Material for concrete floor support plate

Abstract

The invention belongs to the technical field of floor support plates, and particularly relates to a material for a concrete floor support plate, which is prepared from 150 to 170 parts of cement, 30 to 35 parts of mineral admixture, 200 to 250 parts of sand, 100 to 120 parts of gravel, 40 to 45 parts of fiber, 5 to 10 parts of early strength agent and 140 to 150 parts of water. The early strength agent comprises the following components in parts by weight: 20-30 parts of a polycarboxylate superplasticizer, 5-10 parts of modified nano zeolite powder, 5-9 parts of lithium acetate, 3-5 parts of a complexing agent, 5-10 parts of calcium sulfate and 1-4 parts of diisopropanolamine. The fibers, the mineral admixture and the early strength agent are added into the formula, early hydration of cement is promoted, dry shrinkage and cracking caused by too fast later hydration of cement are avoided, the compressive strength and breaking strength of the concrete floor support plate are effectively improved, the maintenance period of the concrete floor support plate is shortened, and the production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of floor bearing plates, and specifically relates to a material for concrete floor bearing plates. Background Art

[0002] In the traditional construction process, floor slab construction occupies a large amount of human, material and time resources, thus restricting the construction progress of the entire project. With the development of prefabricated composite slabs, the amount of formwork used in the floor slab construction process has been reduced, effectively improving the construction efficiency. At present, the research on steel bar truss composite slabs has been relatively mature and is widely used.

[0003] Cement-based steel bar truss floor bearing plates are a kind of formwork materials commonly used in building structures, with the functions of bearing loads, transmitting forces and maintaining structural stability. It is an assembled formwork formed by embedding a galvanized steel grid in the middle of a fiber-reinforced cement pressure plate, embedding a keel on the back and welding it with a steel bar truss. Through mutual cooperation with concrete, a structural system with high load-bearing capacity and rigidity can be formed. This kind of floor bearing plate has the characteristics of simple and intuitive stress. During the construction stage, the steel bar truss provides stiffness for the formwork and bears the self-weight of the concrete and construction loads together with the bottom formwork; during the service stage, the steel bars act as stress bars and bear the service loads together with the concrete. Therefore, the steel bar truss needs to have high flexural strength, compressive strength, impact strength and tensile strength.

[0004] The Chinese patent application document with the publication number CN115974495A discloses a high-performance concrete for composite slabs, its manufacturing method and the composite slab. The weight ratio of the high-performance concrete is calculated in kg / m 3 as follows: cement 450 - 460, fly ash 770 - 790, quartz sand 450 - 460, water reducing agent 9 - 11, water 300 - 305, fiber 15 - 17. This composite slab obtains high-performance concrete by adding fibers and mixing specific proportions of cement, fly ash, quartz sand, water reducing agent and water, improving the compressive, shear and crack resistance of the concrete itself. However, it does not record how to ensure the flexural strength and impact strength of the composite slab by adjusting the proportions of each component in the raw materials. The setting time of this composite slab after forming is relatively long, so the oxidation protection period it needs is relatively long, resulting in an extended production cycle, reduced production capacity and increased production costs. In addition, no coarse aggregate is added to its formula, only quartz sand, cement and fly ash, so its flexural strength, compressive strength and impact strength are relatively low. Summary of the Invention

[0005] In order to solve the technical problems of poor mechanical properties, long curing period and high production cost of concrete floor bearing plates in the above-mentioned existing technologies, the present invention provides a material for concrete floor bearing plates.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A material for a concrete floor slab, comprising the following components in parts by weight: 150 - 170 parts of cement, 30 - 35 parts of mineral admixture, 200 - 250 parts of sand, 100 - 120 parts of gravel, 40 - 45 parts of fiber, 5 - 10 parts of early strength agent, 140 - 150 parts of water; the early strength agent comprises the following components in parts by weight: 20 - 30 parts of polycarboxylate water reducer, 5 - 10 parts of modified nanozeolite powder, 5 - 9 parts of lithium acetate, 3 - 5 parts of complexing agent, 5 - 10 parts of calcium sulfate, 1 - 4 parts of diisopropanolamine.

