Special concrete for ground terrace and preparation method thereof

Abstract

The invention relates to the technical field of concrete, in particular to concrete special for ground terraces and a preparation method of the concrete. The special concrete for the ground and the terrace is prepared from the following raw materials in parts by weight: 300 to 500 kg / m < 3 > of cement, 600 to 750 kg / m < 3 > of fine aggregate, 900 to 1200 kg / m < 3 > of medium-coarse aggregate, 15 to 40 kg / m < 3 > of bentonite, 30 to 60 kg / m < 3 > of high-performance water reducing agent, 10 to 30 kg / m < 3 > of retarder, 10 to 20 kg / m < 3 > of stabilizer, 300 to 600 kg / m < 3 > of water and 10 to 20 kg / m < 3 > of corrosion-resistant enhancer. The retarder is prepared by mixing the following raw materials in parts by weight: 5-20 parts of expanded perlite, 7-15 parts of sodium lignin sulfonate, 4-8 parts of borax, 2-6 parts of sodium hexametaphosphate and 2-7 parts of tartaric acid. The special concrete for the ground and the terrace, prepared by the invention, has good compression resistance, and also has good durability and collapse resistance.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a special concrete for ground flooring and its preparation method. Background Technology

[0002] As the construction industry places increasingly higher demands on the quality of ground engineering projects, the shortcomings of flooring materials are becoming more and more apparent. Currently, while epoxy self-leveling and emery abrasion-resistant flooring processes can provide aesthetically pleasing surface effects, their inherent defects limit their application: poor scratch resistance, prone to delamination, hollowing, cracking, and fading, short overall service life, and high maintenance costs make it difficult to meet the long-term durability requirements of industrial and commercial buildings.

[0003] From a structural perspective, the performance of traditional reinforced concrete pavements heavily relies on foundation treatment and construction quality control. Inaccurate geological surveys, insufficient backfill compaction, or construction defects can easily lead to overall cracking, collapse, and deformation of the pavement under conditions of groundwater fluctuations, uneven settlement, and dynamic loads, resulting in significant safety risks and economic losses. Therefore, improving the mechanical properties and durability of the concrete pavement itself is crucial for enhancing the reliability of the pavement system from its very source.

[0004] At the materials level, traditional floor concrete has long faced an inherent contradiction between workability, strength, and durability. High water-cement ratio formulations used to achieve high fluidity significantly reduce the final compressive strength of the concrete and exacerbate segregation, bleeding, and plastic shrinkage cracking, directly harming construction quality and floor smoothness. Although adding water-reducing agents and fibers can improve performance to some extent, the interfacial bond between conventional fibers and the cement matrix is ​​weak and easily deteriorates in corrosive environments, failing to simultaneously achieve flow stability, long-term durability, and high strength. Therefore, the industry urgently needs a floor-specific concrete that, through material innovation, can synergistically resolve these contradictions of high fluidity, high stability, high strength, and high durability to cope with increasingly demanding engineering application environments. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a special concrete for ground flooring and its preparation method.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A type of concrete specifically for ground flooring, composed of the following raw materials in parts by weight: 300-500 kg / m² 3 Cement, 600-750kg / m 3 Fine aggregate, 900-1200 kg / m³ 3 Medium and coarse aggregate, 15-40 kg / m³ 3Bentonite, 30-60 kg / m 3 High-performance water-reducing agent, 10-30 kg / m 3 Retarder, 10-20 kg / m 3 Stabilizer, 300-600 kg / m 3 Water, 10-20 kg / m 3 Corrosion resistance enhancer;

[0008] The retarder is composed of the following raw materials in parts by weight: 5-20 parts expanded perlite, 7-15 parts sodium lignosulfonate, 4-8 parts borax, 2-6 parts sodium hexametaphosphate, and 2-7 parts tartaric acid.

