Mix proportion optimization method for high-slump-loss-resistant long-distance transportation concrete

Abstract

The invention relates to the field of building materials, and discloses a mix proportion optimization method for high-slump-loss-resistant long-distance transportation concrete, which comprises the following steps: according to the engineering strength requirement of the concrete, designing basic parameters of the concrete, including strength grade, slump, transportation distance and environmental condition; selecting proper raw materials and determining the proportion; carrying out dynamic design and aggregate interface modification treatment, and treating the aggregate by adopting a silane coupling agent and a nano nucleating agent; the mixing process is optimized, and the stirring sequence and time are controlled; carrying out rheological property test and adjustment; slump retaining control is carried out in the transportation process, the slump degree is monitored in real time, and a water reducing agent is supplemented; and finally, verifying the adaptability on the construction site to ensure that the concrete performance meets the requirements. According to the invention, a staged charging and orderly dispersing process is adopted, and dynamic water replenishing and slump retaining control is combined, so that the technical effect of improving the workability of the concrete is achieved, and excessive loss of slump of the concrete in the transportation process is effectively prevented.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a mix ratio optimization method for high-slump-retention concrete for long-distance transportation. Background Art

[0002] Concrete is one of the most fundamental and important materials in modern construction, used in a wide range of projects. However, during transportation, concrete often faces problems such as poor slump retention, insufficient resistance to separation, and insufficient early strength, especially during long transportation times, during hot weather, or during complex construction conditions. These issues not only affect construction efficiency but also lead to a decline in project quality.

[0003] At present, a one-time feeding and mixing process is often used in concrete production. This method ensures the basic strength and workability of concrete by adding and mixing all raw materials at one time. The use of traditional polycarboxylate water-reducing agent technology can effectively reduce the water-cement ratio of concrete and reduce the use of water, thereby improving strength and optimizing fluidity. In addition, some technical solutions improve the basic properties of concrete and improve the smoothness of construction through reasonable aggregate selection and treatment.

[0004] However, the existing technology still has some shortcomings. First, the one-time mixing method lacks control over the concrete's slump-retaining performance, resulting in a rapid decrease in the slump of concrete during transportation, affecting construction quality. Second, although traditional polycarboxylate water-reducing agents improve fluidity, they cannot effectively maintain slump during long-term transportation. In particular, under high temperature or long-term transportation conditions, concrete easily loses fluidity and stability. Moreover, existing aggregate processing technologies have limited modification of the aggregate surface and lack reinforcement of the aggregate-paste interface, resulting in insignificant strength improvement and poor resistance to separation of concrete. To this end, those skilled in the art have proposed a mix ratio optimization method for high-slump-retaining long-distance transportation concrete to address the above problems. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a mix ratio optimization method for high-slump-retention long-distance transportation of concrete, which solves the problems of rapid slump loss, insufficient separation resistance and slow strength improvement during concrete transportation in the existing technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation, comprising the following steps: S1. Design the basic parameters of concrete according to the required engineering strength requirements of concrete, including determining the concrete strength grade, initial slump, transportation distance and ambient temperature and humidity conditions; This step first determines the concrete's design strength grade, initial slump, planned transportation distance, and the temperature and humidity of the construction environment based on the concrete's service conditions. This parameter design establishes input boundary conditions that match the project's actual conditions.

[0007] This step transforms concrete performance design into an "adaptive input-driven" model by prioritizing environmental disturbances (such as temperature and humidity) and construction requirements (such as slump retention time) as control factors. This invention introduces a multidimensional constraint framework guided by engineering requirements, establishing a response mechanism for the material system and laying the foundation for subsequent concrete performance control.

[0008] S2. Based on the basic parameters of the concrete, select and determine appropriate raw materials, and determine the weight ratio of each component according to the designed ratio; Based on the set parameters, suitable raw materials are selected and the weight ratio of each component is determined accordingly, including basic materials such as cement, fly ash, mineral powder, silica fume, sand and gravel, water reducer and functional admixtures.

[0009] The core of this step is to construct a "multiphase composite material system," in which admixtures and cementitious materials synergistically control hydration rates, aggregate particle size grading achieves dense particle packing, and admixtures impart tunable properties to the system. This structure-function coupled raw material combination differs from conventional single-variable control methods.

[0010] S3. Dynamically designing the concrete mix ratio based on the raw materials; After completing the selection of raw materials, the mix parameters are dynamically designed based on environmental variables and performance indicators, including the setting of core indicators such as water-cement ratio, sand ratio, total amount of adhesive, and proportion of slow-release water reducer.

[0011] Mix design is no longer a matter of selecting from static spreadsheets; it now relies on dynamic control based on input from transport conditions. The system incorporates control concepts such as "delayed release effect" and "secondary dispersion capability." By adjusting the reaction sequence and interfacial behavior of different components, it constructs a responsive system that is sensitive to temperature, shear rate, and time, demonstrating significant environmental adaptability.