[0007] In the above technical solution, the early strength of the cement-based material is improved by adding an early strength agent to the material for the concrete floor slab, effectively shortening the production cycle. Among them, nanozeolite has a porous structure and a high specific surface area, can react with the hydration products of cement to generate stable gel products, has a good promoting effect on cement hydration, and can more effectively and quickly absorb the calcium hydroxide enriched on the interface, greatly reducing the orientation degree of calcium hydroxide on the interface, can significantly improve the early and later strength of concrete, and make its microstructure more dense, and has an obvious improvement on the durability of concrete. Lithium acetate can release lithium ions and hydroxide ions during the cement hydration process, thereby increasing the alkalinity of the system, which is beneficial to promoting the dissolution of active silicate and aluminate in fly ash, making the glassy components in fly ash easier to break, releasing more active components to participate in the hydration process. At the same time, lithium hydroxide generated during the hydrolysis of lithium acetate provides nucleation sites for cement hydration, accelerating the cement hydration rate. However, the addition of lithium acetate will promote the transformation of ettringite into monosulfate hydrated calcium aluminate, weakening the framework effect of ettringite and resulting in a reduction in the strength of the cement-based material. In the present invention, calcium sulfate is added to the early strength agent formula. Calcium sulfate can provide sulfate ions and calcium ions for cement hydration, and can cause tricalcium aluminate to react quickly outside the cement gel film to generate ettringite during the cement hydration process, playing a framework role in the early stage of cement hydration and improving the early strength of the cement-based material. Therefore, the common use of lithium acetate and calcium sulfate in the present invention can effectively ensure that the mechanical properties of the cement-based material are greatly improved in the early stage.

[0008] In addition, in the present invention, the compressive strength and brittleness of the materials for concrete floor decks are controlled by controlling the content of the cementitious materials in the material formula. It has been found that as the dosages of cement and mineral admixtures in the materials for concrete floor decks increase, the compressive strength increases, but the brittleness also increases simultaneously and the flexural strength decreases. Therefore, fibers and early-strength agents are added to the formula in the present invention. On the one hand, the polycarboxylate water reducer in the early-strength agent is used to reduce the water-binder ratio, making the hydration of the cementitious materials more sufficient and forming a denser structure, which together with the fibers improves the flexural strength. On the other hand, the early-strength agent is used to promote the early hydration process of cement, effectively increasing the early strength and avoiding the dry shrinkage and cracking caused by the too-fast later hydration and excessive heat release of cement, further improving the flexural strength.

[0009] Further, the preparation method of the polycarboxylate water reducer is as follows: Isoamyl alcohol polyoxyethylene ether and deionized water are added to a reaction kettle, stirred and melted, then methacrylic acid and ammonium persulfate are added, and the temperature is raised to 70 - 80 °C. Meanwhile, a mixed aqueous solution of hydrogen peroxide, acrylic acid, mercaptopropionic acid, diethyl phosphate acrylate, and N-vinyl acetamide is added dropwise, and the dropping time is controlled to be 2 - 2.4 h. After the dropping is completed, the reaction is kept warm for 1 - 1.5 h, and the pH is adjusted to neutral to obtain the polycarboxylate water reducer.

[0010] Through the above technical solution, the molecules of the prepared polycarboxylate water reducer have polyethylene as the linear main chain and polyoxyethylene as the long side chains, and short side chains containing phosphate groups, amide groups, and ester groups are interspersed in the long side chains. These long side chains and short side chains are arranged alternately, making the polycarboxylate water reducer have high dispersion performance, effectively reducing the water-binder ratio of the cement-based materials. The phosphate groups in the molecular side chains can form stable complexes with calcium ions in the cement, the amide groups accelerate the formation of ettringite by interacting with tricalcium aluminate in the cement, and the carboxyl groups after the hydrolysis of the ester groups can be adsorbed on the cement particles again, effectively improving the dispersion performance of the cement particles, reducing the viscosity of the cement system, and improving the mechanical properties of the cement-based materials.

