CN110818340A - Anti-cracking cement mixture and preparation method thereof - Google Patents

Abstract

The invention provides an anti-cracking cement mixture and a preparation method thereof, and relates to the technical field of production of building materials. The anti-crack cement mixture comprises the following components in parts by weight: 46-78 parts of cement, 20-32 parts of sand, 18-26 parts of oil shale ash, 5-8 parts of mineral powder, 3-7 parts of anhydrite, 0.6-3.2 parts of fiber and 0.5-1.2 parts of an additive. The preparation method of the anti-crack cement mixture comprises the steps of proportioning, grinding and mixing. The components of the anti-cracking cement mixture are adjusted, so that the prepared cement mixture has good anti-cracking performance.

Description

Anti-cracking cement mixture and preparation method thereof

Technical Field

The invention relates to the technical field of building material production, in particular to an anti-cracking cement mixture and a preparation method thereof.

Background

Cement refers to a powdered hydraulic inorganic cementitious material. It can be made into slurry after being stirred by adding water, and can be hardened in air or in water, and can firmly bind sand and stone together. The early lime and pozzolan mixtures are similar to modern lime and pozzolan cements, and concrete made by cementing crushed stone with them not only has higher strength after hardening, but also resists erosion by fresh water or salt-containing water.

The production process of silicate cement is representative in cement production, and is characterized by that it uses limestone and clay as main raw material, and adopts the processes of crushing, proportioning and grinding to obtain raw material, then feeds the raw material into cement kiln to calcine it into clinker, and then adds a proper quantity of gypsum to make grinding so as to obtain the invented product.

However, after the concrete block is poured by the existing cement in the later stage, cracks or damaged sites are easy to appear on the ground after the existing cement is used for a period of time, so that the overall strength of the concrete block is influenced, and the service life of the concrete block is shortened.

Disclosure of Invention

In view of the problems in the background art, the invention aims to provide an anti-cracking cement mixture and a preparation method thereof, which improve the anti-cracking property of the mixture by adjusting the components of the cement mixture, have low production cost compared with the traditional cement production, and can avoid environmental pollution caused by a large amount of harmful gas generated in the calcining process.

The invention provides an anti-cracking cement mixture which comprises the following components in parts by weight: 46-78 parts of cement, 20-32 parts of sand, 18-26 parts of oil shale ash, 5-8 parts of mineral powder, 3-7 parts of anhydrite, 0.6-3.2 parts of fiber and 0.5-1.2 parts of an additive.

Preferably, the cement is ordinary portland cement, and the specific surface area of the ordinary portland cement is not less than 360m²/kg。

Preferably, the oil shale ash is oil mill ash and/or powder ash.

Preferably, the oil shale ash residue is a mixture of oil mill ash and powder ash, and the mixing mass ratio of the oil mill ash to the powder ash in the oil shale ash residue is 1 (1.1-1.3).

Preferably, the fibers comprise natural fibers including one or more of cotton fibers, hemp fibers, and coconut fibers.

Preferably, the fibers comprise synthetic fibers including polyacrylonitrile fibers and/or polyamide fibers.

Preferably, the fiber comprises cotton fiber, coconut fiber and polyacrylonitrile fiber, and the mixing mass ratio of the cotton fiber, the coconut fiber and the polyacrylonitrile fiber is (0.8-1): 1-1.2.

Preferably, the additive comprises an antifoaming agent, a stabilizer, a dispersant and a slow release agent.

The invention also provides a preparation method of the anti-cracking cement mixture, which is characterized by comprising the following steps:

step S1, mixing cement, sand, oil shale ash and mineral powder to obtain a first mixture;

step S2, grinding anhydrite to obtain anhydrite powder with 120-170 meshes; mixing anhydrite powder, fibers and an additive to obtain a second mixture;

step S3, mixing the first mixture and the second mixture to obtain cement coarse material;

step S4, grinding the cement coarse material to 320-380 meshes to obtain an anti-cracking cement mixture;

there is no chronological restriction between the step S1 and the step S2.

The technical scheme provided by the invention has the following beneficial effects:

1. at present, most of oil shale ash residues are directly discarded and piled up, and can seriously pollute surrounding water sources, land and organisms after being leached or diffused by rainwater, so that the health of residents is harmed, the pollution range of the oil shale ash residues is usually more than several times of the occupied land area, and the environmental pollution is caused to a great extent. The invention takes the oil shale ash as the admixture of the cement mixture, not only solves the problem of waste pollution of a large amount of oil shale ash, but also ensures that the cement mixture has equivalent compressive strength and rupture strength, enhances the crack resistance of the cement mixture and realizes the reasonable reutilization of wastes.

2. After the oil shale ash is added into the cement mixture, the hardness and the frost resistance of the cement can be enhanced, and the permeability is reduced, thereby improving the performance of the cement.

