Concrete mixing control method suitable for high-temperature and high-humidity environment

Abstract

The invention relates to a concrete mixing control method suitable for a high-temperature and high-humidity environment, which comprises the following steps: spraying and cooling 80-100 parts of coarse aggregate to obtain pretreated coarse aggregate; stirring, spraying and cooling 50-60 parts of fine aggregate, and synchronously adding 0.2-0.4 part of silane coupling agent solution to obtain pretreated fine aggregate; the preparation method comprises the following steps: mixing and dispersing 20-30 parts of superfine slag powder and 5-10 parts of silica fume into 15-20 parts of mixing water containing 1-2 parts of a water reducing agent and 0.3-0.4 part of a retarder, and stirring to obtain pre-activated slurry; adding 60-70 parts of low hydration heat cement into the pre-activated slurry, and stirring step by step to obtain a cementing material; and mixing the pretreated coarse aggregate, the pretreated fine aggregate and 20-30 parts of mixing water, adding a cementing material for mixing after mixing, controlling the temperature in the mixing process, and discharging to obtain the concrete mixture. The concrete has the effects of improving the working performance and the early-stage crack resistance of the concrete, and the hydration heat of the concrete is reduced, so that the setting time of the concrete is delayed.

Description

Technical Field

[0001] The present application relates to the technical field of concrete mixing, and in particular to a concrete mixing control method suitable for high temperature and high humidity environments. Background Art

[0002] In the construction industry, concrete, as one of the most widely used building materials, has a performance that directly impacts the quality and safety of construction projects. When projects are located in high-temperature, high-humidity areas, the concrete mixing process faces a series of unique and complex challenges. In these high-temperature, high-humidity environments, ambient temperatures often exceed 30°C, and relative humidity frequently reaches over 80%, leading to elevated initial temperatures in the concrete raw materials and intense hydration reactions.

[0003] Concrete hydration is inherently an exothermic process, and high temperatures further accelerate its reaction kinetics, creating a vicious cycle of "high temperature promoting hydration, followed by further hydration and temperature increase." Heat builds up within large volumes of concrete and is difficult to dissipate. When the temperature difference between the core and the surface exceeds 20°C, the tensile stress induced by the temperature gradient exceeds the concrete's early tensile strength, leading to through-hole cracks. These cracks not only serve as pathways for harmful media to enter, but also weaken the structure's bearing capacity and shorten its service life, thus requiring improvement. Summary of the Invention

[0004] In order to improve the performance of concrete, the present application provides a concrete mixing control method suitable for high temperature and high humidity environments.

[0005] The present application provides a concrete mixing control method suitable for high temperature and high humidity environments, which adopts the following technical solution: A concrete mixing control method suitable for high temperature and high humidity environments, comprising the following steps: (1) spraying and cooling 80-100 parts of coarse aggregate to obtain pretreated coarse aggregate; stirring and spraying 50-60 parts of fine aggregate to obtain pretreated fine aggregate, and simultaneously adding 0.2-0.4 parts of silane coupling agent solution to obtain pretreated fine aggregate; (2) 20-30 parts of slag powder and 5-10 parts of silica fume are mixed and dispersed into 15-20 parts of mixing water containing 1-2 parts of water reducer and 0.3-0.4 parts of retarder, and stirred to obtain a pre-activated slurry; 60-70 parts of low-hydration hot cement are added to the pre-activated slurry, and stirred step by step to obtain a cementitious material; (3) Mix the pretreated coarse aggregate, the pretreated fine aggregate and 20-30 parts of mixing water. After mixing, add the cementitious material and mix. Control the temperature during the mixing process and discharge the material to obtain a concrete mixture.

[0006] Cooling the coarse aggregate and fine aggregate separately can effectively reduce the evaporation rate of water caused by high temperature and reduce the slump loss; adding silane coupling agent solution when mixing and spraying the fine aggregate to cool it can improve the interface bonding between aggregate and cement paste, improve the fluidity and water retention of concrete, and enable the concrete to maintain good working performance in high temperature and high humidity environments; the pozzolanic reaction of slag powder and silica fume can fill the internal pores of concrete and improve density; water reducer can reduce the water-cement ratio and increase strength; retarder can delay the hydration process of cement, effectively solving the problem of excessive cement hydration speed under high temperature. The problem of too short setting time caused by rapid hydration is solved, ensuring that the concrete has enough time for construction operations; the use of low hydration heat cement can reduce the release of cement hydration heat, reduce the temperature difference between the interior and surface of the concrete, and reduce cracks caused by temperature stress; silane coupling agent improves interfacial bonding, makes the internal structure of concrete more stable, and can effectively inhibit the occurrence of plastic shrinkage cracks. At the same time, the filling effect of slag powder and silica fume also enhances the overall strength and deformation resistance of concrete, further improving its early crack resistance, so that concrete can better meet engineering needs in high temperature and high humidity environments.