[0011] In the above technical solution, before the reaction starts, adding a small amount of methacrylic acid can keep the reaction rate of the initial polymerization reaction stable and avoid the phenomenon of uneven arrangement of the molecular side chains caused by too-fast polymerization; adding mercaptopropionic acid dropwise together with acrylic acid can effectively ensure that the molecules of the polycarboxylate water reducer obtained by polymerization have shorter main chains, which is beneficial to improving the dispersion performance of the polycarboxylate water reducer; adding the aqueous solutions of acrylic acid, diethyl phosphate acrylate, and N-vinyl acetamide together dropwise can effectively ensure the uniformity of the arrangement of the molecular side chains of the polycarboxylate water reducer.

[0012] Furthermore, the mass parts of each component in the preparation method of the polycarboxylate water reducer are as follows: isopentenyl alcohol polyoxyethylene ether 50 - 60 parts, deionized water 100 - 120 parts, methacrylic acid 5 - 8 parts, ammonium persulfate 5 - 8 parts, hydrogen peroxide 5 - 9 parts, acrylic acid 10 - 13 parts, mercaptopropionic acid 3 - 5 parts, diethyl phosphate acrylate 9 - 13 parts, N - vinylacetamide 12 - 15 parts.

[0013] Furthermore, the relative molecular mass of the isopentenyl alcohol polyoxyethylene ether is 2400.

[0014] Further, the preparation method of the modified nano - zeolite powder is as follows: Add nano - zeolite powder into vinyltriethoxysilane, heat to 60 - 65 °C and stir for 2.5 - 3 h, then raise the temperature to 85 - 90 °C, keep the temperature for reaction for 4 - 5 h, cool and then filter to obtain a powder material; Add the powder material, hydrogen peroxide, 2 - acrylamido - 2 - methylpropanesulfonic acid and deionized water I into a reaction kettle, heat to 70 - 75 °C, and dropwise add a mixed solution of mercaptoethanol, L - ascorbic acid and deionized water II under stirring, keep the temperature for reaction for 1.5 - 2 h, cool and filter to obtain the modified nano - zeolite.

[0015] In the above - mentioned technical solution, the nano - zeolite powder is first modified with a silane coupling agent to obtain a nano - zeolite powder with double bonds, and then it is grafted with 2 - acrylamido - 2 - propanesulfonic acid to obtain a modified nano - zeolite powder with amide groups and sulfonic groups. The molecular chains grafted on its surface overcome the van der Waals force between nanoparticles, effectively improving the dispersibility of the nano - zeolite powder in cement - based materials. At the same time, the amide groups contained in the grafted molecular chains can promote the formation of Ca(OH)2, and the sulfonic groups can promote the hydration of dicalcium silicate and significantly increase the early hydration heat release, improving the mechanical properties of cement - based materials.

[0016] Furthermore, the weight parts of each component in the preparation method of the modified nano - zeolite powder are as follows: nano - zeolite powder 20 - 30 parts, vinyltriethoxysilane 30 - 40 parts, hydrogen peroxide 2 - 5 parts, 2 - acrylamido - 2 - methylpropanesulfonic acid 10 - 15 parts, deionized water I 25 - 30 parts, mercaptoethanol 1 - 3 parts, L - ascorbic acid 3 - 5 parts, deionized water II 30 - 40 parts.

[0017] Further, the complexing agent is composed of ethylenediaminetetraacetic acid and citric acid in a mass ratio of 5 - 9:2 - 4.

[0018] Ethylenediaminetetraacetic acid can form a stable complex with calcium ions in calcium sulfate. At the same time, its multi-carboxyl structure can also interact with the carboxyl groups of polycarboxylate superplasticizers. Citric acid has multiple carboxyl groups, which can form a complex with calcium ions and can also interact with the ether groups of polycarboxylate superplasticizers, improving the compatibility between calcium sulfate and polycarboxylate superplasticizers and avoiding the uneven dispersion of calcium sulfate from affecting the early strength performance.

[0019] Furthermore, the mineral admixture is composed of fly ash, silica fume and ground granulated blast-furnace slag in a mass ratio of 4 - 7:2 - 5:9 - 11.

