A high-flowing state concrete prepared by using high-calcium high-fines self-made sand and a preparation method thereof

Abstract

The application discloses a kind of high calcium high content self-made sand preparation of large flow state concrete and preparation method thereof, belong to concrete technical field.The high calcium high content self-made sand preparation of large flow state concrete includes following weight fraction of each component: cement 160~220 parts, fly ash 30~80 parts, mineral powder 50~90 parts, high calcium high content self-made sand 700~1000 parts, coarse aggregate 900~1100 parts, composite admixture 4~10 parts, water 140~180 parts;Wherein, the high calcium high content self-made sand's stone powder content is 15%~20%;The composite admixture includes water reducing agent, composite polyol, composite air entraining agent and sodium lignosulfonate.Under the action of composite admixture, the self-made sand with stone powder content as high as 15%~20% is replaced natural sand in the application, can realize the comprehensive utilization of waste resources, alleviate the problem of natural sand shortage, can also obtain large flow state concrete with excellent working performance and mechanical properties simultaneously.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to a high-fluidity concrete prepared from self-made sand with high calcium and high powder content and a preparation method thereof. BACKGROUND

[0002] With the rapid development of urbanization construction in China, the use of natural river sand is increasing year by year, about 100 billion tons are consumed annually, which cannot meet the market demand at all. In many areas, there is a shortage of river sand, even the depletion of river sand resources. In addition, due to overexploitation of natural sand, even "devastating" sand mining, the entire river ecology is severely damaged, the riverbed water level is lowered, and the water and soil are severely eroded, leaving hidden dangers of flood outbreaks.

[0003] In order to solve the demand dilemma caused by the shortage of natural sand, manufactured sand is widely used. Manufactured sand is mainly made of rock waste of different lithology by mechanical crushing and screening. It can be locally sourced to reduce transportation costs. Due to the existence of a certain soil layer in the rock, a certain amount of mud powder and stone powder will be produced during the crushing process through mechanical impact and rolling. The existence of mud powder will affect the quality of manufactured sand, while the existence of stone powder can make up for the problem of large gaps caused by manufactured sand in concrete. The mud powder contained in the manufactured sand can be removed through the water washing process, and the stone powder in the manufactured sand can be retained. Chinese patent CN108191337A discloses a concrete prepared from artificial sand and stone powder. The concrete includes the following mass fractions of raw materials: 340-480 parts of cementitious material, 690-820 parts of admixture, 990-1100 parts of coarse aggregate, 190-210 parts of water, and 1-3 parts of water reducing agent. The cementitious material is composed of cement and fly ash. The admixture is composed of artificial sand and stone powder. The invention uses artificial sand and stone powder as concrete admixture, which reduces the amount of natural river sand. Not only can it reduce the cost of building prefabricated parts, but also can reduce the environmental impact caused by overexploitation of natural sand. At the same time, by selecting the amount of artificial sand and stone powder, the concrete has good workability and compressive strength, and even the compressive strength and splitting tensile strength are slightly higher than that of the concrete prepared from natural river sand. Moreover, artificial sand and stone powder as admixture also have the effects of reducing concrete shrinkage, improving concrete carbonation resistance and chloride ion penetration resistance. However, compared with natural sand, the compressive strength of the concrete prepared from artificial sand and stone powder can only reach the same level as that of natural river sand. Even in low-strength concrete, the compressive strength of the concrete prepared from artificial sand and stone powder is slightly lower than that of natural river sand, and the workability of the concrete is reduced to some extent.

[0004] Therefore, it is urgent to provide a concrete that can have excellent workability and mechanical properties while using artificial sand with high powder content instead of natural river sand. SUMMARY

[0005] In view of the above problems of the prior art, one of the purposes of the present application is to provide a high-fluidity concrete prepared by using high-calcium high-powder-content self-made sand, which replaces natural river sand with artificial sand with high powder content, so as to realize comprehensive utilization of waste resources, alleviate the problem of shortage of natural sand, and obtain concrete with excellent working performance and mechanical properties.

