Low-fluidity-loss full-replacement machine-made sand pumping concrete and preparation method thereof

Abstract

The invention relates to low-liquidity-loss full-replacement machine-made sand pumping concrete and a preparation method thereof. The low-liquidity-loss full-replacement machine-made sand pumping concrete comprises the following components in parts by mass (kg / m < 3 >): 330-400 parts of cement, 100-150 parts of granulated blast-furnace slag powder, 60-120 parts of fly ash, 700-900 parts of machine-made sand, 800-1000 parts of coarse aggregate, 5.6-14 parts of special functional agent, 5.9-10 parts of high-efficiency water reducing agent and 150-170 parts of water. A special functional agent prepared by mixing self-made polyaspartic acid and sodium hexametaphosphate according to the mass ratio of (7: 1)-(10: 1) is adopted, efficient chelation of amino and phosphate radicals on calcium ions in stone powder on the surface of the machine-made sand is achieved, and the high-quality pretreatment requirement of the machine-made sand is met; according to the concrete, the special functional agent is mixed with the high-efficiency water reducing agent, and the unique long-chain molecular structure of the concrete can gradually play a dispersion role in a concrete system, so that the time-dependent fluidity loss of the concrete is reduced, and the working performance of the machine-made sand concrete reaching a construction site is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to low fluidity loss fully replaced machine-made sand pumping concrete and a preparation method thereof. Background Art

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

[0003] However, in recent years, the amount of sand coming into major rivers in China has dropped significantly, and the output of river sand has decreased significantly, resulting in a regional imbalance between supply and demand. This has not only caused a sharp increase in material prices and increased construction costs, but has also led to low-quality river sand entering the material market to a certain extent. At the same time, excessive sand mining in rivers will not only lead to water pollution, but also easily cause safety hazards to river embankments.

[0004] In view of this, the use of high-quality, low-cost and environmentally friendly machine-made sand to replace river sand to prepare concrete mixtures has become an important development trend in concrete preparation. However, machine-made sand has disadvantages such as high water absorption and low strength, which leads to poor performance of machine-made sand pumped concrete, especially large collapse, poor water retention, insufficient strength, etc., which seriously restricts its large-scale application.

[0005] Therefore, how to provide a low fluidity loss fully replaced machine-made sand pumping concrete and a preparation method thereof is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] The present invention provides a low-fluidity loss fully replaced machine-made sand pumped concrete and a preparation method thereof, which effectively solves the problem of time-dependent workability loss of traditional machine-made sand concrete, ensures the construction performance of concrete, improves the mechanical strength of concrete, solves the problem of shortage of natural river sand resources, reduces the cost of concrete production, and promotes the large-scale application of machine-made sand concrete.

[0007] In order to solve the above technical problems, the present invention includes the following technical solutions:

[0008] A low fluidity loss fully replaced machine-made sand pumping concrete, wherein the components of the concrete are in a mass ratio of (kg / m 3 ):

[0009] Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, machine-made 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 homemade 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%, accounting for 0.1% to 0.15% of the mass of the machine-made sand; the homemade polyaspartic acid accounts for 0.7% to 1.4% of the mass of the machine-made sand.

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

[0012] Furthermore, the coarse aggregate is a natural aggregate with a continuous particle size of 5 to 25 mm.

[0013] The present invention also provides a method for preparing low fluidity loss fully replaced machine-made sand pumped concrete, the method comprising the following steps:

[0014] Step S1, add coarse aggregate into a mixer, then add cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15 to 30 seconds until uniform;

[0015] Step S2, 70% of the special functional agent is mixed evenly with the machine-made sand. After the pretreatment of the machine-made sand is completed, the machine-made sand is put into a mixer and quickly stirred for 5 to 10 seconds until it is uniform to obtain a dry mix;

[0016] Step S3, adding a high-efficiency water reducing agent and the remaining 30% of a special functional agent into water, and mixing them evenly to obtain a mixed solution;

[0017] Step S4, adding 80% of the mixed liquid into the dry mix, and rapidly stirring for 30 to 60 seconds to obtain a wet mix; and

[0018] Step S5, adding the remaining 20% ​​of the mixed liquid into the wet mix, stirring slowly for 60 to 180 seconds until it is uniform, and obtaining low fluidity loss fully replaced machine-made sand pumping concrete.