[0020] Fly ash is a material with potential pozzolanic activity. Under the action of early strength agents, the active components in fly ash can rapidly react with calcium hydroxide generated by cement hydration to form hydration products such as calcium silicate hydrate gel and ettringite, filling the pores of cement-based materials and improving the density of cement-based materials, thereby increasing the compressive strength and flexural strength. However, when the dosage of fly ash exceeds the range limited by the present invention, the compressive strength of the cement-based material decreases. This is because when the fly ash dosage is too high, the calcium silicate hydrate gel generated by the reaction is not sufficient to compensate for the dilution effect brought by fly ash, resulting in a decrease in the compressive strength of the cement-based material. Silica fume has high pozzolanic activity. It can not only react with calcium hydroxide generated by cement hydration to form calcium silicate hydrate gel, but also its high activity can accelerate the hydration reaction of cement and fill the tiny pores between cement particles, improving the density of cement-based materials and thus enhancing the mechanical properties of cement-based materials. Ground granulated blast-furnace slag will undergo a secondary hydration reaction during the cement hydration process. This reaction is relatively slow in the early stage, but as time goes by, ground granulated blast-furnace slag gradually reacts with calcium hydroxide in the cement hydration products to form calcium silicate hydrate gel, and these gels can fill the pores of cement-based materials, improving the density and late strength of cement-based materials.

[0021] Furthermore, the cement is Portland cement with a strength grade of P.O42.5 and an apparent density of 3.10 g / cm 3 ; the sand is composed of coarse sand with a fineness modulus of 3.7 - 3.1 and medium sand with a fineness modulus of 3.0 - 2.3 in a mass ratio of 1:1; the crushed stone is 5 - 25 mm continuously graded crushed stone with an apparent density of 2850 kg / m 3 .

[0022] Furthermore, the fiber is one of polyacrylonitrile fiber, polyester fiber and carbon fiber.

[0023] Compared with the prior art, the materials for concrete floor slabs provided by the present invention have the following technical advantages: (1)The present invention adds fibers and early strength agents to the formulation to promote the early hydration of cement, avoid excessive late hydration of cement resulting in dry shrinkage and cracking, and jointly improve the compressive strength and flexural strength of the floor bearing plate with the fibers; (2)By adding mineral admixtures and early strength agents to the formulation, the present invention effectively improves the early strength of the concrete floor bearing plate, shortens the production cycle, and reduces the production cost; (3)The material formulation for the concrete floor bearing plate provided by the present invention is simple, and the raw materials are easily available, which is conducive to realizing industrial production. Description of the Drawings

[0024] Figure 1 SEM image of the 1-day concrete specimen of the blank control group 1; Figure 2 SEM image of the 1-day concrete specimen of Example 3 group; Figure 3 SEM image of the 7-day concrete specimen of the blank control group 1; Figure 4 SEM image of the 7-day concrete specimen of Example 3 group. Detailed Embodiments

[0025] The following will be further described in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art can make various modifications according to the basic idea of the present invention, but as long as they do not depart from the basic idea of the present invention, they are within the scope of the present invention.

[0026] The cement described in this detailed embodiment is Portland cement with a strength grade of P.O42.5 and an apparent density of 3.10 g / cm 3 ; the sand consists of coarse sand with a fineness modulus of 3.7 - 3.1 and medium sand with a fineness modulus of 3.0 - 2.3 in a mass ratio of 1:1; the crushed stone is 5 - 25 mm continuously graded crushed stone with an apparent density of 2850 kg / m 3 ; the fly ash is Class F Grade II fly ash with a density of 2150 kg / m 3 ; the silica fume is 90-grade silica fume with a density of 180 kg / m 3 ; the slag powder is S95-grade slag powder with a density of 2880 kg / m 3 .

[0027] The relative molecular mass of the isopentenyl polyoxyethylene ether described in this detailed embodiment is 2400.

[0028] Example 1 A material for a concrete floor bearing plate, comprising the following components in parts by weight: 150 g of cement, 30 g of mineral admixture, 200 g of sand, 100 g of gravel, 40 g of polyacrylonitrile fiber, 5 g of early strength agent, 150 g of water; the mineral admixture is composed of fly ash, silica fume and slag powder in a mass ratio of 4:2:9.

[0029] The early strength agent includes the following components in parts by weight: 20 g of polycarboxylate superplasticizer, 10 g of modified nanozeolite powder, 9 g of lithium acetate, 5 g of complexing agent, 10 g of calcium sulfate, 4 g of diisopropanolamine; the complexing agent is composed of ethylenediaminetetraacetic acid and citric acid in a mass ratio of 5:2.