[0007] Preferably, the temperature of the pretreated coarse aggregate and the pretreated fine aggregate in step (1) is lower than 25°C.

[0008] Low-temperature coarse aggregate and fine aggregate can reduce the initial temperature base during the mixing process, effectively inhibit the early hydration reaction of cement particles, and delay the initial setting time. At the same time, the low temperature environment can slow down the evaporation rate of water, allowing the silane coupling agent solution on the surface of the fine aggregate to penetrate more fully and form a stable interface film, thereby enhancing the mechanical meshing force between the aggregate and the paste; the low-temperature aggregate and the subsequently added mixing water form a gradient cooling system, which reduces the internal temperature peak of the concrete, thereby reducing the early microcracks caused by temperature stress.

[0009] Preferably, in step (1), the coarse aggregate is sprayed with cold water having a temperature lower than 10°C and cooled by sunshade; the fine aggregate is sprayed with water mist having a particle size less than 0.5 mm and a temperature lower than 10°C, and is stirred by air blowing, and the moisture content of the pretreated fine aggregate is less than 4%.

[0010] The coarse aggregate is sprayed with cold water combined with sunshade cooling, which can quickly reduce the aggregate temperature to below 25°C, inhibit the early hydration reaction of cement particles, and delay the initial setting time; the fine aggregate is sprayed with small-particle low-temperature water mist, combined with air blowing and stirring, so that the water penetrates evenly and evaporates quickly, ensuring the moisture content is less than 4%, avoiding the problem of over-wetting of aggregate caused by traditional spraying, and accelerating cooling through high-speed airflow; at low temperatures, the silane coupling agent solution can more easily penetrate into the microporous structure of the fine aggregate, forming an interfacial film and enhancing the mechanical meshing force between the aggregate and the paste; through the synergistic effect of precise control of aggregate temperature, moisture content and interface modification, the problems of excessive slump loss of concrete, early hydration heat concentration and plastic shrinkage cracking in high temperature and high humidity environments are effectively suppressed.

[0011] Preferably, the temperature of the mixing water is lower than 15°C.

[0012] Low-temperature mixing water and pre-treated low-temperature coarse aggregate and fine aggregate form a gradient cooling system, which can reduce the concrete outlet temperature and effectively delay the cement hydration reaction rate, thereby extending the initial setting time and improving the slump retention rate; at the same time, low-temperature water can enhance the dispersion effect of the water reducer, so that the cementitious material particles remain in a stable dispersed state and reduce the slump loss caused by high temperature; the low-temperature environment inhibits the hydrolysis rate of the silane coupling agent, so that it forms a denser interface film on the surface of the fine aggregate, enhancing the strength of the aggregate-paste interface transition zone, thereby effectively inhibiting the occurrence of early plastic shrinkage cracks.

[0013] Preferably, in step (2), the mixture is stirred at a speed of 1000-2000 rpm for 1.5-2.5 min to obtain a pre-activated slurry.

[0014] The shear force generated by high-speed stirring can quickly disperse the slag powder and silica fume in the mixing water to form a uniform suspension system, thereby improving the pozzolanic reactivity of the cementitious material; at the same time, high-speed stirring promotes the adsorption of water-reducing agent molecules on the surface of cement particles, enhances the electrostatic repulsion between particles, and delays the cement hydration process; the silica fume in the pre-activated slurry improves the density of concrete through filling effect and micro-aggregate effect, and inhibits the occurrence of early plastic shrinkage cracks; by optimizing the slurry structure and the synergistic effect with the effectiveness of admixtures, the slump retention rate of concrete is improved, the early crack resistance and workability are enhanced, and the setting time is delayed.

[0015] Preferably, after adding the low-hydration hot cement to the preactivated slurry in step (2), the mixture is stirred at a speed of 10-30 rpm for 20-40 s, and then the speed is increased to 40-50 rpm and stirred for 80-100 s, so that the coefficient of variation is less than 3%.

