparing a impervious high-durability mass concrete, which adopts the following technical scheme:

a preparation method of impervious high-durability large-volume concrete comprises the following steps:

s1, mixing and stirring the coarse sand, the fine sand, the mixed fiber and the water for 1-2 hours to obtain a first mixture;

s2, adding the water reducing agent, the pebbles, the cement and the air entraining agent into the first mixture, and uniformly stirring to obtain a second mixture;

and S3, adding the fly ash and the hydrophobic microspheres into the second mixture, and stirring for 1-2h to obtain the concrete.

By adopting the technical scheme, the coarse sand, the fine sand, the mixed fibers and the water are mixed, the mixed fibers can be quickly dispersed by long-time stirring, the coarse sand and the fine sand can play a role in separating the fibers bonded together, and then other steps are sequentially added, so that the expected concrete can be prepared.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the comprehensive performance of the concrete is better through the grading effect of all raw materials; the hydrophobic microspheres can fill micropores in concrete in the anti-permeability effect, and can block water permeation due to the hydrophobic property of the hydrophobic microspheres; the fly ash can also fill the micropores in the concrete, so that the permeation of water by utilizing the connectivity of the micropores can be slowed down to a certain degree; the mixed fiber can destroy the connectivity of micropores in concrete; therefore, the three raw materials are mutually cooperated through respective functions, so that the impermeability of the concrete is greatly improved, and the durability of the concrete is improved.

2. In the preparation of the hydrophobic microspheres, after reacting for a period of time, a small amount of divinylbenzene or trivinylbenzene or trivinylsilane is added dropwise to serve as a crosslinking agent, so that the microspheres with low internal crosslinking density, high surface crosslinking density and high flexibility are formed, and the prepared hydrophobic microspheres have elastic deformation performance. The microspheres obtained in this way can deform under the action of external force, when microcracks appear and the external force becomes smaller or disappears, the deformed microspheres recover to be spherical to form filling, and the hydrophobic effect on the surfaces of the microspheres also causes that water cannot easily pass through the microcracks. Thereby greatly improving the impermeability of the concrete.

3. The compressive strength of the concrete is over 51.2 MPa; the initial slump is below 210mm, and the slump for 2h is less than 204 mm; the water seepage height is below 1.33mm, and the minimum water seepage height can reach 1.10 mm; the mass loss after 300 times of tests of freeze-thaw resistance cycle is less than 0.15 percent, and the elastic modulus loss is less than 0.25 percent; the concrete has the advantages of good comprehensive performance, strong durability and excellent impermeability.

Detailed Description

The present application is described in further detail below with reference to specific contents.

Raw materials

The cement in the application is ordinary portland cement; the average particle size of the stones is 2.5cm, and the maximum particle size is not more than 3 cm; the fineness modulus of the coarse sand is 3.3, and the fineness modulus of the fine sand is 2.2; the residue on a 45-micron square-hole sieve of the fly ash is 7 percent; the length range of the polypropylene fiber is 2-4cm, and the length range of the carbon fiber is 1-3 cm; the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, and the grade is a superior product; the air entraining agent is industrial grade sodium abietate with the model of LS-72; the rest raw materials are common commercial products.

Preparation examples

Preparation example 1

A mixed fiber comprises 25kg of polypropylene fiber and 15kg of carbon fiber, and the two fibers are uniformly mixed to obtain the mixed fiber.

Preparation example 2

The hydrophobic microsphere is prepared by the following steps:

s1, under the nitrogen atmosphere, adding 2.5kg of methacrylate, 8kg of styrene, 0.5kg of methacrylic acid and 0.6kg of double-end vinyl polydimethylsiloxane into 45kg of DMF, then adding 0.075kg of initiator which is azobisisobutyronitrile, heating to 75 ℃, stirring for reaction for 4 hours, then dropwise adding 0.12kg of cross-linking agent which is divinylbenzene, and continuing stirring for reaction for 14 hours to obtain a mixed solution;

and S2, carrying out solid-liquid separation on the mixed liquid obtained in the step S1 through centrifugation, washing the obtained solid with DMF, then washing with ethanol, and then drying to obtain the hydrophobic microspheres.

Examples

Examples 1 to 3

The impervious high-durability mass concrete of examples 1 to 3, whose raw materials and amounts of the raw materials are shown in table 1, was prepared by the following steps:

s1, mixing and stirring the coarse sand, the fine sand, the mixed fiber and the water according to the table 1, and stirring for 1.5 hours to obtain a first mixture; s2, adding the water reducing agent, the pebbles, the cement and the air entraining agent into the first mixture, and uniformly stirring to obtain a second mixture;

and S3, adding the fly ash and the hydrophobic microspheres into the second mixture, and stirring for 1.5 hours to obtain the concrete.

