High-strength concrete containing machine-made sand-river sand and preparation method thereof

Abstract

The invention provides machine-made sand-river sand-containing high-strength concrete and a preparation method thereof, the machine-made sand-river sand-containing high-strength concrete comprises aggregates and an inorganic binder, the aggregates comprise fine aggregates and coarse aggregates, the fine aggregates comprise limestone machine-made sand and river sand, the coarse aggregates are broken stones, the inorganic binder comprises cement, water and a water reducing agent, the mass part of each component is 1740-1844, and the mass part of each component is 100-300. The concrete is prepared from the following components in parts by weight: 258 to 288 parts of limestone machine-made sand, 387 to 432 parts of river sand, 1095 to 1124 parts of gravel, 586 to 684 parts of inorganic binder, 146 to 150 parts of water, 5 to 6 parts of water reducing agent and 435 to 528 parts of cement. The T-beam concrete has good working performance and durability, and the calculated value of the rebound strength of the T-beam can meet the technical requirements of the design strength. The machine-made sand concrete can be widely applied to the field of buildings, and has practical significance in reducing the production cost of engineering concrete, reducing energy consumption, reducing environmental pollution and improving the concrete strength and volume stability of prefabricated T beams.

Description

Technical Field

[0001] The present invention belongs to the technical field of road construction materials, and particularly relates to a high-strength concrete prepared mainly from manufactured sand and river sand and a preparation method thereof. Background Art

[0002] In engineering construction, a large amount of waste soil and slag needs to be excavated for the excavation of underground chambers and the construction of tunnels, which not only occupies a large amount of land resources, but also requires a large amount of capital for the construction and maintenance of waste residue plants. In the mountainous areas of central Yunnan, the proportion of medium bridges and tunnels in expressways is as high as 65%, and the corresponding concrete structure volume is huge, requiring a large amount of high-quality fine aggregate that can be stably supplied and meet the specification requirements as concrete raw materials. In order to reduce project investment and protect the environment at the same time, the waste residue can be reused after treatment.

[0003] At present, natural river sand is still used as the main material in the preparation of high-performance concrete. Due to the characteristics of regional differentiation, small reserves, and non-renewability in the short term of natural river sand, natural river sand has been over-exploited, and the contradiction between supply and demand has become increasingly acute. At present, manufactured sand has gradually replaced the dominant position of natural river sand and has become an important aggregate for preparing concrete.

[0004] Limestone manufactured sand is mechanically crushed, and the mechanical crushing increases the roughness and morphological complexity of the surface of the gravel, directly resulting in irregular particle shape, many edges and corners, large specific surface area, and strong water adsorption ability. It can be seen from the figure that there is stone powder attached to the surface of the manufactured sand. Due to the strong water adsorption of the manufactured sand, the fluidity of the mixture will be reduced after mixing. Compared with river sand, the water demand under the same fluidity is stronger, but it is beneficial to the combination with cement slurry and is beneficial to the mechanical properties. Therefore, the mixed use of manufactured sand and river sand in proportion is an effective way to reduce the internal friction of manufactured sand and improve the workability of concrete, and at the same time can save production costs and achieve the coordinated unity of economy and usability.

[0005] In addition, the irregular particle shape and uneven gradation of manufactured sand are likely to cause a decrease in the workability and strength of concrete. Excessive stone powder and mud content will also affect the performance of concrete, and higher water absorption may affect the slump and setting time of concrete. At the same time, the production cost and environmental impact of manufactured sand are also factors that need to be considered.

[0006] In the current research field, scholars often focus more on the separate study of the work performance or mechanical properties after the admixture of manufactured sand and river sand, and there is relatively little research on the comprehensive work performance and mechanical properties of the two, especially in the aspect of the optimized admixture ratio of high-strength grade concrete.

[0007] Currently, there are problems such as the shortage of natural high-quality river sand aggregates and the deterioration of expressways caused by the low strength of manufactured sand concrete. Considering the current requirements for environmental protection and energy conservation during construction, it is necessary to optimize the existing concrete materials and their mix ratios. Summary of the Invention

[0008] The present invention aims to provide a high-strength concrete prepared mainly from manufactured sand and river sand and its preparation method. While ensuring the mechanical properties of the gel material, it solves the problem of insufficient durability of concrete, reduces the demand for natural high-quality aggregates, effectively reduces transportation costs, and provides a safe and economical scientific basis for the comprehensive application of limestone manufactured sand in T-beam concrete.