[0012] S4. Based on the mix ratio, performing aggregate interface modification treatment, treating the aggregate surface with a silane coupling agent and a nano nucleating agent; After designing the mix ratio, the aggregate surface is composite-treated with silane coupling agent and nano-nucleating agent to form an interface area with higher chemical affinity.

[0013] This treatment mechanism uses silane to form a chemical bridging structure, enhancing the aggregate surface's ability to bind hydration products. Simultaneously, nano-nucleating agents induce the hydration products to preferentially grow at the aggregate interface, creating an interfacial microregion composed of a triple "core-shell-paste" structure. The stability of this microinterface enhances the overall concrete structure's resistance to separation during transport disturbances and forms the microstructural foundation for achieving high collapse resistance.

[0014] S5. Optimizing the concrete mixing process and controlling the mixing sequence and mixing time according to the aggregate interface modification treatment and mix ratio after treatment; Combined with the modified aggregate and mix ratio parameters, the mixing sequence and mixing control conditions are set, including the addition sequence, water distribution in stages, mixing time and speed, and other process details.

[0015] This invention utilizes a "staged addition + orderly dispersion" strategy to slow the hydration rate of early reactions and inhibit the early formation of unstable structures, thereby improving the uniformity and stability of the concrete out of the machine. This optimized mixing strategy helps preserve the concrete's initial workability window, particularly over complex transportation routes, ensuring process reliability for subsequent transportation and pumping.

[0016] S6. Perform rheological property testing and adjustment according to the mix ratio and mixing process; Conduct rheological property tests on mixed concrete to obtain its thixotropy, plastic viscosity and yield stress, and dynamically adjust the mix ratio or additive formula based on the test results.

[0017] The core of this step lies in establishing a feedback loop between performance and structure. By quantitatively testing flowability parameters, the quality of microstructure formation and the degree of interparticle interaction can be determined, enabling precise adjustments to the system architecture. This "test-judgment-adjustment" mechanism embodies the present invention's complete closed-loop strategy, moving from "process feedforward design" to "structural post-control feedback."

[0018] S7. Based on the results of the rheological properties test and adjustment, implement slump control during concrete transportation by real-time monitoring of slump changes and adding water reducing agent; After the concrete enters the transportation stage, slump control is achieved during the process by setting the speed of the mixer truck tank, monitoring the temperature difference and slump changes in real time, and dynamically adding water reducer based on the measured results.

[0019] By treating concrete as a "controllable evolution system," this approach establishes a full-process response mechanism by controlling external disturbances (rotation speed, temperature differential) and internal adjustments (water-reducing agent re-release), breaking through the traditional blind spot of passive waiting during transportation. This combination of state monitoring and dynamic regulation improves the sustainability and stability of concrete performance, a key difference between this method and traditional process approaches.

[0020] S8. Implement collapse control as described above and conduct adaptability verification at the construction site.

[0021] After the concrete arrives at the construction site, slump loss, setting time, early strength and shrinkage deformation are monitored to verify whether it meets the actual construction requirements.

[0022] From a systemic perspective, this step not only verifies the performance endpoint but also serves as a closed-loop verification of the effectiveness of parameter setting and control throughout the entire process. On-site adaptability assessments provide feedback for corrective changes to the aforementioned parameter system, enabling continuous optimization and cross-project adaptability. This represents a sustainable, self-contained concrete quality assurance technology system.

[0023] Preferably, the basic parameters of the designed concrete include: Select the required concrete strength grade C30 to C60; The initial slump is set at 180 ± 20 mm; The transport distance was set to ≤50km or >50km, and different strategies for slow-release of water reducer were adopted; The ambient temperature is set between 5°C and 35°C, and the relative humidity is ≥ 60%.

[0024] In the present invention, in the pre-stage of the concrete mix optimization process, the basic parameter settings are defined. This parameter system consists of four main variables: The concrete strength grade range is set from C30 to C60, covering medium-low to medium-high grades, meeting the performance requirements of common structural components; The initial slump is designed to be 180±20mm, taking into account both pumping fluidity and structural stability; The transport distance is divided into two intervals: ≤50km and >50km, and differentiated mitigation strategies are implemented accordingly; The ambient temperature setting range is 5℃ to 35℃, and the relative humidity is ≥60%, covering the vast majority of concrete construction environments in my country.

[0025] The design logic of this parameter limitation is to establish a unified input interface with transport accessibility, climate stability and operating conditions as variable boundaries, thereby improving the method's wide adaptability to different regions and climate zones.

[0026] Preferably, the selection of the raw materials includes the following components in parts by weight: P·O42.5 grade cement: 200-500 parts; Grade I fly ash: 10-15 parts, S95 slag: 8-12 parts, silica fume: 2-5 parts; 5-25mm continuously graded crushed stone: 55-65 parts and medium sand: 30-35 parts, fineness modulus is 2.3-2.8; Polycarboxylate water reducer: 0.8-1.2 parts; Silane coupling agent: 0.1-0.5 parts; Nano-CaCO3 nucleating agent: 0.05-0.1 parts.