[0030] The preparation method of the polycarboxylate superplasticizer is as follows: Add 50 g of isopentenyl alcohol polyoxyethylene ether and 100 g of deionized water into a reaction kettle, stir and dissolve, add 5 g of methacrylic acid and 5 g of ammonium persulfate, heat up to 70 °C, and simultaneously dropwise add a mixed aqueous solution of 5 g of hydrogen peroxide, 10 g of acrylic acid, 3 g of mercaptopropionic acid, 9 g of diethyl phosphate acrylate, and 12 g of N-vinylacetamide. Control the dropping time to be 2 h. After the dropping is completed, keep the temperature for reaction for 1 h, adjust the pH to neutral to obtain the polycarboxylate superplasticizer.

[0031] The preparation method of the modified nanozeolite powder is as follows: Add 20 g of nanozeolite powder into 30 g of vinyltriethoxysilane, heat to 60 °C and stir for 2.5 h, then heat up to 85 °C, keep the temperature for reaction for 4 h, cool and filter to obtain a powder material; Add the powder material, 2 g of hydrogen peroxide, 10 g of 2-acrylamido-2-methylpropanesulfonic acid and 25 g of deionized water into a reaction kettle, heat to 70 °C, and dropwise add a mixed solution of 1 g of mercaptoethanol, 3 g of L-ascorbic acid and 30 g of deionized water under stirring. Keep the temperature for reaction for 1.5 h, cool and filter to obtain the modified nanozeolite.

[0032] Example 2 A material for a concrete floor slab formwork, including the following components in parts by weight: 170 g of cement, 35 g of mineral admixture, 250 g of sand, 120 g of gravel, 45 g of polyester fiber, 10 g of early strength agent, 140 g of water; the mineral admixture is composed of fly ash, silica fume and slag powder in a mass ratio of 7:5:11.

[0033] The early strength agent includes the following components in parts by weight: 30 g of polycarboxylate superplasticizer, 5 g of modified nanozeolite powder, 5 g of lithium acetate, 3 g of complexing agent, 5 g of calcium sulfate, 1 g of diisopropanolamine; the complexing agent is composed of ethylenediaminetetraacetic acid and citric acid in a mass ratio of 9:4.

[0034] The preparation method of the polycarboxylate water reducer is as follows: Add 60 g of isopentenyl alcohol polyoxyethylene ether and 120 g of deionized water into a reaction kettle, stir and dissolve, add 8 g of methacrylic acid and 8 g of ammonium persulfate, heat up to 80 °C, and simultaneously dropwise add a mixed aqueous solution of 9 g of hydrogen peroxide, 13 g of acrylic acid, 5 g of mercaptopropionic acid, 13 g of diethyl phosphate acrylate, and 15 g of N-vinylacetamide. Control the dropping time to be 2.4 h. After the dropping is completed, keep the temperature for reaction for 1.5 h, and adjust the pH to neutral to obtain the polycarboxylate water reducer.

[0035] The preparation method of the modified nanozeolite powder is as follows: Add 30 g of nanozeolite powder into 40 g of vinyltriethoxysilane, heat to 65 °C and stir for 3 h, then heat up to 90 °C, keep the temperature for reaction for 5 h, cool and filter to obtain a powder material; Add the powder material, 5 g of hydrogen peroxide, 15 g of 2-acrylamido-2-methylpropanesulfonic acid, and 30 g of deionized water into a reaction kettle, heat to 75 °C, and dropwise add a mixed solution of 3 g of mercaptoethanol, 5 g of L-ascorbic acid, and 40 g of deionized water under stirring, keep the temperature for reaction for 2 h, cool and filter to obtain the modified nanozeolite.

[0036] Example 3 A material for a concrete floor slab formwork includes the following components in parts by weight: 160 g of cement, 32 g of mineral admixture, 240 g of sand, 110 g of gravel, 43 g of carbon fiber, 8 g of early strength agent, 145 g of water; The mineral admixture is composed of fly ash, silica fume, and slag powder in a mass ratio of 5:4:10.

[0037] The early strength agent includes the following components in parts by weight: 26 g of polycarboxylate water reducer, 8 g of modified nanozeolite powder, 8 g of lithium acetate, 4 g of complexing agent, 7 g of calcium sulfate, 3 g of diisopropanolamine; The complexing agent is composed of ethylenediaminetetraacetic acid and citric acid in a mass ratio of 7:3.

