Composite hydration temperature rising inhibitor, its preparation method and application

Abstract

The present application belongs to the technical field of concrete admixtures, and particularly discloses a composite hydration temperature rise inhibitor and a preparation method thereof. The present application provides a composite slow-release material with a novel structure to coat retarding acid with hydration temperature rise inhibition and hydrolysis products such as small-molecule sugar produced by hydrolysis of chitosan. When applied to concrete, the composite slow-release material can slowly swell during the cement hydration process, slowly release the retarding acid and small-molecule sugar coated therein, and inhibit the number of nucleation in the early stage of cement hydration by adsorbing cement particles or chelating calcium ions in the cement. The composite slow-release material itself has an adsorption effect and can adsorb early nucleation particles. The number of early nucleation particles is effectively reduced, the cement hydration rate is slowed down, and the purpose of hydration regulation is achieved. Moreover, the slow release of the retarding acid does not cause the problem of excessively prolonged setting time. The composite hydration temperature rise inhibitor has good application in inhibiting temperature cracks of concrete.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, specifically relating to a composite hydration temperature rise inhibitor, its preparation method, and its application in inhibiting temperature cracks in concrete. Background Technology

[0002] Cracks in large-volume concrete have always been a pressing issue in engineering, resulting in significant manpower and material costs for repairs every year. Therefore, reducing the occurrence of cracks in large-volume concrete has become a hot research topic in engineering. There are many causes of concrete cracks, mainly categorized as shrinkage cracks, temperature cracks, and settlement cracks; among these, shrinkage cracks and temperature cracks are the two primary forms of cracks.

[0003] Temperature cracks are caused by large temperature differences in concrete. During the hardening process, the cement in a concrete structure releases a large amount of heat of hydration, causing the internal temperature to rise continuously. This results in a significant temperature difference between the concrete surface and its interior, with the internal expansion exceeding the external expansion. At this point, the concrete surface experiences substantial tensile stress, which the early tensile strength of the concrete is too low to withstand, leading to cracking. Clearly, the key to temperature cracking lies in the large temperature difference between the inside and outside. Therefore, reducing this temperature difference is crucial to minimizing temperature cracking. A common method is to lay cooling water pipes. However, due to the excessive heat release during early cement hydration, especially in thick walls, the cooling efficiency of cooling water pipes is insufficient. If the peak rate of cement hydration heat release can be reduced to a certain extent, and this is combined with cooling water pipes, the temperature difference between the inside and outside of large-volume concrete can be effectively reduced. Materials that can reduce the peak rate of cement hydration heat release are called cement hydration rate regulating materials.

[0004] Currently, there are numerous reports on improved cement hydration rate control materials for addressing temperature cracks, such as CN104710131A, CN 105060762A, JP 2017165627A, and JP 2020093940A. It can be seen that in these reports on hydration temperature rise inhibitors, they are mainly prepared by modifying starch or dextrin. However, since starch or dextrin has low solubility in water, organic solvents are involved in the reaction, which is not in line with environmental protection principles.

[0005] Therefore, in response to the numerous technical problems currently existing, there is an urgent need to develop a new type of concrete hydration temperature rise inhibitor to solve the problem of temperature cracks in concrete. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a composite hydration temperature rise inhibitor. This hydration temperature rise inhibitor achieves the purpose of hydration regulation through the dual effects of slowly releasing the effective hydration temperature rise inhibiting component and adsorbing nucleating substances in early cement. Moreover, its preparation process is simple, generates no waste liquid, and meets environmental protection requirements.

[0007] The inventors of this invention discovered through long-term research that common small-molecule acids such as tartaric acid and citric acid have certain hydration regulation properties, but their direct use results in a severe retardation effect. Furthermore, the inventors also found that controlling the number of nuclei formed in the initial stage of hydration is one of the essential factors for hydration regulation performance.

[0008] Based on this, the present invention provides a composite hydration temperature rise inhibitor, which is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and slow-coagulating acid and chitosan hydrolysate coated in the composite slow-release material.

