An ultra-long-time slump-retaining concrete and a preparation method thereof

Abstract

The application discloses a super-long-time slump-retaining concrete, which comprises a cementitious material system, a light aggregate system, a composite admixture system and water; the components and their dosages in each cubic meter of the concrete include: the cementitious material system 400-450 kg, the light aggregate system 1200-1400 kg, the water 200-220 kg, and the composite admixture system 2.0-3.0% of the mass of the cementitious material system; wherein the cementitious material system takes phosphogypsum, cement, mineral powder, glass microbeads and microsilica powder as main raw materials; and the composite admixture system takes a phosphoric acid group modified retarding type polycarboxylate water reducer, a water-retention and thickening component, an alkali-activated component, an air entraining agent and water as main raw materials. The setting time of the concrete can reach 100-120 h, and the mix can still maintain good workability after 72 h, so that the realization of synchronous cutting and pouring concrete continuous wall process and the like can be effectively ensured, and the application is suitable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an ultra-long-lasting slump-resistant concrete and its preparation method. Background Technology

[0002] Super-retarded concrete is increasingly widely used in the construction industry, providing more flexible options for the construction of special structures and methods. Its unique feature lies in its significantly extended initial setting time compared to conventional concrete, reaching or exceeding 24-48 hours, and even exceeding 100 hours; making super-retarded concrete an ideal material for interlocking piles, SMW (Super-Stone Wheatstone) piles, ultra-long pile foundations, large-volume concrete, and high-rise building foundation slabs.

[0003] For the partial diaphragm wall continuous sawing and simultaneous pouring process (such as patents CN106759262A and CN107964941A), a chainsaw-type cutting box is used to saw grooves, ultra-retarded concrete is poured simultaneously, and a stiffening frame is placed afterward. The lateral pressure of the fluidized concrete propels the equipment to continuously cut forward, forming a cold-joint-free diaphragm wall. This process aims to use the lateral pressure of the fluidized ultra-retarded concrete to propel the equipment laterally forward. This requires the concrete mixture to not only have an extremely long setting time, but also that the concrete after 72 hours possesses good fluidity and low penetration resistance. This ensures that after the excavation is completed, the stiffening frame can be easily inserted into the poured concrete.

[0004] However, traditional super-retarded concrete is left in a static or minimally undisturbed state after pouring, and the fluidity of the formed concrete is generally not subject to special requirements. Its rheological properties, such as viscosity, consistency, and penetration resistance, are usually not specifically improved simultaneously. For example, patent CN106977159A discloses a super-retarded concrete that uses cement as the main cementitious material and adds composite admixtures to improve the retarding effect. These composite admixtures include polycarboxylate superplasticizers, triisopropanolamine fumarate, and molasses. While ensuring the later compressive strength of the concrete, it delays the setting time, but it uses conventional compounded organic sugar retarders and does not address the improvement of the fluidity of the concrete mixture during the retarding period. Patent CN113998939A discloses a phosphogypsum-based super-retarded concrete that uses phosphogypsum as the main cementitious material, forming a phosphogypsum-based super-retarded concrete system. The soluble phosphates, sugar, and sodium gluconate in the phosphogypsum work together to achieve the super-retarding effect, but similarly, it does not address special improvements such as the ability to maintain fluidity.

[0005] Therefore, in response to the process requirements of the synchronous cutting and pouring of concrete continuous wall technology, which involves continuously cutting the diaphragm wall into grooves, synchronously pouring concrete, and finally inserting the reinforcing cage, it is necessary to further explore and develop a type of concrete with ultra-long setting time, low penetration resistance, and ultra-long slump retention. Summary of the Invention