[0009] In the retarder of this invention, expanded perlite, as a lightweight micro-aggregate, improves fluidity and stabilizes the paste and promotes densification by adsorbing water and providing nucleation sites. Tartaric acid, as a powerful retarder, strongly complexes with calcium ions, effectively inhibiting early hydration and moderating the heat of hydration; borax provides a moderate retarding effect; sodium lignosulfonate, while retarding, plays a core dispersing role due to its anionic surface activity, releasing free water. These three components work synergistically to ensure that the concrete maintains its plasticity for a long time during construction, improving its resistance to collapse. Sodium hexametaphosphate, as a highly efficient dispersant, produces a strong synergistic dispersion effect with sodium lignosulfonate, further ensuring uniform suspension of cement, bentonite, etc., through electrostatic repulsion and steric hindrance, preventing flocculation and sedimentation. This is crucial for maintaining a high fluidity state without segregation or bleeding.

[0010] The addition of corrosion-resistant reinforcing agents involves hybridizing organic and inorganic materials through chemical grafting and cross-linking. In plastic slurry, these agents form a weak, three-dimensional polymer fiber network, acting as a skeleton to provide yield stress, directly locking in moisture and aggregates, and endowing concrete with extremely high static stability to resist collapse. Carbon fibers themselves provide excellent fiber reinforcement and bridging, preventing microcrack propagation and significantly improving compressive strength and toughness. Furthermore, the polymer chains grafted onto their surface and the continuous network formed with epoxy resin effectively strengthen the interfacial transition zone between cement paste, fibers, and aggregates, forming an interpenetrating network structure that collectively bears stress, thereby simultaneously improving both final compressive strength and durability.

[0011] Preferably, the water-reducing agent is at least one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, and sulfonate water-reducing agent.

[0012] Preferably, the stabilizer is at least one of potassium methylsilicate, guar gum, polyacrylamide, and cocamidopropyl betaine.

[0013] In floor concrete requiring high fluidity and slump resistance, the combination of traditional retarders and high-efficiency water-reducing agents, while providing high fluidity, also increases the risk of segregation, settling, and plastic shrinkage cracking. This stems from the drastic reduction in paste viscosity, making it impossible to form a stable internal skeleton to support aggregates and retain moisture. Therefore, to achieve a balance between high fluidity and stability, the corrosion-resistant reinforcing agent of this invention is added, fundamentally resolving the contradiction between high fluidity and stability—something that cannot be achieved by a single retarder or ordinary fibers.

[0014] Preferably, the method for preparing the corrosion-resistant reinforcing agent includes the following steps: S1, activating carbon fibers by immersing them in concentrated nitric acid to obtain activated carbon fibers; dispersing the activated carbon fibers in an ethanol aqueous solution, adjusting the pH value to acidic, adding a silane coupling agent to react, and obtaining double-bond modified carbon fibers;

[0015] S2. Under an inert atmosphere, itaconic acid, acrylic acid and water are mixed, the pH is adjusted to acidic, and acrylamide derivative, double bond modified carbon fiber, hydroxyethyl acrylate and initiator are added to carry out a copolymerization reaction to obtain carbon fiber reinforced material.

[0016] S3. Dissolve epoxy resin and carbon fiber reinforcing material in a solvent, add amine crosslinking agent to react, and obtain the corrosion-resistant reinforcing agent.

[0017] With the addition of the corrosion-resistant reinforcing agent of this invention, during the mixing stage, polymer-grafted carbon fibers entangle with each other in the slurry, forming a weak three-dimensional flexible network. This network provides yield stress when static, effectively locking in moisture and aggregates, preventing segregation and sedimentation, and giving the concrete the characteristic of standing firm without collapsing; under shear, the network temporarily breaks down, ensuring leveling. During the hardening stage, a synergistic improvement in high strength, high toughness, and high durability can be achieved. Carbon fiber reinforcement and bridging, with uniformly dispersed carbon fibers, effectively inhibit the propagation of microcracks, significantly improving compressive strength and toughness; the polymer chains and epoxy resin network on its surface form an organic and inorganic interpenetrating structure with cement hydration products, greatly strengthening the weakest fiber-matrix interface transition zone, making stress transfer more efficient, and densifying the microstructure, jointly improving mechanical properties and corrosion resistance.