[0009] Regarding the problems that the characterization and harmful evaluation of fine powder in manufactured sand need to be improved, the influence law of fine powder on concrete performance and the content limit in the specification are controversial, and the removal of fine powder from manufactured sand wastes resources and pollutes the environment, etc., the present invention systematically studies the characteristics of fine powder in manufactured sand, as well as the influence of the characteristics and quantity-quality synergy of fine powder on the performance of fresh and hardened concrete, reveals the influence law and mechanism of action of fine powder on concrete performance, and provides a theoretical basis and technical support for the relaxation of the fine powder content limit and the high-quality application of manufactured sand concrete.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A high-strength concrete containing manufactured sand - river sand, comprising aggregates and inorganic binders. The aggregates include fine aggregates and coarse aggregates. The fine aggregates include limestone manufactured sand and river sand, and the coarse aggregate is crushed stone. The inorganic binders include cement, water, and water reducer. Among them, the mass parts of each component are 1740 - 1844 parts of aggregates, among which 258 - 288 parts are limestone manufactured sand, 387 - 432 parts are river sand, 1095 - 1124 parts are crushed stone, 586 - 684 parts of inorganic binders, among which 146 - 150 parts are water, 5 - 6 parts are water reducer, and 435 - 528 parts are cement.

[0012] Further, the fine powder content of the limestone manufactured sand is 5 - 15%, and the sieve hole size of the fine powder is 0.08 mm.

[0013] Further, the crushing index of the limestone manufactured sand is 22%, the fineness modulus is 2.9, the particle shape is mostly needle-shaped and long strip particles, with many edges and corners, a large specific surface area, and a strong adsorption capacity for water. Its slump and spread value are both smaller than those of river sand.

[0014] Further, the fineness modulus of the river sand is 2.7, the particle shape is close to spherical, the surface is smooth, the fluidity is good, the natural stacking void ratio is smaller than that of manufactured sand. The river sand is mainly composed of semi-transparent quartz particles and mainly contains SiO2, and has good compatibility with cement.

[0015] Furthermore, the coarse aggregate gravel consists of gravel with a particle size of 10 - 25 mm 1 # and 5 - 10 mm 2 # and 1 # the gravel with a particle size of 10 - 25 mm accounts for 90%, 2 # the gravel with a particle size of 5 - 10 mm accounts for 10%.

[0016] Furthermore, the water - reducing agent is a PH - HPC - H type polycarboxylate high - performance retarding water - reducing agent, with a water - reducing rate of 28% and an air content of 3.0%.

[0017] Furthermore, the crushing index of the coarse aggregate is < 20%.

[0018] The preparation method of the high - strength concrete containing manufactured sand - river sand is as follows:

[0019] Step 1: Mechanically crush and screen the limestone, and classify it according to the size of the manufactured sand required for the experiment;

[0020] Step 2: Weigh the required limestone manufactured sand, river sand, and coarse aggregate gravel according to the mass ratio;

[0021] Step 3: Mix the limestone manufactured sand, river sand, and gravel in proportion, add 2 / 3 of the water, and stir with a concrete mixer for 3 - 5 min until evenly mixed without segregation to obtain the aggregate;

[0022] Step 4: Mix the remaining water evenly with the aggregate and cement prepared in Step 3, add the water - reducing agent and mix evenly, place it in a mold, and use a press to apply pressure at a compaction degree of 98% and a loading rate of 1 mm / min until both the upper and lower pressure columns are pressed into the mold, and maintain the pressure for more than 2 min. Demold after 24 h of molding to obtain the concrete part;

[0023] Step 5: After the concrete is poured, cure it under standard temperature and humidity.

[0024] Step 6: After the concrete reaches a certain curing time, remove the mold and test its physical and mechanical properties.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Using the natural soft rock limestone to replace high - quality natural aggregates can well achieve local material utilization, waste recycling, reduce transportation and construction costs, reduce carbon dioxide emissions, and reduce energy

[0027] consumption, thus reducing the overall production cost.

[0028] 2. Solve the problem of insufficient natural high-quality river sand aggregates and meet the performance requirements of T-shaped bridges. The calculated rebound strength of the T-beam can meet the technical requirements of the design strength C50, and its workability and durability are both good. In addition, limestone is widely distributed across the country, which can well solve the problems of cost and resource tension, and has significant economic and social significance in aspects such as protecting the ecological environment and rationally utilizing natural resources.