[0016] After adding low-hydration hot cement to the pre-activated slurry, it is first stirred at a low speed to allow the cement particles to fully infiltrate the pre-activated slurry, preliminarily disperse the cement agglomerates, and evenly distribute the cement particles in the slurry; then the stirring speed is increased, and the water reducer can play a more full role, forming a stable adsorption layer on the surface of the cement particles, effectively delaying the hydration reaction of the cement, thereby extending the initial setting time of the concrete; this stirring method can evenly disperse the slag powder and silica fume in the system, fill the pores of the cement stone, enhance the density of the internal structure of the concrete, ensure the stability and uniformity of the concrete performance, improve the working performance, coagulation performance and early crack resistance of the concrete, and make it more suitable for use in high temperature and high humidity environments.

[0017] Preferably, in step (3), the gelling material is added in 2-4 times, with an interval of 10-20 seconds between each addition; liquid nitrogen is added during mixing, the temperature is controlled at 22-26°C, and the discharge temperature is lower than 25°C.

[0018] Adding cementitious materials in batches with a certain interval between each addition can make the cementitious materials evenly integrated into the system, avoid excessive concentration of local cementitious materials due to one-time addition, and ensure the uniformity and stability of each part of the concrete; controlling the temperature during mixing and discharging, the low temperature environment can effectively inhibit the hydration reaction rate of cement, prolong the initial setting time, so that the concrete has more time for construction operations and improve the working performance of the concrete; low temperature reduces the evaporation of water and the temperature stress inside the concrete, reduces the possibility of early plastic shrinkage cracking, and improves the early crack resistance.

[0019] Preferably, the water reducer comprises a polycarboxylic acid high performance retarding water reducer.

[0020] Polycarboxylic acid molecules adsorb onto the surface of cement particles through a comb-like structure, forming a solvated film, enhancing the electrostatic repulsion between particles and slowing the rate of cement hydration reaction. At the same time, the retarding groups react with tricalcium aluminate in the cement to form a complex, inhibiting the rapid formation of ettringite and effectively controlling the loss of slump over time. The high water-reducing rate of the water-reducing agent can reduce the water-cement ratio, reduce the number of capillaries, and increase the density of concrete, thereby inhibiting the occurrence of early plastic shrinkage cracks. The water-reducing agent works synergistically with the aggregate pretreatment process to form a stable and dispersed cementitious network structure in the low-temperature mixing system, enabling the concrete to maintain excellent workability, controllable setting time and outstanding crack resistance even in high temperature and high humidity environments.

[0021] Preferably, the raw materials for preparing the retarder include sulfonated gluconolactone, aminotri(methylenephosphonic acid) and acrylamide.

[0022] Sulphonated gluconolactone delays the formation of hydration products by chelating calcium ions in cement; aminotrimethylenephosphonic acid is adsorbed on the surface of tricalcium aluminate, inhibiting its rapid hydration, thereby reducing slump loss; acrylamide forms a three-dimensional network structure through copolymerization, enhancing the stability of the retarder in an alkaline environment; the retarder synthesized by the three components can still remain active under high temperature and high humidity conditions, and improves the performance of concrete by inhibiting early hydration of cement, reducing the hydration heat release rate and optimizing the rheological properties of the slurry; the retarder and water reducer work synergistically to reduce water The dispersing effect of the agent provides a more sufficient diffusion path for the retarder molecules, allowing them to be more evenly adsorbed on the surface of cement particles, thereby enhancing the retarding effect; at the same time, the complexing effect of the retarder can stabilize the dispersion state of the water reducer and reduce the slump loss; the two together inhibit the early hydration heat release of cement, reduce the temperature rise rate inside the concrete, and reduce the early cracks caused by temperature stress. Combined with the water-reducing effect of the water reducer and the water-retention effect of the retarder, the concrete can still maintain excellent workability, controllable setting time and good crack resistance in high temperature and high humidity environments.

[0023] Preferably, the mass ratio of the sulfonated gluconolactone, aminotri(methylenephosphonic acid) and acrylamide is 1:0.17:(0.08-0.1).

