A C25 super-plasticizing concrete

Abstract

The application relates to the technical field of concrete, and discloses C25 super-bleeding-retaining concrete, which is prepared from the following raw materials in parts by weight: 40-65 parts of cement, 120-150 parts of coarse aggregate, 70-95 parts of fine aggregate, 12.5-18 parts of water, 0.5-1.8 parts of microcrystalline cellulose and 1-3.2 parts of polymer nanoparticle gel; wherein the polymer nanoparticle gel is composed of carbon aerogel and polylactic acid in a weight ratio of (0.2-0.6):1. The concrete prepared from the specific proportion and components has improved bleeding-retaining performance, can meet the requirements of high-temperature environment and long-time transportation, and has excellent flow performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete, in particular to a C25 super slump-retaining concrete. BACKGROUND

[0002] C25 concrete refers to concrete with a compressive strength of 25 MPa, which is a common medium-strength concrete. It is commonly used in the foundation, floor, column and beam of residential buildings, which can provide sufficient strength and stability to support the structure of the house and meet the general requirements of residential buildings; it is suitable for commercial buildings such as office buildings, shopping malls and hotels; it is also used in the foundation, pavement and pier of roads and bridges, which can withstand traffic load and environmental impact to provide stable pavement and bridge structure; and it is used in underground structures such as basements, underground passages and underground garages, which can provide sufficient strength and waterproof performance to meet the requirements of underground structures.

[0003] However, during the preparation of C25 concrete, due to the remote construction of the mixing station, traffic congestion and road construction on the transportation route, unreasonable or insufficient coordination of the delivery plan of the concrete supplier, insufficient preparation work at the construction site, such as failure to clean the road in advance, failure to set up a suitable unloading point, and adverse weather conditions such as heavy rain and snow disaster, all of which will cause the road to be blocked and the traffic to be disrupted, thus prolonging the transportation time of the concrete, causing the concrete to take a long time to reach the construction site, and thus causing the water in the concrete to gradually evaporate, the slump retention performance to deteriorate, the concrete to become dry and compact, and the concrete to be difficult to flow, affecting the uniformity and strength of the concrete.

[0004] In addition, in a high temperature environment, the water in the concrete evaporates faster, accelerating the hydration reaction of the cement, causing the setting and hardening process of the concrete to speed up, causing the concrete to lose its fluidity and be difficult to maintain its slump, and also affecting the uniformity and strength of the concrete.

[0005] Therefore, there is an urgent need to provide a concrete that can meet long-term transportation and has excellent slump retention performance in a high temperature environment. SUMMARY

[0006] In order to solve at least one of the above technical problems, a concrete that can meet long-term transportation and has excellent slump retention performance in a high temperature environment is developed, and the present application provides a C25 super slump-retaining concrete.

[0007] In one aspect, the present application provides a C25 super slump-retaining concrete, which comprises the following raw materials by weight: cement 40-65 parts, coarse aggregate 120-150 parts, fine aggregate 70-95 parts, water 12.5-18 parts, microcrystalline cellulose 0.5-1.8 parts, and polymeric nanoparticle gel 1-3.2 parts.

[0008] The polymer nanoparticle gel is composed of carbon aerogel and polylactic acid with a weight ratio of (0.2-0.6):1.

[0009] By adopting the technical scheme, the concrete prepared by the application has excellent comprehensive performance, the slump retention performance of the concrete is improved, the concrete can meet the requirements of high-temperature environment and long-time transportation, and the concrete has excellent flow performance.

[0010] The microcrystalline cellulose is added, the dispersion performance of the cement is improved, the cement aggregation phenomenon is reduced, the fiber network structure is formed in the concrete, the dispersion state between the cement particles is improved, the cement and the aggregate are fully mixed, the expansion of cracks is effectively resisted, and the strength and durability of the concrete are improved.

[0011] The polymer nanoparticle gel is added, the polymer nanoparticle gel is composed of carbon aerogel and polylactic acid, can react with cement particles and water molecules to form a stable gel structure, delay water evaporation, keep the concrete fluidity for a long time, improve the slump retention performance of the concrete, keep the concrete fluidity in high-temperature environment and long-time transportation, reduce the pore structure of the concrete, and improve the compactness and durability of the concrete.

[0012] Optionally, the cement is 48-52 parts, the coarse aggregate is 130-140 parts, the fine aggregate is 80-85 parts, the water is 14-16 parts, the microcrystalline cellulose is 1-1.3 parts, and the polymer nanoparticle gel is 1.8-2.4 parts.

[0013] By adopting the technical scheme, the concrete prepared by the application has excellent comprehensive performance, the slump retention performance of the concrete is improved, the concrete can meet the requirements of high-temperature environment and long-time transportation, and the concrete has excellent flow performance.

