Temperature-inhibiting self-compacting impervious waterproof agent

Abstract

The invention discloses a temperature-inhibiting self-compacting impervious waterproof agent and a preparation method thereof, and relates to the technical field of building materials. The waterproof agent comprises the following components in parts by weight: 30 parts of modified bentonite, 20 parts of rubber powder, 20 parts of urea, 15 parts of a retarder, 15 parts of calcium formate, 10 parts of superfine stone powder, 10 parts of an efficient powder shrinkage reducing agent, 7 parts of an organic silicon water repellent, 3 parts of calcium carbonate whiskers, 3 parts of a polycarboxylate superplasticizer, 0.1 part of an air entraining agent, 1 part of cellulose ether and 0.3 part of lithium carbonate. Through the synergistic effect of the lithium carbonate and the cellulose ether, the contradiction between coagulation acceleration and water retention is effectively solved, so that the concrete is more uniform and compact in internal structure while rapidly forming early strength, and the temperature inhibition, self-compaction, anti-permeability and anti-cracking properties in severe environments such as high temperature, low humidity and high salinity are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a temperature-suppressing, self-sealing, waterproofing agent. Background Technology

[0002] In the field of building materials technology, concrete, due to its brittleness, susceptibility to cracking, and the inherent heat release and shrinkage characteristics of cement hydration, has always been a focus of industry attention regarding its structural impermeability, waterproofing, and durability. The causes of concrete leakage and cracking can be mainly divided into two categories: leakage caused by insufficient density, and cracking leading to leakage due to load, chemical shrinkage, drying shrinkage, and temperature shrinkage. Existing technologies typically employ single methods such as adding expanding agents, shrinkage reducing agents, or fibers to address specific issues, but these methods often fail to simultaneously and effectively solve the dual challenges of density and crack resistance, especially in complex practical engineering environments.

[0003] The most fundamental flaw in existing concrete crack-resistant and waterproofing technologies lies in the mismatch between the regulation of its internal hydration process and the demands of the complex external environment. Specifically, water-retaining components added to improve crack resistance slow down cement hydration, leading to slow early strength development and impacting construction progress; while accelerators added to improve early strength accelerate water consumption and exacerbate plastic shrinkage, contradicting the original purpose of water-retaining components. This inherent contradiction between "accelerating setting" and "retaining water" makes it impossible to simultaneously achieve optimal performance in both the critical plasticity period and the early strength formation period of concrete, resulting in a persistently high risk of early cracking and a bottleneck in improving impermeability. Actual measurements show that concrete using conventional admixtures, under standard curing conditions, often has an early (24-hour) compressive strength below 8 MPa, while the flat crack area exceeds 300 mm². 2 / m 2 .

[0004] This is particularly relevant for more demanding engineering environments. For example, in marine engineering projects, inland salt lake areas, or bridge decks where de-icing salt is used in winter, the concrete structure is constantly exposed to Cl... - The environment is characterized by high salinity (at least 0.5%) and corrosive conditions. Simultaneously, the construction environment experiences temperature fluctuations (5℃-35℃) and dry conditions with relative humidity below 60%. Under these combined conditions, salt severely interferes with the effectiveness of water-retaining components, while temperature and humidity changes exacerbate the plastic shrinkage and temperature stress of concrete, significantly reducing the effectiveness of existing single-function admixture systems, or even rendering them completely ineffective. Summary of the Invention

[0005] This application provides a temperature-suppressing, self-compacting, seepage-resistant, and waterproofing agent, which solves the problems existing in the prior art; it achieves temperature suppression, self-compacting, seepage-resistant, and crack-resistant properties in harsh environments such as high temperature, low humidity, and high salinity.

[0006] This application provides a temperature-suppressing, self-compacting, seepage-resistant, and waterproofing agent, comprising the following components in parts by weight: 30 parts modified bentonite, 20 parts adhesive powder, 20 parts urea, 15 parts retarder, 15 parts calcium formate, 10 parts ultrafine stone powder, 10 parts high-efficiency powder shrinkage reducer, 7 parts organosilicon water-repellent agent, 3 parts calcium carbonate whiskers, 3 parts polycarboxylate water-reducing agent, 0.1 parts air-entraining agent, 1 part cellulose ether, and 0.3 parts lithium carbonate.

[0007] Furthermore, the cellulose ether is hydroxypropyl methylcellulose with a viscosity of 37,000-42,000 mPa·s, and 95% of the particles can pass through a 0.3 mm standard sieve.

[0008] Furthermore, the lithium carbonate is passed through a 180-mesh sieve.

