Low-flow-loss fully replaced machine-made sand pumping concrete and preparation method thereof

Abstract

This invention relates to a low-flowability loss fully replaced manufactured sand pumped concrete and its preparation method, wherein the components are in the following mass ratio (kg / m³). 3 The composition of this concrete is as follows: cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, manufactured sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water-reducing agent 5.9-10, and water 150-170. It utilizes a special functional agent prepared by mixing self-made polyaspartic acid and sodium hexametaphosphate in a mass ratio of 7:1 to 10:1. This agent achieves efficient chelation of calcium ions in the stone powder on the surface of the manufactured sand by amino and phosphate groups, meeting the high-quality pretreatment requirements of manufactured sand. The concrete, through the mixing of the special functional agent and the high-efficiency water-reducing agent, allows its unique long-chain molecular structure to gradually exert a dispersing effect within the concrete system, reducing the loss of flowability over time and ensuring the workability of the manufactured sand concrete upon arrival at the construction site.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and specifically relates to a low-flowability loss fully replaced manufactured sand pumped concrete and its preparation method. Background Technology

[0002] Sand and gravel are one of the most basic components of concrete and the second largest natural resource consumed by humankind. With rapid economic development, the demand for infrastructure construction is increasing, and the demand for building materials such as concrete sand and gravel aggregates is also increasing dramatically.

[0003] However, in recent years, the amount of sediment carried by major rivers in China has decreased significantly, resulting in a marked reduction in river sand production and causing regional supply and demand imbalances. This has not only led to a sharp rise in material prices and increased construction costs, but has also, to some extent, resulted in low-quality river sand entering the material market. Furthermore, excessive sand mining in river channels not only causes water pollution but also easily creates safety hazards to riverbanks.

[0004] Therefore, using manufactured sand, which is cost-effective, inexpensive, and environmentally friendly, to replace river sand in the preparation of concrete mixtures has become an important development trend in concrete preparation. However, manufactured sand has disadvantages such as high water absorption and low strength, resulting in poor performance of pumped concrete made from manufactured sand, especially large slump loss, poor water retention, and insufficient strength, which seriously restricts its large-scale application.

[0005] Therefore, how to provide a pumped concrete with low fluidity loss that fully replaces manufactured sand and its preparation method is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] This invention provides a low-flowability loss fully replaced manufactured sand pumped concrete and its preparation method, which effectively solves the problem of workability loss over time in traditional manufactured sand concrete, ensures concrete construction performance, improves concrete mechanical strength, solves the problem of natural river sand resource shortage, reduces concrete production cost, and promotes the large-scale application of manufactured sand concrete.

[0007] To solve the above technical problems, the present invention includes the following technical solutions:

[0008] A low-flowability loss fully replaceable manufactured sand pumped concrete, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0009] Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, manufactured sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water-reducing agent 5.9-10, water 150-170.

[0010] Furthermore, the special functional agent is prepared by mixing self-made polyaspartic acid and commercially available sodium hexametaphosphate in a mass ratio of 7:1 to 10:1, wherein the sodium hexametaphosphate has a purity of 65% to 70% and accounts for 0.1% to 0.15% of the mass of the manufactured sand; and the self-made polyaspartic acid accounts for 0.7% to 1.4% of the mass of the manufactured sand.

[0011] Furthermore, the fineness modulus of the manufactured sand is 2.3 to 3.0, the mud content is ≤0.5%, and the content of stone powder below 600μm is in the range of 15% to 30%.

[0012] Furthermore, the coarse aggregate is a continuous-sized natural aggregate of 5-25 mm.

[0013] This invention also provides a method for preparing pumped concrete with low fluidity loss and fully replaced manufactured sand, the method comprising the following steps:

[0014] Step S1: Add coarse aggregate to the mixer, followed by cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15-30 seconds until uniform.

[0015] Step S2: Mix 70% of the special functional agent with the manufactured sand evenly. After completing the pretreatment of the manufactured sand, put the manufactured sand into the mixer and stir quickly for 5-10 seconds until uniform to obtain a dry mixture.

[0016] Step S3: Add the high-efficiency water-reducing agent and the remaining 30% of the special functional agent to the water, and mix them evenly to obtain a mixture;

[0017] Step S4: Add 80% of the liquid mixture to the dry mixture and stir rapidly for 30-60 seconds to obtain the wet mixture; and

[0018] Step S5: Add the remaining 20% ​​of the mixture to the wet mix and stir slowly for 60-180 seconds until homogeneous to obtain low-flowability loss fully replaced manufactured sand pumped concrete.

