Preparation method of super low water-cement ratio dry hard concrete curb enhancer

Abstract

The application discloses a preparation method of an ultralow water-cement ratio dry hard concrete curbstone reinforcing agent, and belongs to the technical field of concrete additives.The reinforcing agent is prepared by the following steps: cutting and grinding poultry feathers and sheep wool to form powder A; uniformly mixing sodium hydroxide solution, ethanol and alkaline hydrogen peroxide to form solution B; mixing powder A and solution B to form mixed solution C; mixing stearic acid and ethanol to form solution D; adding mixed solution C and solution D into nano calcium silicate emulsion, uniformly dispersing, and solidifying to form solid E; and cutting, crushing and grinding solid E into microparticles to obtain the reinforcing agent.The reinforcing agent is added into dry hard concrete, and the mixed use of poultry feathers and sheep wool is beneficial to maintaining the volume stability of the curbstone and reducing defects; meanwhile, due to the action of sodium stearate and sheep wool fibers, the internal structure and adhesion of the dry hard concrete are improved, and the mechanical properties of the concrete are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building material product preparation and production, in particular to a preparation method of an ultra-low water-cement ratio dry hard concrete curb enhancer. BACKGROUND

[0002] Dry hard concrete curb is a kind of concrete curb prepared under the condition of low water-cement ratio and high forming pressure, which has high compactness and high strength of blank body after forming, and can be demolded immediately in wet state, so as to greatly improve the turnover speed of the mold and the production efficiency. However, in the production process of dry hard concrete, when the water-cement ratio is too low, even after pressing forming, surface cracking or more internal structure pores may occur due to too little free water. Therefore, necessary viscosity modification and enhancement measures are adopted to increase the adhesion between concrete mixture particles, so as to improve the mechanical properties and structural stability. At present, there is no enhancer for dry hard concrete curb. SUMMARY

[0003] Based on the problems such as cracking and mechanical property reduction of dry hard concrete under the condition of low water-cement ratio, the present application provides a preparation method of an ultra-low water-cement ratio dry hard concrete curb enhancer.

[0004] In order to achieve the above-mentioned application purposes, the present application realizes the technical scheme as follows:

[0005] A preparation method of an ultra-low water-cement ratio dry hard concrete curb enhancer, comprising the following steps:

[0006] (1) mixing poultry feathers and sheep wool, cutting the mixture into fibers with a length of less than 1 mm, and further grinding to make the length of the fibers not higher than 100 μm to form powder A;

[0007] The mass ratio of the poultry feathers to the sheep wool in step (1) is 1:2-2:1;

[0008] (2) uniformly mixing sodium hydroxide solution, ethanol I and alkaline hydrogen peroxide to form solution B;

[0009] The mass concentration of the sodium hydroxide solution in step (2) is 30%-45%;

[0010] The mass fractions of the components in step (2) are as follows:

[0011] sodium hydroxide solution 100 parts,

[0012] ethanol I 30-40 parts,

[0013] alkaline hydrogen peroxide 5-10 parts;

[0014] (3) 20 parts by mass of the powder A prepared in step (1) is dissolved in the solution B to form a mixed solution C by ultrasonic dispersion;

[0015] (4) 15-25 parts by mass of stearic acid is added into 30-40 parts by mass of ethanol II to form a solution D;

[0016] (5) The mixed solution C of step (3) and the solution D of step (4) are slowly added into 80-100 parts of the nano calcium silicate emulsion, and then stirred and ultrasonically dispersed to form a solid E;

[0017] (6) The solid E prepared in step (5) is cut and ground into microparticles with a particle size of no more than 50 μm, which is the super low water-cement ratio dry hard concrete curb stone reinforcing agent.

[0018] The bird feather in step (1) is selected from any one of chicken feather, duck feather and goose feather.

[0019] The nano calcium silicate emulsion in step (5) has a solid content of 10-25%.

[0020] In the preparation method, the wool fiber and the bird feather are dissolved in the solution B, mixed with the stearic acid ethanol solution, and then reacted to form sodium stearate, and the alcohol is gradually fixed in the structure of sodium stearate, and at the same time, with the formation of sodium stearate, the pH value of the mixed solution is reduced, and the fiber is gradually precipitated, which increases the stability of the structure and forms a fiber adhesion structure with the nano calcium silicate particles.

[0021] The structure is cut and ground, and the alcohol is gradually precipitated and evaporated during the grinding process to form a porous structure composed of sodium stearate and fiber, which binds a large amount of nano calcium silicate particles. At the same time, through the grinding process, the components can be uniformly mixed, so that the porous structure can absorb a large amount of nano calcium silicate attached to the sodium stearate and the animal feather and wool fiber.

