High-strength lightweight concrete and preparation method thereof

Abstract

The invention relates to high-strength lightweight concrete and a preparation method thereof, and belongs to the technical field of concrete. The lightweight high-strength concrete is prepared from the following components: 300 to 340 parts of slag cement, 250 to 280 parts of expanded perlite micro powder, 10 to 15 parts of modified ceramsite, 20 to 30 parts of polypropylene fiber, 60 to 100 parts of silica fume, 10 to 15 parts of a water reducing agent, 3 to 7 parts of a foaming agent and 220 to 300 parts of water. The lightweight high-strength concrete prepared in the invention ensures the lightweight of the concrete, and the mechanical strength of the lightweight concrete is significantly improved at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete and relates to high-strength lightweight concrete and a preparation method thereof. Background Art

[0002] Lightweight concrete, also known as foamed concrete, is a lightweight, thermally insulating material containing a large number of closed pores. Lightweight concrete is categorized into three types: lightweight aggregate concrete, porous concrete, and macroporous concrete. Lightweight concrete is typically prepared by mechanically preparing a foam from an aqueous solution of a foaming agent. This foam is then added to a slurry consisting of siliceous materials, calcareous materials, water, and various admixtures. The resulting porous material is then mixed, stirred, cast, and cured. The large number of closed pores in foamed concrete gives it the following excellent physical and mechanical properties. Its most prominent feature is the formation of closed foam pores within the concrete, which makes it lightweight and thermally insulating. Due to its excellent properties, lightweight concrete is widely used in energy-saving wall materials and has also found applications in other areas. Its primary applications in China are cast-in-place roof insulation, lightweight wall panels, and compensating foundations.

[0003] However, lightweight concrete has relatively poor crack resistance, especially after hardening, it is prone to cracks, which will affect its integrity and waterproof performance; compared with ordinary concrete, lightweight concrete has slightly lower strength and may not be suitable for some engineering structures with higher strength requirements. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high-strength lightweight concrete, which has improved mechanical properties on the basis of ensuring lightweight performance.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0006] A lightweight, high-strength concrete mainly made from the following ingredients:

[0007] 300-340 parts of slag cement, 250-280 parts of expanded perlite powder, 10-15 parts of modified ceramsite, 20-30 parts of polypropylene fiber, 60-100 parts of silica fume, 10-15 parts of water reducer, 3-7 parts of foaming agent, and 220-300 parts of water.

[0008] Preferably, the water includes 60-120 parts of water for foaming and 160-180 parts of water for mixing.

[0009] Preferably, the slag cement contains 100-110 parts of Portland cement, 150-170 parts of granulated blast furnace slag, 30-35 parts of modified corn cob powder, 8-10 parts of sodium alginate, and 12-15 parts of gypsum.

[0010] Further preferably, the preparation method of the modified corncob powder is:

[0011] Corn cob powder and anhydrous ethanol were mixed, epoxytriethoxysilane was added, and the mixture was stirred at 50° C. for 6 hours and then filtered. The filtrate was washed with ethanol and distilled water respectively, and dried to obtain modified corn cob powder.

[0012] More preferably, in the method for preparing the modified corn cob powder, the mass-volume-volume ratio of corn cob powder, anhydrous ethanol, and epoxytriethoxysilane is (90-100):500:(25-30) in g / mL / mL.

[0013] Preferably, the preparation method of the modified ceramsite is:

[0014] 10-20 parts of red mud, 30-40 parts of kaolin and 2-5 parts of silicon carbide are mixed to obtain a mixture; 25-40 parts of water are added to the mixture, and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes, and naturally cooled to obtain modified ceramsite.

[0015] Preferably, the foaming agent contains 0.3-0.5 parts of tea saponin, 0.5-1.5 parts of cocamidopropyl betaine, 1.1-1.8 parts of sodium dodecylbenzene sulfate, 0.1-0.2 parts of n-butanol, and 1-3 parts of calcium lactate.

[0016] The present invention provides a method for preparing the lightweight high-strength concrete, comprising the following steps:

[0017] Step 1: Portland cement, granulated blast furnace slag, modified corn cob powder, sodium alginate, and gypsum are mixed and ground to obtain slag cement;

[0018] Step 2: mixing the foaming agent with the foaming water and foaming the mixture through a foaming device to obtain a foam slurry;

[0019] Step 3, dry-mixing slag cement, expanded perlite powder, modified ceramsite, and polypropylene fiber, and then adding 1 / 2 of the mixing water for stirring; then adding silica fume, water reducing agent, and the remaining 1 / 2 of the mixing water for stirring and mixing to obtain concrete mortar;

[0020] Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0021] The present invention has the following beneficial effects:

[0022] 1. The concrete prepared by the present invention has the characteristics of high strength and light weight, lower water bleeding rate, lower density, higher compressive and splitting tensile strength, and excellent performance.