[0006] To achieve the above purpose, the specific technical solutions of the present application are as follows:

[0007] A high-fluidity concrete prepared by using high-calcium high-powder-content self-made sand, comprising the following components in parts by weight: cement 160-220 parts, fly ash 30-80 parts, mineral powder 50-90 parts, high-calcium high-powder-content self-made sand 700-1000 parts, coarse aggregate 900-1100 parts, composite admixture 4-10 parts, and water 140-180 parts.

[0008] The high-calcium high-powder-content self-made sand has a stone powder content of 15%-20%.

[0009] The composite admixture comprises a water reducing agent, a composite polyol, a composite air entraining agent, and sodium lignosulfonate.

[0010] In view of the problem that manufactured sand easily causes a large loss of concrete slump, the present application uses high-calcium high-powder-content self-made sand in combination with a composite admixture, and the synergistic effect of the components in the composite admixture can effectively promote the full dispersion of the components of the concrete, thereby reducing the viscosity of the concrete and making the concrete have excellent fluidity, which can compensate for the defect that self-made sand causes a too rapid loss of concrete slump; under the action of the composite admixture, the present application realizes the replacement of natural sand with self-made sand with a stone powder content as high as 15%-20%, and obtains high-fluidity concrete with excellent working performance and mechanical properties.

[0011] Preferably, the composite admixture comprises the following components in mass percentage: water reducing agent 10%-13%, composite polyol 1%-2%, composite air entraining agent 0.1%-1%, sodium lignosulfonate 1%-2%, and water 82%-85%.

[0012] Preferably, the composite polyol comprises glycerol, ethylene glycol, and triethanolamine in a mass ratio of 1:1:1.

[0013] Preferably, the composite air entraining agent comprises tri-terpene saponin, sodium dodecyl sulfate, and sodium laureth sulfate in a mass ratio of 2:2:1.

[0014] Preferably, the high-calcium high-powder-content self-made sand has an average fineness modulus of 2.5-3.2.

[0015] Preferably, the water reducing agent comprises at least one of polycarboxylic acid water reducing agent, naphthalene water reducing agent, and polyamide water reducing agent.

[0016] Preferably, the high-calcium high-fines self-made sand is obtained by crushing and screening limestone.

[0017] Preferably, the preparation method of the high-calcium high-fines self-made sand comprises the following steps: crushing limestone with a particle size of 5-10 mm, and then sequentially passing the crushed material through five-stage vibrating screens with mesh sizes of 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm to obtain self-made sand; and then conveying the obtained self-made sand through a belt, and setting a spraying device at the tail of the belt to spray a surface modifier into the self-made sand, and then homogenizing.

[0018] Preferably, the surface modifier is potassium methyl silicate.

[0019] By spraying the surface modifier potassium methyl silicate solution into the self-made sand, dust removal effect can be achieved, and a hydrophobic film can be formed on the surface of the self-made sand to reduce the adsorption of the self-made sand to water reducing agent and water, thereby further compensating for the defect that the self-made sand causes the slump loss of concrete to be too fast.

[0020] Another object of the present application is to provide a preparation method of the high-flowability concrete prepared by using the high-calcium high-fines self-made sand, which comprises the following steps:

[0021] S1. Measuring water reducing agent, composite polyol, composite air entraining agent, sodium lignosulfonate and water by mass percentage, and mixing uniformly to obtain a composite admixture;

[0022] S2. Measuring cement, fly ash, slag, high-calcium high-fines self-made sand, coarse aggregate, composite admixture and water by weight fraction, and pouring into a mixer to stir uniformly to obtain a concrete mixture;

[0023] S3. Injecting the concrete mixture into a mold to vibrate and form, and obtaining the high-flowability concrete after curing and demolding.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] (1) The high-calcium high-fines self-made sand is used in combination with the composite admixture in the present application, and the synergistic effect of the components in the composite admixture can effectively promote the full dispersion of the components of the concrete, thereby reducing the viscosity of the concrete and making the concrete have excellent flowability, which can compensate for the defect that the self-made sand causes the slump loss of concrete to be too fast; under the action of the composite admixture, the present application realizes the replacement of natural sand with the self-made sand with a high content of stone powder of 15-20%, which not only realizes the comprehensive utilization of waste resources and alleviates the shortage of natural sand, but also obtains high-flowability concrete with excellent working performance and mechanical properties.