[0006] The main objective of this invention is to address the problems and shortcomings of existing ultra-slow-setting concrete technology by providing an ultra-long-lasting slump-holding concrete. This concrete has a setting time of 100-120 hours and maintains good workability of the mixture even after 72 hours (72-hour spread ≥ 500 mm), achieving the design requirements for concrete workability, setting time, penetration resistance, and later-stage strength development. It can effectively ensure the realization of the synchronous cutting and pouring of continuous concrete walls, guaranteeing the compactness, continuity, and efficiency of the construction rhythm, and is suitable for widespread application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An ultra-long-lasting slump-holding concrete comprises a cementitious material system, a lightweight aggregate system, a retarding admixture system, and water. The components and their amounts per cubic meter of concrete include: 400-450 kg of cementitious material system, 1200-1400 kg of lightweight aggregate system, 200-220 kg of water, and the composite admixture system is added at 2.0-3.0% of the mass of the cementitious material system. The cementitious material system primarily uses phosphogypsum, cement, mineral powder, glass microspheres, and silica fume as raw materials, while the composite admixture system primarily uses phosphate-modified retarding polycarboxylate superplasticizer, water-retaining and thickening components, alkali-activated components, air-entraining agents, and water.

[0009] In the above scheme, the mass percentage of phosphogypsum in the cementitious material system is 40-50 wt%.

[0010] Furthermore, in the cementitious material system, the components and their weight percentages include: 40-50% phosphogypsum, 8-10% cement, 25-30% mineral powder, 3-5% glass microspheres, and 5-10% silica fume. The cementitious material uses phosphogypsum combined with various admixtures, which makes the fine particle material gradation reasonable, fully fills the pores between particles, significantly improves the cohesiveness and water saturation of the concrete mix, and ensures that the mix still has good slurry stability after a long period of standing.

[0011] In the above scheme, the phosphogypsum is obtained by aging, drying and screening of phosphogypsum tailings. The aging time is ≥12 months, the water-soluble P2O5 content (dry basis) is 20-200 mg / kg, and the residue on a 150μm sieve is ≤20%.

[0012] In the above scheme, the cement used is ordinary Portland cement; the mineral powder is S95 grade or higher; the glass microspheres have a 45μm sieve residue of ≤10% and a water requirement ratio of ≤95%; the silica fume has a SiO2 content of ≥95% and a specific surface area of ​​≥600m². 2 / kg.

[0013] In the above scheme, the solid content of the composite admixture system is 12-16%, and the water reduction rate is ≥20%.

[0014] In the above scheme, the components and their mass percentages in the composite admixture system include: 30-40% phosphate-modified polycarboxylate superplasticizer, 0.05-0.10% water-retaining and thickening component, 0.2-0.5% alkali-activated component, 0.01-0.05% air-entraining agent, and the balance being water.

[0015] In the above scheme, the phosphate-modified polycarboxylate superplasticizer is prepared by free radical copolymerization in aqueous solution using unsaturated phosphate functional monomers, unsaturated polyoxyethylene ether macromonomers, and unsaturated acids as the main raw materials; wherein, the structural formula of the unsaturated phosphate functional monomer is shown in Formula I;

[0016]

[0017] In the formula, R1 is a C1-C5 alkyl group and R2 is a C1-C3 alkyl group.

[0018] In the above scheme, the unsaturated polyoxyethylene ether macromonomer is one of isopentenyl polyoxyethylene ether and methyl allyl polyoxyethylene ether, with a molecular weight of 1000-4000; the unsaturated acid and its derivatives are one or more of acrylic acid, methacrylic acid, and maleic anhydride.

[0019] In the above scheme, the preparation steps of the unsaturated phosphate functional monomer include:

[0020] 1) Bromination reaction: Triethyl phosphite and brominated unsaturated ester are added to an organic solvent, followed by a catalyst and polymerization inhibitor. The substitution reaction is carried out under certain temperature and pressure conditions, and the intermediate products of the substitution reaction are collected.

[0021] 2) Preparation of unsaturated phosphate functional monomers: Add excess alkali to the intermediate product, stir the reaction at 40-60℃, and simultaneously remove the generated ethanol vapor. Then add acid to adjust the pH value to 4-6 to obtain the unsaturated phosphate functional monomers.

[0022] In the above scheme, the structural formula of the bromounsaturated ester is shown in Formula II;

[0023]

[0024] In the formula, R1 is a C1-C5 alkyl group and R2 is a C1-C3 alkyl group.

[0025] In the above scheme, the structural formula of the triethyl phosphite is shown in Formula III;

[0026]

[0027] In the above scheme, the organic solvent is one of ethanol, methanol, diethyl ether, etc., the catalyst is one of iodine, bromine, copper chloride, etc., and the polymerization inhibitor is hydroquinone.