[0009] The hydrolyzed chitosan / activated fly ash composite slow-release material is formed by cross-linking hydrolyzed chitosan (i.e., obtained by partial hydrolysis of chitosan under strong acid) and activated fly ash (i.e., obtained by activation of fly ash under acidic conditions) under the action of a cross-linking agent.

[0010] The crosslinking agent was specifically chosen as non-toxic and environmentally friendly ammonium zirconium carbonate.

[0011] Partial hydrolysis of chitosan under nitric acid conditions increases its solubility, yielding hydrolyzed chitosan and releasing some small-molecule sugars from the hydrolysis. Meanwhile, activation of fly ash under acidic conditions activates its surface pore structure, allowing the activated fly ash to adsorb small molecules (i.e., the slow-release acid and small-molecule sugars produced by chitosan hydrolysis). Under the action of a cross-linking agent, both materials cross-link through the hydroxyl groups in the cross-linking agent molecules with the hydroxyl groups in the activated fly ash and hydrolyzed chitosan, forming a composite hydration temperature rise-inhibiting material with a slow-release effect. Using nitric acid to provide the acidic conditions for chitosan hydrolysis avoids the problems of residual chloride ions in hydrochloric acid and the weak oxidizing power of sulfuric acid, which hinder chitosan hydrolysis.

[0012] Furthermore, the retarding acid can be selected from any one or a mixture of at least two of tartaric acid, citric acid, oxalic acid, and hydroxyethylidene diphosphonic acid. These retarding acids, while exerting a retarding effect, also have an inhibitory effect on hydration temperature rise.

[0013] The aforementioned composite hydration temperature rise inhibitor of this invention employs a hydrolyzed chitosan / activated fly ash composite slow-release material to encapsulate both a slow-setting acid that inhibits hydration temperature rise and hydrolysis products such as small-molecule sugars generated from chitosan hydrolysis. When applied to concrete, after mixing with cement, on the one hand, the composite hydration temperature rise inhibitor particles slowly swell during cement hydration, and the encapsulated slow-setting acid and small-molecule sugars are slowly released. These can inhibit the number of early nucleation particles in cement hydration by adsorbing cement particles or chelating calcium ions in the cement; on the other hand, the hydrolyzed chitosan / activated fly ash composite slow-release material itself has an adsorption effect, which can adsorb early nucleation particles. Through these two effects, the number of early nucleation particles is effectively reduced, slowing down the cement hydration rate, thereby achieving hydration regulation performance. Furthermore, the slow-setting acid release does not cause excessively prolonged setting time.

[0014] The preparation method of the above-mentioned composite hydration temperature rise inhibitor provided by the present invention includes the following steps:

[0015] S1. Chitosan is hydrolyzed under strong acid at 80℃~90℃ for 2h~4h to obtain a first liquid phase containing partially hydrolyzed chitosan;

[0016] S2. Disperse fly ash and retarding acid thoroughly in water to obtain a second liquid phase;

[0017] S3. Mix the first liquid phase and the second liquid phase evenly, stir for 1 to 2 hours, add the crosslinking agent to crosslink, and continue the reaction for 1 hour to obtain the third liquid phase.

[0018] S4. The third liquid phase is dried and pulverized to obtain the above-mentioned composite hydration temperature rise inhibitor.

[0019] Furthermore, in the first liquid phase, the mass fraction of chitosan is 10.0%–20.0%, and the mass fraction of strong acid is 2.0%–4.0%; in the second liquid phase, the mass fraction of fly ash is 10%–20%, and the mass fraction of retarding acid is 3%–10%.

[0020] Furthermore, in the third liquid phase, the mass ratio of chitosan, fly ash, and crosslinking agent is 1:1 to 2:0.2 to 0.5.

[0021] The preparation method provided by this invention effectively enables the reuse of industrial waste fly ash, which aligns with environmental protection principles. Furthermore, since fly ash is a type of concrete admixture, it is more readily accepted and utilized. Compared to simply using chitosan and fly ash as adsorbents, this invention cross-links the two together, allowing them to also function as a slow-release material.