[0024] The retarder prepared according to the above mass ratio can effectively synergize with the water reducer to improve the working performance, setting performance and crack resistance of concrete in high temperature and high humidity environments.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. Cooling the coarse aggregate and fine aggregate separately can effectively reduce the evaporation rate of water caused by high temperature and reduce the slump loss; adding silane coupling agent solution when mixing and spraying the fine aggregate to cool it can improve the interface bonding between the aggregate and cement paste, improve the fluidity and water retention of the concrete, and enable the concrete to maintain good working performance in high temperature and high humidity environments; the pozzolanic reaction of slag powder and silica fume can fill the internal pores of the concrete and improve the density; the water-reducing agent can reduce the water-cement ratio and increase the strength; the retarder can delay the hydration process of the cement, effectively solving the problem of cement hydration speed under high temperature. The problem of too short setting time caused by too fast setting is solved to ensure that the concrete has enough time for construction operations; the use of low hydration heat cement can reduce the release of cement hydration heat, reduce the temperature difference between the interior and surface of the concrete, and reduce cracks caused by temperature stress; silane coupling agent improves interfacial bonding, makes the internal structure of concrete more stable, and can effectively inhibit the occurrence of plastic shrinkage cracks. At the same time, the filling effect of slag powder and silica fume also enhances the overall strength and deformation resistance of concrete, further improving the early crack resistance, so that the concrete can better meet the engineering needs in high temperature and high humidity environments.

[0026] 2. The coarse aggregate is sprayed with cold water combined with sunshade cooling, which can quickly reduce the aggregate temperature to below 25°C, inhibit the early hydration reaction of cement particles, and delay the initial setting time. The fine aggregate is sprayed with small-particle low-temperature water mist, combined with air mixing to ensure uniform water penetration and rapid evaporation, ensuring a moisture content of <4%. This avoids the problem of over-wetting of aggregate caused by traditional spraying and accelerates cooling through high-speed airflow. At low temperatures, the silane coupling agent solution can more easily penetrate into the microporous structure of the fine aggregate, forming an interfacial film and enhancing the mechanical meshing force between the aggregate and the paste. Through the synergistic effect of precise control of aggregate temperature, water content and interface modification, problems such as rapid slump loss of concrete, early hydration heat concentration, and plastic shrinkage cracking in high temperature and high humidity environments are effectively suppressed.

[0027] 3. Sulphonated gluconolactone chelates calcium ions in cement, delaying the formation of hydration products; aminotrimethylenephosphonic acid adsorbs on the surface of tricalcium aluminate, inhibiting its rapid hydration, thereby reducing slump loss; acrylamide forms a three-dimensional network structure through copolymerization, enhancing the stability of the retarder in an alkaline environment; the retarder synthesized by the three components can still maintain activity under high temperature and high humidity conditions, improving the performance of concrete by inhibiting early hydration of cement, reducing the hydration heat release rate and optimizing the rheological properties of the paste; the retarder and water reducer work synergistically to reduce The dispersing effect of the water agent provides a more sufficient diffusion path for the retarder molecules, allowing them to be more evenly adsorbed on the surface of cement particles, thereby enhancing the retarding effect. At the same time, the complexing effect of the retarder can stabilize the dispersion state of the water reducer and reduce the slump loss. The two together inhibit the early hydration heat release of cement, reduce the temperature rise rate inside the concrete, and reduce early cracks caused by temperature stress. Combined with the water-reducing effect of the water reducer and the water-retention effect of the retarder, the concrete can still maintain excellent workability, controllable setting time and good crack resistance in high temperature and high humidity environments. DETAILED DESCRIPTION

[0028] The present application discloses a concrete mixing control method suitable for high temperature and high humidity environments. The raw materials used in the present application can be obtained from commercially available raw materials unless otherwise specified. The present application is further described in detail in conjunction with the examples below: Raw materials: Gluconolactone (CAS No.: 90-80-2), sodium p-styrenesulfonate (CAS No.: 2695-37-6), ammonium persulfate (CAS No.: 7727-54-0), aminotri(methylenephosphonic acid) (CAS No.: 6419-19-8), acryloyldimethylamine (CAS No.: 16-11-14), 1,2-dimethylaminobenzoic acid ... Amine (CAS No.: 79-06-1), potassium persulfate (CAS No.: 7727-21-1), coarse aggregate is 5-40mm crushed stone with a mud content of ≤1.0%, fine aggregate is 0.15-5mm machine-made sand with a mud content of ≤3.0%, silane coupling agent is KH-550 (CAS No.: 919-30-2), slag powder is S95 grade, water reducer is polycarboxylic acid high-performance retarding water reducer, model BASF Glenium 51, and low-heat hydration cement is low-heat Portland cement P·LH 42.5.