[0028] In the above scheme, the mass ratio of triethyl phosphite, brominated unsaturated ester, catalyst and polymerization inhibitor is 1:0.2-5:0.001-0.01:0.005-0.02.

[0029] In the above scheme, the reaction conditions for the substitution reaction in step 1) are controlled as follows: temperature is 60-120℃, pressure is 0.1-10kPa, and reaction time is 6-10h.

[0030] In the above scheme, the structural formula of the intermediate product is shown in Formula IV;

[0031]

[0032] In the above scheme, the alkali is NaOH.

[0033] In the above scheme, the mass ratio of the intermediate product to the alkali is 1:0.1-0.5.

[0034] In the above scheme, the stirring reaction time in step 2) is 1-2 hours.

[0035] In the above scheme, the acid is dilute hydrochloric acid with a concentration of 10-15 wt%.

[0036] In the above scheme, the preparation steps of the phosphate-modified polycarboxylate superplasticizer include: adding unsaturated phosphate functional monomers, unsaturated polyoxyethylene ether macromonomers, unsaturated acids, initiation systems, and chain transfer agents to a reaction vessel, and performing aqueous free radical copolymerization to obtain the phosphate-modified polycarboxylate superplasticizer; the specific preparation steps include:

[0037] (1) Dissolve the unsaturated polyoxyethylene ether macromonomer in water, then add the unsaturated phosphate functional monomer and the oxidant of the initiation system, and heat to 25-35℃;

[0038] (2) Add an aqueous solution of unsaturated acid and an aqueous solution prepared by the reducing agent and chain transfer agent of the initiating system at a uniform rate for 1-4 hours; after keeping warm for 1-2 hours, add NaOH solution to adjust the pH to 5-6 to obtain the phosphate group modified polycarboxylate superplasticizer.

[0039] In the above scheme, the initiation system used is a composite system of oxidant and reductant, wherein the oxidant is hydrogen peroxide, the reductant is one of ascorbic acid and ferrous sulfate, and the chain transfer agent is one of mercaptoacetic acid and mercaptopropionic acid.

[0040] In the above scheme, the mass ratio of the unsaturated polyoxyethylene ether macromonomer, unsaturated phosphate functional monomer, unsaturated acid, oxidant, reducing agent and chain transfer agent is 100:5-10:3-10:1.0-1.2:0.1-0.3:0.5-0.8.

[0041] In the above scheme, the water-retaining and thickening component is one or more of carboxymethyl cellulose ether, polyacrylamide, and maltodextrin; the alkali-activating component is one or more of NaF, NaOH, and water glass; and the air-entraining agent is a polyether-based air-entraining agent.

[0042] In the above scheme, the lightweight aggregate system consists of lightweight coarse aggregate and fine aggregate, with a sand ratio of 42-48%. The use of rounded, shaped aggregate aims to reduce friction between aggregates of different sizes and to fill the pores in the mix, ensuring that the concrete has high overall fluidity, as well as low penetration and agitation resistance.

[0043] In the above scheme, the lightweight coarse aggregate is 1200-1600 mesh ceramsite with 5-15mm continuous gradation, rounded particle shape with few sharp edges, crushing value ≤15%, and needle-like and flaky content ≤0.5%; the fine aggregate is natural sand with a fineness modulus of 2.4-2.8 and a mud content ≤1%.

[0044] In the above scheme, the water is one of the clean fresh water types such as tap water, river water, and well water.

[0045] This invention also provides a method for preparing ultra-long-lasting slump-resistant concrete, comprising the following steps:

[0046] Step 1: Mix and stir the lightweight coarse aggregate and fine aggregate (forced stirring time 0.5-1 min) to obtain a lightweight aggregate system;

[0047] Step 2: Add the measured cementitious material system to the lightweight aggregate system, and force mix for 1-2 minutes. Add some water during the mixing process to assist in the mixing.

[0048] Step 3: Add the remaining water and composite admixture system to the obtained mixture and mix evenly (forced stirring for 1-2 minutes) to obtain the slump-resistant concrete.

[0049] In the above scheme, the water consumption in step two accounts for 30-50% of the total water consumption.