[0018] The specific reaction mechanism is as follows: S1. First, the carbon fiber is activated in concentrated nitric acid to increase its roughness and introduce a large number of oxygen-containing functional groups such as -COOH and -OH. After activation, the carbon fiber is reacted with a silane coupling agent under heating and stirring conditions to obtain double-bond modified carbon fiber. S2. Using itaconic acid, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, double-bond modified carbon fiber, and hydroxyethyl acrylate as reactants, and ammonium persulfate as an initiator, a polymerization reaction occurs under heating and stirring conditions to obtain carbon fiber reinforced material. The surface of the carbon fiber reinforced material is rich in copolymer layer structure reinforced material with -COOH, -SO3H, and -OH groups. These hydrophilic groups can effectively prevent van der Waals forces through electrostatic repulsion. The resulting agglomeration allows the reinforcing agent to be evenly dispersed in the cement paste, and it can better interact with calcium ions in the cement hydration products through complexation or ionic bonding. These polar groups are the basis for subsequent reactions with epoxy resin and the strong chemical bonding force between the reinforcing agent and cement hydration products in concrete. S3, using epoxy resin and carbon fiber reinforcing material as reaction raw materials, in the presence of a crosslinking agent, a corrosion-resistant reinforcing agent is obtained by heating and crosslinking. The dense three-dimensional crosslinking network formed by epoxy resin and amine crosslinking agent tightly encapsulates the polymer-modified carbon fiber, forming an effective physical barrier that can significantly block the penetration of corrosive media such as moisture, chloride ions, and sulfate ions, thereby improving the long-term corrosion resistance, freeze-thaw resistance, and durability of concrete.

[0019] Furthermore, the preparation method of the corrosion resistance enhancer is as follows:

[0020] S1. Dissolve 8-14 parts by weight of carbon fiber in 60-120 parts by weight of 60-70 wt% concentrated nitric acid solution, react at 70-85℃ and 100-300 rpm for 1-4 hours, filter, wash, and dry to obtain activated carbon fiber; disperse the activated carbon fiber in 80-200 parts by weight of 60-90 wt% ethanol aqueous solution; add 0.5-2 parts by weight of silane coupling agent, react at 50-70℃ and 100-300 rpm for 2-6 hours, filter, wash, and dry to obtain double bond modified carbon fiber;

[0021] S2. Under a nitrogen atmosphere, mix 2-5 parts by weight of itaconic acid, 1-2 parts by weight of acrylic acid and 40-100 parts by weight of water evenly, adjust the pH to 2, add 3-7 parts by weight of acrylamide derivative, 8-12 parts by weight of double bond modified carbon fiber, 0.5-2 parts by weight of hydroxyethyl acrylate and 0.2-1 parts by weight of ammonium persulfate and stir to mix. React at 70-90℃ and 300-600rpm for 1.5-4h, filter, wash and dry to obtain carbon fiber reinforced material;

[0022] S3. Stir 8-12 parts by weight of epoxy resin, 6-8 parts by weight of carbon fiber reinforcement material and 80-160 parts by weight of acetone evenly, add 6-10 parts by weight of amine crosslinking agent, stir and react at 50-70℃ and 200-600rpm for 1-4 hours. After the reaction is completed, distill under reduced pressure to obtain corrosion-resistant reinforcing agent.

[0023] Preferably, the acrylamide derivative is at least one of 2-acrylamido-2-methylpropanesulfonic acid, N-hydroxymethylacrylamide, and N,N'-methylenebisacrylamide.

[0024] Preferably, the silane coupling agent in S1 is any one of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, KH-550, and methacryloyloxymethyltrimethoxysilane.

[0025] Preferably, the amine crosslinking agent in S3 is either diethylenetriamine or triethylenetetramine.