Wherein the mixed fiber is from preparation example 1; hydrophobic microspheres were from preparative example 2.

TABLE 1 materials and amounts (kg) of materials for examples 1-3

	Example 1	Example 2	Example 3
				Cement	150	165	180
Stone (stone)	840	830	820
				Coarse sand	60	70	80
Fine sand	50	40	30
				Fly ash	10	12	15
Mixed fiber	15	10	5
				Hydrophobic microspheres	2	2	2
Water reducing agent	0.5	0.6	0.8
				Air entraining agent	0.6	0.4	0.3
Water (W)	150	160	170

Example 4

The impervious high-durability mass concrete is different from the concrete in example 2 in that the addition amount of the hydrophobic microspheres is 5kg, and the rest steps are the same as those in example 2.

Example 5

A impervious high durability mass concrete, which is different from the concrete of example 2 in that the addition amount of hydrophobic microspheres is 8kg, and the rest steps are the same as those of example 2.

Example 6

A impervious high durability mass concrete, which is different from the concrete of example 2 in that the addition amount of hydrophobic microspheres is 10kg, and the rest steps are the same as those of example 2.

Comparative example

Comparative example 1

A impervious high durability mass concrete, which is different from the concrete of example 2 in that the addition amount of hydrophobic microspheres is 0, and the rest steps are the same as those of example 2.

Comparative example 2

The impervious high-durability large-volume concrete is different from the concrete in the embodiment 2 in that the addition amount of the fly ash is 0, and the rest steps are the same as the embodiment 2.

Comparative example 3

A concrete with high impermeability and durability and large volume is different from the concrete of the embodiment 2 in that the addition amount of the mixed fiber is 0, and the rest steps are the same as the concrete of the embodiment 2.

Comparative example 4

The impervious high-durability mass concrete is different from the concrete in the embodiment 2 in that the addition amounts of the hydrophobic microspheres, the fly ash and the mixed fibers are all 0, and the rest steps are the same as the concrete in the embodiment 2.

Comparative example 5

A impervious high-durability mass concrete is different from that of example 2 in that the addition amount of methacrylic acid in the preparation of hydrophobic microspheres is 0, and the rest steps are the same as those of example 2.

Comparative example 6

A impervious high-durability mass concrete is different from that of example 2 in that the hydrophobic microspheres are prepared by adding divinylbenzene before adding an initiator and then reacting for 18 hours, and the rest of the steps are the same as those of example 2.

Performance test

Detection method/test method

Concrete was prepared according to the preparation methods of examples 1 to 6 and comparative examples 1 to 6, and curing was carried out for 28 days under the same curing conditions, and then the properties thereof were measured according to the following measurement methods, and the measurement results are shown in Table 2.

Compressive strength: detecting according to a test method in GB/T50107-2010 concrete strength test evaluation standard; slump: detecting according to a test method in GB/T50080-2002 'common concrete mixture performance test standard'; anti-permeability performance: detecting according to a test method in GB/T50082-2009 test method standards for the long-term performance and durability of common concrete, wherein the osmotic pressure is 3.5MPa, and the pressurizing time is 48 h;

freeze-thaw resistance: detecting according to a test method in JTGE30-2005 Highway engineering cement and cement concrete test regulations, and detecting the frost resistance of concrete by adopting a rapid freezing tester; wherein, one freeze-thaw cycle takes 2-5h, the freeze-thaw temperature is-18 ℃, and the sample size is 100mm multiplied by 500 mm.

TABLE 2 examination results of examples 1 to 6 and comparative examples 1 to 6

As can be seen from the test data of examples 1-6, comparative examples 1-4, and Table 2, the compressive strength of the concrete of the present application is above 51.2 MPa; the initial slump is below 210mm, and the slump for 2h is less than 204 mm; the water seepage height is below 1.33mm, and the minimum water seepage height can reach 1.10 mm; the mass loss after 300 times of tests of freeze-thaw resistance cycle is less than 0.15 percent, and the elastic modulus loss is less than 0.25 percent; the concrete has the advantages of good comprehensive performance, strong durability and excellent anti-permeability performance.

From the test data of examples 1 to 3, it can be seen that the concrete of example 2 has excellent comprehensive properties and small water penetration height, which indicates that the concrete of example 2 has excellent mixture ratio of the raw materials. The detection data of the examples 4 to 6 show that the water seepage height of the concrete is reduced along with the gradual increase of the addition amount of the hydrophobic microspheres, which indicates that the impermeability of the concrete can be improved to a certain extent by increasing the addition amount of the hydrophobic microspheres.

