Concrete with high light volcanic ash content and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to concrete with high light volcanic ash content and a preparation method of the concrete. According to the high-strength lightweight concrete provided by the invention, the balance of light weight and high strength is realized by adjusting the composition of the raw materials, and meanwhile, the high-strength lightweight concrete has excellent durability, workability and environmental protection performance. Capillary pores in the concrete can be further filled through the volcanic ash effect and the micro aggregate filling effect of the volcanic ash, and the microstructure of an interface transition area is improved, so that the compressive strength of the concrete is improved; the dextran-acrylic resin emulsion is added, so that the chloride ion penetration resistance of the concrete is improved, the durability of the concrete is enhanced, the flexibility and crack resistance of the concrete are improved, and cracks in the construction and use processes are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a concrete containing a high content of lightweight volcanic ash and a preparation method thereof. Background Art

[0002] High-strength lightweight concrete (HSLWC), as a new type of building material, has received extensive attention in recent years in the fields of architecture, bridges, transportation, etc. Its development stems from the higher requirements for material properties in modern architecture, especially the application requirements in high-rise buildings, long-span structures, and harsh environments. Compared with ordinary concrete, high-strength lightweight concrete has a lower density (usually less than 2000 kg / m 3 ) and a higher compressive strength (exceeding 40 Mpa), and at the same time has excellent heat insulation and fire resistance. These characteristics make it show significant advantages in reducing the self-weight of the structure, improving the seismic performance, and enhancing the heat insulation effect. In addition, the application of high-strength lightweight concrete in bridge engineering has also gradually received attention. Its characteristics of light weight, high strength, and high durability make it show superiority in long-span bridges. For example, in new projects, it can extend the span and reduce the pier spacing, while in renovation projects, it can improve the bearing capacity without strengthening the lower structure.

[0003] High-strength lightweight concrete usually contains a large number of pores and lightweight aggregates. Although these components reduce the density of the concrete, they also result in a relatively loose internal structure, making it prone to brittle fracture. This brittleness causes the concrete to be easily broken when subjected to impact or dynamic loads, restricting its application in scenarios with high-performance requirements such as seismic resistance and impact resistance; when subjected to external forces, high-strength lightweight concrete is prone to brittle failure and cannot absorb energy through deformation like ductile materials. This lack of flexibility restricts its application in structures that require a high deformation capacity, such as bridge expansion joints and seismic structures. Summary of the Invention

[0004] The purpose of the present invention is to provide a concrete containing a high content of lightweight volcanic ash and a preparation method thereof, which can maintain a relatively high strength while reducing the density of the concrete and improve the flexibility of lightweight concrete.

[0005] The present invention provides a high-strength lightweight concrete containing a certain amount of pozzolan. The raw materials of the concrete are as follows: Portland cement 20wt% - 30wt%, dextran-acrylic resin emulsion 3wt% - 7wt%, pozzolan 8wt% - 12wt%, expanded glass microspheres 5wt% - 10wt%, ceramsite 10wt% - 20wt%, ceramic sand 10wt% - 15wt%, silica fume 2wt% - 5wt%, water reducing agent 0.3wt% - 0.5wt%, air-entraining agent 0.03wt% - 0.07wt%, water 10wt% - 15wt%. The preparation method of the dextran-acrylic resin emulsion is as follows: Take half of the water, dissolve sodium dodecylbenzenesulfonate in the water, add dextran and stir evenly, then add methyl methacrylate monomer, stir and heat up to 40°C - 50°C, pre-emulsify for 20 - 30 minutes to obtain a pre-emulsion; add the remaining water to the pre-emulsion, stir and heat up to 75°C - 85°C, dropwise add an aqueous solution of potassium persulfate, after the dropping is completed, heat the system up to 90°C - 95°C, and continue to react for 1 - 2 hours. After the reaction is completed, the dextran-acrylic resin emulsion is obtained.