[0019] Furthermore, the method for preparing the self-made polyaspartic acid:

[0020] Step 1: Place a certain mass of white crystalline powder L-aspartic acid into a mortar, then place it in a muffle furnace at 250℃ for heating and reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure that the reaction is complete;

[0021] Step 2: After the reactants have reacted for 60 minutes, the reaction product, polysuccinimide, is removed.

[0022] Step 3: Prepare a 2 mol / L sodium hydroxide solution, add 220-250 g of polysuccinimide to each liter of sodium hydroxide solution, react in a water bath at 60°C for 30 min, remove and cool, and adjust the pH value to 7-7.5 with hydrochloric acid. Thus, a transparent polyaspartic acid liquid with a solid content ≥40% is obtained.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] This invention provides a low-flowability-loss fully replaced manufactured sand pumped concrete and its preparation method, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 The concrete mix consists of: cement 330-400g, granulated blast furnace slag powder 100-150g, fly ash 60-120g, manufactured sand 700-900g, coarse aggregate 800-1000g, special functional agent 5.6-14g, high-efficiency water-reducing agent 5.9-10g, and water 150-170g. This concrete utilizes a special functional agent prepared by mixing self-made polyaspartic acid and sodium hexametaphosphate in a mass ratio of 7:1 to 10:1. Based on its unique long-chain molecular structure and molecular bonding force, it can achieve efficient chelation of calcium ions in the stone powder on the surface of manufactured sand by amino and phosphate groups, meeting the high-quality pretreatment requirements of manufactured sand, significantly reducing the adsorption of high-efficiency water-reducing agent by stone powder, improving concrete workability, and reducing the loss of fluidity over time. By mixing the special functional agent and the high-efficiency water-reducing agent, the unique long-chain molecular structure of this concrete can gradually exert a dispersing effect within the concrete system, reducing the loss of fluidity over time and ensuring the workability of the manufactured sand concrete upon arrival at the construction site.

[0025] This concrete uses 100% manufactured sand to replace traditional river sand, maximizing the resource utilization of solid waste, significantly reducing river sand mining, conserving natural resources, protecting the ecological environment, and lowering concrete production costs, resulting in significant social and economic benefits. The staged preparation method of this invention effectively achieves uniform dispersion of high-efficiency water-reducing agents and special functional agents within the powder, creating conditions for each component of the concrete to perform its function, ensuring uniform mixing, promoting concrete strength development, and guaranteeing the quality of pumped concrete made from manufactured sand. Detailed Implementation

[0026] The following detailed description, in conjunction with specific embodiments, provides a low-flowability-loss fully-replaced manufactured sand pumped concrete and its preparation method provided by the present invention. The advantages and features of the present invention will become clearer from the following description.

[0027] A low-flowability loss fully replaceable manufactured sand pumped concrete, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0028] Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, manufactured sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water-reducing agent 5.9-10, water 150-170.

[0029] Optionally, the special functional agent is prepared by mixing self-made polyaspartic acid and commercially available sodium hexametaphosphate in a mass ratio of 7:1 to 10:1, wherein the sodium hexametaphosphate has a purity of 65% to 70% and accounts for 0.1% to 0.15% of the mass of the manufactured sand; and the self-made polyaspartic acid accounts for 0.7% to 1.4% of the mass of the manufactured sand.

[0030] Optionally, manufactured sand can be used as fine aggregate, with a fineness modulus of 2.3–3.0 and a clay lump content of ≤0.5%.

[0031] The content of stone powder below 600μm is in the range of 15% to 30%.

[0032] Optionally, the coarse aggregate is a 5-25mm continuous-sized natural aggregate that conforms to the national standard "Construction Gravel and Crushed Stone" (GB / T14685-2022).

[0033] Optionally, the cement is P.Ⅱ52.5 silicate cement, the granulated blast furnace slag powder is S95 mineral powder, the fly ash is Grade II fly ash; the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate ≥30%, and the water is ordinary tap water.

[0034] This invention also provides a method for preparing pumped concrete with low fluidity loss and fully replaced manufactured sand, the method comprising the following steps:

[0035] Step S1: Add coarse aggregate to the mixer, followed by cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15-30 seconds until uniform.

[0036] Step S2: Mix 70% of the special functional agent with the manufactured sand evenly. After completing the pretreatment of the manufactured sand, put the manufactured sand into the mixer and stir quickly for 5-10 seconds until uniform to obtain a dry mixture.