[0026] A method for preparing the special concrete for ground flooring includes the following steps:

[0027] (1) Weigh each raw material according to its weight;

[0028] (2) Mix cement, fine aggregate, medium and coarse aggregate and bentonite, add water and stir evenly at 300 rpm to obtain premix;

[0029] (3) Add high-performance water-reducing agent, retarder, stabilizer and corrosion-resistant reinforcing agent to the above premix and continue to stir evenly to obtain special concrete for ground floor.

[0030] The beneficial effects of this invention are as follows: 1. This invention provides a special concrete for ground flooring and its preparation method. Through the synergistic effect of a retarder, stabilizer, and corrosion-resistant reinforcing agent, segregation, bleeding, and plastic shrinkage cracking are effectively prevented while ensuring the initial high fluidity of the concrete. The three-dimensional flexible network formed by the corrosion-resistant reinforcing agent in the slurry can statically lock in water and aggregates, giving the concrete excellent slump resistance and ensuring that it maintains extremely high volume stability even in a high fluidity state.

[0031] 2. The corrosion-resistant reinforcing agent of this invention organically combines the toughening effect of carbon fiber, the interfacial strengthening effect of surface-grafted polymer, and the cross-linking barrier effect of epoxy resin, significantly improving the compressive strength and toughness of concrete. Simultaneously, this dense composite structure effectively blocks the penetration of corrosive media such as moisture and chloride ions, giving the concrete excellent corrosion resistance and freeze-thaw resistance, thereby greatly extending the service life of the flooring. Detailed Implementation

[0032] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0033] The raw materials described in this application are partially described; all other raw materials not described are commercially available.

[0034] The cement was purchased from Guangzhou Qiangsheng Cement Grinding Co., Ltd., brand: P.C42.5.

[0035] The fine aggregate was purchased from Beijing Meiston Technology Development Co., Ltd., with a particle size of 40-80 mesh.

[0036] Medium and coarse aggregates were purchased from Feiyue Stone Processing Plant in Hongqiao District, Tianjin. The particle size is 5-10mm.

[0037] The high-performance water-reducing agent was purchased from Wuhan Huaxuan High-Tech Co., Ltd., model: PC-306.

[0038] Expanded perlite was purchased from Shijiazhuang Aokai Mineral Products Co., Ltd., with a particle size of 1-3mm.

[0039] The carbon fiber was purchased from Toray New Materials (Guangdong) Co., Ltd., item number: 10011.

[0040] Epoxy Resin, Hubei Zhenzhengfeng New Material Co., Ltd., brand name MF-4101H.

[0041] Example 1

[0042] A type of concrete specifically for floor slabs, composed of the following raw materials in parts by weight: 400 kg / m² 3 Cement, 650 kg / m 3 Fine aggregate, 1100 kg / m 3 Medium and coarse aggregate, 20 kg / m 3 Bentonite, 40 kg / m 3 High-performance water-reducing agent, 20kg / m 3 Retarder, 12kg / m 3 Stabilizer, 400 kg / m 3 Water, 12kg / m 3 Corrosion resistance enhancer.

[0043] The water-reducing agent is polycarboxylate superplasticizer PC-360.

[0044] The stabilizer is potassium methylsilicate.

[0045] The retarder is composed of the following raw materials in parts by weight: 10 parts by weight of expanded perlite, 10 parts by weight of sodium lignosulfonate, 6 parts by weight of borax, 4 parts by weight of sodium hexametaphosphate, and 4 parts by weight of tartaric acid.