[0023] 2. During the concrete preparation process of the present invention, it was found that the durability of the concrete obtained by using slag cement was good. However, during the process of using slag cement to prepare concrete, the concrete would bleed. The bleed would cause cracks in the concrete after hardening and leave cavities after the water evaporated, reducing the strength of the concrete. In addition, the grindability of slag cement was very poor, and it was easy to mix unevenly during the mixing process. To solve this problem, the inventor modified the slag cement by adding modified corn cob powder and sodium alginate to increase its cohesiveness and water retention. The sodium alginate reacted with the calcium lactate in the concrete to form a gel and seal the gaps. Modified ceramsite was also added during the preparation process to further enhance the water retention performance. The light weight and high strength of ceramsite, combined with other ingredients, reduced the weight while also enhancing the strength of the concrete, reducing the water bleeding rate of the concrete, and improving the overall performance of the concrete to obtain high-strength lightweight concrete. DETAILED DESCRIPTION

[0024] The present invention is further illustrated below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. After reading this disclosure, modifications of various equivalent forms of the present invention made by those skilled in the art fall within the scope of protection of the claims. The term "1 part" in the following embodiments refers to conventional weight units such as 1 g and 1 kg.

[0025] Example 1

[0026] First, prepare the modified corncob flour:

[0027] 90 parts of corn cob powder and 500 mL of anhydrous ethanol were mixed, 25 mL of epoxytriethoxysilane was added, and the mixture was stirred at 50°C for 6 hours and then filtered. The filtrate was washed three times with ethanol and distilled water respectively, and dried at 80°C overnight to obtain modified corn cob powder.

[0028] Secondly, prepare modified ceramsite:

[0029] 20 parts of red mud, 30 parts of kaolin and 5 parts of silicon carbide are mixed to obtain a mixture; 25 parts of water are added to the mixture and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes and naturally cooled to obtain modified ceramsite.

[0030] Finally, prepare the concrete:

[0031] Step 1: 100 parts of Portland cement, 170 parts of granulated blast furnace slag, 30 parts of modified corn cob powder, 10 parts of sodium alginate, and 12 parts of gypsum are mixed and ground to obtain slag cement.

[0032] Step 2: 0.3 parts of tea saponin, 0.5 parts of cocamidopropyl betaine, 1.1 parts of sodium dodecylbenzene sulfate, 0.1 parts of n-butanol, and 1 part of calcium lactate are mixed with 60 parts of water, and the mixture is foamed using a foaming device to obtain a foam slurry;

[0033] Step 3: dry-mix 340 parts of slag cement, 250 parts of expanded perlite powder, 15 parts of modified ceramsite, and 20 parts of polypropylene fiber, then add 90 parts of mixing water and stir; then add 60 parts of silica fume, 15 parts of water reducer, and 80 parts of mixing water and stir to obtain concrete mortar;

[0034] Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0035] Example 2

[0036] First, prepare the modified corncob flour:

[0037] 100 parts of corn cob powder and 500 mL of anhydrous ethanol were mixed, 30 mL of epoxytriethoxysilane was added, and the mixture was stirred at 50°C for 6 hours and then filtered. The filtrate was washed three times with ethanol and distilled water respectively, and dried at 80°C overnight to obtain modified corn cob powder.

[0038] Secondly, prepare modified ceramsite:

[0039] 10 parts of red mud, 40 parts of kaolin and 2 parts of silicon carbide are mixed to obtain a mixture; 40 parts of water are added to the mixture and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes and naturally cooled to obtain modified ceramsite.

[0040] Finally, prepare the concrete:

[0041] Step 1: 110 parts of Portland cement, 150 parts of granulated blast furnace slag, 35 parts of modified corn cob powder, 8 parts of sodium alginate, and 15 parts of gypsum are mixed and ground to obtain slag cement.

[0042] Step 2: 0.5 parts of tea saponin, 1.5 parts of cocamidopropyl betaine, 1.8 parts of sodium dodecylbenzene sulfate, 0.2 parts of n-butanol, 3 parts of calcium lactate and 120 parts of water are mixed, and the mixture is foamed using a foaming device to obtain a foam slurry;

[0043] Step 3: dry-mix 300 parts of slag cement, 280 parts of expanded perlite powder, 10 parts of modified ceramsite, and 30 parts of polypropylene fiber, then add 80 parts of mixing water and stir; then add 100 parts of silica fume, 10 parts of water reducer, and 90 parts of mixing water and stir to obtain concrete mortar;

[0044] Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0045] Example 3

[0046] First, prepare the modified corncob flour:

[0047] 100 parts of corn cob powder and 500 mL of anhydrous ethanol were mixed, 30 mL of epoxytriethoxysilane was added, and the mixture was stirred at 50°C for 6 hours and then filtered. The filtrate was washed three times with ethanol and distilled water respectively, and dried at 80°C overnight to obtain modified corn cob powder.