[0022] The reinforcing agent prepared in the application is applied in the dry hard concrete, and the mixing amount is 1-3% of the mass of the cementitious material. The above-mentioned reinforcing agent powder is added to the dry hard concrete, and the animal fiber is gradually dissolved in the alkaline solution, but because it carries a large amount of nano calcium silicate crystal nucleus particles, the wool fiber dissolves in the process of forming a hydration calcium silicate crystal nucleus based on itself and gradually growing, forming a wrapped state of fiber and cement hydration product. At the same time, due to the action of sodium stearate and wool fiber, the internal structure and adhesion of dry hard concrete are improved, and the mechanical properties of the concrete are improved.

[0023] If the wool powder or feather powder is directly added into the dry hard concrete curb, it is difficult to achieve good dispersion effect, and it is also unable to play the role of reconnection into fibers after dissolution to have stable structure. The wool itself has the phenomenon of shrinking, which is beneficial to reduce the adverse effect of thermal expansion, but is not conducive to the volume stability in later period. The feather fiber has no shrinking phenomenon, and the space between the fibers is large, and the structure is fluffy. When the two are mixed in a certain proportion and then re-mixed, it is beneficial to maintain the volume stability of the curb and reduce defects. DETAILED DESCRIPTION

[0024] The application will be further described below in combination with examples.

[0025] The component amount in each example and comparative example is calculated by mass fraction.

[0026] Example 1

[0027] (1) The duck feather and the wool are mixed in a mass ratio of 1:2, cut into particles below 1 mm, and further ground to an average particle size of 75 μm to form powder A;

[0028] (2) 100 parts of sodium hydroxide solution (concentration 45%) is uniformly mixed with 30 parts of ethanol and 10 parts of alkaline hydrogen peroxide to form solution B;

[0029] (3) 20 parts of powder A is dissolved in solution B, ultrasonic dispersion and dissolution are performed, and mixture C is formed;

[0030] (4) 15 parts of stearic acid is added into 40 parts of ethanol to form solution D;

[0031] (5) C and D are slowly added into 80 parts of nano calcium silicate emulsion with a solid content of 10%, stirring is uniformly performed, and solid E is formed by solidification;

[0032] (6) Solid E is cut and crushed, and is ground into micro-particles with a particle size of 10-30 μm.

[0033] Example 2

[0034] (1) The chicken feather and the wool are mixed in a mass ratio of 1:1, cut into particles below 1 mm, and further ground to an average particle size of 50 μm to form powder A;

[0035] (2) 100 parts of sodium hydroxide solution (concentration 40%) is uniformly mixed with 35 parts of ethanol and 8 parts of alkaline hydrogen peroxide to form solution B;

[0036] (3) 20 parts of powder A is dissolved in solution B, ultrasonic dispersion and dissolution are performed, and mixture C is formed;

[0037] (4) 20 parts of stearic acid is added into 35 parts of ethanol to form solution D;

[0038] (5) slowly drop C and D into 100 parts of nano calcium silicate emulsion with solid content of 25%, stir uniformly, solidify, form solid E;

[0039] (6) cut and crush solid E into fine particles, and grind into microparticles with particle size of 5-20 μm.

[0040] Example 3

[0041] (1) mix duck feather and sheep wool at a mass ratio of 2:1, cut into particles below 1 mm, and further grind to an average particle size of 60 μm, to form powder A;

[0042] (2) mix 100 parts of sodium hydroxide solution (concentration 30%) with 40 parts of ethanol and 5 parts of basic hydrogen peroxide to form solution B;

[0043] (3) dissolve 20 parts of powder A in solution B, ultrasonically disperse and dissolve to form mixture C;

[0044] (4) add 25 parts of stearic acid to 30 parts of ethanol to form solution D;

[0045] (5) slowly drop C and D into 90 parts of nano calcium silicate emulsion with solid content of 20%, stir uniformly, solidify, form solid E;

[0046] (6) cut and crush solid E into fine particles, and grind into microparticles with particle size of 30-50 μm.

[0047] Comparative Example 1

[0048] Compared with Example 2, only sheep wool is used, and no chicken feather is used.

[0049] Comparative Example 2

[0050] Compared with Example 2, only chicken feather is used, and no sheep wool is used.

[0051] Comparative Example 3

[0052] Compared with Example 2, no ethanol is added in the sodium hydroxide solution, and no ethanol is added in the stearic acid.

[0053] Comparative Example 4

[0054] Compared with Example 2, no sheep wool and no poultry feather are used.

[0055] Comparative Example 5

[0056] Compared with Example 2, chicken feather and sheep wool are used at a ratio of 1:3.

[0057] Comparative Example 6

[0058] Compared with Example 2, the ratio of chicken feather and wool is 3:1.

