Concrete hydration temperature rise inhibitor as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to a concrete hydration temperature rise inhibitor and a preparation method and application thereof. The concrete hydration temperature rise inhibitor is of a core-shell structure composed of an inner core and a shell layer. Wherein the core comprises a porous material and a hydration temperature rise inhibition material loaded on the porous material, and the hydration temperature rise inhibition material comprises 2-phosphonobutane-1, 2, 4-tricarboxylic acid, modified starch, 1-hydroxyethylidene-1, 1-diphosphonic acid, sodium polyacrylate and cellulose ether. The concrete hydration temperature rise inhibitor has an efficient hydration heat inhibition effect, the proportion of a hydration temperature rise inhibition material in the inhibitor is large, meanwhile, an exothermic temperature peak can be accurately inhibited, and no negative influence is caused to a hydration induction period.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and in particular relates to a concrete hydration temperature rise inhibitor and a preparation method and application thereof. Background Art

[0002] Mass concrete is widely used in port projects, municipal road projects, underground projects, water conservancy and hydropower projects, etc. due to its large pouring volume. Due to the large size of the mass concrete structure, a large amount of heat generated during cement hydration cannot be quickly transferred to the surface, resulting in temperature accumulation inside, resulting in a large temperature difference between the inside and outside of the concrete. Under the influence of thermal expansion and contraction, temperature stress will cause the surface to receive tension, so the concrete is very prone to cracking, which will destroy the integrity of the concrete, seriously affect the mechanical properties of the concrete, and threaten the safety of the entire project. Therefore, it is particularly important to control the cement hydration temperature within a reasonable range to ensure the overall concrete construction effect.

[0003] The current methods for controlling the temperature of large-volume concrete construction mainly include the following: internal physical cooling, by adding ice cubes, ice water, distilled water, etc., these substances are added to the concrete to reduce the temperature of the concrete; pre-cooling treatment can also be used, before pouring the concrete, the formwork can be rinsed with low-temperature water, or the formwork can be sprayed with water before pouring the concrete, which can reduce the temperature of the formwork surface and thus reduce the temperature rise of the concrete. External physical cooling, using waterproof and heat-insulating measures, by laying awnings on the concrete surface, using heat-insulating materials and other measures, can reduce solar radiation, prevent the concrete surface from being affected by high temperature, and thus reduce the temperature of the concrete surface.

[0004] In general, the internal and external physical cooling methods used in the prior art achieve cooling from the water temperature and the outer surface, which can alleviate the problem of large-volume hydration temperature rise to a certain extent, but the internal temperature of large-volume concrete will still rise significantly, resulting in an increased risk of temperature difference cracks. In addition, the implementation process of the above method is relatively complicated, which also increases the difficulty of engineering construction and affects construction efficiency. By adding admixtures such as retarders and hydration heat inhibitors, the cement hydration heat peak can be directly reduced, and the temperature gradient between the inside and outside of the concrete can be reduced. The operation is simple and effective, which is one of the research hotspots for inhibiting temperature cracks in concrete. Summary of the invention

[0005] In view of the problem that existing large-volume concrete has a large temperature difference between the inside and the outside due to high internal temperature, and thermal expansion and contraction cause concrete cracking, the present invention provides a concrete hydration temperature rise inhibitor and a preparation method and application thereof.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] A concrete hydration temperature rise inhibitor has a core-shell structure consisting of a core and a shell layer; wherein the core comprises a porous material and a hydration temperature rise inhibitor material loaded on the porous material, and the hydration temperature rise inhibitor material comprises 2-phosphonobutane-1,2,4-tricarboxylic acid, modified starch, hydroxyethylidene diphosphonic acid, sodium polyacrylate and cellulose ether.

[0008] The present invention loads the inhibitor on a porous material. After the outer shell melts, the inhibitor in the porous material undergoes a desorption process, and the process accelerates with increasing temperature, thereby achieving an effect of precise release according to the hydration heat. At the same time, the porous material used in the present invention itself has a certain adsorption effect on cement particles, thereby increasing the contact area between the inhibitor and cement.

[0009] Preferably, based on the total mass of the core-shell structure being 100%, the mass fraction of the hydration temperature rise suppression material is 30% to 40%, the mass fraction of the porous material is 40% to 50%, and the mass fraction of the shell layer is 10% to 30%.

[0010] Preferably, the hydration temperature rise suppression material comprises, by mass, 10 to 20 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 5 to 10 parts of modified starch, 10 to 15 parts of hydroxyethylidene diphosphonic acid, 1 to 5 parts of sodium polyacrylate, and 5 to 10 parts of cellulose ether.