[0048] Secondly, prepare modified ceramsite:

[0049] 15 parts of red mud, 35 parts of kaolin and 3 parts of silicon carbide are mixed to obtain a mixture; 35 parts of water are added to the mixture and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes and naturally cooled to obtain modified ceramsite.

[0050] Finally, prepare the concrete:

[0051] Step 1: 105 parts of Portland cement, 160 parts of granulated blast furnace slag, 33 parts of modified corn cob powder, 9 parts of sodium alginate, and 13 parts of gypsum are mixed and ground to obtain slag cement.

[0052] Step 2: 0.4 parts of tea saponin, 1.3 parts of cocamidopropyl betaine, 1.5 parts of sodium dodecylbenzene sulfate, 0.1 parts of n-butanol, and 1.7 parts of calcium lactate are mixed with 100 parts of water, and the mixture is foamed using a foaming device to obtain a foam slurry;

[0053] Step 3: dry-mix 320 parts of slag cement, 270 parts of expanded perlite powder, 13 parts of modified ceramsite, and 25 parts of polypropylene fiber, then add 90 parts of mixing water and stir; then add 80 parts of silica fume, 13 parts of water reducer, and 90 parts of mixing water and stir to obtain concrete mortar;

[0054] Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0055] Comparative Example 1

[0056] Step 1: 0.4 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 1.3 parts of cocamidopropyl betaine, 1.5 parts of sodium dodecylbenzene sulfate and 100 parts of water are mixed, and the mixture is foamed by a foaming device to obtain a foam slurry;

[0057] Step 2: dry-mix 320 parts of Portland cement, 300 parts of river sand, 230 parts of fly ash, and 25 parts of polypropylene fiber, then add 90 parts of mixing water and stir; then add 80 parts of silica fume, 13 parts of water reducer, and 90 parts of mixing water and stir to obtain concrete mortar;

[0058] Step 3: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0059] Comparative Example 2

[0060] First, prepare the modified ceramsite:

[0061] 15 parts of red mud, 35 parts of kaolin and 3 parts of silicon carbide are mixed to obtain a mixture; 35 parts of water are added to the mixture and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes and naturally cooled to obtain modified ceramsite.

[0062] Then, prepare the concrete:

[0063] Step 1, after mixing 0.4 parts of tea saponin, 1.3 parts of cocamidopropyl betaine, and 1.5 parts of sodium dodecylbenzene sulfate with 100 parts of water, foaming the mixture through a foaming device to obtain a foam slurry;

[0064] Step 2: dry-mix 320 parts of ordinary slag cement, 270 parts of expanded perlite powder, 13 parts of modified ceramsite, and 25 parts of polypropylene fiber, and then add 90 parts of mixing water for stirring; then add 80 parts of silica fume, 13 parts of water reducer, and 90 parts of mixing water for stirring and mixing to obtain concrete mortar;

[0065] Step 3: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0066] Comparative Example 3

[0067] First, prepare the modified corncob flour:

[0068] 100 parts of corn cob powder and 500 mL of anhydrous ethanol were mixed, 30 mL of epoxytriethoxysilane was added, and the mixture was stirred at 50°C for 6 hours and then filtered. The filtrate was washed three times with ethanol and distilled water respectively, and dried at 80°C overnight to obtain modified corn cob powder.

[0069] Then, prepare the concrete:

[0070] Step 1: 105 parts of Portland cement, 160 parts of granulated blast furnace slag, 33 parts of modified corn cob powder, and 13 parts of gypsum are mixed and ground to obtain slag cement.

[0071] Step 2: mixing 0.4 parts of tea saponin, 1.3 parts of cocamidopropyl betaine, and 1.5 parts of sodium dodecylbenzene sulfate with 100 parts of water, and foaming the mixture using a foaming device to obtain a foam slurry;

[0072] Step 3: dry-mix 320 parts of slag cement, 270 parts of expanded perlite powder, 13 parts of ceramsite, and 25 parts of polypropylene fiber, then add 90 parts of mixing water and stir; then add 80 parts of silica fume, 13 parts of water reducer, and 90 parts of mixing water and stir to obtain concrete mortar;

[0073] Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

[0074] Performance Test 1

[0075] Concrete Bleeding Rate Test: A pressure water seepage meter was used to measure the amount of water seepage from the concrete obtained in the above embodiment and calculate the water bleeding rate. The water bleeding rate was calculated based on the test results.