[0006] Preferably, the mass ratio of sodium dodecylbenzenesulfonate, dextran, methyl methacrylate monomer, water and potassium persulfate is 0.03 - 0.05:0.1 - 0.2:0.5 - 0.8:1. 2 - 1.5:0.005 - 0.01.

[0007] Preferably, after the reaction is completed, the system is cooled to 40°C.

[0008] Preferably, the water reducing agent is a polycarboxylate-based water reducing agent.

[0009] Preferably, the air-entraining agent is triterpenoid saponin.

[0010] Preferably, the concentration of the aqueous solution of potassium persulfate is 0.5wt% - 1wt%.

[0011] Preferably, the time for dropwise adding the aqueous solution of potassium persulfate is 20 - 30 minutes.

[0012] The present invention also provides a preparation method of the high-strength lightweight concrete described in the above technical solution. The method includes the following steps: Soak the ceramsite and ceramic sand for 12 - 24 hours, then fish them out to obtain fully water-absorbed ceramsite and ceramic sand; then add Portland cement, dextran-acrylic resin emulsion, pozzolan, expanded glass microspheres and silica fume to obtain a solid mixture; mix the water reducing agent, air-entraining agent and water, and then add them to the solid mixture and stir evenly to obtain the high-strength lightweight concrete.

[0013] Preferably, the water for soaking the ceramsite and ceramic sand is different from the water in the raw materials.

[0014] The beneficial effects of the present invention: The high-strength lightweight concrete provided by the present invention achieves a balance between light weight and high strength by adjusting the composition of raw materials, and at the same time has excellent durability, workability and environmental protection performance. Its economy and versatility make it have broad application prospects in the fields of high-rise buildings, bridges, thermal insulation structures, etc. The pozzolanic effect and micro-aggregate filling effect of pozzolan can further fill the capillary pores in the concrete and improve the microstructure of the interfacial transition zone, thereby increasing the compressive strength of the concrete. In addition, the reaction between pozzolan and the hydration products of cement generates more C-S-H gels, filling the pores in the concrete and forming a complex three-dimensional structure, significantly improving the density and durability of the concrete; the addition of vitrified microspheres, ceramsite and ceramic sand reduces the density of the concrete while maintaining relatively high strength; the addition of dextran-acrylic resin emulsion improves the chloride ion penetration resistance of the concrete, enhances the durability of the concrete, improves the flexibility and crack resistance of the concrete, and reduces cracks during construction and use. Detailed Embodiments

[0015] To further illustrate the present invention, a concrete containing a high content of lightweight pozzolan and its preparation method provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0016] Unless otherwise specified, all products used in the embodiments of the present invention are conventional commercially available products.

[0017] Example 1 Take 5 g of sodium dodecylbenzenesulfonate and dissolve it in 70 g of water. Add 20 g of dextran and stir evenly. Then add 60 g of methylacrylic acid monomer, stir and heat up to 50 °C, and pre-emulsify for 30 min to obtain a pre-emulsion. Add 70 g of water to the pre-emulsion, stir and heat up to 80 °C, dropwise add a 0.5 wt% aqueous solution of potassium persulfate. After reacting for 30 min, the dropping is completed, and the total dropping amount is 0.5 g. Raise the temperature of the system to 90 °C and continue to react for 1 h. After the reaction is completed, cool to 40 °C to obtain dextran-acrylic resin emulsion for standby.

[0018] By mass, weigh 275 parts of portland cement, 50 parts of dextran-acrylic resin emulsion, 100 parts of pozzolan, 100 parts of vitrified microspheres, 200 parts of ceramsite, 120 parts of ceramic sand, 30 parts of silica fume, 4.5 parts of polycarboxylate water reducer (purchased from Shanghai Jinchuang Chemical Co., Ltd., Melflux 4930 F), 0.5 part of industrial-grade triterpenoid saponin and 120 parts of water for standby.