[0029] 3. The fine powder content in the manufactured sand can refine the internal pore structure of the concrete to improve the compactness of the concrete. The 7-day compressive strength of the concrete is greater than 85% of the design value; the slump of the concrete is

[0030] 160 - 200 mm, making it non-segregating, with good cohesion, non-bleeding, and a small slump loss over time, giving the concrete good workability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1(a) Manufactured sand

[0032] Figure 1(b) Natural river sand

[0033] Figure 2 Gradation curves of manufactured sand and river sand

[0034] Figure 3(a) Morphology observation diagram of natural river sand magnified 20 times

[0035] Figure 3(b) Morphology observation diagram of manufactured sand magnified 20 times

[0036] Figure 4 Fine powder diagram of manufactured sand

[0037] Figure 5 (a) Compressive failure mode

[0038] Figure 5 (b) Splitting tensile failure mode

[0039] Figure 6 Compressive strength change curve under different fine powder contents

[0040] Figure 7 Splitting tensile strength change curve under different fine powder contents

[0041] Figure 8 Compressive strength change curve of concrete under different mass ratios of natural river sand and manufactured sand

[0042] Figure 9 Splitting tensile strength change curve of concrete under different mass ratios of natural river sand and manufactured sand

[0043] Mechanical property indexes of C50 concrete of limestone manufactured sand and river sand in Figure 10 DETAILED DESCRIPTION OF THE INVENTION

[0044] Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those without specific technical or conditions noted in the embodiments, the techniques or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained by purchase.

[0045] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereby.

[0046] Example 1:

[0047] The high-strength concrete containing manufactured sand-river sand includes aggregates and inorganic binders. The aggregates include fine aggregates and coarse aggregates. The fine aggregates include limestone manufactured sand and river sand. The coarse aggregates are crushed stones. The inorganic binders include cement, water, and water-reducing agent.

[0048] The mass parts of each component are 1748 parts of aggregates, among which, 258 parts of limestone manufactured sand, 387 parts of river sand, and 1103 parts of crushed stones; 628 parts of inorganic binders, among which 148 parts of water, 6 parts of water-reducing agent, and 528 parts of cement.

[0049] Preferably, the content of fine powder in the limestone manufactured sand is 5%, and the sieve pore size of the fine powder is 0.08 mm.

[0050] Preferably, the crushing index of the limestone manufactured sand is 22%, the fineness modulus is 2.9, the particle shape is mostly needle-like and long strip particles, with many edges and corners, large specific surface area, strong adsorption capacity for water, and its slump and spread value are both smaller than those of river sand.

[0051] Preferably, the fineness modulus of the river sand is 2.7, the particle shape is close to spherical, the surface is smooth, the fluidity is good, the natural stacking void ratio is smaller than that of manufactured sand, the river sand is mainly composed of translucent quartz particles and mainly contains SiO2, and it has good compatibility with cement.

[0052] Preferably, the coarse aggregate crushed stone consists of 1 # with a particle size of 10 - 25 mm and 2 # composed of 1 # 90% of the crushed stone and 2 # 10% of the crushed stone.

[0053] Preferably, the water-reducing agent is the PH-HPC-H type polycarboxylate high-performance retarder water-reducing agent produced by a water-reducing agent factory in Shanxi, with a water-reducing rate of 28% and an air content of 3.0%.

[0054] Preferably, the cement is the P·C42.5 grade composite Portland cement produced by a company in Yiliang, Yunnan, with a standard consistency water consumption of 26.4% and a density of 3.20 (g / cm3 )。

[0055] Preparation method:

[0056] Step 1: Mechanically crush and screen the limestone, and classify it according to the size of the manufactured sand required for the experiment;

[0057] Step 2: Weigh the required manufactured sand of limestone, river sand, and coarse aggregate gravel according to the mass ratio;

[0058] Step 3: Mix the manufactured sand of limestone, river sand, and gravel in proportion, add 2 / 3 of the water, and stir with a concrete mixer for 3 - 5 minutes until evenly mixed. Then let it stand for 2 - 4 hours without segregation to obtain the aggregate;

[0059] Step 4: Mix the remaining water with the aggregate and cement prepared in Step 3 evenly, add the water reducing agent and mix evenly. Place it in a mold, and use a press to apply pressure at a compaction degree of 98% and a loading rate of 1 mm / min until both the upper and lower pressure columns are pressed into the mold, and maintain the pressure for more than 2 minutes. Demold after 24 hours of molding to obtain the concrete component;

[0060] Step 5: After the concrete is poured, cure it under standard temperature and humidity.

[0061] Step 6: After the concrete reaches a certain curing time, remove the mold and test its physical and mechanical properties.

[0062] Example 2:

[0063] The high-strength concrete containing manufactured sand - river sand includes aggregate and inorganic binder. The aggregate includes fine aggregate and coarse aggregate. The fine aggregate includes manufactured sand of limestone and river sand, and the coarse aggregate is gravel. The inorganic binder includes cement, water, and water reducing agent;

[0064] The mass parts of each component are 1800 parts of aggregate, among which, 274 parts of manufactured sand of limestone, 410 parts of river sand, and 1116 parts of gravel; 631.25 parts of inorganic binder, among which 148 parts of water, 5.75 parts of water reducing agent, and 477.5 parts of cement.

