A kind of concrete applicable to high-temperature construction environment and its preparation method

Abstract

This application relates to the field of concrete, and more specifically, it relates to a concrete applicable to high-temperature construction environments and a preparation method thereof. A concrete applicable to high-temperature construction environments, by mass parts, comprises the following raw materials: 185 - 205 parts of cement, 70 - 150 parts of mineral admixture, 130 - 160 parts of water, 650 - 710 parts of fine aggregate, 1100 - 1300 parts of coarse aggregate, 3 - 8 parts of water reducing agent, 25 - 40 parts of rice husk ash, 25 - 40 parts of pineapple leaf fiber, and 5 - 15 parts of boron carbide; the preparation method thereof is: mixing the cement and the mineral admixture until uniform to obtain a dry mixture; adding water, rice husk ash, pineapple leaf fiber, and boron carbide into the dry mixture and mixing until uniform to obtain a mixed material; adding the fine aggregate, the coarse aggregate, and the water reducing agent into the mixed material and mixing until uniform to obtain the concrete. This application has the advantage of alleviating the influence of high temperature on the strength of concrete.

Description

Technical Field

[0001] This application relates to the field of concrete, and more specifically, it relates to a kind of concrete applicable to high-temperature construction environment and its preparation method. Background Art

[0002] In concrete construction, high-temperature weather not only includes the situation of high ambient temperature in summer, but also includes the situations of relatively high external ambient temperature, low concrete pouring temperature, low relative humidity, strong wind, strong sunlight irradiation, etc. High-temperature weather generally occurs at any time of the year in tropical or arid climate regions. The mixing, pouring and curing of concrete in high-temperature weather will increase the hydration rate of cement and the temperature evaporation rate in the concrete, thus having an adverse impact on the concrete performance, making the concrete prone to cracking and having low strength. Therefore, there is still room for improvement. Summary of the Invention

[0003] In order to alleviate the influence of high temperature on the strength of concrete, this application provides a kind of concrete applicable to high-temperature construction environment and its preparation method.

[0004] In the first aspect, this application provides a kind of concrete applicable to high-temperature construction environment, adopting the following technical scheme:

[0005] A kind of concrete applicable to high-temperature construction environment, by mass parts, includes the following raw materials: 185 - 205 parts of cement, 70 - 150 parts of mineral admixture, 130 - 160 parts of water, 650 - 710 parts of fine aggregate, 1100 - 1300 parts of coarse aggregate, 3 - 8 parts

[0006] superplasticizer, 25 - 40 parts of rice husk ash, 25 - 40 parts of pineapple leaf fiber, 5 - 15 parts of boron carbide.

[0007] By adopting the above technical scheme, under the common cooperation of rice husk ash, pineapple leaf fiber and boron carbide, the pore structure inside the concrete can be effectively improved, enabling the rice husk ash and pineapple leaf fiber to be evenly dispersed and filling the pores inside the concrete to form a special structure. Moreover, under the cooperation of the three, the hydrophilic effect of rice husk ash is improved, having a stronger ability to attract water; free water is strongly attracted by the rice husk ash and stays in the pores; the pineapple leaf fiber distributed near the rice husk ash will absorb a part of the free water staying in the pores into its interior and output it evenly and continuously during subsequent curing, alleviating the situation of rapid evaporation of water at high temperature, thereby improving the strength of the concrete.

[0008] The special structure formed can enable the substance produced after the reaction of rice husk ash and cement hydration products to wrap the pineapple leaf fibers, that is, surround the outside of the pineapple leaf fibers. Even if the free water in the pineapple leaf fibers is released in advance due to high temperature, its evaporation effect will be slowed down because of this wrapping and surrounding, and after the water is released, it will also contact the cement hydration products wrapped on the outside immediately, which can just promote the secondary hydration of the hydration products and provide a good environment for the subsequent release of free water by the pineapple leaf fibers.

[0009] The water slowly released by the pineapple leaf fibers undergoes secondary hydration with the hydration products wrapped on the outside, forming a large amount of C-S-H gel and spherical fine particles. These C-S-H gels and fine particles adhere to the surface of the pineapple leaf fibers, which can effectively increase the surface roughness of the pineapple leaf fibers, thereby further increasing the mechanical bite tightness between the pineapple leaf fibers and the concrete matrix, effectively inhibiting the generation and extension of cracks, and thus improving the anti-cracking effect of the concrete obtained under high-temperature construction conditions.