[0038] The preparation method of the polycarboxylate water reducer is as follows: Add 56 g of isopentenyl alcohol polyoxyethylene ether and 110 g of deionized water into a reaction kettle, stir and dissolve, add 7 g of methacrylic acid and 7 g of ammonium persulfate, heat up to 75 °C, and simultaneously dropwise add a mixed aqueous solution of 8 g of hydrogen peroxide, 12 g of acrylic acid, 4 g of mercaptopropionic acid, 11 g of diethyl phosphate acrylate, and 14 g of N-vinylacetamide. Control the dropping time to be 2.2 h. After the dropping is completed, keep the temperature for reaction for 1.3 h, and adjust the pH to neutral to obtain the polycarboxylate water reducer.

[0039] The preparation method of the modified nano-zeolite powder is as follows: Add 27 g of nano-zeolite powder to 36 g of vinyltriethoxysilane, heat to 63 °C and stir for 2.8 h, then raise the temperature to 88 °C, keep the temperature for reaction for 4.5 h, cool and filter to obtain a powder material; Add the powder material, 4 g of hydrogen peroxide, 13 g of 2-acrylamido-2-methylpropanesulfonic acid and 28 g of deionized water to a reaction kettle, heat to 74 °C, and dropwise add a mixed solution of 2 g of mercaptoethanol, 4 g of L-ascorbic acid and 35 g of deionized water under stirring, keep the temperature for reaction for 1.8 h, cool and filter to obtain the modified nano-zeolite.

[0040] Comparative Example 1 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the early strength agent of this comparative example, an equal amount of calcium sulfate is used to replace lithium acetate.

[0041] Comparative Example 2 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the early strength agent of this comparative example, an equal amount of lithium acetate is used to replace calcium sulfate.

[0042] Comparative Example 3 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the preparation method of the polycarboxylate water reducer in this comparative example, methacrylic acid is not added.

[0043] Comparative Example 4 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the preparation method of the polycarboxylate water reducer in this comparative example, an equal amount of N-vinylacetamide is used to replace diethyl acrylate phosphate.

[0044] Comparative Example 5 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in this comparative example, an equal amount of nano-zeolite powder is used to replace the modified nano-zeolite powder.

[0045] Comparative Example 6 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the preparation method of the modified nano-zeolite powder in this comparative example, an equal amount of deionized water is used to replace 2-acrylamido-2-methylpropanesulfonic acid.

[0046] Comparative Example 7 The materials for the concrete floor formwork used in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that: in the preparation method of the modified nano-zeolite powder in this comparative example, an equal amount of acrylamide is used to replace 2-acrylamido-2-methylpropanesulfonic acid.

[0047] Test Example Test Specimen: The materials for concrete floor slabs provided in Examples 1 - 3 and Comparative Examples 1 - 7 were mixed evenly and then poured into a mold of 75×75×285. After vibration, it was cured for 1 day and then demolded. After demolding, it was continuously cured to obtain test specimens; no early-strength agent was added in Comparative Example 1, and no mineral admixture was added in Comparative Example 2; Test Method: According to GB / T 50081-2019 "Standard Test Method for Physical and Mechanical Properties of Concrete", the compressive strength and flexural strength of the test specimens cured to the ages of 1d, 7d, and 28d were tested.

[0048] The test results are shown in Table 1.

[0049] Table 1 Test Results of Mechanical Properties

[0050] As can be seen from Table 1, the compressive strength of the materials for concrete floor slabs provided by the present invention at 1d is 32.9 - 34.2 MPa, the compressive strength at 7d is 68.5 - 69.7 MPa, and the compressive strength at 28d is 80.3 - 83.2 MPa; the flexural strength at 1d is 7.5 - 8.3 MPa, the flexural strength at 3d is 12.1 - 12.9 MPa, and the flexural strength at 28d is 15.2 - 16.5 MPa. Compared with the comparative examples, the compressive strength and flexural strength of the materials for concrete floor slabs provided in Examples 1 - 3 of the present invention have been improved to a certain extent, which shows that the materials for concrete floor slabs provided by the present invention have good mechanical properties.