[0027] In terms of the raw material system, the present invention clearly stipulates the types of materials used and their weight ratio ranges, including: cementitious material part: P·O42.5 grade cement is used as the base material, with mineral admixtures such as Class I fly ash, S95 mineral powder, and silica fume; Aggregate: Continuously graded crushed stone (particle size range 5-25mm) is used in combination with medium sand. The fineness modulus of sand is controlled at 2.3-2.8 to ensure a good gradation structure. Chemical admixture part: polycarboxylic acid water reducer is used as the basic plasticizer; silane coupling agent is used for aggregate surface modification; nano-CaCO3 nucleating agent assists in forming uniform hydration nuclei.

[0028] The above-mentioned material system constructs a three-phase synergistic structure: the colloidal phase imparts hydration activity, the particle phase provides skeleton bearing capacity, and the interfacial phase realizes structural adhesion, thereby ensuring the fluidity and stability of the concrete system at the macro level, and improving its interfacial strength and hydration uniformity at the micro level, forming the material basis for the regulation of concrete performance.

[0029] Preferably, the dynamic design of concrete mix ratio includes: The water-binder ratio is controlled at 0.32-0.38; The sand rate is set at 40-45%; The total amount of adhesive material is 400-550 parts; The slow-release water-reducing agent is 5-15 parts, and the initial water-reducing rate of the slow-release water-reducing agent is set as: 25-28% when the transportation distance is ≤ 50km or 22-25% when the transportation distance is > 50km; Hydration regulator ratio: the molar ratio of sodium gluconate to aluminum sulfate is 1:0.2-0.5.

[0030] The present invention further clarifies the core parameters that should be controlled in the dynamic mix design process, specifically including: The water-cement ratio is controlled between 0.32–0.38 to achieve a balance between strength and workability; The sand ratio is set at 40–45% to regulate the slurry encapsulation; The total amount of adhesive used is 400–550 parts to ensure sufficient gel; The slow-release water-reducing agent is controlled at 5–15 parts, and its initial water-reducing rate is set at 25–28% (≤50km) or 22–25% (>50km); In terms of hydration regulator, the molar ratio of sodium gluconate to aluminum sulfate was set at 1:0.2–0.5 to regulate the hydration reaction process.

[0031] The implementation principle of this dynamic design is: taking the transportation distance as the main variable, combining the admixture release behavior and early hydration reaction, and constructing a reaction window through the "speed regulation-quantity control-delay" mechanism, thereby enhancing the temporal stability and shear stability of concrete.

[0032] Preferably, the aggregate interface modification treatment includes: Dilute the silane coupling agent into a 1% aqueous solution and spray it evenly on the aggregate surface; After 24 hours of curing, a hybrid interface layer of organic and inorganic materials is formed; The nano-CaCO3 nucleating agent was premixed with 30% mixing water, and the nucleating agent was evenly distributed using an ultrasonic disperser with a frequency of 40 kHz and a time of 10 minutes.

[0033] The aggregate interface modification method proposed in the present invention includes two types of modification paths: A silane coupling agent diluted to 1% aqueous solution is evenly sprayed onto the aggregate surface to form a stable chemical bridge between the aggregate and cement paste through its bifunctional structure; The nano-CaCO3 nucleating agent was premixed with 30% mixing water and treated with an ultrasonic disperser with a frequency of 40 kHz and an action time of 10 minutes to form uniformly distributed crystal nuclei to promote early hydration nucleation.

[0034] The innovation of this treatment solution lies in the use of a dual-path "chemical coupling + physical induction" to enhance interface performance, which not only enhances the bonding strength between the paste and aggregate, but also stabilizes the hydration dynamics behavior of the interface area, thereby improving the structural integrity of the overall concrete system under transportation disturbances.

[0035] Preferably, the optimized concrete mixing process includes: First add the aggregate, then add 70% of the water, then add the glue, nano slurry and water reducer, and finally add the remaining water; use a forced mixer with a speed of 45 rpm and a mixing time of 180 ± 10 seconds; Ensure that the concrete outlet temperature is ≤35℃.

[0036] With respect to the mixing process, the present invention clearly stipulates the following sequence and parameters: The order of adding materials is "aggregate → 70% water → adhesive + nano slurry + water reducer → remaining water", constructing a multi-stage homogenous dispersion process; the stirring is carried out using a forced mixer with a speed set at 45 rpm; The stirring time is controlled at 180±10 seconds; The temperature of concrete leaving the machine shall not exceed 35℃.

[0037] This mixing process accelerates the early uniform formation of the slurry by scientifically distributing water and reactants, while avoiding uneven hydration of the cementitious material due to excessive addition of water at one time, enhancing the stability of particle distribution during the mixing process, and ultimately improving the rheological coordination of the concrete in its initial state.