[0046] The preparation method of the corrosion resistance enhancer is as follows:

[0047] S1. Dissolve 10 parts by weight of carbon fiber in 80 parts by weight of 68 wt% concentrated nitric acid solution, react at 75℃ and 200 rpm for 2 h, filter, wash, and dry to obtain activated carbon fiber; disperse the activated carbon fiber in 120 parts by weight of 80 wt% ethanol aqueous solution; add 1 part by weight of silane coupling agent, react at 60℃ and 200 rpm for 4 h, filter, wash, and dry to obtain double bond modified carbon fiber; the silane coupling agent is N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane;

[0048] S2. Under a nitrogen atmosphere, 3 parts by weight of itaconic acid, 1.4 parts by weight of acrylic acid, and 50 parts by weight of water are mixed evenly, and the pH is adjusted to 2. Then, 5 parts by weight of acrylamide derivative, 10 parts by weight of double bond modified carbon fiber, 1 part by weight of hydroxyethyl acrylate, and 0.5 parts by weight of ammonium persulfate are added and stirred. The mixture is reacted at 80°C and 500 rpm for 2 hours. After filtration, washing, and drying, carbon fiber reinforced material is obtained. The acrylamide derivative is 2-acrylamido-2-methylpropanesulfonic acid.

[0049] S3. Mix 10 parts by weight of epoxy resin, 6 parts by weight of carbon fiber reinforcement material and 100 parts by weight of acetone evenly, add 8 parts by weight of diethylenetriamine, and stir at 60℃ and 400 rpm for 2 hours. After the reaction is completed, distill under reduced pressure to obtain corrosion-resistant reinforcing agent.

[0050] The method for preparing concrete specifically for ground flooring includes the following steps:

[0051] (1) Weigh each raw material according to its weight;

[0052] (2) Mix cement, fine aggregate, medium and coarse aggregate and bentonite, add water and stir evenly at 300 rpm to obtain premix;

[0053] (3) Add high-performance water-reducing agent, retarder, stabilizer and corrosion-resistant reinforcing agent to the above premix and continue to stir evenly to obtain special concrete for ground floor.

[0054] Example 2

[0055] It is basically the same as Example 1, except that the silane coupling agent used in the preparation method of the corrosion resistance enhancer is KH-550.

[0056] Example 3

[0057] The method is basically the same as that in Example 1, except that the silane coupling agent used in the preparation method of the corrosion resistance enhancer is methacryloyloxymethyltrimethoxysilane.

[0058] Example 4

[0059] It is basically the same as Example 1, except that the acrylamide derivative in the preparation method of the corrosion resistance enhancer is N-hydroxymethylacrylamide.

[0060] Example 5

[0061] The method is basically the same as in Example 1, except that the acrylamide derivative used in the preparation method of the corrosion resistance enhancer is N,N'-methylenebisacrylamide.

[0062] Example 6

[0063] The method is basically the same as in Example 1, except that the acrylamide derivative in the preparation method of the corrosion resistance enhancer is composed of 2-acrylamido-2-methylpropanesulfonic acid and N,N'-methylenebisacrylamide in a mass ratio of 1:1.

[0064] Comparative Example 1

[0065] A type of concrete specifically for floor slabs, composed of the following raw materials in parts by weight: 400 kg / m² 3 Cement, 650 kg / m 3 Fine aggregate, 1100 kg / m 3 Medium and coarse aggregate, 20 kg / m 3 Bentonite, 40 kg / m 3 High-performance water-reducing agent, 20kg / m3 retarder, 12kg / m3 3 Stabilizer, 400 kg / m 3 water.

[0066] The water-reducing agent is polycarboxylate superplasticizer PC-360.

[0067] The stabilizer is potassium methylsilicate.

[0068] The retarder is composed of the following raw materials in parts by weight: 10 parts by weight of expanded perlite, 10 parts by weight of sodium lignosulfonate, 6 parts by weight of borax, 4 parts by weight of sodium hexametaphosphate, and 4 parts by weight of tartaric acid.

[0069] The method for preparing concrete specifically for ground flooring includes the following steps:

[0070] (1) Weigh each raw material according to its weight;

[0071] (2) Mix cement, fine aggregate, medium and coarse aggregate and bentonite, add water and stir evenly at 300 rpm to obtain premix;

[0072] (3) Add high-performance water-reducing agent, retarder, stabilizer and corrosion-resistant reinforcing agent to the above premix and continue to stir evenly to obtain special concrete for ground floor.