[0037] Step S3: Add the high-efficiency water-reducing agent and the remaining 30% of the special functional agent to the water, and mix them evenly to obtain a mixture;

[0038] Step S4: Add 80% of the liquid mixture to the dry mixture and stir rapidly for 30-60 seconds to obtain the wet mixture; and

[0039] Step S5: Add the remaining 20% ​​of the mixture to the wet mix and stir slowly for 60-180 seconds until homogeneous to obtain low-flowability loss fully replaced manufactured sand pumped concrete.

[0040] Furthermore, the method for preparing the self-made polyaspartic acid:

[0041] Step 1: Place a certain mass of white crystalline powder L-aspartic acid into a mortar, then place it in a muffle furnace at 250℃ for heating and reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure that the reaction is complete;

[0042] Step 2: After the reactants have reacted for 60 minutes, the reaction product, polysuccinimide, is removed.

[0043] Step 3: Prepare a 2 mol / L sodium hydroxide solution, add 220-250 g of polysuccinimide to each liter of sodium hydroxide solution, react in a water bath at 60°C for 30 min, remove and cool, and adjust the pH value to 7-7.5 with hydrochloric acid. Thus, a transparent polyaspartic acid liquid with a solid content ≥40% is obtained.

[0044] Example 1:

[0045] The mix design and performance indicators of ordinary semi-replaced manufactured sand concrete are as follows:

[0046] Table 1. Mix proportions of ordinary semi-replacement manufactured sand concrete (kg / m³) 3 )

[0047]

[0048] Table 2 Performance Indicators of Ordinary Semi-replacement Manufactured Sand Concrete

[0049]

[0050] The mix design and performance indicators of the low-flowability-loss fully replaced manufactured sand pumped concrete of this invention are as follows:

[0051] Table 3 Mix proportions for pumped concrete with low fluidity loss and full replacement of manufactured sand. ( kg / m 3 )

[0052]

[0053] Table 4 Performance Indicators of Pumped Concrete with Low Flowability Loss and Full Replacement of Manufactured Sand

[0054]

[0055] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A low-flowability loss fully replaceable manufactured sand pumped concrete, characterized in that, The components of the concrete are specified in kg / m³. 3 The mass ratio is: Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, manufactured sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water-reducing agent 5.9-10, water 150-170; The special functional agent is prepared by mixing self-made polyaspartic acid and commercially available sodium hexametaphosphate in a mass ratio of 7:1 to 10:1, wherein the sodium hexametaphosphate has a purity of 65% to 70% and accounts for 0.1% to 0.15% of the mass of the manufactured sand; the self-made polyaspartic acid accounts for 0.7% to 1.4% of the mass of the manufactured sand. The method for preparing the self-made polyaspartic acid: Step 1: Place a certain mass of white crystalline powder L-aspartic acid into a mortar, then place it in a muffle furnace at 250℃ for heating and reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure that the reaction is complete; Step 2: After the reactants have reacted for 60 minutes, the reaction product, polysuccinimide, is removed. Step 3: Prepare a 2 mol / L sodium hydroxide solution, add 220~250 g of polysuccinimide to each liter of sodium hydroxide solution, react in a water bath at 60℃ for 30 min, remove and cool, and adjust the pH value to 7~7.5 with hydrochloric acid. Thus, a transparent liquid of polyaspartic acid with a solid content ≥40% is prepared.

2. The low-flowability-loss fully-replaces-manufactured-sand pumped concrete according to claim 1, characterized in that, The manufactured sand has a fineness modulus of 2.3 to 3.0, a clay content of ≤0.5%, and a stone powder content of 15% to 30% for particles smaller than 600μm.

3. The low-flowability-loss fully replaced manufactured sand pumped concrete according to claim 1, characterized in that, The coarse aggregate is a continuous-sized natural aggregate of 5-25mm.

4. The method for preparing low-flowability loss fully replaced manufactured sand pumped concrete according to any one of claims 1 to 3, characterized in that, The method includes the following steps: Step S1: Add coarse aggregate to the mixer, followed by cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15-30 seconds until uniform. Step S2: Mix 70% of the special functional agent with the manufactured sand evenly. After completing the pretreatment of the manufactured sand, put the manufactured sand into the mixer and stir quickly for 5-10 seconds until uniform to obtain a dry mixture. Step S3: Add the high-efficiency water-reducing agent and the remaining 30% of the special functional agent to the water, and mix them evenly to obtain a mixture; Step S4: Add 80% of the liquid mixture to the dry mixture and stir rapidly for 30-60 seconds to obtain the wet mixture; as well as Step S5: Add the remaining 20% ​​of the mixture to the wet mix and stir slowly for 60~180s until homogeneous to obtain low fluidity loss fully replaced manufactured sand pumped concrete.

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