[0038] Preferably, the rheological properties testing and adjustment include: The thixotropic index is 1.8-2.3, the plastic viscosity is 8-12 Pa·s, and the yield stress is 35-50 Pa; When the thixotropic index is less than 1.8, add 0.02% of nano-nucleating agent; When the plastic viscosity is greater than 12 Pa·s, the sand ratio should be appropriately reduced by 1-2%.

[0039] After concrete mixing is completed, its performance evaluation is achieved by measuring rheological parameters. The measurement indicators include: The thixotropic index ranges from 1.8–2.3; The plastic viscosity range is 8–12 Pa·s; Yield stress range is 35–50 Pa; When the thixotropic index is lower than the set lower limit, add 0.02% nano nucleating agent; When the plastic viscosity exceeds the upper limit, the sand ratio should be appropriately reduced by 1-2%.

[0040] The design logic of this step is to use rheological parameters as external signals that characterize the microstructural state of concrete. By analyzing and adjusting these signals, the mix proportioning or particle grading system is back-tracked in real time, thereby achieving systematic and stable control of the rheological state of concrete, ensuring its good pumpability and anti-separation properties.

[0041] Preferably, the implementation of collapse control includes: The mixer truck speed is set to 2-4 rpm; Real-time monitoring of the mixer tank temperature to ensure that the temperature difference does not exceed 8°C; The slump change of concrete is checked every 30 kilometers, and water reducing agent is added through the automatic adding system when necessary.

[0042] During the concrete transportation process, the present invention implements the following control strategies: Control the mixer truck speed within the range of 2–4 rpm to maintain uniform mixing; Real-time monitoring of the internal and external temperatures of the mixing tank, with the temperature difference controlled to no more than 8°C; The slump is tested every 30 km, and water reducing agent is added using the automatic adding system when necessary.

[0043] This solution inherently introduces real-time controllability into the transportation process, establishing a closed-loop "disturbance-feedback-response" control channel. Its control logic emphasizes the temporal evolution of concrete properties, mitigating performance drift through dynamic interventions. This prevents unstable concrete properties at the transport endpoint and ensures consistent delivery to on-site construction sites.

[0044] Preferably, the adaptability verification performed at the construction site to confirm whether the concrete meets the engineering requirements during the construction process by slump loss and strength testing includes: The slump loss of concrete after 2 hours shall not exceed 30mm; The difference between initial setting time and final setting time is controlled within 30 minutes; The strength reaches 70% of the design value in 3 days; After 56 days, the shrinkage rate of concrete is controlled at 400×10 -6 the following.

[0045] After transportation, the following adaptability verification is carried out at the construction site: Detect slump loss within 2 hours; Measure the difference between initial setting time and final setting time; Determine the compressive strength level at 3 days of age; The drying shrinkage level was determined at 56 days of age.

[0046] This verification method forms a closed-loop performance endpoint for the system of the present invention. Its significance lies not only in performance confirmation but also in the retrospective verification and validation of the rationality of front-end parameter settings. Through on-site indicator feedback, a closed-loop logic of "planning-implementation-verification-correction" is formed, enabling the method to adapt across batches and self-correct across operating conditions.

[0047] In summary, this application includes at least one of the following beneficial technical effects: 1. The present invention adopts a staged feeding and orderly dispersion process, combined with dynamic water replenishment and slump control, to achieve the technical effect of improving the workability of concrete. Compared with the traditional one-time feeding method in the prior art, the present invention can effectively prevent excessive loss of slump of concrete during transportation, and avoids the separation and sedimentation problems caused by uneven feeding in traditional methods.

[0048] 2. The present invention uses a slow-release water-reducing agent in conjunction with a hydration regulator to achieve the technical effect of improving the early strength and anti-separation properties of concrete. Compared with the use of a single water-reducing agent in the prior art, the present invention effectively regulates the cement hydration process, increases the strength growth rate, and reduces the water bleeding rate, thereby significantly improving the stability and uniformity of concrete during transportation.

[0049] 3. The present invention combines the use of silane coupling agent to treat aggregate and nano-CaCO3 nucleating agent to achieve the technical effect of improving the compressive strength and separation resistance of concrete. Compared with the existing solutions that do not use aggregate modification materials, the present invention improves the bonding between aggregate and paste through interface reinforcement and nano-nucleation, thereby improving the overall mechanical properties and stability of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0053] Please see the attached Figure 1 : Example 1: 1. Basic parameters for designing concrete: Concrete strength grade: C45; initial slump: 180mm; transportation distance: 55km; ambient temperature and humidity: 30℃, relative humidity 70%.

[0054] 2. Raw material selection and ratio: Cement: 350 parts of P·O42.5 grade cement; Mineral admixtures: Grade I fly ash: 12 parts; S95 slag: 10 parts; silica fume: 3 parts; aggregate: 5-25mm continuously graded crushed stone: 60 parts; medium sand (fineness modulus 2.6): 33 parts; Admixtures: Polycarboxylate water reducer: 1.0 part; silane coupling agent: 0.3 part; nano-CaCO3 nucleating agent: 0.08 part.