[0050] By using the above steps to prepare concrete, the coarse and fine aggregates can be initially mixed evenly and then added to the cementitious material system. Adding admixtures can ensure that the solids and liquids can be fully integrated and mixed during the mixing process, thus ensuring that the prepared concrete meets the requirements for ultra-retarded setting and ultra-slump retention.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] 1) The ultra-long slump-resistant concrete of this invention employs a multi-component cementitious material system and a lightweight aggregate system, wherein phosphogypsum is the main cementitious material and ceramsite is the coarse aggregate, making full use of various industrial solid wastes. Furthermore, the phosphogypsum cementitious material system itself contains a large amount of soluble phosphorus and fluoride ion impurities. Combined with the phosphate-modified polycarboxylate superplasticizer designed in this invention, it can significantly inhibit the formation of calcium ions. 2+ The dissolution of the product slows down the consumption of free water and the generation of hydration products, which can further achieve better dispersion and slump retention. It can achieve ultra-long-term slump retention without the need to introduce conventional retarders (such as sugar and sodium gluconate).

[0053] 2) This invention combines material control, mix proportion optimization, and optimized design of retarding polycarboxylate superplasticizer to significantly extend the setting time of concrete without affecting its workability at the mixer, and maintain good workability of concrete for a considerable period of time (72h spread ≥400mm), while simultaneously meeting indicators such as workability, penetration resistance, and later strength development.

[0054] 3) The ultra-long-term slump-resistant concrete described in this invention still has good fluidity after long-term standing, and has low viscosity and low penetration resistance. It is suitable for working conditions with special requirements for concrete setting time and secondary operations after standing. It is particularly suitable for the jacking force requirements of concrete and the penetration requirements of post-framework in the process of synchronous cutting and pouring of concrete continuous walls. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to embodiments, so as to facilitate a clearer understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0056] Unless otherwise specified, all the following examples are conducted under standard conditions or conditions recommended by the manufacturer. Unless otherwise specified, all raw materials used in the following examples are commercially available.

[0057] In the following embodiments, the preparation method of the composite admixture system includes the following steps:

[0058] (1) Preparation of functional monomers:

[0059] ① Bromination reaction: Triethyl phosphite and ethyl 4-bromocrotonate were added to anhydrous ethanol solvent, followed by the catalyst copper chloride and the polymerization inhibitor hydroquinone. The substitution reaction was carried out at 80℃ and 5kPa for 8 hours, and the intermediate products of the substitution reaction were collected. The mass ratio of triethyl phosphite, ethyl 4-bromocrotonate, copper chloride and hydroquinone was 1:3:0.01:0.01.

[0060] ② Preparation of unsaturated phosphate functional monomers: Add 0.5 times the mass of NaOH to the intermediate product, react at 40-60℃ with stirring for 2 hours, remove the generated ethanol vapor, and then add 10wt% dilute hydrochloric acid to adjust the pH value to 4-6 to obtain the unsaturated phosphate functional monomers.

[0061] (2) Preparation of phosphate-modified polycarboxylate superplasticizer by free radical copolymerization in aqueous solution, the specific preparation steps include:

[0062] ① Dissolve the isopentenyl polyoxyethylene ether macromonomer in water in a container, then add the unsaturated phosphate functional monomer and hydrogen peroxide as the oxidant for the initiation system, and heat to 35°C;

[0063] ② Add an aqueous solution of acrylic acid and an aqueous solution prepared by ferrous sulfate as a reducing agent and mercaptoacetic acid as a chain transfer agent initiating system at a uniform rate for 3 hours; after keeping warm for 1 hour, add NaOH solution to adjust the pH to 5-6 to obtain the phosphate ester group modified polycarboxylate superplasticizer.

[0064] The mass ratio of unsaturated polyoxyethylene ether macromonomer, unsaturated phosphate functional monomer, unsaturated acid, oxidant, reducing agent and chain transfer agent is 100:10:5:1.0:0.2:0.6.

[0065] (3) Compound formulation of composite admixture system

[0066] The components and their mass percentages in the composite admixture system include: 40% phosphate-modified polycarboxylate superplasticizer, 0.10% water-retaining and thickening component (maltodextrin), 0.2% alkali-activating component (water glass), 0.01% air-entraining agent (commercially available Zhuben Oil CHUPOL AE-503), and the balance being water, which is prepared by stirring.