[0022] The composite hydration temperature rise inhibitor provided by this invention can be applied to concrete to suppress temperature cracks. The composite hydration temperature rise inhibitor is added to the concrete at an amount of 0.6% to 1% of the total mass of cementitious materials in the pre-added concrete. Detailed Implementation

[0023] The embodiments of the present invention will now be described in detail. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the various embodiments of the invention and various modifications suitable for particular intended applications.

[0024] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, or product that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, or products.

[0025] In the various preparation embodiments of the present invention, a variety of composite hydration temperature rise inhibitors with different proportions and compositions are provided. To demonstrate their excellent performance in suppressing temperature cracks when applied to concrete, the composite hydration temperature rise inhibitors provided in the various preparation embodiments were applied to the concrete preparation process, and the properties of the obtained concrete specimens were measured.

[0026] Preparation Example 1

[0027] This preparation example provides a composite hydration temperature rise inhibitor and its preparation method, including the following steps:

[0028] (1) Add 100g chitosan and 20g nitric acid to 880g water and carry out hydrolysis reaction at 80℃ for 4h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0029] (2) Disperse 200g fly ash and 30g citric acid in 770g water to obtain a second liquid phase.

[0030] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1 hour, add 20g of zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0031] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and citric acid and chitosan hydrolysate coated in the composite slow-release material.

[0032] Preparation Example 2

[0033] This preparation example provides a composite hydration temperature rise inhibitor and its preparation method, including the following steps:

[0034] (1) Add 100g chitosan and 20g nitric acid to 380g water and carry out hydrolysis reaction at 90℃ for 2h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0035] (2) Disperse 100g fly ash and 40g tartaric acid in 860g water to obtain a second liquid phase.

[0036] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 2 hours, add 50g of zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0037] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and tartaric acid and chitosan hydrolysate coated in the composite slow-release material.

[0038] Preparation Example 3

[0039] This preparation example provides a composite concrete hydration temperature rise inhibitor and its preparation method, including the following steps:

[0040] (1) Add 150g chitosan and 30g nitric acid to 820g water and carry out hydrolysis reaction at 85℃ for 3h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0041] (2) Disperse 225g of fly ash and 120g of hydroxyethylidene diphosphonic acid in 1155g of water to obtain a second liquid phase.

[0042] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1.5 hours, add 45g of ammonium zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0043] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and hydroxyethylidene diphosphonic acid and chitosan hydrolysate coated in the composite slow-release material.

[0044] Preparation Example 4

[0045] This preparation example provides a composite concrete hydration temperature rise inhibitor and its preparation method, including the following steps:

[0046] (1) 160g chitosan and 35g nitric acid were added to 805g water and hydrolyzed at 82℃ for 2.5h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0047] (2) Disperse 256g of fly ash and 71g of citric acid in 1095g of water to obtain a second liquid phase.

[0048] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1.6 hours, add 64g of ammonium zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0049] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and citric acid and chitosan hydrolysate coated in the composite slow-release material.

[0050] Preparation Example 5

[0051] This preparation example provides a composite concrete hydration temperature rise inhibitor and its preparation method, including the following steps:

[0052] (1) 180g of chitosan and 27g of nitric acid were added to 793g of water and hydrolyzed at 84℃ for 3.4h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0053] (2) Disperse 234g of fly ash and 126g of oxalic acid in 1440g of water to obtain a second liquid phase.

[0054] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1.2 h, add 61.2 g of zirconium carbonate, continue the cross-linking reaction for 1 h, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0055] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and oxalic acid and chitosan hydrolysate coated in the composite slow-release material.

[0056] Preparation Example 6

[0057] This preparation example provides a composite concrete hydration temperature rise inhibitor and its preparation method, including the following steps:

[0058] (1) 130g chitosan and 28g nitric acid were added to 842g water and hydrolyzed at 88℃ for 3.1h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0059] (2) Disperse 234g fly ash, 30g citric acid and 44g tartaric acid in 1819g water to obtain the second liquid phase.

[0060] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1.3 hours, add 55.9 g of ammonium zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0061] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, and citric acid, tartaric acid and chitosan hydrolysate coated in the composite slow-release material.