[0055] 3. Dynamic design of mix ratio: Water-cement ratio: 0.35; sand ratio: 42%; total adhesive consumption: 450 parts; slow-release water reducer: 8% (initial water reduction rate is 25%); hydration regulator ratio: molar ratio of sodium gluconate to aluminum sulfate 1:0.4.

[0056] 4. Aggregate interface modification treatment: Silane coupling agent: dilute to 1% aqueous solution, spray evenly on the aggregate surface, and cure for 24 hours; Nano-CaCO3 nucleating agent: premixed with 30% mixing water, using a 40kHz ultrasonic disperser for 10 minutes.

[0057] 5. Mixing process: Adding order: aggregate → 70% water → adhesive + nano slurry + water reducer → remaining water; Mixer speed: 45 rpm; Stirring time: 180 seconds; Output temperature: ≤35℃.

[0058] 6. Rheological properties testing and adjustment: Thixotropic index: 2.0; Plastic viscosity: 9 Pa·s; Yield stress: 38Pa; Adjustment: If the thixotropic index is lower than 1.8, add 0.02% nano-nucleating agent; if the plastic viscosity exceeds 12 Pa·s, appropriately reduce the sand ratio by 1-2%.

[0059] 7. Collapse control during transportation: Mixer truck speed: 2rpm; Check the slump change every 30km: if the slump decreases by more than 15%, add water reducing agent.

[0060] 8. Construction site adaptability verification: Slump loss: no more than 30mm within 2 hours; Strength test: The strength reaches 70% of the design value in 3 days.

[0061] Example 2: 1. Basic parameters for designing concrete: Concrete strength grade: C30; initial slump: 160mm; transportation distance: 45km; ambient temperature and humidity: temperature 25℃, relative humidity 65%.

[0062] 2. Raw material selection and ratio: Cement: 250 parts of P·O42.5 grade cement; Mineral admixtures: Grade I fly ash: 10 parts; S95 slag: 8 parts; silica fume: 2 parts; aggregate: 5-25mm continuously graded gravel: 55 parts; medium sand (fineness modulus 2.4): 30 parts; Admixtures: Polycarboxylate water reducer: 0.8 parts; silane coupling agent: 0.1 parts; nano-CaCO3 nucleating agent: 0.05 parts.

[0063] 3. Dynamic design of mix ratio: Water-binder ratio: 0.32; Sand rate: 40%; Total amount of adhesive material: 400 parts; Slow-release water reducer: 5% (initial water reduction rate is 25%); Hydration regulator ratio: the molar ratio of sodium gluconate to aluminum sulfate is 1:0.2.

[0064] 4. Aggregate interface modification treatment: Silane coupling agent: dilute to 1% aqueous solution, spray evenly on the aggregate surface, and cure for 24 hours; Nano-CaCO3 nucleating agent: premixed with 30% mixing water, using a 40kHz ultrasonic disperser for 10 minutes.

[0065] 5. Mixing process: Adding order: aggregate → 70% water → adhesive + nano slurry + water reducer → remaining water; Mixer speed: 40 rpm; Mixing time: 170 seconds; Output temperature: ≤35℃.

[0066] 6. Rheological properties testing and adjustment: Thixotropic index: 1.8; Plastic viscosity: 8 Pa·s; Yield stress: 35Pa; Adjustment: If the thixotropic index is lower than 1.8, add 0.02% nano-nucleating agent; if the plastic viscosity exceeds 12 Pa·s, appropriately reduce the sand ratio by 1-2%.

[0067] 7. Collapse control during transportation: Mixer truck speed: 3rpm; Check the slump change every 30km: if the slump decreases by more than 15%, add water reducing agent.

[0068] 8. Construction site adaptability verification: Slump loss: no more than 30mm within 2 hours; Strength test: The strength reaches 70% of the design value in 3 days.

[0069] Example 3: 1. Basic parameters for designing concrete: Concrete strength grade: C60; initial slump: 200mm; transportation distance: 70km; ambient temperature and humidity: temperature 35℃, relative humidity 75%.

[0070] 2. Raw material selection and ratio: Cement: 450 parts of P·O42.5 grade cement; Mineral admixtures: Grade I fly ash: 15 parts; S95 slag: 12 parts; silica fume: 5 parts; aggregate: 5-25mm continuously graded crushed stone: 65 parts; medium sand (fineness modulus 2.7): 35 parts; Admixtures: Polycarboxylate water reducer: 1.2 parts; silane coupling agent: 0.5 parts; nano-CaCO3 nucleating agent: 0.1 parts.

[0071] 3. Dynamic design of mix ratio: Water-binder ratio: 0.38; Sand rate: 43%; Total amount of adhesive material: 520 parts; Slow-release water reducer: 15% (initial water reduction rate is 22%); Hydration regulator ratio: the molar ratio of sodium gluconate to aluminum sulfate is 1:0.5.