[0019] Soak ceramsite and ceramsite sand in water for 24 h to obtain fully water-absorbed ceramsite and ceramsite sand; then add the weighed portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres and silica fume to obtain a solid mixture; mix the weighed water reducing agent, industrial grade triterpenoid saponin and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0020] Example 2 Dissolve 5 g of sodium dodecylbenzenesulfonate in 65 g of water, add 20 g of dextran, stir evenly, then add 70 g of methylacrylic acid monomer, stir and heat up to 50 °C, pre-emulsify for 30 min to obtain a pre-emulsion; add 65 g of water to the pre-emulsion, stir and heat up to 80 °C, dropwise add a 0.5 wt% aqueous solution of potassium persulfate, finish dropping after reacting for 30 min, the total dropping amount is 0.5 g, raise the temperature of the system to 90 °C, continue to react for 1 h, after the reaction is completed, cool to 40 °C to obtain the dextran-acrylic resin emulsion for standby.

[0021] Weigh 210 parts of portland cement, 70 parts of dextran-acrylic resin emulsion, 120 parts of volcanic ash, 85 parts of vitrified microspheres, 180 parts of ceramsite, 150 parts of ceramsite sand, 50 parts of silica fume, 4.5 parts of polycarboxylate water reducing agent, 0.5 part of industrial grade triterpenoid saponin and 130 parts of water for standby by mass.

[0022] Soak ceramsite and ceramsite sand in water for 20 h to obtain fully water-absorbed ceramsite and ceramsite sand; then add the weighed portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres and silica fume to obtain a solid mixture; mix the weighed polycarboxylate water reducing agent, industrial grade triterpenoid saponin and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0023] Example 3 Dissolve 5 g of sodium dodecylbenzenesulfonate in 65 g of water, add 20 g of dextran, stir evenly, then add 70 g of methylacrylic acid monomer, stir and heat up to 50 °C, pre-emulsify for 30 min to obtain a pre-emulsion; add 65 g of water to the pre-emulsion, stir and heat up to 80 °C, dropwise add a 0.5 wt% aqueous solution of potassium persulfate, finish dropping after reacting for 30 min, the total dropping amount is 0.5 g, raise the temperature of the system to 90 °C, continue to react for 1 h, after the reaction is completed, cool to 40 °C to obtain the dextran-acrylic resin emulsion for standby.

[0024] Weigh 300 parts of portland cement, 70 parts of dextran-acrylic resin emulsion, 100 parts of volcanic ash, 80 parts of vitrified microspheres, 180 parts of ceramsite, 100 parts of ceramsite sand, 40 parts of silica fume, 3.5 parts of polycarboxylate water reducing agent, 0.5 part of industrial grade triterpenoid saponin and 126 parts of water for standby by mass.

[0025] Soak ceramsite and ceramic sand in water for 20 h to obtain fully water-absorbed ceramsite and ceramic sand; then add the weighed portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres, and silica fume to obtain a solid mixture; mix the weighed polycarboxylate water reducer, industrial-grade triterpenoid saponin, and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0026] Control Example 1 Weigh 275 parts of portland cement, 100 parts of volcanic ash, 100 parts of vitrified microspheres, 200 parts of ceramsite, 120 parts of ceramic sand, 30 parts of silica fume, 4.5 parts of polycarboxylate water reducer, 0.5 part of industrial-grade triterpenoid saponin, and 120 parts of water for standby in terms of mass parts.

[0027] Soak ceramsite and ceramic sand in water for 24 h to obtain fully water-absorbed ceramsite and ceramic sand; then add the weighed portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres, and silica fume to obtain a solid mixture; mix the weighed polycarboxylate water reducer, industrial-grade triterpenoid saponin, and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0028] Control Example 2 Weigh 275 parts of portland cement, 50 parts of acrylic resin emulsion (purchased from Changzhou Guangshu Chemical Technology Co., Ltd., GS-201 acrylic emulsion), 100 parts of volcanic ash, 100 parts of vitrified microspheres, 200 parts of ceramsite, 120 parts of ceramic sand, 30 parts of silica fume, 4.5 parts of polycarboxylate water reducer, 0.5 part of industrial-grade triterpenoid saponin, and 120 parts of water for standby in terms of mass parts.