[0073] Comparative Example 2

[0074] It is basically the same as Example 1, except that the corrosion-resistant reinforcing agent is carbon fiber.

[0075] Comparative Example 3

[0076] The method is basically the same as in Example 1, except that the preparation method of the corrosion resistance enhancer is as follows:

[0077] S1. Dissolve 10 parts by weight of carbon fiber in 80 parts by weight of 68wt% concentrated nitric acid solution, react at 75℃ and 200rpm for 2h, filter, wash, and dry to obtain activated carbon fiber.

[0078] S2. In a nitrogen atmosphere, 3 parts by weight of itaconic acid, 1.4 parts by weight of acrylic acid and 50 parts by weight of water are mixed evenly, the pH is adjusted to 2, 5 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts by weight of activated carbon fiber, 1 part by weight of hydroxyethyl acrylate and 0.5 parts by weight of ammonium persulfate are added and stirred. The mixture is reacted at 80°C and 500 rpm for 2 hours, filtered, washed and dried to obtain the corrosion-resistant reinforcing agent.

[0079] Comparative Example 4

[0080] The method is basically the same as in Example 1, except that the preparation method of the corrosion resistance enhancer is as follows:

[0081] S1. Dissolve 10 parts by weight of carbon fiber in 80 parts by weight of 68 wt% concentrated nitric acid solution, react at 75℃ and 200 rpm for 2 h, filter, wash, and dry to obtain activated carbon fiber; disperse the activated carbon fiber in 120 parts by weight of 80 wt% ethanol aqueous solution; add 1 part by weight of silane coupling agent, react at 60℃ and 200 rpm for 4 h, filter, wash, and dry to obtain double bond modified carbon fiber; the silane coupling agent is N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane;

[0082] S2. Mix 10 parts by weight of epoxy resin, 6 parts by weight of double bond modified carbon fiber and 100 parts by weight of acetone evenly, add 8 parts by weight of diethylenetriamine, and stir at 60℃ and 400 rpm for 2 hours. After the reaction is completed, distill under reduced pressure to obtain corrosion-resistant reinforcing agent.

[0083] Comparative Example 5

[0084] The method is basically the same as in Example 1, except that the preparation method of the corrosion resistance enhancer is as follows:

[0085] S1. Disperse 10 parts by weight of carbon fiber in 120 parts by weight of 80 wt% ethanol aqueous solution; add 1 part by weight of silane coupling agent, react at 60℃ and 200 rpm for 4 h, filter, wash and dry to obtain double bond modified carbon fiber; the silane coupling agent is N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane.

[0086] S2. Under a nitrogen atmosphere, 3 parts by weight of itaconic acid, 1.4 parts by weight of acrylic acid, and 50 parts by weight of water are mixed evenly, and the pH is adjusted to 2. Then, 5 parts by weight of acrylamide derivative, 10 parts by weight of double bond modified carbon fiber, 1 part by weight of hydroxyethyl acrylate, and 0.5 parts by weight of ammonium persulfate are added and stirred. The mixture is reacted at 80°C and 500 rpm for 2 hours. After filtration, washing, and drying, carbon fiber reinforced material is obtained. The acrylamide derivative is 2-acrylamido-2-methylpropanesulfonic acid.

[0087] S3. Mix 10 parts by weight of epoxy resin, 6 parts by weight of carbon fiber reinforcement material and 100 parts by weight of acetone evenly, add 8 parts by weight of diethylenetriamine, and stir at 60℃ and 400 rpm for 2 hours. After the reaction is completed, distill under reduced pressure to obtain corrosion-resistant reinforcing agent.

[0088] Comparative Example 6

[0089] It is basically the same as Example 1, except that no stabilizer is added to the special concrete for ground flooring.

[0090] Comparative Example 7

[0091] It is basically the same as Example 1, except that no retarder is added to the concrete for ground flooring.