[0010] Preferably, the mass ratio of the rice husk ash, pineapple leaf fibers, and boron carbide is (28 - 35):(25 - 30):(6 - 10).

[0011] By adopting the above technical solution, further limiting the mass ratio of the rice husk ash, pineapple leaf fibers, and boron carbide further promotes the cooperation of the three, improves the pore structure inside the concrete, makes the three disperse more evenly, and is beneficial to improving the compressive and anti-cracking effects of the concrete.

[0012] Preferably, the pineapple leaf fibers are treated by the following steps:

[0013] Place the pineapple leaf fibers in an inert gas at 100 - 120 °C and heat-treat for 15 - 30 min;

[0014] Take out the heat-treated pineapple leaf fibers and soak them in a 3 - 10% alkali solution for 10 - 20 min;

[0015] Take them out and filter them dry to obtain modified pineapple leaf fibers.

[0016] Part of the cement slurry will flow into the fiber bundles of the pineapple leaf fibers. If the bite degree between the pineapple leaf fibers and the matrix is too low, it is easy to shift or break away from the concrete system, which is not conducive to the subsequent release of free water and reaction with the hydration products surrounded on the outside, thus affecting the strength of the concrete.

[0017] By adopting the above technical solution, treating the pineapple leaf fibers by a specific method changes the structure and surface properties of the pineapple leaf fibers, effectively increasing the bite degree between the pineapple leaf fibers and the concrete matrix, and making the pineapple leaf fibers more firmly distributed in the concrete.

[0018] Preferably, the mass ratio of the pineapple leaf fiber to the alkali solution is 1:(3 - 5).

[0019] By adopting the above technical solution, the ratio between the pineapple leaf fiber and the alkali solution is further defined, so that the pineapple leaf fiber is more fully soaked, and the structure and performance of the pineapple leaf fiber are promoted to change rapidly.

[0020] Preferably, the fine aggregate includes one or more mixtures of river sand, sea sand, and machine-made sand.

[0021] Preferably, the fine aggregate includes river sand and machine-made sand, and the mass ratio of the river sand to the machine-made sand is 1:(2.5 - 3.5) based on the mass of the river sand.

[0022] By adopting the above technical solution, specific river sand and machine-made sand are selected as the fine aggregate, and the mixing ratio between the two is further defined, so that the machine-made sand with regular shape and the river sand with irregular shape can be fully utilized, and the cement paste can be more firmly combined with the fine aggregate.

[0023] In the second aspect, the present application provides a preparation method of concrete applicable to a high-temperature construction environment, adopting the following technical solution:

[0024] A preparation method of concrete applicable to a high-temperature construction environment includes the following steps:

[0025] Mix cement and mineral admixture evenly to obtain a dry mixture;

[0026] Add water, rice husk ash, pineapple leaf fiber, and boron carbide into the dry mixture and mix evenly to obtain a mixed material;

[0027] Add fine aggregate, coarse aggregate, and water reducer into the mixed material and mix evenly to obtain concrete.

[0028] Preferably, place the rice husk ash in a high-temperature environment of 600 - 650 °C and calcine it for 30 - 60 min, and then grind it to a particle size of 25 - 30 μm to obtain modified rice husk ash;

[0029] The modified rice husk ash is mixed with water, pineapple leaf fiber, and boron carbide together.

[0030] By adopting the above technical solution, special treatment is carried out on the rice husk ash, which can effectively improve the hydrophilic degree of the rice husk ash and enhance the water absorption effect; and the rice husk ash with smaller particle size and more uniform texture after special treatment can effectively improve the cooperation effect with boron carbide and pineapple leaf fiber.

[0031] In summary, the present application has the following beneficial effects:

[0032] 1. With the cooperation of rice husk ash, pineapple leaf fiber and boron carbide, the pore structure inside the concrete can be effectively improved, so that the rice husk ash and pineapple leaf fiber can be evenly dispersed and filled in the pores inside the concrete to form a special structure. In addition, with the cooperation of the three, the hydrophilic effect of rice husk ash is improved, and it has a stronger ability to attract water; free water is strongly attracted by rice husk ash and retained in the holes; the pineapple leaf fiber distributed near the rice husk ash will absorb part of the free water retained in the holes into the interior, and evenly and continuously output it during subsequent maintenance, alleviating the rapid evaporation of water at high temperature, thereby improving the strength of concrete.