[0019] Furthermore, the homemade polyaspartic acid preparation method is:

[0020] Step 1: Put a certain amount of white crystalline powder L-aspartic acid into a mortar, and then put it into a muffle furnace at 250°C for heating reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure sufficient reaction;

[0021] Step 2: After the reactants react for 60 minutes, the reaction product polysuccinimide is taken out;

[0022] Step 3: prepare 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 minutes, take out and cool, and adjust the pH value to 7-7.5 with hydrochloric acid, so as to prepare a transparent liquid of polyaspartic acid with a solid content of ≥40%.

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

[0024] The present invention provides a low fluidity loss fully replaced machine-made sand pumping concrete and a preparation method thereof. The components of the concrete are in a mass ratio of (kg / m 3 ): cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, machine-made sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water reducer 5.9-10, water 150-170. The concrete adopts a special functional agent prepared by mixing homemade polyaspartic acid and sodium hexametaphosphate in a mass ratio of 7:1-10:1. Based on its unique long-chain molecular structure and molecular binding force, it can achieve efficient chelation of amino and phosphate groups to calcium ions in stone powder on the surface of machine-made sand, meet the high-quality pretreatment requirements of machine-made sand, significantly reduce the adsorption of stone powder on high-efficiency water reducer, improve the workability of concrete, and reduce the loss of concrete fluidity over time. The concrete is mixed with a special functional agent and a high-efficiency water reducer. Its unique long-chain molecular structure can gradually play a dispersing role in the concrete system, reduce the loss of concrete fluidity over time, and ensure the working performance of the machine-made sand concrete arriving at the construction site.

[0025] The concrete uses machine-made sand to replace 100% of traditional river sand, which can maximize the resource utilization of solid waste, significantly reduce the amount of river sand mining, save natural resources, protect the ecological environment, and also reduce the cost of concrete production, with significant social and economic benefits. The step-by-step preparation method of the present invention can effectively achieve uniform dispersion of high-efficiency water reducer and special functional agent in the powder, create conditions for each component of concrete to play its function, ensure uniform mixing of concrete and promote the development of concrete strength, and ensure the quality of machine-made sand pumped concrete. DETAILED DESCRIPTION

[0026] The following is a further detailed description of a low fluidity loss fully replaced machine-made sand pumping concrete and a preparation method thereof provided by the present invention in conjunction with specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0027] A low fluidity loss fully replaced machine-made sand pumping concrete, wherein the components of the concrete are in a mass ratio of (kg / m 3 ):

[0028] Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, machine-made 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 homemade 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 machine-made sand; and the homemade polyaspartic acid accounts for 0.7% to 1.4% of the mass of the machine-made sand.

[0030] Optionally, machine-made sand is used as fine aggregate, with a fineness modulus of 2.3 to 3.0 and a mud content of ≤0.5%.

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

[0032] Optionally, the coarse aggregate is a natural aggregate with a continuous particle size of 5 to 25 mm that complies with the national standard "Pebble and Crushed Stone for Construction" (GB / T14685-2022).

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

[0034] The present invention also provides a method for preparing low fluidity loss fully replaced machine-made sand pumped concrete, the method comprising the following steps:

[0035] Step S1, add coarse aggregate into a mixer, then add cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15 to 30 seconds until uniform;

[0036] Step S2, 70% of the special functional agent is mixed evenly with the machine-made sand. After the pretreatment of the machine-made sand is completed, the machine-made sand is put into a mixer and quickly stirred for 5 to 10 seconds until it is uniform to obtain a dry mix;

[0037] Step S3, adding a high-efficiency water reducing agent and the remaining 30% of a special functional agent into water, and mixing them evenly to obtain a mixed solution;

[0038] Step S4, adding 80% of the mixed liquid into the dry mix, and rapidly stirring for 30 to 60 seconds to obtain a wet mix; and

[0039] Step S5, adding the remaining 20% ​​of the mixed liquid into the wet mix, stirring slowly for 60 to 180 seconds until it is uniform, and obtaining low fluidity loss fully replaced machine-made sand pumping concrete.