[0026] (2) The surface modifier is used in the preparation of the high-calcium high-powder-content self-made sand, which can play a dust removal effect and form a hydrophobic film on the surface of the self-made sand, thereby reducing the adsorption of the self-made sand to the water reducing agent and water, and further making up for the defect of the self-made sand that causes the concrete slump loss to be too fast.

[0027] (3) The high-flowability concrete has good flowability, and the slump / extension reaches 240mm / 630mm, and the 2h slump / extension reaches 220mm / 590mm, and the slump and extension loss of the concrete is small, and the mechanical property of the concrete is excellent, reaching 44.5MPa, which is obviously better than that of the conventional machine-made sand. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0029] The high-flowability concrete prepared by using the high-calcium high-powder-content self-made sand comprises the following components in parts by weight: cement 160-220 parts, fly ash 30-80 parts, mineral powder 50-90 parts, high-calcium high-powder-content self-made sand 700-1000 parts, coarse aggregate 900-1100 parts, composite admixture 4-10 parts, and water 140-180 parts.

[0030] The average fineness modulus of the high-calcium high-powder-content self-made sand is 2.5-3.2, and the stone powder content is 15%-20%.

[0031] The composite admixture comprises the following components in mass percentage: water reducing agent 10%-13%, composite polyol 1%-2%, composite air entraining agent 0.1%-1%, sodium lignosulfonate 1%-2%, and water 82%-85%.

[0032] The water reducing agent can be selected from at least one of polycarboxylic acid water reducing agent, naphthalene series water reducing agent, and polyamide water reducing agent; preferably, the polycarboxylic acid water reducing agent with a solid content of 18% and a water reducing rate of 23.5%.

[0033] In the following examples and comparative examples, the cement is P•O 42.5 ordinary portland cement, the fly ash is II-grade fly ash, the mineral powder is S95-grade mineral powder, and the coarse aggregate is 5-25mm continuous gradation macadam; the apparent density of the machine-made sand is 2650kg / m 3 , and the loose bulk density is 1510kg / m 3, fineness modulus 2.7, stone powder content 6.8%, MB value 1.3; the fineness modulus of river sand is 2.6, and the apparent density is 2630kg / m 3 , loose bulk density 1540kg / m 3 , fineness modulus 2.6, silt content 1.9%, and mud content 0%.

[0034] Example 1

[0035] The example provides a high-flow-state concrete prepared by using high-calcium high-powder-content self-made sand, which comprises the following components in parts by weight: cement 200 parts, fly ash 70 parts, mineral powder 80 parts, high-calcium high-powder-content self-made sand 855 parts, coarse aggregate 980 parts, composite admixture 5 parts, and water 165 parts.

[0036] The fineness modulus of the high-calcium high-powder-content self-made sand is 2.8, and the stone powder content is 15%. The preparation method comprises the following steps: crushing limestone with a particle size of 5-10mm, and then sequentially passing the crushed materials through five-stage vibrating screens with mesh sizes of 3.5mm / 3.5mm / 3.5mm / 3.5mm / 3.5mm to obtain self-made sand; then conveying the obtained self-made sand to a finished product bin through a belt, and setting a spraying device at the tail of the belt to spray a surface modifier into the self-made sand at a rate of 1.1t / h, and then homogenizing; the surface modifier is composed of deionized water and methyl potassium silicate at a mass ratio of 25:1.