[0011] Preferably, the modified starch is one or more of cationic starch, anionic starch, hydroxypropyl starch phosphate, hydroxypropyl glycerol distarch, and hydroxyalkyl starch.

[0012] Preferably, the porous material comprises lithium slag and molecular sieve in a mass ratio of 1:3 to 1:1.5.

[0013] Further preferably, the lithium slag comprises the following components in mass percentage: SiO2 40%-60%, MgO 0.1%-1%, Al2O3 15%-30%, Fe2O3 0.5%-5%, CaO 5%-10%, K2O 0.1%-1%; the molecular sieve is one or more of M41S mesoporous molecular sieve, MCM-41 mesoporous molecular sieve, KIT-6 mesoporous molecular sieve, and SBA-15 mesoporous molecular sieve.

[0014] More preferably, the particle size of the lithium slag is less than 0.08 mm, and the particle size of the molecular sieve is 0.2 mm to 0.8 mm.

[0015] Preferably, the cellulose ether is one or more of methyl cellulose ether, hydroxypropyl methyl cellulose ether, hydroxyethyl cellulose ether, and carboxymethyl cellulose ether; more preferably, it is hydroxypropyl methyl cellulose ether.

[0016] Preferably, the raw material of the shell layer is one or more of paraffin, polyvinyl alcohol, polyvinyl stearate, polybutylene adipate, and polycaprolactam.

[0017] The present invention also provides a method for preparing the above concrete hydration temperature rise inhibitor, comprising the following steps:

[0018] 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphonic acid are added into water and stirred evenly; then modified starch and sodium polyacrylate are added and heated and stirred evenly; then cellulose ether and water are added and stirred evenly to obtain a hydration temperature rise suppression material;

[0019] Loading the hydration temperature rise suppression material onto a porous material by impregnation to obtain a core raw material;

[0020] The shell raw material is heated and melted, and then the core raw material is added to obtain the core-shell structured concrete hydration temperature rise inhibitor through a granulation process.

[0021] The present invention also provides application of the concrete hydration temperature rise inhibitor in large-volume concrete.

[0022] Preferably, the amount of the hydration temperature rise inhibitor is 0.1% to 0.5% based on the weight of the cementitious material in the mass concrete.

[0023] The beneficial effects of the present invention are at least:

[0024] 1) The present invention provides a sustained-release hydration temperature rise inhibitor, in which the components of the hydration temperature rise inhibitor material have a complementary effect, wherein 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphonic acid have a high efficiency hydration heat inhibition effect, and at the same dosage, the hydration heat reduction rate is more than twice that of conventional retarders such as sodium gluconate, white sugar and the like, and the core component mainly reduces the hydration exothermic temperature peak and has no negative impact on the setting time; the polyhydroxy cross-linked structure of modified starch and cellulose ether can increase the coating of the material on cement particles and fully release the phosphorus-containing components with an inhibitory effect; and sodium polyacrylate has a certain particle dispersion effect, which increases the contact area between the inhibitor material and the cement particles, and can maximize the effect of the material in inhibiting the hydration temperature rise;

[0025] 2) A sustained-release hydration temperature rise inhibitor provided by the present invention, wherein the hydration temperature rise inhibitor material is loaded in a porous material, wherein the pore size of the lithium slag material is 5 to 50 nm, and can adsorb sodium polyacrylate, modified starch, etc. with a larger molecular size, while the molecular sieve has a straight pore type and a pore size of 2 to 10 nm, and can adsorb small molecular substances such as 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphonic acid. The two porous materials work synergistically to achieve the effective loading of the hydration temperature rise inhibitor material and increase the proportion of the hydration temperature rise inhibitor material in the inhibitor;

[0026] 3) The present invention provides a sustained-release hydration temperature rise inhibitor, which adopts a core-shell structure, and the raw materials of the shell layer are one or more of paraffin, polyvinyl alcohol, polyvinyl stearate, polybutylene adipate, and polycaprolactam. After the temperature reaches 40-70°C (the temperature at the peak of cement hydration exothermic peak), the outer shell structure of the structure melts, releasing the porous material loaded with the hydration temperature rise inhibitor material inside, and then the hydration temperature rise inhibitor material dissolves into the interstitial liquid and adsorbs to the surface of cement particles, reacts with the surface hydration products, inhibits the hydration reaction, and reduces the hydration heat. This structure has no effect on the early stage of cement hydration. After the hydration temperature rises to melt the shell structure, the hydration temperature rise inhibitor material loaded on the pore wall of the porous material dissolves, adsorbs, and reacts with the hydration products to achieve a sustained release effect. At the same time, it can accurately inhibit the exothermic temperature peak and has no negative impact on the hydration induction period;

[0027] 4) The present invention provides a slow-release hydration temperature rise inhibitor. The lithium slag used in the porous material is mainly an industrial by-product produced by the new energy industry. The application of this material can reduce environmental pollution, increase the value of waste slag, and promote the development of new energy related industries. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used.