[0033] 2. The water slowly released by the pineapple leaf fiber undergoes secondary hydration with the hydration products wrapped on the outside, forming a large amount of CSH gel and spherical fine particles. These CSH gel and fine particles adhere to the surface of the pineapple leaf fiber, which can effectively improve the surface roughness of the pineapple leaf fiber, thereby further improving the mechanical bite tightness between the pineapple leaf fiber and the concrete matrix, effectively inhibiting the formation and extension of cracks, thereby improving the anti-cracking effect of the concrete obtained under high temperature construction conditions. DETAILED DESCRIPTION

[0034] The present application is further described in detail below in conjunction with embodiments.

[0035] The raw materials used in the following examples and comparative examples are all commercially available products.

[0036] Preparation Example

[0037] Preparation Example 1

[0038] A modified pineapple leaf fiber is obtained by modification treatment according to the following steps:

[0039] Step 1): placing the pineapple leaf fiber in a sealed container filled with helium at 105° C. for heat treatment for 20 minutes.

[0040] Step 2): Take out the pineapple leaf fiber obtained in step 1), and soak it in 8% NaOH solution for 12 minutes.

[0041] The mass ratio of pineapple leaf fiber to NaOH solution is 1:4.

[0042] Step 3): Take out the pineapple leaf fiber soaked in step 2), place it in hot air at 40° C. for drying for 60 minutes to obtain modified pineapple leaf fiber.

[0043] Preparation Example 2

[0044] A modified pineapple leaf fiber, which is different from Preparation Example 1 in that:

[0045] In step 1), heat treatment is carried out for 30 min in a sealed container filled with helium at 100 °C.

[0046] In step 2), it is placed in a 3% NaOH solution and soaked for 20 min. The mass ratio of pineapple leaf fiber to the NaOH solution is 1:3.

[0047] Preparation Example 3

[0048] A modified pineapple leaf fiber, which is different from Preparation Example 1 in that:

[0049] In step 1), heat treatment is carried out for 15 min in a sealed container filled with helium at 120 °C.

[0050] In step 2), it is placed in a 10% NaOH solution and soaked for 10 min. The mass ratio of pineapple leaf fiber to the NaOH solution is 1:5.

[0051] Preparation Example 4

[0052] A modified pineapple leaf fiber, which is different from Preparation Example 1 in that step 1) is omitted.

[0053] Preparation Example 5

[0054] A modified pineapple leaf fiber, which is different from Preparation Example 1 in that step 2) is omitted.

[0055] Examples

[0056] Example 1

[0057] A concrete applicable to high-temperature construction environments, comprising the following raw materials: Portland cement, mineral admixture, water, fine aggregate, coarse aggregate, water reducer, rice husk ash, pineapple leaf fiber, boron carbide.

[0058] The mineral admixture is blast furnace slag powder and fly ash.

[0059] The fine aggregate is river sand and manufactured sand. The mass ratio of river sand to manufactured sand is 1:2.66, that is, the river sand is 188 kg and the manufactured sand is 500 kg.

[0060] The river sand is ordinary river sand with a fineness modulus of 2.7, medium sand in Zone II; the manufactured sand is fine sand with a fineness modulus of 1.8.

[0061] The coarse aggregate is 1-2 stone.

[0062] The water reducer is a polycarboxylate water reducer.

[0063] The pineapple leaf fiber is the pineapple leaf fiber prepared in Preparation Example 1.

[0064] The specific dosage of each raw material is shown in Table 1.

[0065] The embodiments of the present application also disclose a preparation method for concrete applicable to high-temperature construction environments, including the following steps:

[0066] Step 01): Mix cement and mineral admixtures and stir until uniform to obtain a dry mixture.

[0067] Step 02): Sequentially add water, rice husk ash, pineapple leaf fiber, and boron carbide into the dry mixture and mix until evenly stirred to obtain a mixed material.

[0068] Step 03): Add fine aggregate, coarse aggregate, and water reducer into the mixed material and mix until evenly stirred to obtain concrete.

[0069] Example 2

[0070] A kind of concrete applicable to high-temperature construction environments, different from Example 1 in that

[0071] The mass ratio of rice husk ash, pineapple leaf fiber, and boron carbide is 28:30:10.

[0072] The pineapple leaf fiber is the pineapple leaf fiber prepared by Preparation Example 2.

[0073] The fine aggregate is river sand and manufactured sand. The mass ratio of river sand to manufactured sand is 1:2.5, that is, the river sand is 197 kg and the manufactured sand is 491 kg.

[0074] Example 3

[0075] A kind of concrete applicable to high-temperature construction environments, different from Example 1 in that

[0076] The mass ratio of rice husk ash, pineapple leaf fiber, and boron carbide is 35:25:6.