[0029] Example 1 Preparation of retarder 1 kg of gluconolactone, 1.15 kg of sodium p-styrenesulfonate and 21.5 g of ammonium persulfate were dispersed in 2 L of deionized water, nitrogen was introduced to exhaust the air, and the mixture was stirred at 200 rpm in a 70 ° C water bath for 4 h. After the reaction was completed, the mixture was cooled to below 30 ° C, and the pH was adjusted to 7 with 1 mol / L sodium hydroxide solution. The mixture was concentrated under reduced pressure and freeze-dried to obtain sulfonated gluconolactone.

[0030] 0.8 kg of sulfonated gluconolactone and 0.136 kg of aminotri(methylenephosphonic) acid were dispersed in 1.5 L of deionized water and stirred at 200 rpm until fully dissolved to obtain a mixed solution. After nitrogen was introduced into the mixed solution to expel air, the solution was heated in a water bath to 75° C., 0.064 kg of acrylamide was added in three portions with an interval of 15 minutes between each addition. After the first addition of acrylamide, a 5% potassium persulfate aqueous solution containing 12.5 g of potassium persulfate was added dropwise for 1 hour. After the addition was complete, the mixture was stirred at 80° C. at 200 rpm for 4 hours, cooled to below 30° C., and then the pH was adjusted to 7 with a 1 mol / L sodium hydroxide solution to obtain a retarder.

[0031] Concrete mixing control method suitable for high temperature and high humidity environment (1) 80 parts of coarse aggregate are sprayed with cold water at a temperature below 10°C for cooling, and after spraying, they are shielded with a sunshade and cooled to below 25°C to obtain pretreated coarse aggregate; 50 parts of fine aggregate are sprayed with water mist at a temperature below 10°C and a particle size of less than 0.5 mm for cooling, and at the same time, they are assisted by air blowing treatment, 0.2 parts of silane coupling agent solution is added when spraying the fine aggregate, and the mass concentration of the silane coupling agent solution is 5%, and the temperature is cooled to below 25°C to obtain pretreated fine aggregate, and the water content of the pretreated fine aggregate is less than 4%; (2) 20 parts of slag powder and 5 parts of silica fume are mixed and dispersed into 15 parts of mixing water containing 1 part of water reducer and 0.3 part of retarder, the mixing water temperature is lower than 15°C, and stirred at a speed of 1000 rpm for 2.5 minutes to obtain a preactivated slurry; 60 parts of low-hydration hot cement are added to the preactivated slurry, first stirred at a speed of 10 rpm for 40 seconds, and then increased to 40 rpm and stirred for 100 seconds, so that the coefficient of variation is less than 3%, to obtain a cementitious material; (3) Pretreated coarse aggregate, pretreated fine aggregate and 20 parts of mixing water are mixed, and the mixing water temperature is lower than 15°C. After mixing, cementitious materials are added in two times, with an interval of 20 seconds between each addition; liquid nitrogen is added during mixing, and the temperature is controlled at 22-26°C. The material is discharged, and the temperature during discharge is lower than 25°C to obtain a concrete mixture.

[0032] Example 2 Preparation of retarder 1 kg of gluconolactone, 1.15 kg of sodium p-styrenesulfonate and 21.5 g of ammonium persulfate were dispersed in 2 L of deionized water, nitrogen was introduced to exhaust the air, and the mixture was stirred at 200 rpm in a 70 ° C water bath for 4 h. After the reaction was completed, the mixture was cooled to below 30 ° C, and the pH was adjusted to 7 with 1 mol / L sodium hydroxide solution. The mixture was concentrated under reduced pressure and freeze-dried to obtain sulfonated gluconolactone.

[0033] 0.79 kg of sulfonated gluconolactone and 0.13 kg of aminotri(methylenephosphonic) acid were dispersed in 1.5 L of deionized water and stirred at 200 rpm until fully dissolved to obtain a mixed solution. After nitrogen was introduced into the mixed solution to expel air, the mixed solution was heated in a water bath to 75° C., 0.08 kg of acrylamide was added in three portions with an interval of 15 minutes between each addition. After the first addition of acrylamide, a 5% potassium persulfate aqueous solution containing 12.5 g of potassium persulfate was added dropwise for 1 hour. After the addition was complete, the mixture was stirred at 80° C. at 200 rpm for 4 hours, cooled to below 30° C., and then the pH was adjusted to 7 with a 1 mol / L sodium hydroxide solution to obtain a retarder.