[0037] The composite admixture comprises the following components in mass percentages: polycarboxylic acid water reducer 12.5%, composite polyol 1.5%, composite air entraining agent 0.5%, sodium lignosulfonate 1.5%, and water 84%; the composite polyol comprises glycerol, ethylene glycol and triethanolamine at a mass ratio of 1:1:1; the composite air entraining agent comprises tri-terpene saponin, sodium dodecyl sulfate and sodium laureth sulfate at a mass ratio of 2:2:1.

[0038] The example also provides a preparation method of the high-flow-state concrete prepared by using high-calcium high-powder-content self-made sand, which comprises the following steps:

[0039] S1. mixing water reducer, composite polyol, composite air entraining agent, sodium lignosulfonate and water in mass percentages to obtain a composite admixture;

[0040] S2. weighing cement, fly ash, mineral powder, high-calcium high-powder-content self-made sand, coarse aggregate, composite admixture and water in parts by weight, and pouring them into a mixer to stir uniformly to obtain a concrete mixture;

[0041] S3. pouring the concrete mixture into a mold to vibrate and form, and obtaining the high-flow-state concrete after curing and demolding.

[0042] Example 2

[0043] The mass flow state concrete of the embodiment is basically the same as that of Embodiment 1, and the difference is that the mass flow state concrete of the embodiment comprises the following components in parts by weight: cement 180 parts, fly ash 50 parts, mineral powder 80 parts, high calcium high powder content self-made sand 880 parts, coarse aggregate 1000 parts, composite admixture 4.7 parts, and water 160 parts;

[0044] The fineness modulus of the high calcium high powder content self-made sand is 2.7, and the stone powder content is 18%.

[0045] The composite admixture comprises the following components in mass percentage: polycarboxylate superplasticizer 13%, composite polyol 1%, composite air entraining agent 0.1%, sodium lignosulfonate 1%, and water 84.9%; the composite polyol comprises glycerol, ethylene glycol, and triethanolamine in a mass ratio of 1:1:1; the composite air entraining agent comprises triterpenoid saponin, sodium dodecyl sulfate, and sodium laureth sulfate in a mass ratio of 2:2:1.

[0046] Comparative Example 1

[0047] The concrete of the comparative example is basically the same as that of Embodiment 1, and the difference is that the concrete of the comparative example comprises the following components in parts by weight: cement 200 parts, fly ash 70 parts, mineral powder 80 parts, river sand 427.5 parts, machine-made sand 427.5 parts, coarse aggregate 980 parts, composite admixture 5 parts, and water 165 parts.

[0048] That is, compared with Embodiment 1, the river sand and the machine-made sand are used to replace the high calcium high powder content self-made sand in the comparative example.

[0049] Comparative Example 2

[0050] The concrete of the comparative example is basically the same as that of Embodiment 1, and the difference is that the concrete of the comparative example comprises the following components in parts by weight: cement 200 parts, fly ash 70 parts, mineral powder 80 parts, high calcium high powder content self-made sand 427.5 parts, machine-made sand 427.5 parts, coarse aggregate 980 parts, composite admixture 5 parts, and water 165 parts.

[0051] That is, compared with Embodiment 1, the machine-made sand is used to replace 50% of the high calcium high powder content self-made sand in the comparative example.

[0052] Comparative Example 3

[0053] The concrete of the comparative example is basically the same as that of Embodiment 1, and the difference is that the concrete of the comparative example comprises the following components in parts by weight: cement 200 parts, fly ash 70 parts, mineral powder 80 parts, high calcium high powder content self-made sand 171 parts, machine-made sand 684 parts, coarse aggregate 980 parts, composite admixture 5 parts, and water 165 parts.

[0054] That is, compared with Example 1, the comparative example uses machine-made sand to replace 80% of the high-calcium high-fines self-made sand.