It can be seen from the test data of example 2 and comparative examples 1 to 4 that the water penetration height of the concrete is greatly reduced without adding any one of the hydrophobic microspheres, the fly ash and the mixed fibers, which indicates that the excellent impermeability of the concrete of the present application is obtained by the mutual cooperation of the hydrophobic microspheres, the fly ash and the mixed fibers. The hydrophobic microspheres can fill micropores in concrete, and can block water permeation due to the hydrophobic property of the hydrophobic microspheres, and meanwhile, the hydrophobic microspheres have elasticity, so that when the acting force of the concrete on the hydrophobic microspheres is reduced, the hydrophobic microspheres can elastically deform, and the generated microcracks can be filled, and the water permeation can be blocked; the fly ash can also fill the micropores in the concrete, so that the permeation of water by utilizing the connectivity of the micropores can be slowed down to a certain degree; the mixed fiber can destroy the connectivity of micropores in concrete; therefore, the three raw materials are mutually cooperated through respective functions, and the impermeability of the concrete is greatly improved.

As can be seen from the detection data of the example 2 and the comparative examples 5 to 6, when the methacrylic acid is not added during the preparation of the hydrophobic microspheres, the hydrophobic microspheres have stronger hydrophobicity, so that the hydrophobic microspheres are poorer in dispersion in concrete and form an agglomeration phenomenon, and therefore, the impermeability of the concrete is reduced; when the hydrophobic microspheres are prepared, divinyl benzene is not added in a delayed mode, the microspheres cannot form a structure with low internal crosslinking density and high surface crosslinking degree, namely deformation cannot occur, and when micro cracks are generated after concrete is dried, the micro cracks cannot be filled, so that the water permeability of the concrete is reduced.

The embodiments of the present invention are preferred embodiments of the present application, and the scope of the present application is not limited by the embodiments of the present application, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (8)

1. An impervious high durability bulky concrete which is characterized in that: the composite material comprises the following raw materials in parts by weight: 180 parts of cement, 840 parts of pebble 820, 60-80 parts of coarse sand, 30-50 parts of fine sand, 10-15 parts of fly ash, 5-15 parts of mixed fiber, 2-10 parts of hydrophobic microspheres, 0.5-0.8 part of water reducer, 0.3-0.6 part of air entraining agent and 170 parts of water 150;

the preparation method of the hydrophobic microspheres comprises the following steps:

s1, adding 2-3 parts by weight of methacrylate, 7-9 parts by weight of styrene, 0.3-0.6 part by weight of methacrylic acid and 0.5-0.7 part by weight of double-ended vinyl polydimethylsiloxane into 40-50 parts by weight of DMF (dimethyl formamide) in a nitrogen atmosphere, stirring until the two-ended vinyl polydimethylsiloxane is dissolved, adding 0.07-0.08 part by weight of initiator, heating to 70-80 ℃, stirring for reaction for 3-5 hours, then dropwise adding 0.1-0.15 part by weight of divinylbenzene, trivinylbenzene or trivinylsilane, and then continuously stirring for reaction for 12-15 hours to obtain a mixed solution;

and S2, carrying out solid-liquid separation on the mixed liquid obtained in the S1, washing the obtained solid, and drying to obtain the hydrophobic microspheres.

2. The impervious high durability mass concrete of claim 1, wherein: the addition amount of the hydrophobic microspheres is 5-8 parts by weight.

3. The impervious high durability mass concrete of claim 1, wherein: the initiator is azobisisobutyronitrile or azobisisoheptonitrile.

4. The impervious high durability mass concrete of claim 1, wherein: the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

5. The impervious high durability mass concrete of claim 1, wherein: the mixed fiber comprises the following raw materials in parts by weight: 20-30 parts of polypropylene fiber and 10-20 parts of carbon fiber.

6. The impervious high durability mass concrete of claim 5, wherein: the length of the polypropylene fiber is 2-4cm, and the length of the carbon fiber is 1-3 cm.

7. The impervious high durability mass concrete of claim 1, wherein: the residue of the 45 mu m square-hole sieve of the fly ash is less than or equal to 7 percent.

8. A method for preparing a high durability, impervious bulk concrete according to any one of claims 1 to 7 wherein: which comprises the following steps:

s1, mixing and stirring the coarse sand, the fine sand, the mixed fiber and the water for 1-2 hours to obtain a first mixture;

s2, adding the water reducing agent, the pebbles, the cement and the air entraining agent into the first mixture, and uniformly stirring to obtain a second mixture;

and S3, adding the fly ash and the hydrophobic microspheres into the second mixture, and stirring for 1-2h to obtain the concrete.