[0062] Preparation Example 7

[0063] This preparation example provides a composite concrete hydration temperature rise inhibitor and its preparation method, including the following steps:

[0064] (1) 170g chitosan and 33g nitric acid were added to 797g water and hydrolyzed at 81℃ for 3.8h to obtain a first liquid phase containing partially hydrolyzed chitosan and chitosan hydrolysate (mainly small molecule sugars).

[0065] (2) 187g fly ash, 33.57g citric acid, 25g oxalic acid, 50g hydroxyethylidene diphosphonic acid and 25g tartaric acid were fully dispersed in 1015.14g water to obtain the second liquid phase.

[0066] (3) Mix the first liquid phase and the second liquid phase evenly, stir for 1.3 hours, add 42.5 g of zirconium carbonate, continue the cross-linking reaction for 1 hour, pour the reaction mixture into a tray, place it in an oven to dry, and pulverize it to obtain the composite hydration temperature rise inhibitor.

[0067] This composite hydration temperature rise inhibitor is composed of a hydrolyzed chitosan / activated fly ash composite slow-release material, as well as various slow-release acids (citric acid, oxalic acid, hydroxyethylidene diphosphonic acid and tartaric acid) and chitosan hydrolysate coated in the composite slow-release material.

[0068] The composite hydration temperature rise inhibitor provided by this invention can be applied to concrete to improve its crack resistance.

[0069] Generally, it is added to the concrete at a rate of 0.6% to 1% of the total mass of cementitious materials in the concrete to obtain crack-resistant concrete specimens.

[0070] Tables 1 and 2 below show the application of the composite hydration temperature rise inhibitors obtained in the above preparation examples in concrete.

[0071] Table 1 shows the basic mix proportions of the crack-resistant concrete specimens provided in Application Examples 1 to 7.

[0072]

[0073] Table 2 shows the dosage of composite hydration temperature rise inhibitor in the crack-resistant concrete specimens provided in Application Examples 1 to 7.

[0074]

[0075] In the above-described application embodiments of the present invention, the cement used in Table 1 is Conch Cement, the fly ash is Grade I fly ash, the sand is medium sand with a fineness modulus of 2.6 to 2.9, the aggregate is basalt with a particle size of 16 mm to 25 mm and the aggregate is basalt with a particle size of 5 mm to 16 mm, and an appropriate water-reducing agent is added to obtain a suitable concrete state. Furthermore, the dosage of the composite hydration temperature rise inhibitor in Table 2 refers to its mass percentage relative to the total mass of cementitious materials (cement and fly ash) in the concrete.

[0076] Meanwhile, in order to demonstrate the anti-cracking effect of the composite hydration temperature rise inhibitor provided in the above preparation embodiments of the present invention when applied to concrete, the following comparative experiments were conducted.

[0077] Comparative Example 1

[0078] No hydration temperature rise inhibitors were added in this comparative example; that is, the first concrete comparative specimen was made only according to the concrete foundation mix proportions shown in Table 1 above.

[0079] Comparative Example 2

[0080] The first comparative hydration temperature rise inhibitory component used in this comparative example differs from that in Preparation Example 1 in that it uses equal amounts of chitosan, fly ash, citric acid and zirconium carbonate directly mixed physically, without hydrolysis and cross-linking reactions, as shown in Preparation Example 1.

[0081] The first comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 1% (i.e., the corresponding dosage in Application Example 1 above) to prepare a second concrete comparative specimen.

[0082] Comparative Example 3

[0083] The second comparative hydration temperature rise inhibitor used in this comparative example differs from that in preparation example 2 in that fly ash is not used in step (2); otherwise, the second comparative hydration temperature rise inhibitor is obtained in accordance with the preparation example 2.

[0084] The second comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 0.9% (i.e., the corresponding dosage in Application Example 2 above) to prepare the third concrete comparative specimen.

[0085] Comparative Example 4

[0086] The third comparative hydration temperature rise inhibitory component used in this comparative example differs from that in preparation example 3 in that: in step (2), fly ash is not used; otherwise, it is the same as described in preparation example 3, and the obtained reaction product is directly and physically mixed with an equal amount of fly ash in preparation example 3 to obtain the third comparative hydration temperature rise inhibitory component.