[0014] Optionally, the polymer nanoparticle gel is composed of the carbon aerogel and the polylactic acid with a weight ratio of (0.32-0.4):1.

[0015] By adopting the technical scheme, the polymer nanoparticle gel prepared by the application can increase the flowability of the concrete, make the concrete easier to process and pour, improve the slump retention performance of the concrete, and make the concrete keep water retention and slump for a long time during construction.

[0016] Optionally, the average particle size of the carbon aerogel is 200-500 nm.

[0017] Optionally, the specific surface area of the carbon aerogel is 1000-1500 m 2 / g.

[0018] By adopting the above technical solutions, the carbon aerogel with specific average particle size and specific surface area is adopted in the application, so that the carbon aerogel has high specific surface area, can adsorb and hold a certain amount of moisture, form hydrate colloid, can prolong the holding time of moisture in the concrete, reduce the evaporation and loss of moisture, and improve the water retention performance of the concrete; and prolong the slump retention time of the concrete, that is, keep the slump of the concrete from decreasing, which is very beneficial for the case of long-distance transportation or long construction time, can ensure the fluidity and plasticity of the concrete for a long time during the construction process; and increase the friction between the particles in the concrete, reduce the loss inertia of the concrete, can reduce the loss and delamination phenomenon of the concrete during the construction process, and improve the construction quality.

[0019] Optionally, the polylactic acid is a polyethylene glycol-polylactic acid copolymer.

[0020] By adopting the above technical solutions, the polyethylene glycol-polylactic acid copolymer and the carbon aerogel are adopted to prepare the polymer nanoparticle gel, which can improve the water retention of the concrete, reduce the evaporation and loss of moisture, and prolong the slump retention time of the concrete, so that the slump retention performance of the concrete is more excellent.

[0021] Optionally, the average particle size of the microcrystalline cellulose is not greater than 15 μm.

[0022] By adopting the above technical solutions, the microcrystalline cellulose with specific average particle size is adopted in the application, which improves the adsorption with the surface of the cement particles, forms a covering layer of cementitious material between the cement particles, reduces the mutual adsorption force and coalescence force between the particles, thereby promoting the dispersion of the cement particles; improves the fluidity of the cement slurry, reduces the viscosity of the slurry, and makes the slurry more easily flow and fill; and increases the stability of the cement slurry, prevents the delamination and sedimentation of the slurry.

[0023] Optionally, the fineness modulus of the fine aggregate is 1.5-1.8.

[0024] By adopting the above technical solutions, the fineness modulus of the fine aggregate is 1.5-1.8, and the particle size distribution is relatively uniform, so that the concrete has good plasticity and fluidity, and the strength, crack resistance and durability of the concrete are improved.

[0025] Optionally, the coarse aggregate is steel slag.

[0026] Optionally, the fine aggregate is river sand.

[0027] In summary, the application has at least one of the following beneficial technical effects:

[0028] 1. The concrete prepared by the specific ratio and components has excellent comprehensive performance, the slump retention performance of the concrete is improved, and the requirements of high temperature environment and long time transportation can be met;

[0029] 2. The microcrystalline cellulose added in the application can improve the dispersion performance of the cement, reduce the agglomeration phenomenon of the cement, form a fiber network structure in the concrete, improve the dispersion state between the cement particles, promote the full mixing of the cement and the aggregate, effectively resist the expansion of cracks, and improve the strength and durability of the concrete;

[0030] 3. The application also adds polymer nanoparticle gel, which is composed of carbon aerogel and polylactic acid, can react with cement particles and water molecules, form a stable gel structure, delay the evaporation of water, keep the fluidity of the concrete for a long time, improve the slump retention performance of the concrete, and keep the fluidity of the concrete in high temperature environment and long time transportation. DETAILED DESCRIPTION

[0031] The application will be further described in detail in combination with the embodiments.

[0032] The application designs a C25 super slump retention concrete, which comprises the following raw materials in parts by weight: cement 40-65 parts, coarse aggregate 120-150 parts, fine aggregate 70-95 parts, water 12.5-18 parts, microcrystalline cellulose 0.5-1.8 parts, and polymer nanoparticle gel 1-3.2 parts.

[0033] The polymer nanoparticle gel is composed of carbon aerogel and polylactic acid in a weight ratio of (0.2-0.6):1.

[0034] The preparation method of the polymer nanoparticle gel is as follows: carbon aerogel and polylactic acid are put into a container and mixed and stirred to prepare the polymer nanoparticle gel.

[0035] The preparation method of the concrete is as follows: refer to GB / T50080-2016.

[0036] The chemical composition of the steel slag includes: SiO2 is 12-14%, Al2O3 is 4-5%, Fe2O3 is 45-49%, CaO is 28-30%, and MgO is 4-5%.