[0034] Concrete mixing control method suitable for high temperature and high humidity environment (1) 100 parts of coarse aggregate are sprayed with cold water at a temperature below 10°C for cooling, and after spraying, they are covered with a sunshade and cooled to below 25°C to obtain pretreated coarse aggregate; 60 parts of fine aggregate are sprayed with water mist at a temperature below 10°C and a particle size of less than 0.5 mm for cooling, and at the same time, air blowing is performed as an auxiliary. When spraying the fine aggregate, 0.4 parts of a silane coupling agent solution is added, and the mass concentration of the silane coupling agent solution is 5%. The temperature is cooled to below 25°C to obtain pretreated fine aggregate, and the water content of the pretreated fine aggregate is less than 4%; (2) 30 parts of slag powder and 10 parts of silica fume are mixed and dispersed into 20 parts of mixing water containing 2 parts of water reducer and 0.4 parts of retarder, the mixing water temperature is lower than 15°C, and stirred at a speed of 2000 rpm for 1.5 minutes to obtain a preactivated slurry; 70 parts of low-hydration hot cement are added to the preactivated slurry, first stirred at a speed of 30 rpm for 20 seconds, and then increased to 50 rpm and stirred for 80 seconds, so that the coefficient of variation is less than 3%, thereby obtaining a cementitious material; (3) Pretreated coarse aggregate, pretreated fine aggregate and 30 parts of mixing water are mixed, and the mixing water temperature is lower than 15°C. After mixing, cementitious materials are added in 4 times, with an interval of 10 seconds between each addition; liquid nitrogen is added during mixing, and the temperature is controlled at 22-26°C. The material is discharged, and the temperature during discharge is lower than 25°C to obtain a concrete mixture.

[0035] Example 3 Preparation of retarder 1 kg of gluconolactone, 1.15 kg of sodium p-styrenesulfonate and 21.5 g of ammonium persulfate were dispersed in 2 L of deionized water, nitrogen was introduced to exhaust the air, and the mixture was stirred at 200 rpm in a 70 ° C water bath for 4 h. After the reaction was completed, the mixture was cooled to below 30 ° C, and the pH was adjusted to 7 with 1 mol / L sodium hydroxide solution. The mixture was concentrated under reduced pressure and freeze-dried to obtain sulfonated gluconolactone.

[0036] 0.79 kg of sulfonated gluconolactone and 0.14 kg of aminotri(methylenephosphonic) acid were dispersed in 1.5 L of deionized water and stirred at 200 rpm until fully dissolved to obtain a mixed solution. After nitrogen was introduced into the mixed solution to expel air, the solution was heated in a water bath to 75° C., 0.07 kg of acrylamide was added in three portions with an interval of 15 minutes between each addition. After the first addition of acrylamide, a 5% potassium persulfate aqueous solution containing 12.5 g of potassium persulfate was added dropwise for 1 hour. After the addition was complete, the mixture was stirred at 80° C. at 200 rpm for 4 hours, cooled to below 30° C., and then the pH was adjusted to 7 with a 1 mol / L sodium hydroxide solution to obtain a retarder.

[0037] Concrete mixing control method suitable for high temperature and high humidity environment (1) 90 parts of coarse aggregate are sprayed with cold water at a temperature below 10°C for cooling, and after spraying, they are shielded with a sunshade and cooled to below 25°C to obtain pretreated coarse aggregate; 55 parts of fine aggregate are sprayed with water mist at a temperature below 10°C and a particle size of less than 0.5 mm for cooling, and at the same time, they are assisted by air blowing treatment, 0.3 parts of silane coupling agent solution is added when spraying the fine aggregate, and the mass concentration of the silane coupling agent solution is 5%, and the temperature is cooled to below 25°C to obtain pretreated fine aggregate, and the water content of the pretreated fine aggregate is less than 4%; (2) 25 parts of slag powder and 7.5 parts of silica fume were mixed and dispersed into 17.5 parts of mixing water containing 1.5 parts of water reducer and 0.35 parts of retarder, the mixing water temperature was lower than 15°C, and stirred at a speed of 1500 rpm for 2 minutes to obtain a preactivated slurry; 65 parts of low-hydration hot cement were added to the preactivated slurry, and stirred at a speed of 20 rpm for 30 seconds, and then increased to 45 rpm and stirred for 90 seconds, so that the coefficient of variation was less than 3%, thereby obtaining a cementitious material; (3) Mix the pretreated coarse aggregate, pretreated fine aggregate and 25 parts of mixing water, the mixing water temperature is lower than 15 ° C. After mixing, add the cementitious material in three times, with an interval of 15 seconds between each addition; add liquid nitrogen during mixing, control the temperature at 22-26 ° C, and discharge the material. The temperature of the material is lower than 25 ° C when discharging to obtain a concrete mixture.