3. The invention reasonably mixes the components of the cement mixture, and compositely mixes the contents of the oil shale ash, the mineral powder and the fiber on the basis of the traditional cement mixture, thereby integrally improving the crack resistance of the cement.

4. The fiber added into the mixture can be natural fiber and synthetic fiber, the common crack-resistant effect of the two composite fibers can be effectively utilized, the crack-resistant effect of the oil shale ash on the cement mixture can be compounded with the crack-resistant effect of the fiber, the fiber can reduce the plastic shrinkage crack of the cement, the brittleness and toughness of the cement can be improved by the oil shale ash, and the performance of the cement mixture is further improved due to the superposition of the effects of the two admixtures.

5. The invention reduces the variety and the addition amount of the additive and saves the production cost.

Detailed Description

The invention provides an anti-cracking cement mixture which comprises the following components in parts by weight: 46-78 parts of cement, 20-32 parts of sand, 18-26 parts of oil shale ash, 5-8 parts of mineral powder, 3-7 parts of anhydrite, 0.6-3.2 parts of fiber and 0.5-1.2 parts of an additive. Preferably, the anti-crack cement mixture comprises the following components in parts by weight: 50-72 parts of cement, 26-32 parts of sand, 20-25 parts of oil shale ash, 5-7 parts of mineral powder, 4-6 parts of anhydrite, 0.8-2.0 parts of fiber and 0.8-1.2 parts of additive. More preferably, the anti-crack cement mixture comprises the following components in parts by weight: 64 parts of cement, 26 parts of sand, 20 parts of oil shale ash, 6 parts of mineral powder, 6 parts of anhydrite, 1.8 parts of fiber and 0.9 part of additive.

In the present invention, the cement is preferably ordinary portland cement ofThe specific surface area is preferably not less than 360m²/kg, more preferably not less than 400m²In terms of/kg. The ordinary Portland cement preferably adopts 42.5-grade ordinary Portland cement, the 7d compressive strength is 34.52MPa, and the flexural strength is 6.38 MPa. The 28d compressive strength is 46.44MPa, and the flexural strength is 7.55 MPa.

The source of the sand is not particularly limited in the present invention, and any sand material conventionally commercially available in the art, such as fine sand, may be used.

In the present invention, the oil shale ash is preferably oil mill ash and/or powder ash, more preferably a mixture of oil mill ash and powder ash. When the oil shale ash is preferably a mixture of oil mill ash and powder ash, the mixing mass ratio of the oil mill ash and the powder ash in the oil shale ash is preferably 1 (1.1-1.3), and more preferably 1: 1.2. In the present invention, the source of the above-mentioned putty and powder ash is not particularly limited, and any commercially waste putty and powder ash may be recovered.

In the invention, the oil shale ash is doped to separate cement particles, so that the cement is more fully hydrated, and because the oil shale ash has the characteristics of a gray matter material, the generated colloid can improve the strength of concrete, particularly the later strength, and the oil shale ash is used for replacing part of cement, wherein the spherical glass body can play a role in lubricating, so that the workability of the cement is improved, the hydration heat of the cement can be reduced, and the anti-cracking capability of the concrete is enhanced. As the fine particles in the oil shale ash are distributed in the cement, the filling effect of the holes and the chemical composition of the oil shale ash containing silicon oxide and aluminum oxide are subjected to secondary hydration reaction with cement hydrate, and the product can effectively reduce the internal gaps of the concrete and improve the anti-permeability performance of the concrete.

The ore powder is prepared from commercially available ore powder, preferably S115 ore powder.

The anhydrite is not limited by the source of the anhydrite, and any commercially available product which is conventional in the art can be used.

In the present invention, the fibers preferably comprise natural fibers, which preferably comprise one or more of cotton fibers, hemp fibers, and coconut fibers.

In the present invention, the fibers preferably comprise synthetic fibers, which preferably comprise polyacrylonitrile fibers and/or polyamide fibers.

In the invention, the fiber more preferably comprises cotton fiber, coconut fiber and polyacrylonitrile fiber, and the mixing mass ratio of the cotton fiber, the coconut fiber and the polyacrylonitrile fiber is preferably (0.8-1): 08-1): 1-1.2, and more preferably 0.8:0.8: 1.2.

In the invention, the addition of the fiber is equivalent to the formation of cracks in the cement cementing body, so that the integrity of the cement is reduced, the splitting strength is weakened, and after the fiber is distributed in three-dimensional disorderly direction in the cementing body, the fiber and the cementing body generate interface adsorption binding power and mechanical occlusal force, so that the high tensile property of the fiber can be fully exerted, the tensile property of the cement is improved, and the splitting strength is enhanced.