[0009] Furthermore, the modified bentonite is prepared by the following method: sodium-based bentonite is mixed with ferric sulfate solution with a concentration of 1 mol / L at a mass ratio of 1:10, stirred at a speed of 1000 rpm for 1 hour, and then aged at room temperature for 24 hours; the aged slurry is filtered, washed with water, dried and ground, and finally the powder is passed through a 0.075 mm standard sieve.

[0010] Furthermore, the preparation method of the temperature-suppressing self-sealing waterproofing agent is as follows: Lithium carbonate, calcium formate, and ultrafine stone powder are added to a mixer at a speed of 400 r / min for 6 minutes. While the mixer is running, modified bentonite is added, the speed is increased to 500 r / min, and mixing continues for 8 minutes. Then, adhesive powder, urea, retarder, high-efficiency powder shrinkage reducer, calcium carbonate whiskers, and polycarboxylate superplasticizer are added in sequence, and the speed is maintained at 500 r / min for 13 minutes. Slowly and evenly sprinkle the premixed cellulose ether mixture into the running mixer, adjust the mixer speed to 200 r / min, and mix for 20 minutes; then add all the remaining ingredients, increase the mixer speed to 500 r / min, and continue mixing for 10 minutes to obtain the final product.

[0011] Furthermore, the premixing method for the cellulose ether mixture is as follows: the cellulose ether is manually stirred for 2 minutes in a small premixer with an equal weight of organosilicon hydrophobic agent and air-entraining agent to form a loose mixture.

[0012] Furthermore, the premixing method for the cellulose ether mixture is as follows: the cellulose ether is manually stirred for 2 minutes in a small premixer with an equal weight of organosilicon hydrophobic agent and air-entraining agent, and then lithium acid is added for premixing. The mixture is then mixed at 300 r / min for 15 min to complete the premixing.

[0013] Furthermore, the lithium carbonate added to the premix accounts for 30% of the total mass of lithium carbonate.

[0014] Furthermore, the lithium carbonate added in the premix is ​​also coated with hydroxypropyl cellulose phthalate, specifically by coating lithium carbonate and hydroxypropyl cellulose phthalate at a mass ratio of 1:0.4 using a solvent evaporation method.

[0015] Furthermore, the lithium carbonate added to the premix accounts for 50% of the total mass of lithium carbonate.

[0016] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: By employing a combination of lithium carbonate and cellulose ethers, particularly hydroxypropyl methylcellulose, this technique effectively addresses the technical problems in existing concrete technologies, such as slow early strength development, high risk of plastic shrinkage cracking, and significant performance degradation under high temperature, low humidity, and high salinity environments, caused by the mutual constraint between the concrete's setting and water-retention functions. This results in improved workability, rapid early strength development, high internal density, excellent impermeability, and significantly enhanced crack resistance. Furthermore, by adding lithium carbonate in stages and coating some of it, precise and intelligent control of the cement hydration process is achieved, further mitigating the heat release during hydration and optimizing the development of mechanical properties and long-term durability. Detailed Implementation

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0018] Example 1: A temperature-suppressing, self-compacting, seepage-resistant, and waterproofing agent, comprising, by weight: 30 parts modified bentonite, 20 parts adhesive powder, 20 parts urea, 15 parts retarder, 15 parts calcium formate, 10 parts ultrafine stone powder, 10 parts high-efficiency powder shrinkage reducer, 7 parts organosilicon water-repellent agent, 3 parts calcium carbonate whiskers, 3 parts polycarboxylate water-reducing agent, 0.1 parts air-entraining agent, 1 part cellulose ether, and 0.3 parts lithium carbonate; The cellulose ether is hydroxypropyl methylcellulose, with a viscosity (20℃, 2% aqueous solution) of 37000-42000 mPa·s and a particle size of ≥95% passing through a 0.3mm standard sieve.

[0019] Lithium carbonate passed through an 180-mesh sieve Modified bentonite was prepared by mixing sodium-based bentonite with 1 mol / L Fe2(SO4)3 solution at a mass ratio of 1:10, stirring at 1000 r / min for 1 h until uniformly mixed, and then aging at room temperature for 24 h. The aged slurry was then subjected to filtration, washing, drying and grinding at room temperature. Finally, the powder was passed through a 0.075 μm standard sieve to obtain modified bentonite.