[0038] Example 4 Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that in Example 4, the amount of sulfonated gluconolactone is 0.82 kg, the amount of aminotri(methylenephosphonic acid) is 0.14 kg, and the amount of acrylamide is 0.04 kg.

[0039] Example 5 Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that in Example 5, the amount of sulfonated gluconolactone is 0.76 kg, the amount of aminotri(methylenephosphonic acid) is 0.13 kg, and the amount of acrylamide is 0.11 kg.

[0040] Example 6 Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the coarse aggregate and the fine aggregate are not pre-cooled, and the coarse aggregate and the fine aggregate are directly used for mixing.

[0041] Example 7 Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that the temperature of the mixing water in Example 7 is 20°C.

[0042] Example 8 Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that in step (2) of Example 8, stirring is performed at a speed of 500 rpm for 5 minutes to obtain a pre-activated slurry.

[0043] Example 9 Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that in step (2) of Example 9, after adding low-hydration hot cement to the preactivated slurry, it is first stirred at a speed of 40 rpm for 15 seconds, and then the speed is increased to 60 rpm and stirred for 70 seconds.

[0044] Example 10 Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that the gelling material is added all at once in step (3) of Example 10.

[0045] Comparative Example 1 Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the retarder in Comparative Example 1 is replaced by sulfonated gluconolactone.

[0046] Comparative Example 2 Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that conventional mixing means is used to prepare the concrete mixture in Comparative Example 2.

[0047] 90 parts of room temperature coarse aggregate, 55 parts of room temperature fine aggregate, 25 parts of slag powder, 7.5 parts of silica fume and 65 parts of low hydration hot cement were mixed, and dry-mixed at a speed of 50 rpm for 1 minute. 42.5 parts of mixing water were added, and the mixing water contained 1.5 parts of water reducer, 0.2 parts of retarder and 0.3 parts of 5% silane coupling agent solution. The mixture was wet-mixed at a speed of 300 rpm for 3 minutes, and the material was discharged to obtain a concrete mixture.

[0048] Performance testing (1) The GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures was selected as the standard to test the slump, initial setting time and final setting time of the samples. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0049] (2) GB / T 50107 Concrete Strength Test and Evaluation Standard and GB / T 50204 Concrete Structure Engineering Construction Quality Acceptance Code were selected as the standards. The plastic shrinkage cracking was tested using the flat plate method. The samples were placed at 30°C and 75% humidity for 24 hours. The total cracking area per unit area was calculated. Each sample was tested three times and the average value was taken after measurement. The results are recorded in Table 1.

[0050] Table 1 Test results of concrete slump, initial setting time, final setting time and early crack resistance As shown in Table 1, the slump of Examples 1-3 is between 190-200 mm, the initial setting time is greater than 4.9 h, the final setting time is greater than 9.1 h, and the total cracking area is less than 93 mm. 2 / m 2 , which shows that the concrete prepared in this application has good working performance, setting performance and early crack resistance.

[0051] As can be seen from Table 1, the only difference between Examples 4 and 5 and Example 3 is that the mass ratio of sulfonated gluconolactone, aminotri(methylenephosphonic acid) and acrylamide in Example 4 is 1:0.17:0.05, and the mass ratio of sulfonated gluconolactone, aminotri(methylenephosphonic acid) and acrylamide in Example 5 is 1:0.17:0.15. Compared with Example 3, the performance of Examples 4 and 5 is reduced. This is because the optimal ratio is destroyed. Excessive acrylamide will aggravate the entanglement of molecular chains, hinder the diffusion of the retarder, and reduce the retarding efficiency. The reduction of acrylamide will affect the formation of the three-dimensional network, reduce its stability, easily decompose at high temperature, and affect the dispersibility, thereby reducing the performance of the concrete.

[0052] As can be seen from Table 1, the only difference between Examples 6 and 7 and Example 3 is that the coarse aggregate and fine aggregate were not pre-cooled in Example 6, while the mixing water temperature was increased in Example 7. Compared with Example 3, the performance of Examples 6 and 7 was reduced. This is because the increase in the temperature of the aggregate and the mixing water both accelerates the hydration reaction, resulting in faster evaporation of water, which in turn leads to a decrease in the performance of the concrete.