[0055] Comparative Example 4

[0056] The concrete of the comparative example is basically the same as that of Example 1, except that the high-calcium high-fines self-made sand has a fineness modulus of 3.1 and a stone powder content of 9.1%; and the preparation method steps are as follows: the limestone with a particle size of 5-10 mm is crushed, and then the crushed material is sequentially passed through five-stage vibrating screens with screen hole diameters of 4.0 mm / 4.0 mm / 3.5 mm / 3.5 mm / 3.5 mm to obtain self-made sand; then the obtained self-made sand is conveyed to the finished product bin by a belt, and a spraying device is arranged at the tail of the belt to spray a surface modifier into the self-made sand at a rate of 1.1 t / h, followed by homogenization; the surface modifier is deionized water and potassium methyl silicate with a mass ratio of 25:1.

[0057] Comparative Example 5

[0058] The concrete of the comparative example is basically the same as that of Example 1, except that the composite admixture includes the following components by mass percentage: polycarboxylate superplasticizer 12.5%, composite air-entraining agent 0.5%, sodium lignosulfonate 3%, and water 84%.

[0059] Comparative Example 6

[0060] The concrete of the comparative example is basically the same as that of Example 1, except that the composite admixture includes the following components by mass percentage: polycarboxylate superplasticizer 12.5%, composite polyol 1.5%, composite air-entraining agent 0.5%, sodium lignosulfonate 1.5%, and water 84%; the composite polyol includes glycerol and ethylene glycol with a mass ratio of 1:1.

[0061] Comparative Example 7

[0062] The concrete of the comparative example is basically the same as that of Example 1, except that the preparation method steps of the high-calcium high-fines self-made sand are as follows: the limestone with a particle size of 5-10 mm is crushed, and then the crushed material is sequentially passed through five-stage vibrating screens with screen hole diameters of 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm to obtain self-made sand; then the obtained self-made sand is conveyed to the finished product bin by a belt, and a spraying device is arranged at the tail of the belt to spray tap water into the self-made sand at a rate of 1.5 t / h, followed by homogenization.

[0063] That is, compared with Example 1, the comparative example does not use a surface modifier when preparing the high-calcium high-fines self-made sand.

[0064] Test Example

[0065] The slump and spread of the concrete mix of each example and the comparative example were detected according to the relevant provisions of GB / T 50080-2016 "Standard Test Methods for Properties of Concrete Mixes"; and the 7d and 28d compressive strength of the concrete was determined according to the provisions of GB / T 50081-2019 "Standard Test Methods for Mechanical Properties of Ordinary Concrete".

[0066] Table 1: Performance test results of the concrete

[0067]

[0068] As can be seen from the test results in Table 1, the high-flow concrete of the present application has excellent working performance and mechanical properties, with a slump / spread of 240 mm / 630 mm, and a 2h slump / spread of 220 mm / 590 mm, and the slump and spread of the concrete are less lost, and the mechanical properties of the concrete are excellent, with a 28d compressive strength of up to 44.5 MPa.

[0069] By comparing the slump and compressive strength data of Example 1 and Comparative Example 1 (reference group), it can be seen that, under the condition that the amounts of the components of the concrete are consistent, the use of high-calcium high-powder-content self-made sand can improve the working performance and mechanical properties of the concrete, specifically, the slump / spread can be increased by 20 mm / 30 mm, and the 28d compressive strength can be increased by 7.4 MPa.

[0070] By comparing Example 1 and Comparative Examples 2-3, it can be found that, with the increase of the amount of high-calcium high-powder-content self-made sand in the fine aggregate, the working performance and mechanical properties of the concrete are improved. Compared with Example 1, the powder content of the self-made sand in Comparative Example 4 is 9.1%, the slump / spread of the concrete is reduced by 20 mm / 30 mm, and the 28d compressive strength is reduced by 5.3 MPa.