In the present invention, the additive includes an antifoaming agent, a stabilizer, a dispersant and a sustained-release agent.

In the present invention, the defoaming agent is preferably a commercially available defoaming agent P803. The stabilizer is preferably polyvinyl alcohol and/or polyvinylpyrrolidone. The dispersant is preferably a non-ionic dispersant and/or an anionic dispersant. The non-ionic dispersing agent can be polyethylene glycol octyl phenyl ether, Arabic gum, polyoxyethylene lauryl ether and oleic acid monoglyceride, and preferably polyethylene glycol octyl phenyl ether and oleic acid monoglyceride. The anionic dispersant can be polypropionic acid, ammonium poly (meth) acrylate, sodium lauryl sulfate, sodium laureth sulfate and sodium cetyl polyoxyethylene ether phosphate, preferably sodium lauryl sulfate, polypropionic acid and sodium cetyl polyoxyethylene ether phosphate. The corrosion inhibitor is preferably sodium gluconate or aluminum silicate.

The purchase channel of the admixture is not particularly limited in the present invention, and the admixture can be any commercially available branded product in the field.

The invention also provides a preparation method of the anti-crack cement mixture, which comprises the following steps:

step S1, mixing cement, sand, oil shale ash and mineral powder to obtain a first mixture;

step S2, grinding anhydrite to obtain anhydrite powder with 120-170 meshes; mixing anhydrite powder, fibers and an additive to obtain a second mixture;

step S3, mixing the first mixture and the second mixture to obtain cement coarse material;

step S4, grinding the cement coarse material to 320-380 meshes to obtain an anti-cracking cement mixture;

there is no chronological restriction between the step S1 and the step S2.

In step S1, cement, sand, oil shale ash and mineral powder are mixed to obtain a first mixture. In step S1, the mixing is preferably performed by stirring. The stirring speed is preferably 900 to 1200rpm, and more preferably 1000 to 1100 rpm. The stirring time is preferably 25-45 min, and more preferably 30-40 min; the specific device for mixing in step S1 is not particularly limited, and conventional devices such as a mixing bowl may be used.

The present invention grinds the anhydrite at step S2. In the present invention, the grinding is preferably performed by ball milling. The rotation speed of the ball mill is preferably 450 to 600r/min, and more preferably 500 to 600 r/min. The milling time of the mill for ball milling is preferably 20 to 50min, more preferably 30 to 50 min. After grinding, anhydrite is preferably obtained in a sieved manner. The particle size of the anhydrite powder is preferably 120-170 meshes, and more preferably 130-160 meshes.

After the anhydrite powder is obtained, the anhydrite powder, the fiber and the additive are mixed to obtain a second mixture; in step S2, the mixing is preferably performed by stirring. The stirring speed is preferably 360-700 rpm, and more preferably 420-660 rpm. The stirring time is preferably 18-42 min, and more preferably 20-40 min; the specific device for mixing in step S2 is not particularly limited, and conventional devices such as a mixing bowl may be used.

After the first mixture and the second mixture are obtained, the first mixture and the second mixture are mixed in step S3 to obtain the cement coarse material. In step S3, the specific method and apparatus for mixing are not particularly limited, and any conventional method or apparatus may be used.

After the cement coarse material is obtained, the present invention grinds the cement coarse material at step S4. In this step S4, the grinding is preferably carried into a grinder by a conveyor belt for grinding. The rotation speed of the grinding is preferably 16-28 rpm, and more preferably 20-26 rpm. The grinding time is preferably 40-80 min, and more preferably 50-70 min. And grinding to obtain the anti-crack cement mixture.

The technical solution provided by the present invention will be clearly and completely described below with reference to the embodiments. It should be noted that the examples listed below are only some examples of the present invention, and not all examples. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Mixing 46 parts of cement, 22 parts of sand, 19 parts of oil shale ash and 5 parts of mineral powder in a mixing barrel at the stirring speed of 1000rpm for 30min to obtain a first mixture. And grinding the anhydrite by a ball milling mode, wherein the rotating speed of a grinding machine is 500r/min, the grinding is carried out for 30min, and the anhydrite powder with 120 meshes is obtained after the grinding and sieving. Mixing 4 parts of anhydrite powder, 0.8 part of fiber and 0.5 part of additive in a mixing barrel at the stirring speed of 360rpm for 18min to obtain a second mixture. And mixing the first mixture and the second mixture to obtain the cement coarse material. And conveying the cement coarse material into a grinder through a conveyer belt for grinding at the rotating speed of 16rpm for 40min to 320 meshes to obtain the anti-crack cement mixture.