[0092] Test Example 1

[0093] Basic performance testing: The tests were conducted in accordance with JGJ / T70-2009 "Standard for Test Methods of Basic Performance of Building Mortar". The concrete for floor slabs prepared in the above examples and comparative examples were first made into structural specimens. The concrete structural specimens were then cured in an environment with a humidity greater than 95% for 28 days. The compressive strength and compressive strength loss rate were tested. A prism-shaped mold with a size of 40mm×40mm×160mm was made, and a hole with a diameter of 6.5mm was made in the neutral of each of the two end faces of the mold. Four parallel samples were tested, and the average value was taken. The results are shown in Table 1.

[0094] Table 1. Test results of basic performance of concrete for ground flooring

[0095] compressive strength (MPa) Compressive strength loss rate % Example 1 59.9 0.21 Example 2 57.7 0.63 Example 3 58.4 0.42 Example 4 59.3 0.31 Example 5 58.3 0.48 Example 6 61.1 0.08 Comparative Example 1 48.9 1.89 Comparative Example 2 52.6 2.67 Comparative Example 3 54.4 2.58 Comparative Example 4 54.8 2.54 Comparative Example 5 55.9 2.44 Comparative Example 6 50.1 3.78 Comparative Example 7 41.6 5.23

[0096] Test Example 2

[0097] Durability test: The concrete samples prepared in the examples and comparative examples were made into samples for durability test. The test was conducted in accordance with the test method of GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete". Five samples were tested for each group, and the average value was taken. The results are shown in Table 2.

[0098] Slump resistance test: The slump of the concrete samples prepared by the above examples and comparative examples for floor slabs was tested in accordance with the national standard GB8076-2008 "Concrete Admixtures". The initial slump was 195 mm, and the slump was measured after 1 hour. Each group was tested 4 times and the average value was taken. The results are shown in Table 2.

[0099] Table 2. Test results of durability and collapse resistance.

[0100] Durability index (relative value) Slump / mm Example 1 97 180 Example 2 94 175 Example 3 95 177 Example 4 96 178 Example 5 94 176 Example 6 100 185 Comparative Example 1 60 160 Comparative Example 2 68 162 Comparative Example 3 74 168 Comparative Example 4 81 164 Comparative Example 5 84 170 Comparative Example 6 72 162 Comparative Example 7 54 145

[0101] The results above show that the special concrete for ground flooring prepared by this invention has good compressive strength, as well as good durability and anti-collapse properties. The compressive strength of Example 1 is 59.9 MPa with a loss rate of 0.21%, which is attributed to the formation of a stable interpenetrating network within the concrete, with carbon fiber as the skeleton, polymer as the reinforcement, and epoxy resin as the barrier. Example 1 uses 2-acrylamido-2-methylpropanesulfonic acid, whose highly polar sulfonic acid groups provide excellent dispersibility and interfacial interactions. Example 4 uses N-hydroxymethylacrylamide; although its active hydroxymethyl groups provide later reaction sites, it is slightly inferior in terms of immediate dispersion and reinforcement. Example 5 uses N,N'-methylenebisacrylamide, which, as a crosslinking agent, mainly strengthens the network structure within the polymer but fails to effectively improve compatibility with the external cement matrix. Example 6 combines 2-acrylamido-2-methylpropanesulfonic acid from Example 1 with N,N'-methylenebisacrylamide from Example 5, achieving an optimal balance of strength, durability, and workability by combining excellent external dispersion and adhesion with a robust internal polymer network structure.