[0077] The pineapple leaf fiber is the pineapple leaf fiber prepared by Preparation Example 3.

[0078] The mass ratio of river sand to manufactured sand is 1:3.5, that is, the river sand is 153 kg and the manufactured sand is 535 kg.

[0079] Table 1

[0080]

[0081] Example 4

[0082] A kind of concrete applicable to high-temperature construction environments, different from Example 1 in that the pineapple leaf fiber is the pineapple leaf fiber prepared by Preparation Example 4.

[0083] Example 5

[0084] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 1 in that the pineapple leaf fiber is the pineapple leaf fiber prepared in Preparation Example 5.

[0085] Example 6

[0086] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 1 in that the mass ratio of river sand to manufactured sand is 1:0.5, that is, the river sand is 459 kg and the manufactured sand is 229 kg.

[0087] Example 7

[0088] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 1 in that the fine aggregate is river sand, that is, the river sand is 688 kg and the manufactured sand is 0 kg.

[0089] Example 8

[0090] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 1 in that

[0091] Step 01): Place the rice husk ash in a high-temperature environment of 650 °C and calcine for 20 min.

[0092] After taking it out, grind the rice husk ash that has been calcined at high temperature until the particle size of the rice husk ash is 25 - 30 μm, that is, the modified rice husk ash is obtained.

[0093] Step 02): Mix the cement and mineral admixture and stir until uniform to obtain a dry mixture.

[0094] Step 03): Add water, modified rice husk ash, pineapple leaf fiber, and boron carbide to the dry mixture in sequence and mix until evenly stirred to obtain a mixed material.

[0095] Step 04): Add fine aggregate, coarse aggregate, and water reducer to the mixed material and mix until evenly stirred to obtain concrete.

[0096] Example 9

[0097] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 8 in that in Step 01), the rice husk ash is placed in a high-temperature environment of 600 °C and calcined for 60 min.

[0098] Example 10

[0099] A kind of concrete applicable to high-temperature construction environment, which is different from that of Example 8 in that in Step 01), the rice husk ash is placed in an environment of 200 °C for calcination.

[0100] Comparative Example

[0101] Comparative Example 1

[0102] A kind of concrete applicable to high-temperature construction environment, which is different from that in Example 1 in that rice husk ash is replaced by silica fume, that is, the amount of rice husk ash is 0 kg and the amount of silica fume is 30 kg.

[0103] Comparative Example 2

[0104] A kind of concrete applicable to high-temperature construction environment, which is different from that in Example 1 in that pineapple leaf fiber is replaced by palm fiber, that is, the amount of pineapple leaf fiber is 0 kg and the amount of palm fiber is 28 kg.

[0105] Comparative Example 3

[0106] A kind of concrete applicable to high-temperature construction environment, which is different from that in Example 1 in that boron carbide is replaced by boron nitride, that is, the amount of boron carbide is 0 kg and the amount of boron nitride is 8 kg.

[0107] Comparative Example 4

[0108] A kind of concrete applicable to high-temperature construction environment, which is different from that in Example 1 in that the amount of rice husk ash is 22 kg, the amount of pineapple leaf fiber is 22 kg, and the amount of boron carbide is 22 kg.

[0109] Performance detection test

[0110] The concrete mixtures of Examples 1-10 and Comparative Examples 1-4 were prepared into cube specimens of 150 mm×150 mm×300 mm according to the provisions of GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and then placed in a box-type resistance furnace for heating, and the temperature was raised to 80 °C at a heating rate of 5 °C / min and kept at a constant temperature for 8 h.

[0111] The specimens treated at high temperature were taken out from the box-type resistance furnace, and the specimens were cooled to 35 °C by natural cooling and cured under the condition of maintaining 35 °C.

[0112] Then, the 28-day compressive strength and splitting tensile strength of the specimens were detected according to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".

[0113] The detection results are shown in Table 2.

[0114] Table 2

[0115]

[0116]

[0117] From the comparison of the test data of Example 1 and Comparative Examples 1-3 in Table 2, it can be seen that the compressive strength and splitting tensile strength of the concrete prepared in Comparative Examples 1-3 after curing in a high-temperature environment are far lower than those of Example 1. This shows that with the combined use of rice husk ash, pineapple leaf fiber, and boron carbide, a special structure can be formed, which is beneficial to slowing down the evaporation rate of free water under high-temperature conditions and can also release water to promote secondary hydration, thereby improving the tensile strength and splitting tensile strength of the prepared concrete. Comparative Examples 1-3 arbitrarily omitted any one of rice husk ash, pineapple leaf fiber, and boron carbide on the basis of Example 1, and the concrete prepared by destroying the above special combination could not alleviate the influence of high temperature on the concrete structure.