[0059] Comparative Example 7

[0060] Compared with Example 2, no chicken feather is used, only 30 parts of wool is used.

[0061] Comparative Example 8

[0062] Compared with Example 2, the solid E is cut and ground into 75-100 μm particles.

[0063] Comparative Example 9

[0064] Compared with Example 2, the wool powder and chicken feather powder are not dissolved in step (3), and are mixed with the enhancer after the completion of steps (2), (4), (5) and (6).

[0065] Comparative Example 10

[0066] Compared with Example 2, only wool powder and chicken feather powder are used.

[0067] Comparative Example 11

[0068] Compared with Example 2, no nano calcium silicate emulsion is used. In the preparation process, solution C and solution D are directly mixed.

[0069] Application Example

[0070] Two kinds of super low water-cement ratio dry hard concrete curb stones with different mixing ratios are prepared respectively. The curb stone preparation method is as follows: after being pressed and formed under the condition of 3-5 MPa, it is statically cured for 2 h, taken out after being steam cured for 24 h, and continuously cured until 28 d, and its performance is tested. The particle shape enhancer prepared in Examples 1-3 is added into the dry hard concrete curb stone 2, and the mixing amount is 2% of the amount of cementitious materials. After being uniformly stirred with the raw materials, the dry hard concrete curb stone is prepared.

[0071] The mixing ratio of the dry hard concrete curb stone 1 is as follows:

[0072]

[0073] The mixing ratio of the dry hard concrete curb stone 2 is as follows:

[0074]

[0075] The compressive strength of the curb stone is tested according to the requirements of GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the crack number is visually observed, and the specific data indexes are shown in Table 1:

[0076] Table 1 Indexes of Curb Stone

[0077]

[0078]

[0079] As can be seen from Table 1, the dry concrete curb stones prepared by using the mixing ratio 1 and the mixing ratio 2 can be seen that the water consumption is increased, the concrete cracks are reduced, but the compressive strength is decreased. Further adding the reinforcing agent on the basis of the mixing ratio 2, that is, the data in the examples 1-3 can be found that the cracks of the concrete curb stone are close to even completely disappear, and the compressive strength is increased.

[0080] As can be seen by comparing the comparative example 1, the comparative example 2, the comparative example 4 and the example 2, the use of wool or poultry feathers alone can cause the compressive strength of the curb stone to decrease. The use of wool alone can cause the shrinkage of the wool itself, the dissolved wool is used in the curb stone, the shrinkage force is generated, the more the amount of the wool is mixed, the greater the density of the mixed wool is, the greater the dry shrinkage is, and the cracks are generated. However, the use of the feather does not cause the shrinkage phenomenon, but the thermal expansion of the curb stone during the steam curing process cannot be well absorbed, so that the thermal expansion generates some cracks. When the wool and the feather are mixed, the shrinkage of the wool fiber is fully utilized to resist the thermal expansion, the adhesion between the feather fiber and the cementitious material is improved, the matrix strength is improved, and the cracks are reduced. The use of the wool or the poultry feather alone can cause the thermal expansion of the masonry during the early steam curing process, and the expansion cracks are generated. In the example, the chicken feather and the wool are used together, so that the dry shrinkage caused by the excessive wool is avoided, and the adverse effects of the thermal expansion are also avoided.

[0081] As can be seen by comparing the comparative example 3 and the example 2, the use of the ethanol can cause the compressive strength of the curb stone to decrease and the cracks to increase, which is mainly because the ethanol can be constrained in the system during the generation of sodium stearate from stearic acid and sodium hydroxide (similar to solid alcohol), when the ethanol is cut and ground, the ethanol is volatilized, and a large number of porous structures of sodium stearate and feather and wool fiber structures are formed, the nano calcium silicate particles can be released and adsorbed on the sodium stearate and the fiber structure, the sodium stearate is used to improve the workability of the concrete, with the sodium stearate uniformly mixed into the concrete, the chicken feather and the wool fiber are dissolved and dispersed, and the early strength of the curb stone is improved. At the same time, the nano calcium silicate attached to the fiber can enhance the adhesion between the fiber and the cementitious material and the matrix, improve the mechanical properties of the slurry, and reduce the generation of cracks. In the comparative example 3, the ethanol is not used, so that the cutting and grinding are difficult, the nano calcium silicate cannot be effectively adsorbed, the fiber and the cementitious material are not combined closely, the early strength development of the curb stone is not uniform, the cracks are increased, and the strength is decreased.