[0029] In the following examples, information of each reagent used is shown in Table 1.

[0030] Table 1 Information of reagents used in the examples

[0031]

[0032] Example 1

[0033] A concrete hydration temperature rise inhibitor, which is a core-shell structure composed of a core and a shell; wherein the core includes a porous material and a hydration temperature rise inhibitor material loaded on the porous material;

[0034] The hydration temperature rise suppression material is composed of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxypropyl starch phosphate, hydroxyethylidene diphosphonic acid, sodium polyacrylate and hydroxypropyl methylcellulose ether;

[0035] The porous material is lithium slag and molecular sieve in a mass ratio of 1:2;

[0036] The raw material of the shell layer is paraffin.

[0037] The preparation method of concrete hydration temperature rise inhibitor is as follows:

[0038] (1) Preparation of hydration temperature rise suppression material: Weigh 10 g of 2-phosphonobutane-1,2,4-tricarboxylic acid and 15 g of hydroxyethylidene diphosphonic acid, add them to 20 g of water, and stir evenly; then weigh 7 g of hydroxypropyl starch phosphate and 3 g of sodium polyacrylate, add them thereto, heat to 60° C., stir for 20 min, and finally add 6 g of hydroxypropyl methylcellulose ether and 35 g of water, and continue stirring for 30 min to obtain a hydration temperature rise suppression material;

[0039] (2) Porous material loaded with hydration temperature rise suppression material: 15 g of lithium slag and 30 g of molecular sieve were added to the suppression material in step 1, stirred for 20 min, and filtered after standing for 24 h (the amount of hydration temperature rise suppression material loaded can be calculated based on the weight and concentration of the solution before and after filtration). The filter cake is the porous material loaded with hydration temperature rise suppression material;

[0040] (3) Shell assembly: After drying the porous material loaded with the hydration temperature rise suppressing material in step 2, a granular hydration temperature rise suppressing agent is prepared by a boiling granulation method. The blower at the bottom of the equipment generates wind force, driving the porous dried material to contact with 20g of molten paraffin sprayed evenly on the top, and the two are bonded to each other to form 1-2mm particles.

[0041] Example 2

[0042] A concrete hydration temperature rise inhibitor, which is a core-shell structure composed of a core and a shell; wherein the core includes a porous material and a hydration temperature rise inhibitor material loaded on the porous material;

[0043] The hydration temperature rise suppression material is composed of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxypropyl starch phosphate, hydroxyethylidene diphosphonic acid, sodium polyacrylate and carboxymethyl cellulose ether;

[0044] The porous material is lithium slag and molecular sieve in a mass ratio of 1:3;

[0045] The raw material of the shell layer is polyvinyl alcohol.

[0046] The preparation method of concrete hydration temperature rise inhibitor is as follows:

[0047] (1) Preparation of hydration temperature rise suppression material: Weigh 10 g of 2-phosphonobutane-1,2,4-tricarboxylic acid and 15 g of hydroxyethylidene diphosphonic acid, add them to 20 g of water, and stir evenly; then weigh 7 g of hydroxypropyl starch phosphate and 3 g of sodium polyacrylate, add them, heat to 60° C., stir for 20 min, and finally add 4 g of carboxymethyl cellulose ether and 30 g of water, and continue stirring for 30 min to obtain a hydration temperature rise suppression material;

[0048] (2) Porous material loaded with hydration temperature rise suppression material: 10 g of lithium slag and 30 g of molecular sieve were added to the suppression material in step 1, stirred for 20 min, allowed to stand for 24 h and then filtered. The filter cake was the porous material loaded with hydration temperature rise suppression material;

[0049] (3) Shell assembly: After drying the porous material loaded with the hydration temperature rise suppressing material in step 2, a granular hydration temperature rise suppressing agent is prepared by a boiling granulation method. The blower at the bottom of the equipment generates wind force, driving the dried material to contact with 20g of molten polyvinyl alcohol evenly sprayed on the top, and the two are bonded to each other to form 1-2mm particles.