[0118] From the comparison of the test data of Comparative Example 4, it can be seen that although the tensile strength and splitting tensile strength of the concrete in Comparative Example 4 are slightly better than those in Comparative Examples 1-3, they are far lower than those of the concrete in Example 1. This shows that even if the three core raw materials of rice husk ash, pineapple leaf fiber, and boron carbide are used, but arbitrarily destroying the special use ratio combination among them, the three cannot have a special cooperation effect, and the prepared concrete cannot have good compressive strength and splitting tensile strength.

[0119] From the comparison of the test data of Example 1 and Examples 4 and 5 in Table 2, it can be seen that the compressive strength and crack resistance effect of the concrete prepared in Examples 4 and 5 are both lower than those of Example 1. This shows that pineapple leaf fiber needs to be treated by special heating and alkali immersion. The lack of any one treatment will have a greater impact on the structural change of pineapple leaf fiber and cannot form a specific special structure, thereby affecting the cooperation effect of rice husk ash, pineapple leaf fiber, and boron carbide.

[0120] From the comparison of the test data of Example 1 and Examples 6-7 in Table 2, it can be seen that after changing the type and proportion of fine aggregate in Examples 6 and 7, the compressive strength and splitting tensile strength of the prepared concrete both decrease to varying degrees.

[0121] From the comparison of the test data of Example 1 and Examples 8-10 in Table 2, it can be seen that special modification treatment of rice husk ash is beneficial to improving the cooperation effect between rice husk ash, pineapple leaf fiber, and boron carbide, thereby further improving the compressive strength and splitting tensile strength of concrete under high-temperature conditions.

[0122] This specific embodiment is only an explanation of the present application and does not limit the present application. Those skilled in the art can make modifications without creative contributions to this embodiment after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A kind of concrete applicable to high-temperature construction environment, characterized in that, By mass parts, it includes the following raw materials: 185 - 205 parts of cement, 70 - 150 parts of mineral admixture, 130 - 160 parts of water, 650 - 710 parts of fine aggregate, 1100 - 1300 parts of coarse aggregate, 3 - 8 parts of water reducer, 25 - 40 parts of rice husk ash, 25 - 40 parts of pineapple leaf fiber, 5 - 15 parts of boron carbide; The mineral admixture is blast furnace slag powder and fly ash; The following steps are used to process the pineapple leaf fiber: Place the pineapple leaf fiber in an inert gas at 100 - 120 °C for heat treatment for 15 - 30 min; Take out the heat-treated pineapple leaf fiber and soak it in a 3 - 10% alkali solution for 10 - 20 min; Take it out and filter it dry to obtain modified pineapple leaf fiber.

2. The concrete applicable to high-temperature construction environments according to claim 1, characterized in that: The mass ratio of the rice husk ash, pineapple leaf fiber, and boron carbide is (28 - 35):(25 - 30):(6 - 10).

3. The concrete applicable to high-temperature construction environments according to claim 1, characterized in that: The mass ratio of the heat-treated pineapple leaf fiber to the alkali solution is 1:(3 - 5).

4. The concrete applicable to high-temperature construction environments according to claim 1, wherein: The fine aggregate includes one or more mixtures of river sand, sea sand, and machine-made sand.

5. The concrete applicable to a high-temperature construction environment according to claim 4, characterized in that: The fine aggregate includes river sand and machine-made sand, and the mass ratio of river sand to machine-made sand is 1:(2.5 - 3.5), based on the mass of river sand.

6. A preparation method for concrete applicable to high-temperature construction environments according to any one of claims 1-5, characterized in that, It includes the following steps: Mix the cement and mineral admixture evenly to obtain a dry mix; Add water, rice husk ash, pineapple leaf fiber, and boron carbide to the dry mix and mix evenly to obtain a mixed material; Add fine aggregate, coarse aggregate, and water reducer to the mixed material and mix evenly to obtain concrete.

7. The preparation method of the concrete applicable to a high-temperature construction environment according to claim 6, characterized in that: Place the rice husk ash in a high-temperature environment of 600 - 650 °C for calcination for 30 - 60 min, and then grind it to a particle size of 25 - 30 μm to obtain modified rice husk ash; The modified rice husk ash is mixed with water, pineapple leaf fiber, and boron carbide together.

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