[0067] In the following examples, the phosphogypsum used was aged phosphogypsum provided by Wuxue Xiangyun Chemical Co., Ltd., with a soluble P2O5 content of 107 mg / kg and a 16.9% residue on a 150 μm sieve; the cement was ordinary Portland cement, P.O42.5 type, provided by Huaxin Cement Co., Ltd.; the mineral powder used was S95 grade, provided by Wuhan Wuxin New Building Materials Co., Ltd.; the glass microspheres used were provided by Wuhan Yangluo Power Plant; the silica fume had a silicon content ≥98% and a specific surface area of ​​700 m². 2 / kg, provided by Sichuan Langtian Resources Comprehensive Utilization Co., Ltd.

[0068] The lightweight coarse aggregate used is ceramsite, with a particle size distribution range of 5-15mm and a mesh size of 1200-1400; the fine aggregate is yellow sand, with a fineness modulus of 2.8.

[0069] Test indicators include: spread after discharge and 72 hours, collapse and emptying time, penetration resistance, agitation resistance, initial setting time, final setting time, and strength (14d, 28d, 42d). The workability of concrete after long-term settling is described as four levels: soft, average, viscous, and loss of plasticity. Penetration resistance is evaluated using manual penetration resistance and manual mixing resistance, and is divided into three levels: low resistance, average resistance, and high resistance. Evaluation methods include inserting a plastic drainage pipe with a diameter of approximately 2cm into a concrete container to a height of approximately 2m and mixing the mixture with a shovel.

[0070] Examples 1-5

[0071] The mix proportions of the ultra-long slump-holding concrete described in Examples 1-5 are shown in Table 1. The concrete is prepared according to the following method:

[0072] Step 1: Mix the ceramsite and yellow sand in a certain proportion and stir for 0.5 minutes to obtain a lightweight aggregate system;

[0073] Step 2: Add phosphogypsum, cement, mineral powder, glass microspheres and silica fume to the above mixture in sequence, and stir for 1 minute. During the stirring process, add 50% of the amount of water to assist stirring.

[0074] Step 3: Add the remaining water and composite admixture system to the above mixture in sequence, stir for 1.5 minutes until evenly mixed, and the ultra-long slump-hold concrete is obtained.

[0075] Table 1. Mix proportions of concrete described in Examples 1-5 and Comparative Examples 1-4 (kg / m³) 3 )

[0076]

[0077]

[0078] Comparative Examples 1-4

[0079] The only difference between Comparative Example 1 and Example 1 is that the admixture used is a conventional commercially available ordinary retarded polycarboxylate high-performance water-reducing agent, while the other proportions are the same as in Example 1.

[0080] The only difference between Comparative Example 2 and Example 1 is that phosphogypsum in the cementitious material system is replaced with natural dihydrate gypsum, while the other proportions remain the same as in Example 1.

[0081] The only difference between Comparative Example 3 and Example 1 is that phosphogypsum in the cementitious material system is removed and replaced with cement, mineral powder and glass microspheres, while keeping the total amount of cementitious material unchanged, and other proportions are the same as in Example 1.

[0082] The only difference between Comparative Example 4 and Example 1 is that crushed stone is used instead of the ceramsite, while the other proportions remain the same as in Example 1.

[0083] The setting time, slump, spread, void time, and compressive strength of concrete specimens were tested according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and GB / T 50107-2010 "Standard for Testing and Evaluation of Concrete Strength". The state descriptions were based on the manual mixing state and manual penetration state of the mixture. The test results are shown in Table 2 below.

[0084] Table 2. Test results of concrete samples from Examples 1-5 and Comparative Examples 1-4

[0085]

[0086]

[0087] Based on the test data from Examples 1, 4, 5 and Comparative Example 1, it can be seen that the selection and dosage of admixtures have a significant impact on the workability and retarding time of ultra-long slump-holding concrete. Conventional retarding water-reducing agents cannot meet the special requirements of ultra-retarded ultra-slump-holding concrete, such as long-term slow-release slump-holding, workability over time, and viscosity reduction, and the condition deteriorates significantly.