[0082] Comparing Comparative Example 4 and Example 2, it can be seen that the mechanical properties decrease significantly and the number of cracks increases significantly. This is because, when wool and poultry feathers are not added at the same time, the effect of fiber reinforcement disappears, and the adhesion of fibers to nano-sodium silicate also disappears. Without the reinforcement and toughening effect of fibers on the structure, the thermal expansion effect of the concrete during the early steam curing cannot be offset, resulting in a large number of thermal expansion cracks, increasing the structural defects. The structural defects are further aggravated due to the shrinkage of the structure in the later stage, resulting in poorer structural stability, mechanical properties, and more cracks.

[0083] Comparing Comparative Example 5, Comparative Example 7, and Example 2, it can be seen that too much wool is added, resulting in a decrease in performance. This is because too much wool increases its own thermal shrinkage, which offsets the thermal expansion effect in the early stage, but increases the shrinkage in the early stage. As the kerb dries further in the later stage, the shrinkage will further intensify, causing the structural stability to decrease, the number of cracks to increase, and the mechanical properties to decrease.

[0084] Comparing Comparative Example 6 and Example 2, it can be seen that too much poultry feather is added, resulting in a decrease in mechanical properties. Because the space between the fibers is large and the structure is fluffy, adding too much will result in a decrease in structural density and performance.

[0085] Comparing Comparative Example 8 and Example 2, it can be seen that when the product is ground into larger particles, the mechanical properties of the kerb decrease and the number of cracks increases. This is because the particle size is large, and the effect of the crystalline nucleus gradually weakens. Moreover, it contains a large amount of fibers, and the larger the particle size, the more difficult it is to disperse uniformly in the slurry, resulting in a decrease in its positive effect.

[0086] Comparing Comparative Example 9, Comparative Example 10, and Example 2, it can be seen that using wool powder and poultry feather powder alone or not dissolving wool powder and poultry feather powder and directly adding them to other composite materials will result in a decrease in the performance of the kerb and an increase in the number of cracks. This is because wool powder and poultry feather powder have a fluffy structure, which affects the bonding between the slurry and the aggregate, resulting in poor bonding and a decrease in performance. However, dissolving and then forming fibers can improve uniformity, reduce size, reduce adverse effects and fluffiness, and improve bonding.

[0087] Comparing Comparative Example 11 and Example 2, it can be seen that the performance of the dry hard concrete kerb also decreases without adding nano-calcium silicate emulsion. This is because nano-calcium silicate acts as a crystalline nucleus and adheres to the surface of the fiber, promoting the growth of hydrated calcium silicate around the fiber, improving the adhesion and toughness of the fiber and the hydration product, reducing the occurrence of cracks, and increasing the strength.

Claims

1. A method for preparing an ultra-low water-cement ratio dry-hard concrete curb reinforcement agent, characterized in that, Includes the following steps: (1) After mixing poultry feathers and wool, cut them into fibers with a length of less than 1 mm and grind them further to form powder A; The mass ratio of poultry feathers to wool in step (1) is 1:2 to 2:1; (2) Mix sodium hydroxide solution with ethanol I and alkaline hydrogen peroxide evenly to form solution B; (3) Dissolve the powder A obtained in step (1) in solution B, and disperse and dissolve it by ultrasonication to form a mixture C; (4) Stearic acid is added to ethanol II to form solution D; (5) The mixture C obtained in step (3) and the solution D obtained in step (4) are slowly added dropwise to the nano calcium silicate emulsion, stirred and ultrasonically dispersed evenly, and then solidified to form solid E; (6) Cut and crush the solid E obtained in step (5) and grind it into micro particles, which is the ultra-low water-cement ratio dry hard concrete curb stone reinforcing agent.

2. The preparation method according to claim 1, characterized in that, In step (1), the length of powder A is no more than 100µm.

3. The preparation method according to claim 1, characterized in that, The mass fractions of raw material components for each step are as follows: 100 parts of sodium hydroxide solution Ethanol I 30-40 parts, 5-10 parts of alkaline hydrogen peroxide Powder A, 20 parts 15-25 parts stearic acid Ethanol II 30-40 parts, 80-100 parts of nano-calcium silicate emulsion; The mass concentration of the sodium hydroxide solution in step (2) is 30%~45%.

4. The preparation method according to claim 1, characterized in that, The poultry feathers mentioned in step (1) are selected from any one of chicken feathers, duck feathers, or goose feathers.

5. The preparation method according to claim 3, characterized in that, The solid content of the nano-calcium silicate emulsion in step (5) is 10-25%.

6. The preparation method according to claim 1, characterized in that, The particle size of the microparticles in step (6) is no greater than 50µm.

7. A method for applying the reinforcing agent prepared by the preparation method according to any one of claims 1 to 6, characterized in that, This reinforcing agent is used in dry-hard concrete, and its dosage is 1 to 3% of the mass of the cementitious material.

Images