[0071] Compared with Example 1, the composite admixture of Comparative Example 5 lacks composite polyol, and the amount of sodium lignosulfonate is correspondingly increased, the 2h slump loss of the concrete is increased, the viscosity of the concrete mix is increased, and the working performance of the concrete is significantly reduced. It shows that, with the use of high-powder-content self-made sand, the composite admixture can effectively promote the full dispersion of the components of the concrete under the joint action of water reducing agent, air entraining agent and polyol, thereby reducing the viscosity of the concrete and making the concrete have excellent fluidity.

[0072] Compared with Example 1, the composite polyol in Comparative Example 6 lacks triethanolamine, the 2h slump loss of the concrete is increased, the viscosity of the concrete mix is increased, and the working performance of the concrete is significantly reduced. It shows that, with the use of high-powder-content self-made sand, the composite admixture can effectively promote the full dispersion of the components of the concrete under the joint action of glycerol, ethylene glycol and triethanolamine, thereby reducing the viscosity of the concrete and making the concrete have excellent fluidity.

[0073] Compared with Example 1, the slump / extension of the concrete prepared by using the high-calcium high-fines self-made sand of Comparative Example 7 without using the surface modifier is reduced by 20 mm / 30 mm, and the 28d compressive strength is reduced by 4.7 MPa.

[0074] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high fluidity concrete prepared using high calcium high-fines self-made sand, characterized in that, The cement 160-220 parts by weight, fly ash 30-80 parts by weight, mineral powder 50-90 parts by weight, high calcium high powder content self-made sand 700-1000 parts by weight, coarse aggregate 900-1100 parts by weight, composite admixture 4-10 parts by weight, and water 140-180 parts by weight are included. The stone powder content of the high calcium high powder content self-made sand is 15-20%. The composite admixture includes water reducing agent, composite polyol, composite air entraining agent and sodium lignosulfonate; the composite polyol includes glycerol, ethylene glycol and triethanolamine in a mass ratio of 1:1:

1. The preparation method of the high calcium high powder content self-made sand is as follows: the limestone with a particle size of 5-10 mm is crushed, and then the crushed material is sequentially passed through five-stage vibration screens with mesh sizes of 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm / 3.5 mm to obtain self-made sand; then the obtained self-made sand is conveyed by a belt, and a spraying device is arranged at the tail of the belt to spray the aqueous solution of potassium methyl silicate into the self-made sand, and then the self-made sand is homogenized.

2. A high fluidity concrete prepared using high calcium high powder content self-made sand according to claim 1, characterized in that, The composite admixture includes the following components in mass percentages: water reducing agent 10-13%, composite polyol 1-2%, composite air entraining agent 0.1-1%, sodium lignosulfonate 1-2%, and water 82-85%.

3. A high fluidity concrete prepared using high calcium high powder content self-made sand according to claim 1, characterized in that, The composite air entraining agent includes triterpenoid saponin, sodium dodecyl sulfate and sodium lauryl polyoxyethylene sulfate in a mass ratio of 2:2:

1.

4. A high fluidity concrete prepared using high calcium high powder content self-made sand according to claim 1, characterized in that, The average fineness modulus of the high calcium high powder content self-made sand is 2.5-3.

2.

5. A high fluidity concrete prepared using high calcium high-fines self-made sand as claimed in claim 1, wherein, The water reducing agent includes at least one of polycarboxylic acid water reducing agent, naphthalene series water reducing agent and polyamide water reducing agent.

6. A method of manufacturing a high fluidity concrete using self-made sand with high calcium and high powder content according to any one of claims 1 to 5, characterized in that, The method includes the following steps: S1. The water reducing agent, composite polyol, composite air entraining agent, sodium lignosulfonate and water are weighed in mass percentages and mixed uniformly to obtain a composite admixture; S2. The cement, fly ash, mineral powder, high calcium high powder content self-made sand, coarse aggregate, composite admixture and water are weighed in parts by weight, poured into a mixer and stirred uniformly to obtain a concrete mixture; S3. The concrete mixture is poured into a mold and vibrated to form a large flow state concrete after curing and demolding.

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