[0040] Furthermore, the homemade polyaspartic acid preparation method is:

[0041] Step 1: Put a certain amount of white crystalline powder L-aspartic acid into a mortar, and then put it into a muffle furnace at 250°C for heating reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure sufficient reaction;

[0042] Step 2: After the reactants react for 60 minutes, the reaction product polysuccinimide is taken out;

[0043] Step 3: prepare 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 minutes, take out and cool, and adjust the pH value to 7-7.5 with hydrochloric acid, so as to prepare a transparent liquid of polyaspartic acid with a solid content of ≥40%.

[0044] Embodiment 1:

[0045] Ordinary semi-replacement machine-made sand concrete mix design and performance indicators are as follows:

[0046] Table 1 Common semi-replacement machine-made sand concrete mix ratio (kg / m 3 )

[0047]

[0048] Table 2 Performance indexes of common semi-replaced machine-made sand concrete

[0049]

[0050] The mix design and performance index of the low fluidity loss fully replaced machine-made sand pumped concrete of the present invention are as follows:

[0051] Table 3 Mix proportion of low fluidity loss fully replaced machine-made sand pumping concrete ( kg / m 3 )

[0052]

[0053] Table 4 Performance indexes of low fluidity loss fully replaced machine-made sand pumped concrete

[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 express several embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A low fluidity loss fully replaced machine-made sand pumping concrete, characterized in that: The mass ratio of each component of the concrete is (kg / m 3 ): Cement 330-400, granulated blast furnace slag powder 100-150, fly ash 60-120, machine-made sand 700-900, coarse aggregate 800-1000, special functional agent 5.6-14, high-efficiency water reducing agent 5.9-10, water 150-170.

2. The low fluidity loss fully replaced machine-made sand pumped concrete according to claim 1 is characterized in that: The special functional agent is prepared by mixing homemade 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 machine-made sand; the homemade polyaspartic acid accounts for 0.7% to 1.4% of the mass of the machine-made sand.

3. The low fluidity loss fully replaced machine-made sand pumped concrete according to claim 1 is characterized in that: The fineness modulus of the machine-made sand is 2.3-3.0, and the mud content is ≤ 0.5%, the stone powder content below 600μm is in the range of 15% to 30%.

4. The low fluidity loss fully replaced machine-made sand pumped concrete according to claim 1 is characterized in that: The coarse aggregate is natural aggregate with a continuous particle size of 5 to 25 mm.

5. The method for preparing low fluidity loss fully replaced machine-made sand pumped concrete according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step S1, add coarse aggregate into a mixer, then add cement, granulated blast furnace slag powder and fly ash, and stir slowly for 15 to 30 seconds until uniform; Step S2, 70% of the special functional agent is mixed evenly with the machine-made sand. After the pretreatment of the machine-made sand is completed, the machine-made sand is put into a mixer and quickly stirred for 5 to 10 seconds until it is uniform to obtain a dry mix; Step S3, adding a high-efficiency water reducing agent and the remaining 30% of a special functional agent into water, and mixing them evenly to obtain a mixed solution; Step S4, adding 80% of the mixed liquid into the dry mix, and rapidly stirring for 30 to 60 seconds to obtain a wet mix; as well as Step S5, adding the remaining 20% ​​of the mixed liquid into the wet mix, stirring slowly for 60 to 180 seconds until it is uniform, and obtaining low fluidity loss fully replaced machine-made sand pumping concrete.

6. The preparation method according to claim 5, characterized in that: The homemade polyaspartic acid preparation method: Step 1: Put a certain amount of white crystalline powder L-aspartic acid into a mortar, and then put it into a muffle furnace at 250°C for heating reaction; during the heating process, take out the reactant every 10 minutes and grind it until it is uniform and fine to ensure sufficient reaction; Step 2: After the reactants react for 60 minutes, the reaction product polysuccinimide is taken out; Step 3: prepare 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 minutes, take out and cool, and adjust the pH value to 7-7.5 with hydrochloric acid, so as to prepare a transparent liquid of polyaspartic acid with a solid content of ≥40%.

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