[0102] As can be seen from Comparative Examples 1-5, Comparative Example 2, using only raw carbon fibers, exhibited extremely limited reinforcing effect due to weak interfacial bonding and easy agglomeration. Comparative Example 5, using unactivated carbon fibers, suffered from insufficient surface functional groups, resulting in poor subsequent coupling and grafting effects. Comparative Example 3, lacking a silane coupling agent, lacked molecular bridges connecting inorganic fibers and organic polymers, making it difficult for carbon fibers to effectively participate in network construction. Comparative Example 4, without copolymerization, failed to graft copolymers rich in highly polar functional groups onto the carbon fiber surface, severely weakening its chemical bonding ability with the cement matrix. Furthermore, Comparative Example 6, without added stabilizers, reduced the interaction between calcium methylsilicate and cement colloids, hindering uniform mixing of the concrete, slowing the crystallization rate of the cement colloids, thereby reducing the concrete's strength and density, leading to shrinkage and collapse, and decreasing its stability and durability. Comparative Example 7, without added composite retarder, resulted in excessively rapid concrete hydration, a sharp loss of slump, and a loose, defective internal microstructure, resulting in the worst strength and durability.

Claims

1. A special concrete for ground flooring, characterized in that, Composed of the following raw materials by weight: 300-500 kg / m 3 Cement, 600-750 kg / m 3 Fine aggregate, 900-1200 kg / m³ 3 Medium and coarse aggregate, 15-40 kg / m³ 3 Bentonite, 30-60 kg / m 3 High-performance water-reducing agent, 10-30 kg / m 3 Retarder, 10-20 kg / m 3 Stabilizer, 300-600 kg / m 3 Water, 10-20 kg / m 3 Corrosion resistance enhancer; The retarder is composed of the following raw materials in parts by weight: 5-20 parts expanded perlite, 7-15 parts sodium lignosulfonate, 4-8 parts borax, 2-6 parts sodium hexametaphosphate, and 2-7 parts tartaric acid.

2. The special concrete for ground flooring as described in claim 1, characterized in that, The water-reducing agent is at least one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, and sulfonate water-reducing agent.

3. The special concrete for ground flooring as described in claim 1, characterized in that, The stabilizer is at least one of potassium methylsilicate, guar gum, polyacrylamide, and cocamidopropyl betaine.

4. The special concrete for ground flooring as described in claim 1, characterized in that, The method for preparing the corrosion-resistant reinforcing agent includes the following steps: S1, activating carbon fibers by immersing them in concentrated nitric acid to obtain activated carbon fibers; dispersing the activated carbon fibers in an ethanol aqueous solution, adjusting the pH value to acidic, adding a silane coupling agent to react, and obtaining double-bond modified carbon fibers. S2. Under an inert atmosphere, itaconic acid, acrylic acid and water are mixed, the pH is adjusted to acidic, and acrylamide derivative, double bond modified carbon fiber, hydroxyethyl acrylate and initiator are added to carry out a copolymerization reaction to obtain carbon fiber reinforced material. S3. Dissolve epoxy resin and carbon fiber reinforcing material in a solvent, add amine crosslinking agent to react, and obtain the corrosion-resistant reinforcing agent.

5. The special concrete for ground flooring as described in claim 4, characterized in that, The silane coupling agent is any one of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, KH-550, and methacryloyloxymethyltrimethoxysilane.

6. The special concrete for ground flooring as described in claim 4, characterized in that, The weight ratio of itaconic acid, acrylic acid, acrylamide derivative, double bond modified carbon fiber and hydroxyethyl acrylate in S2 is (2-5):(1-2):(3-7):(8-12):(0.5-2), and the copolymerization reaction is carried out at 70-90℃ and 300-600rpm for 1.5-4h.

7. The special concrete for ground flooring as described in claim 4, characterized in that, The acrylamide derivative is at least one of 2-acrylamido-2-methylpropanesulfonic acid, N-hydroxymethylacrylamide, and N,N'-methylenebisacrylamide.

8. The special concrete for ground flooring as described in claim 4, characterized in that, The amine crosslinking agent in S3 is either diethylenetriamine or triethylenetetramine.

9. A method for preparing special concrete for ground flooring as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh each raw material according to its weight; (2) Mix cement, fine aggregate, medium and coarse aggregate and bentonite, add water and stir evenly at 300 rpm to obtain premix; (3) Add high-performance water-reducing agent, retarder and stabilizer to the above premix and continue to stir evenly to obtain special concrete for ground floor.