[0088] Based on the test data from Example 1 and Comparative Examples 2 and 3, it can be seen that the retarding time of this type of ultra-long slump-holding concrete is related to the amount of phosphogypsum. When there is no phosphogypsum in the cementitious system, the ultra-long slump-holding effect cannot be achieved. When natural gypsum is used to replace phosphogypsum, the retarding and slump-holding effect is poor.

[0089] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A type of ultra-long-lasting slump-holding concrete, characterized in that, It includes cementitious material systems, lightweight aggregate systems, composite admixture systems, and water; The components and their amounts per cubic meter of concrete include: 400-450 kg of cementitious materials, 1200-1400 kg of lightweight aggregate, 200-220 kg of water, and 2.0-3.0% of the mass of the composite admixture system. The cementitious materials system primarily uses phosphogypsum, cement, mineral powder, glass microspheres, and silica fume as raw materials. The composite admixture system uses phosphate-modified retarding polycarboxylate superplasticizer, water-retaining and thickening components, alkali-activated components, air-entraining agents, and water as raw materials. The phosphate-modified polycarboxylate superplasticizer is prepared by free radical copolymerization of unsaturated phosphate functional monomers, unsaturated polyoxyethylene ether macromonomers, and unsaturated acids in aqueous solution; wherein, the structural formula of the unsaturated phosphate functional monomer is shown in Formula I; I； In the formula, R1 is a C1-C5 alkyl group, and R2 is a C1-C3 alkyl group; The lightweight aggregate system consists of lightweight coarse aggregate and fine aggregate, with a sand ratio of 42-48%; the lightweight coarse aggregate is 1200-1600 mesh ceramsite with a 5-15mm continuous gradation; the fine aggregate is natural sand with a fineness modulus of 2.4-2.8 and a mud content of ≤1%.

2. The ultra-long-term slump-resistant concrete according to claim 1, characterized in that, The cementitious material system comprises the following components and their respective weight percentages: phosphogypsum 40-50%, cement 8-10%, mineral powder 25-30%, glass microspheres 3-5%, and silica fume 5-10%.

3. The ultra-long-term slump-resistant concrete according to claim 1, characterized in that, The phosphogypsum is obtained by aging, drying and screening phosphogypsum tailings, with a water-soluble P2O5 content of 20-200 mg / kg and a residue of ≤20% on a 150 μm sieve.

4. The ultra-long-term slump-resistant concrete according to claim 1, characterized in that, The components and their mass percentages in the composite admixture system include: 30-40% phosphate-modified polycarboxylate superplasticizer, 0.05-0.10% water-retaining and thickening component, 0.2-0.5% alkali-activated component, 0.01-0.05% air-entraining agent, and the balance being water.

5. The ultra-long-term slump-holding concrete according to claim 1, characterized in that, The unsaturated polyoxyethylene ether macromonomer is one of isopentenyl polyoxyethylene ether and methyl allyl polyoxyethylene ether, with a molecular weight of 1000-4000; the unsaturated acid is one or more of acrylic acid and methacrylic acid.

6. The ultra-long-term slump-holding concrete according to claim 1, characterized in that, The free radical copolymerization also introduces oxidants, reducing agents and chain transfer agents; the mass ratio of the unsaturated polyoxyethylene ether macromonomer, unsaturated phosphate functional monomer, unsaturated acid, oxidant, reducing agent and chain transfer agent is 100:5-10:3-10:1.0-1.2:0.1-0.3:0.5-0.

8.

7. The ultra-long-term slump-resistant concrete according to claim 4, characterized in that, The water-retaining and thickening component is one or more of carboxymethyl cellulose ether, polyacrylamide, and maltodextrin; the alkali-activating component is one or more of NaF, NaOH, and water glass; and the air-entraining agent is a polyether-based air-entraining agent.

8. The method for preparing ultra-long-lasting slump-resistant concrete according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Mix and stir the lightweight coarse aggregate and fine aggregate to obtain a lightweight aggregate system; Step 2: Add the measured cementitious material system to the lightweight aggregate system and mix it. Add some water during the mixing process to assist in the mixing. Step 3: Add the remaining water and composite admixture system to the obtained mixture and mix evenly to obtain the slump-resistant concrete.

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