[0072] 4. Aggregate interface modification treatment: Silane coupling agent: dilute to 1% aqueous solution, spray evenly on the aggregate surface, and cure for 24 hours; Nano-CaCO3 nucleating agent: premixed with 30% mixing water, using a 40kHz ultrasonic disperser for 10 minutes.

[0073] 5. Mixing process: Adding order: aggregate → 70% water → adhesive + nano slurry + water reducer → remaining water; Mixer speed: 50 rpm; Stirring time: 200 seconds; Output temperature: ≤35℃.

[0074] 6. Rheological properties testing and adjustment: Thixotropic index: 2.2; Plastic viscosity: 11 Pa·s; Yield stress: 42Pa; Adjustment: If the thixotropic index is lower than 1.8, add 0.02% nano-nucleating agent; if the plastic viscosity exceeds 12 Pa·s, appropriately reduce the sand ratio by 1-2%.

[0075] 7. Collapse control during transportation: Mixer truck speed: 4rpm; Check the slump change every 30km: if the slump decreases by more than 15%, add water reducing agent.

[0076] 8. Construction site adaptability verification: Slump loss: no more than 30mm within 2 hours; Strength test: The strength reaches 70% of the design value in 3 days.

[0077] Comparative Example 1: Compared with Example 1, the difference is that no silane coupling agent is used to perform interface modification treatment on the aggregate, the aggregate is used directly without surface spraying and curing, and the rest are the same.

[0078] Comparative Example 2: Compared with Example 1, the difference is that no nano-CaCO3 nucleating agent is added, and the rest are the same.

[0079] Comparative Example 3: Compared with Example 1, the difference is that no slow-release water reducer is used, and ordinary polycarboxylic acid water reducer (added once) is used instead, and the water reducer ratio is not dynamically adjusted according to the transportation distance. The rest are the same.

[0080] Comparative Example 4: Compared with Example 1, the difference is that no hydration regulator is used (sodium gluconate and aluminum sulfate are not added), and the rest are the same.

[0081] Comparative Example 5: Compared with Example 1, the difference is that the stirring process is changed to the traditional mixing process (all raw materials and admixtures are added at one time, the stirring time is 120 seconds, and the staged feeding + orderly dispersion process is cancelled), and the rest are the same.

[0082] Comparative Example 6: Compared with Example 1, the difference is that no dynamic slump control is performed during transportation (slump changes are not monitored, and water reducing agent is not added). During transportation, the concrete performance is supported only by the initial design ratio. The rest are the same.

[0083] Experiment 1: Purpose of the experiment: The comprehensive effects of silane coupling agent and nano-CaCO3 nucleating agent on the slump retention performance, early strength development and anti-separation performance of concrete were studied to evaluate its engineering adaptability in long-distance transportation.

[0084] Experimental groups: Example 1: Concrete sample containing silane coupling agent and nano-CaCO3 nucleating agent (prepared product); Comparative Example 1: concrete sample with silane coupling agent removed and containing only nano-CaCO3 nucleating agent; Comparative Example 2: Ordinary concrete sample without silane coupling agent and nano-CaCO3.

[0085] Experimental steps: 1. Carry out the initial slump test by using a standard slump cone and measure the initial slump values ​​of three groups of samples immediately after the concrete is mixed; 2. Simulate transportation of concrete samples for 60 minutes using a room temperature vibration platform to simulate the transportation environment, and then test the slump again to obtain the slump loss; 3. Prepare standard compressive test pieces (100 mm cubes), cure them for 3 days, 7 days, and 28 days, and test the compressive strength; 4. Conduct a separation resistance test to evaluate the separation tendency by screening stability index (uniformity of coarse aggregate distribution) and visual observation of concrete paste segregation (experimental data are shown in Table 1).

[0086] Table 1: Test results of concrete properties in each group of Experiment 1 From Table 1, we can get: In this experiment, Example 1 introduced a silane coupling agent to modify the surface of the coarse aggregate, which significantly improved the interfacial affinity between the aggregate and the cement paste, thereby enhancing the adhesion of the paste to the aggregate surface and effectively suppressing the decline in workability caused by the "slurry absorption" of the aggregate. This is also reflected in the fact that its slump after 60 minutes only lost 15 mm, which is far better than the comparative example group.

[0087] Furthermore, the introduction of nano-CaCO3 nucleating agents has a positive effect on early strength development, with the strength at 3 and 7 days significantly higher than that of the control. This effect can be attributed to the nucleation effect of the nanoparticles promoting the rapid formation of hydration products, providing more microcrystalline nuclei, shortening the hydration induction period, and thus improving early mechanical properties.

[0088] Based on the anti-separation results, Example 1 exhibited the best stability. This is due to the hydrophobic layer formed by the silane coupling agent, which increased the interfacial energy, enabling better coordinated movement of the aggregate with the slurry during mixing and transportation, reducing the sinking of coarse aggregate and the floating of the slurry. These synergistic effects clearly demonstrate the practical application value of the combined use of silane coupling agents and nano-nucleating agents under complex construction conditions.