[0087] The third comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 0.7% (i.e., the corresponding dosage in Application Example 3 above) to prepare the fourth concrete comparative specimen.

[0088] Comparative Example 5

[0089] The fourth comparative hydration temperature rise inhibitory component used in this comparative example differs from that in preparation example 2 in that: in step (1), chitosan is not used, and the same amount of nitric acid and water as in example 2 are used to prepare the first liquid phase; the rest is as described in preparation example 2, and the fourth comparative hydration temperature rise inhibitory component is obtained.

[0090] The fourth comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 0.9% (i.e., the corresponding dosage in Application Example 2 above) to prepare the fifth concrete comparative specimen.

[0091] Comparative Example 6

[0092] The fifth comparative hydration temperature rise inhibitory component used in this comparative example differs from the preparation example 3 in that: in step (1), chitosan is not used, and the same amount of nitric acid and water as in Example 3 are used to prepare the first liquid phase. The remaining steps are the same as in Example 3, and the final dried and pulverized product is physically mixed with the same amount of chitosan as in Example 3 to obtain the fifth comparative hydration temperature rise inhibitory component.

[0093] The fifth comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 0.7% (i.e., the corresponding dosage in Application Example 3 above) to prepare the sixth concrete comparative specimen.

[0094] Comparative Example 7

[0095] The sixth comparative hydration temperature rise inhibitory component used in this comparative example differs from that in preparation example 3 in that: in step (3), zirconium ammonium carbonate is not used, but 15g of glutaraldehyde is used instead, crosslinked at 60℃ for 1h, the reaction mixture is poured into a tray, placed in an oven to dry, and pulverized to obtain the sixth comparative hydration temperature rise inhibitory component.

[0096] The sixth comparative hydration temperature rise inhibitory component was added to the concrete foundation mix shown in Table 1 at a dosage of 0.7% (i.e., the corresponding dosage in Application Example 3 above) to prepare the seventh comparative concrete specimen.

[0097] The concrete specimens obtained in the above application examples and comparative examples were tested using the following instruments, methods, and standards:

[0098] The rate of heat release during cement hydration was determined using a TAM AIR isothermal calorimeter from TA Instruments, Inc. (USA). The test temperature was 20℃, and the test specimen was neat cement paste with a water-cement ratio of 0.4.

[0099] The reduction in the peak value of the maximum heat release rate was used as the criterion for determining the hydration temperature rise inhibitor of this invention. Under the same conditions, the greater the reduction in the peak value of the heat release rate, the better the cement hydration control performance. The test method was performed in accordance with GB / T 2022-1980.

[0100] The compressive strength and setting time of concrete shall be performed in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0101] The test results obtained from each application example and comparative example are shown in Table 3 below.

[0102] Table 3 Test data from different application examples and comparative examples

[0103]

[0104] As can be seen from the test data in Table 3, compared with the first concrete control block in Comparative Example 1 without any crack-resistant materials, the concrete blocks in each application embodiment of the present invention, which are incorporating the composite cement hydration temperature rise inhibitor provided in the preparation embodiment of the present invention, can all exhibit certain hydration regulation performance without affecting compressive strength. This is achieved through the slow-release effect of hydrolyzed chitosan crosslinking activated fly ash coating with retarding acid and adsorption technology. This significantly reduces the peak value of the maximum hydration rate and controls the initial setting time within a reasonable range, thus balancing the suppression of temperature cracks and meeting the setting time requirements for engineering applications. It is evident that the hydration temperature rise inhibitor provided by the present invention plays a role in hydration regulation and shortening the setting time (compared to the direct application of retarding acid).

[0105] Compared with Application Example 1, Comparative Example 2, which directly added equal amounts of each component without reacting or cross-linking them, had a significantly longer initial setting time and a more obvious retarding effect; moreover, its hydration temperature rise inhibition effect was also poor.

[0106] Compared with Application Example 2, the method in Comparative Example 3, which did not apply activated fly ash to the hydration temperature rise inhibitor, resulted in a significantly prolonged initial setting time and a significant retarding effect; moreover, its hydration temperature rise inhibition effect was also poor.