[0050] Example 3

[0051] A concrete hydration temperature rise inhibitor, which is a core-shell structure composed of a core and a shell; wherein the core includes a porous material and a hydration temperature rise inhibitor material loaded on the porous material;

[0052] The hydration temperature rise suppression material is composed of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxypropyl glycerol distarch, hydroxyethylidene diphosphonic acid, sodium polyacrylate and hydroxypropyl methylcellulose ether;

[0053] The porous material is lithium slag and molecular sieve in a mass ratio of 1:2;

[0054] The raw material of the shell layer is paraffin.

[0055] The preparation method of concrete hydration temperature rise inhibitor is as follows:

[0056] (1) Preparation of hydration temperature rise suppression material: Weigh 10 g of 2-phosphonobutane-1,2,4-tricarboxylic acid and 10 g of hydroxyethylidene diphosphonic acid, add them to 20 g of water, and stir evenly; then weigh 10 g of hydroxypropyl glycerol distarch and 3 g of sodium polyacrylate, add them, heat to 60° C., stir for 20 min, and finally add 4 g of hydroxypropyl methylcellulose ether and 30 g of water, and continue stirring for 30 min to obtain a hydration temperature rise suppression material;

[0057] (2) Porous material loaded with hydration temperature rise suppression material: 15 g of lithium slag and 30 g of molecular sieve were added to the suppression material in step 1, stirred for 20 min, allowed to stand for 24 h and then filtered. The filter cake was the porous material loaded with hydration temperature rise suppression material;

[0058] (3) Shell assembly: After drying the porous material loaded with the hydration temperature rise suppressing material in step 2, a granular hydration temperature rise suppressing agent is prepared by a boiling granulation method. The blower at the bottom of the equipment generates wind force, driving the dried material to contact with 20g of molten paraffin sprayed evenly on the top, and the two are bonded to each other to form 1-2mm particles.

[0059] Example 4

[0060] A concrete hydration temperature rise inhibitor, which is a core-shell structure composed of a core and a shell; wherein the core includes a porous material and a hydration temperature rise inhibitor material loaded on the porous material;

[0061] The hydration temperature rise suppression material is composed of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxypropyl glycerol distarch, hydroxyethylidene diphosphonic acid, sodium polyacrylate and hydroxypropyl methylcellulose ether;

[0062] The porous material is lithium slag and molecular sieve in a mass ratio of 1:1.5;

[0063] The raw material of the shell layer is paraffin.

[0064] The preparation method of concrete hydration temperature rise inhibitor is as follows:

[0065] (1) Preparation of hydration temperature rise suppression material: Weigh 10 g of 2-phosphonobutane-1,2,4-tricarboxylic acid and 10 g of hydroxyethylidene diphosphonic acid, add them to 20 g of water, and stir evenly; then weigh 10 g of hydroxypropyl glycerol distarch and 3 g of sodium polyacrylate, add them, heat to 60° C., stir for 20 min, and finally add 4 g of hydroxypropyl methylcellulose ether and 30 g of water, and continue stirring for 30 min to obtain a hydration temperature rise suppression material;

[0066] (2) Porous material loaded with hydration temperature rise suppression material: 16 g of lithium slag and 24 g of molecular sieve were added to the suppression material in step 1, stirred for 20 min, allowed to stand for 24 h and then filtered. The filter cake was the porous material loaded with hydration temperature rise suppression material;

[0067] (3) Shell assembly: After drying the porous material loaded with the hydration temperature rise suppressing material in step 2, a granular hydration temperature rise suppressing agent is prepared by a boiling granulation method. The blower at the bottom of the equipment generates wind force, driving the dried material to contact with 20g of molten paraffin sprayed evenly on the top, and the two are bonded to each other to form 1-2mm particles.

[0068] Comparative Example 1

[0069] Compared with Example 1, the only difference is that 2-phosphonobutane-1,2,4-tricarboxylic acid in the core inhibitory material is removed, and the other conditions are consistent with Example 1.

[0070] Comparative Example 2

[0071] Compared with Example 2, the only difference is that the sodium polyacrylate in the core inhibition material is removed, and the other conditions are the same as those in Example 2.

[0072] Comparative Example 3

[0073] Compared with Example 3, the only difference is that the lithium slag is removed, the porous material is 45g of molecular sieve, and the other conditions are consistent with Example 3.

[0074] Comparative Example 4

[0075] Compared with Example 4, the only difference is that the porous material loaded with the hydration temperature rise suppression material is obtained by grinding after drying without granulation.

[0076] Test example

[0077] An isothermal calorimeter (TAM Air, TA CO.) was used to test the heat of cement hydration. The test temperature was 20°C, cement was 10g, water was 4g, and no inhibitor was added to the blank sample. The amount of inhibitor used in the examples and comparative examples was 0.1% of the cement mass. The results are shown in Table 2 below.