[0053] As can be seen from Table 1, the only differences between Examples 8, 9, and 10 and Example 3 are: in Example 8, preactivated slurry is obtained by low-speed stirring, in Example 9, the stirring speed is increased after adding low-hydration hot cement, and in Example 10, the cementitious material is added all at once. Compared with Example 3, the performance of Examples 8, 9, and 10 is reduced. This is because low-speed stirring affects the uniformity and activity of the preactivated slurry, resulting in insufficient slurry encapsulation; increasing the stirring speed after adding cement will increase the temperature, resulting in accelerated hydration reaction; and adding the cementitious material all at once will cause uneven dispersion of the cementitious material, aggravate local hydration, concentrate internal stress, and thus reduce the performance of the concrete.

[0054] As can be seen from Table 1, the only difference between Comparative Example 1 and Example 3 is that the retarder in Comparative Example 1 is replaced with sulfonated gluconolactone. Compared with Example 3, the performance of Comparative Example 1 is reduced. This is because the retarder only uses sulfonated gluconolactone, which lacks synergistic effect between components and also reduces the synergistic effect with the water reducer. As a result, the slump decreases, the water-reducing and retarding effects are weakened, the temperature rise is rapid, and the shrinkage stress increases, resulting in a significant decline in performance.

[0055] As can be seen from Table 1, the only difference between Comparative Example 2 and Example 3 is that conventional concrete mixing is used in Comparative Example 2, and the performance of Comparative Example 2 is significantly reduced compared with Example 3. This is because the hydration reaction is rapid and the shrinkage is out of control due to the lack of temperature control and the one-time mixing. As a result, the performance is significantly reduced.

[0056] This specific embodiment is merely an explanation of the present application and does not limit the present application. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present application. The technical scope of the present application is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A concrete mixing control method suitable for high temperature and high humidity environments, characterized by: The following steps are involved: (1) 80-100 parts of coarse aggregate are sprayed and cooled to obtain pretreated coarse aggregate; 50-60 parts of fine aggregate are stirred and sprayed to cool, and 0.2-0.4 parts of silane coupling agent solution are added simultaneously to obtain pretreated fine aggregate; (2) 20-30 parts of slag powder and 5-10 parts of silica fume are mixed and dispersed into 15-20 parts of mixing water containing 1-2 parts of water reducer and 0.3-0.4 parts of retarder, and stirred to obtain a pre-activated slurry; 60-70 parts of low-hydration hot cement are added to the pre-activated slurry, and stirred in steps to obtain a cementitious material; (3) Mix the pretreated coarse aggregate, pretreated fine aggregate and 20-30 parts of mixing water. After mixing, add the cementitious material and mix. Control the temperature during the mixing process and discharge the material to obtain a concrete mixture.

2. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 1, characterized in that: The temperature of the pretreated coarse aggregate and the pretreated fine aggregate in step (1) is lower than 25°C.

3. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 2, characterized in that: In the step (1), the coarse aggregate is sprayed with cold water having a temperature lower than 10°C and cooled by sunshade; the fine aggregate is sprayed with water mist having a particle size less than 0.5 mm and a temperature less than 10°C, and is stirred by air, and the moisture content of the pretreated fine aggregate is less than 4%.

4. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 1, characterized in that: The temperature of the mixing water is lower than 15°C.

5. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 1, characterized in that: In the step (2), the mixture is stirred at a speed of 1000-2000 rpm for 1.5-2.5 minutes to obtain a pre-activated slurry.

6. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 5, characterized in that: In step (2), after adding the low-hydration hot cement to the pre-activated slurry, the mixture is stirred at a speed of 10-30 rpm for 20-40 s, and then the speed is increased to 40-50 rpm and stirred for 80-100 s, so that the coefficient of variation is less than 3%.

7. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 1, characterized in that: In step (3), the gelling material is added in 2-4 times, with an interval of 10-20 seconds between each addition; liquid nitrogen is added during mixing, the temperature is controlled at 22-26°C, and the discharge temperature is lower than 25°C.

8. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 1, characterized in that: The water reducer includes a polycarboxylic acid high-performance retarding water reducer.

9. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 8, characterized in that: The raw materials for preparing the retarder include sulfonated gluconolactone, aminotrimethylenephosphonic acid and acrylamide.

10. The concrete mixing control method suitable for high temperature and high humidity environment according to claim 9, characterized in that: The mass ratio of the sulfonated gluconolactone, aminotri(methylenephosphonic acid) and acrylamide is 1:0.17:(0.08-0.1).

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