[0020] The adhesive powder is a fast-dissolving resin adhesive powder; The calcium carbonate whiskers have a particle size of 0.5–1.5 μm, a length of 20–40 μm, and a needle-like content of >95%; Ultrafine stone powder is an ultrafine powder material made by grinding siliceous or calcareous natural stone to a specific surface area of ​​1000-1500 m² / kg. The retarder is sodium gluconate; The high-efficiency powder shrinkage reducing agent is a polyethylene glycol alkyl shrinkage reducing agent; The air-entraining agent is sodium dodecyl sulfate; Its preparation method is as follows: The measured lithium carbonate, calcium formate, and ultrafine stone powder were added to a mixer. The mixer speed was 400 r / min, and the mixing time was 6 minutes. While the mixer was running, modified bentonite was added, the speed was increased to 500 r / min, and the mixing was continued for 8 minutes. Then, the adhesive powder, urea, retarder, high-efficiency powder shrinkage reducer, calcium carbonate whiskers, and polycarboxylate superplasticizer were added in sequence, and the speed was maintained at 500 r / min for 13 minutes. The measured cellulose ether and an equal weight of organosilicon water-repellent agent and air-entraining agent are manually stirred for 2 minutes in a small premixer to form a loose mixture. The premixed cellulose ether mixture is then slowly and evenly sprinkled into a running mixer. The mixer speed is adjusted to 200 r / min and the mixing time is 20 minutes. Then, all the remaining ingredients are added, the mixer speed is increased to 500 r / min, and the mixture is continued to mix for another 10 minutes to obtain the final product.

[0021] To verify the water retention and long-term durability of cellulose ether under high temperature and low humidity conditions, a control experiment was conducted, which was a test to verify the combination of cellulose ether and lithium carbonate; except for the cellulose ether and lithium carbonate to be verified, the other components were the same as in Example 1. The experiments included: Experiment 1: blank control, without cellulose ether and lithium carbonate; Experiment 2: containing 0.5 parts of cellulose ether; Experiment 3: containing 1 part of cellulose ether; Experiment 4: containing 2 parts of cellulose ether; Experiment 5: containing 1 part of cellulose ether and 0.1 parts of lithium carbonate; Experiment 6: containing 1 part of cellulose ether and 0.3 parts of lithium carbonate; Experiment 7: containing 1 part of cellulose ether and 0.5 parts of lithium carbonate; Experiment 8: containing 0.3 parts of lithium carbonate. The concrete mix design used in the experiment was as follows: 170 parts water, 190 parts cement (P·O 42.5), 80 parts mineral powder, 80 parts fly ash, 777 parts river sand (containing 2.45% mud), 1023 parts crushed stone (5-31.5mm continuous gradation), 6.5 parts water-reducing agent, and 17.5 parts waterproofing agent. The experimental environment simulated high-temperature and low-humidity conditions: temperature 35℃, relative humidity 50%, and the mixing water contained 3.5% NaCl to simulate a high-salt environment. The testing standards referred to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The impermeability test was conducted using the penetration height method (impermeability pressure 1.6 MPa, constant pressure for 24 hours), and the crack resistance test was conducted using the plate cracking test (size 800 mm × 600 mm × 100 mm, containing 7 crack inducers, surface wind speed ≥ 5 m / s); the test results are shown in Table 1.

[0022] Table 1 Experimental results of the embodiments

[0023] Cellulose ether is a high-molecular-weight polymer whose molecular chains extend in water to form a hydration layer, significantly increasing the solution viscosity. This effectively encapsulates and fixes free water, reducing its migration ability. Furthermore, on the concrete surface, hydroxypropyl methylcellulose molecules can form an extremely thin water-retaining film, greatly slowing down the rate of water evaporation into the atmosphere. The reduction in crack area indicates that hydroxypropyl methylcellulose has water-retaining properties, inhibiting plastic shrinkage and improving the crack resistance of concrete. With the increase of hydroxypropyl methylcellulose, the slump decreases, and the retarding effect of hydroxypropyl methylcellulose and the microbubbles it introduces slightly affect the density of the cement paste. Lithium carbonate is a highly efficient accelerator that can significantly accelerate the early hydration reaction of tricalcium silicate in silicate cement, shorten the setting time, and rapidly form early strength. However, it also indicates that the addition of lithium carbonate alone can exacerbate plastic cracking due to excessively rapid hydration and rapid water consumption, which is not conducive to volume stability under high temperature conditions. Lithium carbonate addresses the side effects of hydroxypropyl methylcellulose (HMC): The retarding effect of HMC inevitably leads to slow early strength development in concrete. In high-salt environments, the large amount of sodium and chloride ions in the solution severely interferes with the hydration of HMC molecular chains, causing them to shrink and drastically reduce water retention capacity. The addition of lithium carbonate, whose released lithium ions are among the most potent cement hydration accelerators known, counteracts the excessive retarding caused by HMC, ensuring that the concrete can build up sufficient strength in the early stages without affecting the construction progress such as formwork removal. Lithium carbonate also consumes free water and calcium ions in the pore solution, reducing the ionic strength and allowing its water retention function to function normally during the critical few hours of the concrete's plastic stage. Hydroxypropyl methylcellulose addresses the side effects of lithium carbonate: Lithium carbonate accelerates hydration, which exacerbates water consumption and temperature rise, easily causing cracking. Hydroxypropyl methylcellulose, through its strong water retention capacity, provides an internal curing environment for accelerated hydration, preventing a surge in capillary pressure and plastic shrinkage caused by excessive water consumption, thereby effectively inhibiting cracking. Hydroxypropyl methylcellulose's water-retention properties ensure the full hydration of cement, while lithium carbonate-guided rapid hydration generates a denser early hydration product structure; the combination of the two allows concrete to rapidly develop strength while having a more uniform and dense internal structure.