[0107] Compared with Application Example 3, Comparative Example 4 did not apply activated fly ash to the hydration temperature rise inhibitor, but instead used a direct physical mixing method, resulting in a significantly prolonged initial setting time and a significant retarding effect; moreover, its hydration temperature rise inhibition effect was also poor.

[0108] Compared with Application Example 2, the method in Comparative Example 5, which did not apply chitosan to the hydration temperature rise inhibitor, resulted in a significantly longer initial setting time and a more pronounced retarding effect; furthermore, its hydration temperature rise inhibition effect was also poor.

[0109] Compared with Application Example 3, Comparative Example 6 did not apply chitosan to the hydration temperature rise inhibitor, but instead used a direct physical mixing method, resulting in a significantly prolonged initial setting time and a significant retarding effect; moreover, its hydration temperature rise inhibition effect was also poor.

[0110] Compared with Application Example 3, Comparative Example 7 did not apply ammonium zirconium carbonate to the hydration temperature rise inhibitor, but instead used glutaraldehyde to replace the crosslinking method. The initial setting time was slightly shortened and the retarding effect was weakened; however, its hydration temperature rise inhibition effect was significantly worse, and it still could not meet the requirement of taking into account both effects in this invention.

[0111] In summary, it can be seen that the composite slow-release material formed by the cross-linking of hydrolyzed chitosan and activated fly ash, as well as the chitosan hydrolysate and slow-setting acid coated by the two, all play an important role in its comprehensive effect of stabilizing strength, controlling reasonable slow-setting time by releasing slow-setting acid, and inhibiting hydration temperature rise.

[0112] Although the invention has been shown and described with reference to specific embodiments, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents.

Claims

1. A composite hydration temperature rise inhibitor, characterized in that, The material comprises a hydrolyzed chitosan / activated fly ash composite slow-release material, and slow-release acid and chitosan hydrolysate coated in the composite slow-release material; wherein the hydrolyzed chitosan / activated fly ash composite slow-release material is formed by cross-linking hydrolyzed chitosan and activated fly ash under the action of a cross-linking agent; wherein the hydrolyzed chitosan is obtained by partial hydrolysis of chitosan under the action of a strong acid, and the activated fly ash is obtained by activating fly ash under acidic conditions; the cross-linking agent is ammonium zirconium carbonate; and the strong acid is nitric acid.

2. The composite hydration temperature rise inhibitor according to claim 1, characterized in that, The slow-setting acid is selected from at least one of tartaric acid, citric acid, oxalic acid, and hydroxyethylidene diphosphonic acid.

3. A method for preparing the composite hydration temperature rise inhibitor as described in claim 1 or 2, characterized in that, Including the following steps: S1. Chitosan is hydrolyzed under strong acid at 80℃~90℃ for 2 h~4 h to obtain a first liquid phase containing partially hydrolyzed chitosan. S2. Disperse fly ash and retarding acid thoroughly in water to obtain a second liquid phase; S3. Mix the first liquid phase and the second liquid phase evenly, stir for 1 h to 2 h, add the crosslinking agent to crosslink, and continue the reaction for 1 h to obtain the third liquid phase; S4. The third liquid phase is dried and pulverized to obtain the composite hydration temperature rise inhibitor.

4. The preparation method according to claim 3, characterized in that, In the first liquid phase, the mass fraction of chitosan is 10.0%~20.0%, and the mass fraction of strong acid is 2.0%~4.0%; in the second liquid phase, the mass fraction of fly ash is 10%~20%, and the mass fraction of retarding acid is 3%~10%.

5. The preparation method according to claim 3, characterized in that, In the third liquid phase, the mass ratio of chitosan, fly ash and crosslinking agent is 1:1~2:0.2~0.

5.

6. The application of a composite hydration temperature rise inhibitor as described in claim 1 or 2, characterized in that, The composite hydration temperature rise inhibitor is added to the concrete at a dosage of 0.6% to 1% of the total mass of cementitious materials in the pre-added concrete.

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