[0051] Compared with Example 3, in Comparative Example 1, an equal amount of calcium sulfate was used to replace lithium acetate in the early strength agent. The 1-day and 7-day compressive strengths and flexural strengths of the prepared concrete specimens increased, indicating that calcium sulfate can promote the increase of early compressive and flexural strengths. The 28-day compressive strength and flexural strength decreased, indicating that lithium acetate can effectively promote the release of active components from fly ash to participate in the hydration process, and the strengthening effect of calcium sulfate on the mechanical properties of cement-based materials is weaker than that of the hydration of fly ash active components on the mechanical properties of cement-based materials. In Comparative Example 2, an equal amount of lithium acetate was used to replace calcium sulfate in the early strength agent, and the compressive strength and flexural strength of the prepared concrete specimens decreased to varying degrees. This shows that too much lithium acetate will weaken the framework effect of ettringite, and the addition of calcium sulfate can effectively improve the mechanical properties of concrete specimens. In Comparative Example 3, methacrylic acid was not added in the preparation method of the polycarboxylate water reducer, and the 1-day and 7-day compressive strengths and flexural strengths of the prepared concrete specimens decreased. This is because the uneven arrangement of the molecular side chains of the polycarboxylate water reducer leads to poor dispersibility of the cement, affecting the early hydration process of the cement. In Comparative Example 4, an equal amount of N-vinylacetamide was used to replace diethyl acrylate phosphate in the preparation method of the polycarboxylate water reducer, and the 1-day and 7-day compressive strengths and flexural strengths of the prepared concrete specimens decreased. This shows that the phosphate group and ester group in the molecular side chain of the polycarboxylate water reducer can effectively improve the mechanical properties of concrete specimens. In Comparative Example 5, the nanozeolite powder was not modified, and the compressive strength and flexural strength of the prepared concrete specimens both decreased. This is due to the uneven distribution of the unmodified zeolite powder in the concrete specimens. In Comparative Example 6, an equal amount of deionized water was used to replace 2-acrylamide-2-methylpropanesulfonic acid in the preparation method of the modified nanozeolite powder. In Comparative Example 7, an equal amount of acrylamide was used to replace 2-acrylamide-2-methylpropanesulfonic acid in the preparation method of the modified nanozeolite powder. The 1-day and 7-day compressive strengths and flexural strengths of the prepared concrete specimens decreased, and the 28-day compressive strength and flexural strength decreased slightly. This shows that in the present invention, grafting reaction of 2-acrylamide-2-methylpropanesulfonic acid on the nanozeolite powder modified by silane coupling agent can effectively improve the early strength of concrete specimens and further improve the dispersion performance of the modified nanozeolite powder in concrete specimens, and the effect of grafting acrylamide is significantly inferior to that of grafting 2-acrylamide-2-methylpropanesulfonic acid.

[0052] The present invention also performed scanning electron microscopy tests on the 1-day and 7-day concrete specimens of Example 3 and the blank control group. The preparation method of the concrete specimens in the blank control group was similar to that of Example 3, and the difference between it and Example 3 was that no early strength agent was added in the blank control group. The test results are as Figures 1 - 4 .

[0053] From Figure 1 and Figure 2It can be seen that compared with the blank control group, more calcium silicate hydrate and ettringite appeared in the concrete specimens after adding the early-strength agent at the age of 1d, and they were stacked more closely with each other. From Figure 3 and Figure 4 it can be seen that compared with the blank control group, the grain distribution of the concrete specimens after adding the early-strength agent was more uniform, and the grains grew into clusters. This shows that the early-strength agent provided by the present invention can not only promote the early hydration process of cement, but also refine the grains, improve the compactness of concrete, and thus enhance the mechanical properties of concrete.

[0054] The above embodiments are only illustrative of the present invention and do not limit the present invention. Those skilled in the art shall not modify the above embodiments without departing from the spirit and scope of the present invention. All equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the technical idea of the present invention still fall within the protection scope of the present invention.