[0024] Example 2: Example 1 uses a combination of lithium carbonate and hydroxypropyl methylcellulose to make the concrete more uniform and denser in internal structure while rapidly developing strength. In order to further improve the early performance and long-term durability of concrete, further improvements are made based on Example 1.

[0025] Its preparation method is as follows: The measured first lithium carbonate, calcium formate, and ultrafine stone powder were added to a mixer. The mixer speed was 400 r / min, and the mixing time was 6 minutes. While the mixer was running, modified bentonite was added, the speed was increased to 500 r / min, and the mixing was continued for 8 minutes. Then, the adhesive powder, urea, retarder, high-efficiency powder shrinkage reducer, calcium carbonate whiskers, and polycarboxylate superplasticizer were added in sequence, and the speed was maintained at 500 r / min for 13 minutes. The measured cellulose ether and an equal weight of organosilicon hydrophobic agent and air-entraining agent were manually stirred for 2 minutes in a small premixer to form a loose mixture; then the mixture was premixed with the second lithium carbonate at 300 r / min for 15 min to complete the premixing. Slowly and evenly sprinkle the premixed cellulose ether mixture into the running mixer, adjust the mixer speed to 200 r / min, and mix for 20 minutes; then add all the remaining ingredients, increase the mixer speed to 500 r / min, and continue mixing for 10 minutes to obtain the final product.

[0026] The mass ratio of the first lithium carbonate to the second lithium carbonate is 7:3; The first lithium carbonate serves to fully mix the early-strength components, forming a highly active early-strength core; the second lithium carbonate serves to uniformly disperse with hydroxypropyl methylcellulose, physically isolating the hydroxypropyl methylcellulose. The detection method is the same as in Example 1. The only difference in the experimental grouping is the mass ratio of the first lithium carbonate and the second lithium carbonate. The experimental results are shown in Table 2. Table 2 Experimental results of Example 2

[0027] The experimental results clearly show that the staged addition strategy of lithium carbonate has a significant impact on the performance of concrete. Staged addition of lithium carbonate significantly optimizes the hydration process and final performance of concrete. The peak time of hydration exothermic reaction in Case 2 was delayed compared to the control group with a single addition, indicating a smoother hydration process. This smoother hydration process resulted in better workability retention. Case 2 achieved the highest 1-day and 28-day compressive strengths while maintaining a relatively fast setting time. In terms of durability, Case 2 also performed best, demonstrating excellent impermeability and crack resistance. This performance improvement stems from the precise control of the cement hydration process through the staged addition strategy. When lithium carbonate is added in two stages, the larger dose in the first stage dissolves rapidly, providing sufficient lithium ions to initiate cement hydration. Especially in high-salt environments, these lithium ions can quickly consume free water and calcium ions in the pore solution, effectively reducing the interference of salt ions on the hydration of hydroxypropyl methylcellulose molecules, creating favorable conditions for the normal functioning of hydroxypropyl methylcellulose's water-retention function. Meanwhile, in the second stage, lithium carbonate is partially encapsulated and physically isolated by hydroxypropyl methylcellulose, which delays its dissolution and reaction time. This avoids excessive concentration of hydration heat and prevents microstructural stress concentration and defects caused by excessively high instantaneous hydration heat.

[0028] Example 3: In order to make more intelligent optimizations, further improvements were made based on Example 2.