[0029] Soak ceramsite and ceramic sand in water for 24 h to obtain fully water-absorbed ceramsite and ceramic sand; then add the weighed portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres, and silica fume to obtain a solid mixture; mix the weighed polycarboxylate water reducer, industrial-grade triterpenoid saponin, and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0030] Control Example 3 Dissolve 5 g of sodium dodecylbenzenesulfonate in 70 g of water, add 20 g of dextran, stir evenly, then add 60 g of methyl methacrylate monomer, stir and heat up to 50 °C, and pre-emulsify for 30 min to obtain a pre-emulsion; add 70 g of water to the pre-emulsion, stir and heat up to 80 °C, dropwise add a 0.5 wt% aqueous solution of potassium persulfate, finish dropping after reacting for 30 min, the total dropping amount is 0.5 g, raise the temperature of the system to 90 °C, continue to react for 1 h, after the reaction is completed, cool to 40 °C to obtain a dextran-acrylic resin emulsion for standby.

[0031] Weigh 375 parts by mass of Portland cement, 50 parts of dextran-acrylic resin emulsion, 100 parts of vitrified microspheres, 200 parts of ceramsite, 120 parts of ceramsite sand, 30 parts of silica fume, 4.5 parts of polycarboxylate superplasticizer (purchased from Shanghai Jinchuang Chemical Co., Ltd., Melflux 4930 F), 0.5 part of industrial-grade triterpenoid saponin, and 120 parts of water for standby.

[0032] Soak the ceramsite and ceramsite sand in water for 24 h to obtain fully water-absorbed ceramsite and ceramsite sand; then add the weighed Portland cement, dextran-acrylic resin emulsion, vitrified microspheres, and silica fume to obtain a solid mixture; mix the weighed polycarboxylate superplasticizer, industrial-grade triterpenoid saponin, and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0033] Comparative Example 4 Dissolve 5 g of sodium dodecylbenzenesulfonate in 70 g of water, add 20 g of dextran, stir evenly, then add 60 g of methyl methacrylate monomer, stir and heat up to 50 °C, and pre-emulsify for 30 min to obtain a pre-emulsion; add 70 g of water to the pre-emulsion, stir and heat up to 80 °C, dropwise add a 0.5 wt% aqueous solution of potassium persulfate, finish dropping after reacting for 30 min, the total dropping amount is 0.5 g, raise the temperature of the system to 90 °C, continue to react for 1 h, after the reaction is completed, cool to 40 °C to obtain dextran-acrylic resin emulsion for standby.

[0034] Weigh 275 parts by mass of Portland cement, 50 parts of dextran-acrylic resin emulsion, 130 parts of volcanic ash, 100 parts of vitrified microspheres, 200 parts of ceramsite, 120 parts of ceramsite sand, 4.5 parts of polycarboxylate superplasticizer (purchased from Shanghai Jinchuang Chemical Co., Ltd., Melflux 4930 F), 0.5 part of industrial-grade triterpenoid saponin, and 120 parts of water for standby.

[0035] Soak the ceramsite and ceramsite sand in water for 24 h to obtain fully water-absorbed ceramsite and ceramsite sand; then add the weighed Portland cement, dextran-acrylic resin emulsion, volcanic ash, and vitrified microspheres to obtain a solid mixture; mix the weighed superplasticizer, industrial-grade triterpenoid saponin, and water, and then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

[0036] Test Example 1 Use the high-strength lightweight concrete prepared in Examples 1 to 3 and Comparative Examples 1 to 4 as samples respectively to conduct the following tests.

[0037] Conduct compressive strength tests on the samples according to the method specified in GB / T 29062-2012, and test the dry apparent density of the samples according to the method specified in JGJ 51-2002. The test results are shown in Table 1.