Example 2

Mixing 78 parts of cement, 30 parts of sand, 21 parts of oil shale ash and 8 parts of mineral powder in a mixing barrel at the stirring speed of 900rpm for 25min to obtain a first mixture. And grinding the anhydrite by a ball milling mode, wherein the rotating speed of a grinding machine is 450r/min, the grinding is carried out for 20min, and the anhydrite powder with 130 meshes is obtained after the grinding and sieving. Mixing 7 parts of anhydrite powder, 3.2 parts of fiber and 1.2 parts of additive in a mixing barrel at the stirring speed of 420rpm for 26min to obtain a second mixture. And mixing the first mixture and the second mixture to obtain the cement coarse material. Conveying the cement coarse material into a grinder through a conveyer belt for grinding at the rotating speed of 20rpm for 50min to 340 meshes to obtain the anti-crack cement mixture.

Example 3

Mixing 64 parts of cement, 26 parts of sand, 20 parts of oil shale ash and 6 parts of mineral powder in a mixing barrel at the stirring speed of 1100rpm for 35min to obtain a first mixture. And grinding the anhydrite by a ball milling mode, wherein the rotating speed of a grinding machine is 550r/min, the grinding is carried out for 30min, and the anhydrite powder with 150 meshes is obtained after the grinding and sieving. Mixing 6 parts of anhydrite powder, 1.8 parts of fiber and 0.9 part of additive in a mixing barrel at a stirring speed of 500rpm for 32min to obtain a second mixture. And mixing the first mixture and the second mixture to obtain the cement coarse material. Conveying the cement coarse material into a grinder through a conveyer belt for grinding, wherein the rotating speed is 24rpm, the grinding time is 55min, and the grinding time is 360 meshes, so that the anti-crack cement mixture is obtained.

Comparative example

A cement mixture was prepared by mixing 60 parts of cement, 30 parts of sand, 5 parts of mineral powder and 5 parts of anhydrite according to the mixing method and the grinding mesh number of example 1.

The crack resistance data of the cement mixture are shown in table 1.

TABLE 1 crack resistance data for cement mixes

The anti-cracking performance test is carried out according to JC/T951-2005 'Cement mortar anti-cracking performance test method', the proportioned cement mixture of each embodiment and comparative example is prepared into an experimental test piece, the test piece is cast by a mould made of a wood frame, and the size of the test piece is 910mm x 600mm x 20 mm. After the test piece is formed, irradiating for 4 hours by using a 1000W iodine tungsten lamp, blowing the surface of the test piece for 24-30 hours by using a fan with the air speed of 4-5m/s, and measuring the length and width d of a crack to obtain the cracking index W and the anti-cracking performance ratio gamma.

Claims (9)

1. The anti-cracking cement mixture is characterized by comprising the following components in parts by weight: 46-78 parts of cement, 20-32 parts of sand, 18-26 parts of oil shale ash, 5-8 parts of mineral powder, 3-7 parts of anhydrite, 0.6-3.2 parts of fiber and 0.5-1.2 parts of an additive.

2. The crack-resistant cement mixture according to claim 1, wherein the cement is ordinary portland cement having a specific surface area of not less than 360m²/kg。

3. The crack-resistant cement mix according to claim 1, wherein the oil shale waste is oil mill ash and/or powder ash.

4. The anti-cracking cement mixture according to claim 3, wherein the oil shale ash is a mixture of oil mill ash and powder ash, and the mixing mass ratio of the oil mill ash to the powder ash in the oil shale ash is 1 (1.1-1.3).

5. The crack-resistant cement mix as claimed in claim 1, wherein the fibers comprise natural fibers including one or more of cotton fibers, hemp fibers and coconut fibers.

6. The crack resistant cement mix as claimed in claim 1, wherein said fibers comprise synthetic fibers including polyacrylonitrile fibers and/or polyamide fibers.

7. The crack-resistant cement mixture according to claim 5 or 6, wherein the fiber comprises cotton fiber, coconut fiber and polyacrylonitrile fiber, and the mixing mass ratio of the cotton fiber, the coconut fiber and the polyacrylonitrile fiber is (0.8-1): 0.8-1: 1-1.2.

8. The anti-crack cement mixture according to claim 1, wherein the admixture comprises an antifoaming agent, a stabilizer, a dispersant and a slow-release agent.

9. The preparation method of the crack-resistant cement mixture according to any one of claims 1 to 8, characterized by comprising the steps of:

step S1, mixing cement, sand, oil shale ash and mineral powder to obtain a first mixture;

step S2, grinding anhydrite to obtain anhydrite powder with 120-170 meshes; mixing anhydrite powder, fibers and an additive to obtain a second mixture;

step S3, mixing the first mixture and the second mixture to obtain cement coarse material;

step S4, grinding the cement coarse material to 320-380 meshes to obtain an anti-cracking cement mixture;

there is no chronological restriction between the step S1 and the step S2.