[0029] The second lithium carbonate is further coated with hydroxypropyl cellulose phthalate. The lithium carbonate and hydroxypropyl cellulose phthalate are coated by solvent evaporation at a mass ratio of 1:0.4, with a coating rate of 35%-45%. The mass ratio of the first lithium carbonate to the second lithium carbonate is 1:1. After experimental grouping, the mass ratio of lithium carbonate 1 to lithium carbonate 2 was 3:1, 1:1, and 1:3; the experimental results are shown in Table 3. Table 3 Experimental results of Example 3

[0030] The introduction of a pH-responsive system significantly altered the hydration exothermic characteristics. The second peak time of the hydration exothermic reaction in a 1:1 lithium carbonate mass ratio was delayed, indicating effective regulation of the hydration process. This not only did not impair mechanical properties but also led to better strength development. This performance improvement stems from the intelligent hydration regulation mechanism created by the pH-responsive system. In the initial stage of concrete mixing, the first lithium carbonate dissolves rapidly, releasing lithium ions to initiate cement hydration—a process similar to that of traditional accelerators. However, as hydration progresses, the pH of the pore solution continuously rises. When the coating dissolution threshold (pH 13.5-13.7) is reached, the second lithium carbonate begins to play its role. The release of coated lithium carbonate is not based on a simple time delay but on pH changes directly related to the degree of hydration. This intelligent response mechanism produces multiple positive effects: First, the accelerator effect is precisely distributed to different stages of hydration, ensuring not only early strength development but also providing continuous power during the hydration deceleration period, preventing hydration stagnation. Second, by smoothing the hydration exothermic process, the generation of microcracks caused by temperature stress is reduced. Third, this smooth hydration process creates more favorable conditions for the water retention function to function, enabling it to effectively inhibit water evaporation and reduce the risk of plastic shrinkage during the plastic stage of concrete.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent, characterized in that, The product comprises the following components in parts by weight: 30 parts modified bentonite, 20 parts adhesive powder, 20 parts urea, 15 parts retarder, 15 parts calcium formate, 10 parts ultrafine stone powder, 10 parts high-efficiency powder shrinkage reducer, 7 parts organosilicon hydrophobic agent, 3 parts calcium carbonate whiskers, 3 parts polycarboxylate superplasticizer, 0.1 parts air-entraining agent, 1 part cellulose ether, and 0.3 parts lithium carbonate.

2. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 1, characterized in that, The cellulose ether is hydroxypropyl methylcellulose with a viscosity of 37,000-42,000 mPa·s, and 95% of the particles can pass through a 0.3 mm standard sieve.

3. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 1, characterized in that, Lithium carbonate passes through a 180-mesh sieve.

4. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 1, characterized in that, Modified bentonite is prepared by the following method: sodium-based bentonite is mixed with ferric sulfate solution with a concentration of 1 mol / L at a mass ratio of 1:10, stirred at a speed of 1000 rpm for 1 hour, and then aged at room temperature for 24 hours; the aged slurry is filtered, washed with water, dried and ground, and finally the powder is passed through a 0.075 mm standard sieve.

5. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 1, characterized in that, The preparation method of the temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent is as follows: Lithium carbonate, calcium formate, and ultrafine stone powder are added to a mixer at a speed of 400 r / min for 6 minutes. While the mixer is running, modified bentonite is added, the speed is increased to 500 r / min, and mixing continues for 8 minutes. Then, adhesive powder, urea, retarder, high-efficiency powder shrinkage reducer, calcium carbonate whiskers, and polycarboxylate superplasticizer are added in sequence, and the speed is maintained at 500 r / min for 13 minutes. Slowly and evenly sprinkle the premixed cellulose ether mixture into the running mixer, adjust the mixer speed to 200 r / min, and mix for 20 minutes; Then add all the remaining ingredients, increase the mixer speed to 500 rpm, and continue mixing for 10 minutes to obtain the final product.

6. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 5, characterized in that, The premixing method for the cellulose ether mixture is as follows: the cellulose ether is manually stirred for 2 minutes in a small premixer with an equal weight of organosilicon hydrophobic agent and air-entraining agent to form a loose mixture.

7. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 5, characterized in that, The premixing method for the cellulose ether mixture is as follows: the cellulose ether is manually stirred for 2 minutes in a small premixer with an equal weight of organosilicon hydrophobic agent and air-entraining agent, and then lithium carbonate is added for premixing. The mixture is then mixed at 300 r / min for 15 min to complete the premixing.

8. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 7, characterized in that, The lithium carbonate added to the premix accounts for 30% of the total mass of lithium carbonate.

9. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 5, characterized in that, The lithium carbonate added in the premix is ​​also coated with hydroxypropyl cellulose phthalate, specifically by coating lithium carbonate and hydroxypropyl cellulose phthalate at a mass ratio of 1:0.4 using a solvent evaporation method.

10. The temperature-suppressing, self-sealing, seepage-resistant, and waterproofing agent as described in claim 9, characterized in that, The lithium carbonate added to the premix accounts for 50% of the total mass of lithium carbonate.

Images