[0076] Table 1 Bleeding rate of different concrete modules

[0077] Module Water bleeding rate (%) Example 1 0.3 Example 2 0.2 Example 3 0.5 Comparative Example 1 1.5 Comparative Example 2 1.1 Comparative Example 3 0.9

[0078] As can be seen from the results in Table 1, the water bleeding rate of the concrete prepared by the present invention is lower than that of the concrete in Comparative Examples 1-3.

[0079] Performance Test 2

[0080] Concrete density test: The concrete modules of each embodiment were weighed and their density was calculated. Three replicates were made for each sample, and the average value was taken. The test results are shown in Table 2.

[0081] Table 2 Density of different concrete modules

[0082]

[0083]

[0084] As can be seen from the results in Table 2, the density of the concrete blocks prepared in each embodiment meets the requirements of lightweight concrete. However, the density of the concrete modules obtained in Examples 1-3 is significantly lower than that of the concrete modules obtained in Comparative Examples 1-3. This shows that the concrete modules prepared in the present invention have the characteristic of being lightweight.

[0085] Performance Test 3

[0086] Concrete strength test: The mechanical properties of the modules prepared from the concrete of each implementation method were tested in accordance with GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete". The results are shown in Table 3.

[0087] Table 3 Strength of different concrete modules

[0088] Module Compressive strength (MPa) Splitting tensile strength (MPa) Example 1 63.9 5.3 Example 2 65.1 4.9 Example 3 62.5 5.1 Comparative Example 1 49.3 2.9 Comparative Example 2 55.8 3.7 Comparative Example 3 52.6 3.5

[0089] As can be seen from the results in Table 3, the compressive strength and splitting tensile strength of the concrete prepared by the present invention are significantly higher than the concrete prepared in Comparative Examples 1-3.

Claims

1. A lightweight high-strength concrete, characterized in that: The lightweight high-strength concrete is prepared from the following ingredients: 300-340 parts of slag cement, 250-280 parts of expanded perlite powder, 10-15 parts of modified ceramsite, 20-30 parts of polypropylene fiber, 60-100 parts of silica fume, 10-15 parts of water reducer, 3-7 parts of foaming agent, and 220-300 parts of water.

2. The lightweight high-strength concrete according to claim 1, characterized in that: The water includes 60-120 parts of water for foaming and 160-180 parts of water for mixing.

3. The lightweight high-strength concrete according to claim 1, characterized in that: The slag cement contains 100-110 parts of Portland cement, 150-170 parts of granulated blast furnace slag, 30-35 parts of modified corn cob powder, 8-10 parts of sodium alginate and 12-15 parts of gypsum.

4. The lightweight high-strength concrete according to claim 1, characterized in that: The preparation method of the modified corncob powder is: Corn cob powder and anhydrous ethanol were mixed, epoxytriethoxysilane was added, and the mixture was stirred at 50° C. for 6 hours and then filtered. The filtrate was washed with ethanol and distilled water respectively, and dried to obtain modified corn cob powder.

5. The lightweight high-strength concrete according to claim 4, characterized in that: In the modified corn cob powder preparation method, the mass-volume-volume ratio of corn cob powder, anhydrous ethanol, and epoxytriethoxysilane is (90-100):500:(25-30) in g / mL / mL.

6. The lightweight high-strength concrete according to claim 1, characterized in that: The preparation method of the modified ceramsite is: 10-20 parts of red mud, 30-40 parts of kaolin and 2-5 parts of silicon carbide are mixed to obtain a mixture; 25-40 parts of water are added to the mixture, and the mixture is fully stirred to prepare 6-10 mm spherical ceramsite raw material; the ceramsite raw material is sintered in a rotary kiln at a high temperature of 1200° C. for 15 minutes, and naturally cooled to obtain modified ceramsite.

7. The lightweight high-strength concrete according to claim 1, characterized in that: The foaming agent contains 0.3-0.5 parts of tea saponin, 0.5-1.5 parts of cocamidopropyl betaine, 1.1-1.8 parts of sodium dodecylbenzene sulfate, 0.1-0.2 parts of n-butanol and 1-3 parts of calcium lactate.

8. A method for preparing the lightweight high-strength concrete according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Portland cement, granulated blast furnace slag, modified corn cob powder, sodium alginate, and gypsum are mixed and ground to obtain slag cement; Step 2: mixing the foaming agent with the foaming water and foaming the mixture through a foaming device to obtain a foam slurry; Step 3: dry-mix slag cement, expanded perlite powder, modified ceramsite, and polypropylene fiber, then add 1 / 2 of the mixing water and stir; then add silica fume, water reducer, and the remaining 1 / 2 of the mixing water and stir to obtain concrete mortar; Step 4: Mix the foam slurry and concrete mortar evenly and inject them into the mold. After curing, demoulding is performed to obtain lightweight concrete.

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