[0089] Experiment 2: Purpose of the experiment: The effects of slow-release water-reducing agents and hydration regulators (sodium gluconate and aluminum sulfate) on the performance of concrete during long-term transportation were tested, and their regulatory mechanisms on slump retention, strength growth and rheological properties were explored.

[0090] Experimental groups: Example 1: containing a slow-release water reducer + a hydration regulator (sodium gluconate and aluminum sulfate); Comparative Example 3: Containing ordinary polycarboxylate water reducer + hydration regulator (sodium gluconate and aluminum sulfate); Comparative Example 4: Contains ordinary polycarboxylate water-reducing agent, without adding hydration control agent.

[0091] Experimental steps: 1. After mixing each group of samples separately, first conduct an initial slump test and record the results.

[0092] 2. Using standard curing conditions (25°C, humidity control), test the 28-day compressive strength of concrete samples.

[0093] 3. After the sample has been allowed to stand for 120 minutes, a slump rebound test is performed to evaluate the change in slump during transportation.

[0094] 4. Use a rheometer to test the plastic viscosity, yield stress and fluidity index of the samples and analyze the differences in rheological properties.

[0095] 5. The samples were tested for their resistance to separation and their stability was evaluated by the segregation index and water bleeding rate (the experimental data are shown in Table 2).

[0096] Table 2: Effects of water reducing agent type and hydration regulator on concrete properties From Table 2, we can get: Based on the experimental results, Example 1 outperformed Comparative Examples 3 and 4, particularly in terms of slump retention, anti-separation, and rheological properties. Mechanistic analysis suggests that slow-release water reducers can effectively control water retention in cement pastes, delaying the hydration reaction of cement particles and maintaining the workability of concrete over extended periods. Furthermore, the addition of hydration regulators (such as sodium gluconate and aluminum sulfate) can regulate the rate and amount of hydrate formation in the cement paste, preventing strength loss caused by premature hydration while enhancing early strength gains.

[0097] In contrast, despite the addition of a hydration regulator, Comparative Example 3, due to the use of a conventional polycarboxylate superplasticizer, exhibited poor water-reducing properties, failing to maintain the concrete's fluidity. This resulted in significant slump loss and high bleeding rates, reflecting deficiencies in workability control. Comparative Example 4, on the other hand, omitted the use of a hydration regulator, resulting in an overly rapid early hydration reaction, uneven strength growth, and prone to segregation after long-term transportation, ultimately impacting its overall performance.

[0098] Experimental results confirm the mechanism by which the synergistic effect of a slow-release water-reducing agent and a hydration regulator enhances concrete performance. The slow-release water-reducing agent controls the hydration of cement particles, while the hydration regulator optimizes the hydration reaction, achieving better strength growth and controlling rheological properties. Consequently, this combination significantly improves concrete's stability, strength, and workability.

[0099] Experiment 3: Purpose of the experiment: The effects of different mixing processes and collapse control methods (such as staged feeding and dynamic water replenishment control) on the workability, stability and anti-separation performance of concrete during long-term transportation are studied, and their regulation mechanism on the rheological and mechanical properties of concrete is explored.

[0100] Experimental groups: Example 1: Staged feeding + orderly dispersion process + dynamic water replenishment and collapse control; Comparative Example 5: One-time feeding and mixing + no dynamic water replenishment control; Comparative Example 6: One-time feeding and mixing + no dynamic water replenishment control.

[0101] Experimental steps: 1. Mix each group of samples according to the design requirements. First, conduct an initial slump test and record the initial fluidity of each group of concrete.

[0102] 2. Let the mixed sample stand for 120 minutes to simulate the transportation state, measure the slump change, and calculate its slump loss value.

[0103] 3. Use a rheometer to measure the plastic viscosity, yield stress and thixotropic index of the sample to evaluate its fluidity and rheological properties.

[0104] 4. Conduct a separation resistance test on fresh concrete samples and evaluate the stability of concrete by measuring the bleeding rate and segregation index.

[0105] 5. Under standard curing conditions (25°C humidity control), the 3d and 7d compressive strength of each group of concrete was tested to evaluate its early strength and long-term mechanical properties (experimental data are shown in Table 3).

[0106] Table 3: Effects of mixing process and slump control on concrete properties From Table 3 we can get: Experimental results show that the concrete of Example 1 exhibits superior workability and resistance to separation, particularly maintaining good slump during transportation and significantly increasing strength. Mechanistic analysis suggests that the phased addition and orderly dispersion process effectively reduces collision and friction between aggregates, ensuring the uniformity of the concrete paste and thus improving the fluidity and stability of the concrete. Furthermore, dynamic water replenishment control, by adjusting the water content, prevents excessive volatilization or separation, effectively slowing the decay of slump and enhancing the concrete's resistance to separation.

[0107] In contrast, Comparative Examples 5 and 6 performed poorly, particularly in slump loss and bleeding rate, both showing significant disadvantages. This was primarily due to the lack of dynamic water replenishment control, which resulted in rapid water loss from the cement paste during transportation, significantly reducing the fluidity and stability of the concrete. The shortcomings of the one-shot mixing process were also evident in the experiment, as the concrete failed to disperse effectively, leading to significant slump loss during transportation.