[0038] Table 1 Compressive strength of samples

[0039] As can be seen from Table 1, compared with Comparative Example 1, the concretes prepared in Examples 1 to 3 have higher compressive strength and lower dry apparent density, indicating that the use of dextran-acrylic resin emulsion in the present invention can maintain a relatively high strength while reducing the density of concrete; the compressive strength of the sample in Comparative Example 2 is lower than that in Example 1, indicating that the dextran-acrylic resin emulsion of the present invention has better effects than the conventional acrylic resin emulsion after being used in concrete; the strength of the sample in Example 1 is much higher than that in Comparative Examples 3 and 4, indicating that the addition of pozzolan can effectively improve the concrete strength, and the simultaneous use of pozzolan and silica fume in the preparation of concrete is beneficial to further improve the compressive strength of concrete.

[0040] The durability of the samples was detected according to the method specified in GB / T 50082-2009, and the crack resistance of the samples was detected according to the method specified in GB / T 50081-2002. The results are shown in Table 2.

[0041] Table 2 Durability of samples

[0042] As can be seen from Table 2, in Comparative Example 1, no emulsion was used to prepare concrete, and in Comparative Example 2, only the conventional acrylic resin emulsion was used. Compared with Example 1, the K values of their anti-sulfate erosion coefficients are both relatively low. The use of dextran-acrylic resin emulsion in the present invention can effectively improve the anti-sulfate erosion ability of concrete, and thus improve the durability.

[0043] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments according to these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A high-strength lightweight concrete containing a volcanic ash content, characterized in that, The raw materials of the concrete are as follows: Portland cement 20wt% - 30wt%, dextran-acrylic resin emulsion 3wt% - 7wt%, volcanic ash 8wt% - 12wt%, vitrified microspheres 5wt% - 10wt%, ceramsite 10wt% - 20wt%, ceramsite sand 10wt% - 15wt%, silica fume 2wt% - 5wt%, water reducing agent 0.3wt% - 0.5wt%, air entraining agent 0.03wt% - 0.07wt%, water 10wt% - 15wt%. The preparation method of the dextran-acrylic resin emulsion is as follows: Take half of the water, dissolve sodium dodecylbenzenesulfonate in the water, add dextran and stir evenly, then add methyl methacrylate monomer, stir and heat up to 40°C - 50°C, pre-emulsify for 20 - 30 min to obtain a pre-emulsion; add the remaining water to the pre-emulsion, stir and heat up to 75°C - 85°C, dropwise add an aqueous solution of potassium persulfate, after the dropping is completed, raise the temperature of the system to 90°C - 95°C, and continue to react for 1 - 2 h. After the reaction is completed, the dextran-acrylic resin emulsion is obtained.

2. The high-strength lightweight concrete according to claim 1, wherein The mass ratio of sodium dodecylbenzenesulfonate, dextran, methyl methacrylate monomer, water and potassium persulfate is 0.03 - 0.05:0.1 - 0.2:0.5 - 0.8:1.2 - 1.5:0.005 - 0.

01.

3. The high-strength lightweight concrete according to claim 1, wherein After the reaction is completed, the system is cooled to 40°C.

4. The high-strength lightweight concrete according to claim 1, wherein, The water reducing agent is a polycarboxylate-based water reducing agent.

5. The high-strength lightweight concrete according to claim 1, characterized in that, The air entraining agent is triterpenoid saponin.

6. The high-strength lightweight concrete according to claim 1, characterized in that, The concentration of the aqueous solution of potassium persulfate is 0.5wt% - 1wt%.

7. The high-strength lightweight concrete according to claim 1, characterized in that, The time for dropping the aqueous solution of potassium persulfate is 20 - 30 min.

8. The preparation method of the high-strength lightweight concrete according to any one of claims 1 to 7, characterized in that, The method includes the following steps: Soak the ceramsite and ceramsite sand for 12 - 24 h, fish them out to obtain fully water-absorbed ceramsite and ceramsite sand; then add Portland cement, dextran-acrylic resin emulsion, volcanic ash, vitrified microspheres and silica fume to obtain a solid mixture. Mix the water reducing agent, air entraining agent and water, then add them to the solid mixture and stir evenly to obtain high-strength lightweight concrete.

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