[0037] The physical indexes of the cement are as follows:

[0038] Standard consistency: 27.8%;

[0039] Density: 2.96 g / cm 3 ;

[0040] Specific surface area: 356 m 2 / kg;

[0041] Initial setting time: 249 min;

[0042] Final setting time: 311 min;

[0043] 3d flexural strength: 5.6 MPa;

[0044] 28d flexural strength: 8 MPa;

[0045] 3d compressive strength: 27.9 MPa;

[0046] 28d compressive strength: 55 Mpa.

[0047] The raw materials of the present application are as follows, and unless otherwise specified, the raw materials of the present application are all from the market:

[0048] Polyethylene glycol-polylactic acid copolymer: Xi'an Qiyue Biological Technology Co., Ltd., purity 95%;

[0049] Polylactic acid: (Alpha) Zhengzhou Alpha Chemical Co., Ltd., item number 26100-51-6;

[0050] Microcrystalline cellulose: purity 99%;

[0051] Water: selected from tap water.

[0052] Detection items and detection methods:

[0053] Change in slump over time: detected according to GB / T 8076-2008. Specific embodiments

[0055] Examples 1-5

[0056] Example 1-5 The specific raw material dosage of a C25 super slump-retaining concrete is shown in Table 1.

[0057] Table 1

[0058]

[0059] Among them, the average particle size of microcrystalline cellulose is 15 μm, and the fine aggregate is river sand;

[0060] The polymer nanoparticle gel is composed of carbon aerogel and polylactic acid, the average particle size of the carbon aerogel is 200 nm, the specific surface area is 1000 m 2 / g, and the weight ratio of carbon aerogel and polylactic acid and the fineness modulus of fine aggregate are shown in Table 2.

[0061] Table 2

[0062]

[0063] Comparative Example 1

[0064] Based on Example 3, except that an equal amount of microcrystalline cellulose is used to replace the polymer nanoparticle gel, the other components and preparation methods are consistent with Example 3.

[0065] Comparative Example 2

[0066] Based on Example 3, except that an equal amount of polymer nanoparticle gel is used to replace the microcrystalline cellulose, the other components and preparation methods are consistent with Example 3.

[0067] Comparative Example 3

[0068] Based on Example 3, except that an equal amount of carbon aerogel is used to replace the polylactic acid, the other components and preparation methods are consistent with Example 3.

[0069] Comparative Example 4

[0070] Based on Example 3, except that an equal amount of polylactic acid is used to replace the carbon aerogel, the other components and preparation methods are consistent with Example 3.

[0071] The concrete prepared in Examples 1-5 and Comparative Examples 1-4 is subjected to performance testing, and the test results are shown in Table 3.

[0072] Table 3

[0073]

[0074]

[0075] As can be seen from Examples 1-5 and Table 3, the concrete prepared in the present application has excellent slump retention performance. The slump loss is small when the slump is detected for 1 h and 4 h at 30°C and 50°C, respectively, and the stability performance is excellent. In a high temperature environment and during long-term transportation, the stability performance is excellent.

[0076] As can be seen from Comparative Examples 1-2, Example 3 and Table 3, the concrete prepared in the present application using the microcrystalline cellulose and polymer nanoparticle gel system has good dispersion performance. Compared with the single use of microcrystalline cellulose or polymer nanoparticle gel, the slump retention performance of the concrete can be better improved, and the high temperature resistance is more excellent.

[0077] From Comparative Example 3-4, Example 3 and Table 3, it can be seen that the polymer nanoparticle gel prepared from carbon aerogel and polylactic acid used in the application can better improve the slump retention performance of concrete; the inventors speculate that carbon aerogel is a material with a porous structure, has a large specific surface area and pore volume, when carbon aerogel is added to concrete, it can adsorb and hold a certain amount of moisture, form hydrate colloid, thereby improving the flow performance of concrete, and can act as a carrier to improve the dispersibility of polylactic acid in concrete, increase the contact area with cement and aggregate; at the same time, polylactic acid is a high molecular polymer, has good dispersibility and adhesion, can coat cement particles and interact with cement colloid to form a uniformly dispersed colloid system, thereby improving the flow performance and slump retention performance of concrete.

[0078] Example 6-8

[0079] Based on Example 3, except that the weight ratio of carbon aerogel and polylactic acid is different, the other components and preparation methods are the same as those of Example 3, wherein the total weight of carbon aerogel and polylactic acid remains unchanged.

[0080] Example 6

[0081] The weight ratio of carbon aerogel and polylactic acid is 0.32:1.

[0082] Example 7

[0083] The weight ratio of carbon aerogel and polylactic acid is 0.36:1.

[0084] Example 8

[0085] The weight ratio of carbon aerogel and polylactic acid is 0.38:1.