Claims

1. A material for concrete floor bearing plates, characterized in that, It comprises components in the following parts by weight: 150 - 170 parts of cement, 30 - 35 parts of mineral admixture, 200 - 250 parts of sand, 100 - 120 parts of crushed stone, 40 - 45 parts of fiber, 5 - 10 parts of early strength agent, 140 - 150 parts of water; The early strength agent comprises components in the following parts by weight: 20 - 30 parts of polycarboxylate superplasticizer, 5 - 10 parts of modified nano zeolite powder, 5 - 9 parts of lithium acetate, 3 - 5 parts of complexing agent, 5 - 10 parts of calcium sulfate, 1 - 4 parts of diisopropanolamine.

2. The material for concrete floor slabs according to claim 1, characterized in that, The preparation method of the polycarboxylate superplasticizer is as follows: Add isopentenyl alcohol polyoxyethylene ether and deionized water into a reaction kettle, stir and dissolve, add methacrylic acid and ammonium persulfate, heat up to 70 - 80 °C, and simultaneously dropwise add a mixed aqueous solution of hydrogen peroxide, acrylic acid, mercaptopropionic acid, diethyl phosphate acrylate, and N - vinyl acetamide, control the dropping time to be 2 - 2.4 h, after the dropping is completed, keep the temperature for reaction for 1 - 1.5 h, adjust the pH value to neutral to obtain the polycarboxylate superplasticizer.

3. The material for concrete floor formwork according to claim 2, characterized in that, The mass parts of each component in the preparation method of the polycarboxylate superplasticizer are: 50 - 60 parts of isopentenyl alcohol polyoxyethylene ether, 100 - 120 parts of deionized water, 5 - 8 parts of methacrylic acid, 5 - 8 parts of ammonium persulfate, 5 - 9 parts of hydrogen peroxide, 10 - 13 parts of acrylic acid, 3 - 5 parts of mercaptopropionic acid, 9 - 13 parts of diethyl phosphate acrylate, 12 - 15 parts of N - vinyl acetamide.

4. The material for concrete floor formwork according to claim 2, characterized in that, The relative molecular mass of the isopentenyl alcohol polyoxyethylene ether is 2400.

5. The material for concrete floor decks according to claim 1, characterized in that, The preparation method of the modified nano zeolite powder is as follows: Add nano zeolite powder into vinyltriethoxysilane, heat to 60 - 65 °C and stir for 2.5 - 3 h, then heat up to 85 - 90 °C, keep the temperature for reaction for 4 - 5 h, cool and filter to obtain a powdery material; Add the powdery material, hydrogen peroxide, 2 - acrylamido - 2 - methylpropanesulfonic acid and deionized water I into a reaction kettle, heat to 70 - 75 °C, and dropwise add a mixed solution of mercaptoethanol, L - ascorbic acid and deionized water II under stirring, keep the temperature for reaction for 1.5 - 2 h, cool and filter to obtain the modified nano zeolite.

6. The material for concrete floor slabs according to claim 5, characterized in that, The weight parts of each component in the preparation method of the modified nano zeolite powder are: 20 - 30 parts of nano zeolite powder, 30 - 40 parts of vinyltriethoxysilane, 2 - 5 parts of hydrogen peroxide, 10 - 15 parts of 2 - acrylamido - 2 - methylpropanesulfonic acid, 25 - 30 parts of deionized water I, 1 - 3 parts of mercaptoethanol, 3 - 5 parts of L - ascorbic acid, 30 - 40 parts of deionized water II.

7. The material for concrete floor decking according to claim 1, characterized in that, The complexing agent is composed of ethylenediaminetetraacetic acid and citric acid in a mass ratio of 5 - 9:2 - 4.

8. The material for concrete floor formwork according to claim 1, characterized in that, The mineral admixture is composed of fly ash, silica fume and slag powder in a mass ratio of 4 - 7:2 - 5:9 - 11.

9. The material for concrete floor decking according to claim 1, wherein The cement is Portland cement with a strength grade of P.O42.5 and an apparent density of 3.10 g / cm 3 ; the sand is composed of coarse sand with a fineness modulus of 3.7 - 3.1 and medium sand with a fineness modulus of 3.0 - 2.3 in a mass ratio of 1:1; the crushed stone is 5 - 25 mm continuously graded crushed stone with an apparent density of 2850 kg / m 3 .

10. The material for concrete floor decks according to claim 1, characterized in that, The fiber is one of polyacrylonitrile fiber, polyester fiber and carbon fiber.

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