[0108] Example 1, through precise hydration control and rheological property adjustment, ensures the fluidity of concrete while enhancing its structural stability. Conventional mixing processes (such as Comparative Examples 5 and 6) fail to optimize the distribution of the cement paste, resulting in poor slump retention and ultimately affecting the strength and anti-segregation properties of the concrete.

[0109] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation, characterized in that: The following steps are involved: S1. Design the basic parameters of concrete according to the required engineering strength requirements of concrete, including determining the concrete strength grade, initial slump, transportation distance and ambient temperature and humidity conditions; S2. Based on the basic parameters of the concrete, select and determine appropriate raw materials, and determine the weight ratio of each component according to the designed ratio; S3. Dynamically designing the concrete mix ratio based on the raw materials; S4. Based on the mix ratio, performing aggregate interface modification treatment, treating the aggregate surface with a silane coupling agent and a nano nucleating agent; S5. Optimizing the concrete mixing process and controlling the mixing sequence and mixing time according to the aggregate interface modification treatment and mix ratio after treatment; S6. Perform rheological property testing and adjustment according to the mix ratio and mixing process; S7. Based on the results of the rheological properties test and adjustment, implement slump control during concrete transportation by real-time monitoring of slump changes and adding water reducing agent; S8. Implement collapse control as described above and conduct adaptability verification at the construction site.

2. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The basic parameters of the designed concrete include: Select the required concrete strength grade C30 to C60; The initial slump is set at 180 ± 20 mm; The transport distance was set to ≤50km or >50km, and different strategies for slow-release of water reducer were adopted; The ambient temperature is set between 5°C and 35°C, and the relative humidity is ≥ 60%.

3. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The selection of the raw materials includes the following components in parts by weight: P·O42.5 grade cement: 200-500 parts; Grade I fly ash: 10-15 parts, S95 slag: 8-12 parts, silica fume: 2-5 parts; 5-25mm continuously graded crushed stone: 55-65 parts and medium sand: 30-35 parts, fineness modulus is 2.3-2.8; Polycarboxylate water reducer: 0.8-1.2 parts; Silane coupling agent: 0.1-0.5 parts; Nano-CaCO3 nucleating agent: 0.05-0.1 parts.

4. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The dynamic design of concrete mix ratio includes: The water-binder ratio is controlled at 0.32-0.38; The sand ratio is set at 40-45%; The total amount of adhesive material is 400-550 parts; The slow-release water-reducing agent is 5-15 parts, and the initial water-reducing rate of the slow-release water-reducing agent is set as: 25-28% when the transportation distance is ≤ 50km or 22-25% when the transportation distance is > 50km; Hydration regulator ratio: the molar ratio of sodium gluconate to aluminum sulfate is 1:0.2-0.

5.

5. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The aggregate interface modification treatment includes: Dilute the silane coupling agent into a 1% aqueous solution and spray it evenly on the aggregate surface; After 24 hours of curing, a hybrid interface layer of organic and inorganic materials is formed; The nano-CaCO3 nucleating agent was premixed with 30% mixing water, and the nucleating agent was evenly distributed using an ultrasonic disperser with a frequency of 40 kHz and a time of 10 minutes.

6. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The optimized concrete mixing process includes: First add the aggregate, then add 70% of the water, then add the glue, nano slurry and water reducer, and finally add the remaining water; Use a forced mixer with a speed controlled at 45 rpm and a stirring time of 180 ± 10 seconds; Ensure that the concrete exit temperature is ≤35℃.

7. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The rheological properties testing and adjustment include: The thixotropic index is 1.8-2.3, the plastic viscosity is 8-12 Pa·s, and the yield stress is 35-50 Pa; When the thixotropic index is less than 1.8, add 0.02% of nano-nucleating agent; When the plastic viscosity is greater than 12 Pa·s, the sand ratio should be appropriately reduced by 1-2%.

8. The method for optimizing the mix ratio of high-slump-proof concrete for long-distance transportation according to claim 1, characterized in that: The implementation of collapse control includes: The mixer truck speed is set to 2-4 rpm; Real-time monitoring of the mixer tank temperature to ensure that the temperature difference does not exceed 8°C; The slump change of concrete is checked every 30 kilometers, and water reducing agent is added through the automatic adding system when necessary.

9. The method for optimizing the mix ratio of high-slump-retaining concrete for long-distance transportation according to claim 1, characterized in that: The adaptability verification at the construction site is carried out through slump loss and strength tests to confirm whether the concrete meets the project requirements during the construction process, including: The slump loss of concrete after 2 hours shall not exceed 30mm; The difference between initial setting time and final setting time is controlled within 30 minutes; The strength reaches 70% of the design value in 3 days; After 56 days, the shrinkage rate of concrete is controlled at 400×10 -6 the following.

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