[0086] Example 9

[0087] Based on Example 7, except that an equal amount of polyethylene glycol-polylactic acid copolymer is used to replace polylactic acid, the other components and preparation methods are the same as those of Example 7.

[0088] The concrete prepared in Examples 6-9 was subjected to performance testing, and the test results are shown in Table 4.

[0089] Table 4

[0090]

[0091] From Examples 6-8, 3 and Table 4, it can be seen that the concrete prepared by using a more optimal ratio of carbon aerogel and polylactic acid in the application has more excellent slump retention performance;

[0092] From the examples 9, 7 and table 4, it can be seen that the concrete prepared by using equal amount of polyethylene glycol-polylactic acid copolymer instead of polylactic acid has more excellent slump retention performance. The polyethylene glycol-polylactic acid copolymer has higher water retention performance, can adsorb and maintain a certain amount of moisture, thereby prolonging the water retention time in the concrete, reducing the evaporation and loss of water, improving the water retention performance of the concrete, and prolonging the slump retention time of the concrete.

[0093] Examples 10-11

[0094] Based on the example 9, except that the average particle size and the surface area of the carbon aerogel are different, the other components and the preparation method are consistent with the example 9.

[0095] Example 10

[0096] The average particle size of the carbon aerogel is 350 nm, and the specific surface area is 1200 m 2 / g.

[0097] Example 11

[0098] The average particle size of the carbon aerogel is 500 nm, and the specific surface area is 1500 m 2 / g.

[0099] Examples 12-13

[0100] Based on the example 10, except that the average particle size of the microcrystalline cellulose is different, the other components and the preparation method are consistent with the example 10.

[0101] Example 12

[0102] The average particle size of the microcrystalline cellulose is 8 μm.

[0103] Example 13

[0104] The average particle size of the microcrystalline cellulose is 2 μm.

[0105] The concrete prepared in the examples 10-13 is subjected to performance detection, and the detection results are shown in table 5.

[0106] Table 5

[0107]

[0108] From the examples 10-11, 9 and table 5, it can be seen that the present application adopts a more optimal range of average particle size and specific surface area of carbon aerogel, so that the carbon aerogel has a high specific surface area, can adsorb and hold a certain amount of moisture, form a hydrate colloid, can prolong the holding time of moisture in concrete, reduce the evaporation and loss of moisture, improve the water retention performance of concrete, and prolong the slump retention time of concrete, and increase the friction between particles in concrete, reduce the loss inertia of concrete, can reduce the loss and delamination phenomenon of concrete during construction, improve the construction quality;

[0109] From the examples 12-13, 10 and table 5, it can be seen that the present application adopts a more optimal range of average particle size of microcrystalline cellulose, improves the adsorption with the surface of cement particles, forms a covering layer of cementitious material between the cement particles, reduces the mutual adsorption force and coalescence force between the particles, thereby promoting the dispersion of cement particles, improving the fluidity of cement paste, and improving the slump retention performance of concrete.

[0110] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made in accordance with the principles of the present application shall be covered within the protection scope of the present application.

Claims

1. A C25 super-plasticized concrete, characterized in that, The cement is 40-65 parts, the coarse aggregate is 120-150 parts, the fine aggregate is 70-95 parts, the water is 12.5-18 parts, the microcrystalline cellulose is 0.5-1.8 parts, and the polymer nanoparticle gel is 1-3.2 parts by weight; The polymer nanoparticle gel is composed of carbon aerogel and polylactic acid in a weight ratio of (0.2-0.6):

1. The average particle size of the carbon aerogel is 200-500 nm, the specific surface area of the carbon aerogel is 1000-1500 m 2 / g, and the average particle size of the microcrystalline cellulose is not more than 15 μm.

2. The C25 super-plasticized concrete according to claim 1, characterized in that, The cement is 48-52 parts, the coarse aggregate is 130-140 parts, the fine aggregate is 80-85 parts, the water is 14-16 parts, the microcrystalline cellulose is 1-1.3 parts, and the polymer nanoparticle gel is 1.8-2.4 parts.

3. The C25 super-plasticized concrete according to claim 1, characterized in that, The polymer nanoparticle gel is composed of carbon aerogel and polylactic acid in a weight ratio of (0.32-0.4):

1.

4. The C25 super-plasticized concrete according to claim 1, characterized in that, The polylactic acid is a polyethylene glycol-polylactic acid copolymer.

5. The C25 super-plasticized concrete according to claim 1, characterized in that, The fineness modulus of the fine aggregate is 1.5-1.

8.

6. The C25 super-plasticized concrete according to claim 1, characterized in that, The coarse aggregate is steel slag.

7. The C25 super-plasticized concrete according to claim 1, wherein, The fine aggregate is river sand.

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