[0078] Table 2 Cement hydration heat test of samples

[0079]

[0080]

[0081] Note: The effective loading amount of the inhibitor material refers to the mass proportion of the inhibitor material in the entire prepared inhibitor.

[0082] As can be seen from Table 2, the sample of the embodiment has a small inhibitory effect when the heat release of cement hydration is small in the early stage, but at the peak period of cement heat release (12h-24h), the hydration heat inhibition rate can reach more than 40%, and the exothermic peak is reduced while slow release; among them, the effect of Example 1 is the most obvious, and the 6h inhibition rate of Example 2 is higher. The reason for the lower 24h inhibition rate is that polyvinyl alcohol dissolves faster than paraffin; Examples 3 and 4 are basically the same. After removing 2-phosphonobutane-1,2,4-tricarboxylic acid from Comparative Example 1, its early (6h) and late (24h) inhibition rates are reduced, because this component has a strong adsorption force with cement hydration products and has a significant function of inhibiting hydration reactions. Comparative Example 2 removes sodium polyacrylate, resulting in a decrease in the dispersion performance of the inhibitor after release, and a decrease in the contact area with cement particles and hydration products, so the late inhibition rate is slightly reduced; Comparative Example 3 removes lithium slag, resulting in a weakened inhibitor slow release effect, so the early inhibition rate increases and the late inhibition rate decreases; Comparative Example 4 is not granulated, and there is basically no slow release effect.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A concrete hydration temperature rise inhibitor, characterized in that: The invention relates to a core-shell structure composed of a core and a shell layer; wherein the core comprises a porous material and a hydration temperature rise suppression material loaded on the porous material, and the hydration temperature rise suppression material comprises 2-phosphonobutane-1,2,4-tricarboxylic acid, modified starch, hydroxyethylidene diphosphonic acid, sodium polyacrylate and cellulose ether.

2. The concrete hydration temperature rise inhibitor according to claim 1, characterized in that: Taking the total mass of the core-shell structure as 100%, the mass fraction of the hydration temperature rise suppression material is 30% to 40%, the mass fraction of the porous material is 40% to 50%, and the mass fraction of the shell layer is 10% to 30%.

3. The concrete hydration temperature rise inhibitor according to claim 1 or 2, characterized in that: The hydration temperature rise suppression material comprises, by weight: 10 to 20 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 5 to 10 parts of modified starch, 10 to 15 parts of hydroxyethylidene diphosphonic acid, 1 to 5 parts of sodium polyacrylate, and 5 to 10 parts of cellulose ether.

4. The concrete hydration temperature rise inhibitor according to claim 1 or 2, characterized in that: The modified starch is one or more of cationic starch, anionic starch, hydroxypropyl starch phosphate, hydroxypropyl glycerol distarch, and hydroxyalkyl starch.

5. The concrete hydration temperature rise inhibitor according to claim 1 or 2, characterized in that: The porous material comprises lithium slag and molecular sieve in a mass ratio of 1:3 to 1:1.

5.

6. The concrete hydration temperature rise inhibitor according to claim 1 or 2, characterized in that: The cellulose ether is one or more of methyl cellulose ether, hydroxypropyl methyl cellulose ether, hydroxyethyl cellulose ether and carboxymethyl cellulose ether; preferably hydroxypropyl methyl cellulose ether.

7. The concrete hydration temperature rise inhibitor according to claim 1 or 2, characterized in that: The raw material of the shell layer is one or more of paraffin, polyvinyl alcohol, polyvinyl stearate, polybutylene adipate and polycaprolactam.

8. The method for preparing the concrete hydration temperature rise inhibitor according to any one of claims 1 to 7, characterized in that: The following steps are involved: 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphonic acid are added into water and stirred evenly; then modified starch and sodium polyacrylate are added and heated and stirred evenly; then cellulose ether and water are added and stirred evenly to obtain a hydration temperature rise suppression material; Loading the hydration temperature rise suppression material onto a porous material by impregnation to obtain a core raw material; The shell raw material is heated and melted, and then the core raw material is added to obtain the core-shell structured concrete hydration temperature rise inhibitor through a granulation process.

9. Use of the concrete hydration temperature rise inhibitor according to any one of claims 1 to 7 in large-volume concrete.

10. The use according to claim 9, characterized in that: The dosage of the hydration temperature rise inhibitor is 0.1% to 0.5% based on the weight of the cementitious material in the mass concrete.

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