[0065] The rest is the same as Example 1.

[0066] Example 3:

[0067] The high-strength concrete containing manufactured sand - river sand includes aggregate and inorganic binder. The aggregate includes fine aggregate and coarse aggregate. The fine aggregate includes manufactured sand of limestone and river sand, and the coarse aggregate is gravel. The inorganic binder includes cement, water, and water reducing agent;

[0068] The mass parts of each component are 1843 parts of aggregate, among which, there are 287.6 parts of limestone manufactured sand, 431.4 parts of river sand, and 1124 parts of crushed stone; 588.56 parts of inorganic binder, among which there are 148 parts of water, 5.26 parts of water reducer, and 435.3 parts of cement.

[0069] The rest of the content is the same as that of Example 1.

[0070] The present invention selects natural river sand and manufactured sand in three particle size ranges of 0.63 - 1.25 mm, 1.25 - 2.5 mm, and 2.5 - 5 mm, and uses two indexes of aspect ratio and roundness to characterize the particle morphology of the sand, as shown in Figure 1.

[0071] The calculation methods of each index of the manufactured sand and river sand particles are as follows:

[0072] Aspect ratio of the particle: R d = d1 / d2;

[0073] d1 - the maximum length of the particle image;

[0074] d2 - the maximum width of the particle image;

[0075] Near roundness of the particle: R T = S 2 / 4πA;

[0076] S - the perimeter of the particle image;

[0077] A - the area of the particle image.

[0078] Thus, the comprehensive aspect ratio and near roundness statistical table 1 of the river sand and manufactured sand can be obtained.

[0079] Comprehensive aspect ratio and near roundness statistical table 1 of river sand and manufactured sand

[0080]

[0081] From the comparison between the manufactured sand and the river sand in the table, it can be clearly seen that the aspect ratios of the manufactured sand in the three particle size ranges of 0.63 - 1.25 mm, 1.25 - 2.5 mm, and 2.5 - 5 mm are all greater than those of the natural sand, indicating that there are more needle-like and rod-shaped long particles in the manufactured sand, as shown in the appendix Figure 4 . While the aspect ratio of the river sand is smaller, the proportion of needle-like and rod-shaped long particles in the river sand is smaller, and there are more approximately spherical particles, as shown in the appendix Figure 4 . By comparison, it can be known that the particle shape of the river sand is close to spherical, and there are more needle-like particles in the manufactured sand.

[0082] In the present invention, the content of fine powder in the manufactured sand of the concrete material is 5%, and the concrete strength reaches the maximum value at this time. The control factor of the fine powder test is the content of fine powder in the manufactured sand. Five kinds of fine powder contents in the manufactured sand are set, which are 0, 5, 10, 15, and 20% respectively. For the test design grouping, see Table 2.

[0083] Table 2 Test grouping table for the influence of fine powder content on the mechanical properties of manufactured sand concrete

[0084]

[0085] The fine powder in the manufactured sand is sieved through a sieve with a hole size of 0.08 mm to obtain manufactured sand with different contents of fine powder. The fine powder in the manufactured sand obtained by sieving is as Figure 4 shown.

[0086] Under the condition that the concrete mix ratio remains unchanged, according to the preset content of fine powder in the manufactured sand, manufactured sand concrete with different fine powder contents is mixed to study the influence law of the content ratio of fine powder in the manufactured sand on the mechanical properties of concrete. For the uniaxial compression and splitting tensile tests of concrete and the failure modes, see Figure 5 .

[0087] After the concrete specimens for the fine powder content test are cured under standard conditions for 28 days, the test for detecting the compressive strength, splitting tensile strength, and elastic modulus is shown in Appendix Figure 6 , Appendix Figure 7 . It can be seen from the figure that under the condition of the same mix ratio, the compressive strength of the concrete first increases and then decreases with the increase of the fine powder content. When the fine powder content is 5%, the compressive strength of the concrete reaches the maximum value.

[0088] In the present invention, the influence of the ratio of different natural river sand and manufactured sand combined fine aggregates on the compressive strength and splitting tensile strength of concrete is particularly studied, and relevant experiments are carried out. The control factor of the test is the type of fine aggregates and the combined mass ratio. Five combinations of the mass ratio of natural river sand and manufactured sand are set. For the test design grouping, see Table 3.

[0089] Table 3 Test grouping of the mechanical properties of concrete with combined fine aggregates of manufactured sand and river sand

[0090]

[0091] To avoid the influence of the difference in the gradation of coarse aggregates, the river sand and the manufactured sand are sieved into five grades, and the fine aggregates of the river sand and the manufactured sand with similar gradations are configured. Under the condition that the concrete mix ratio remains unchanged, according to the preset mass ratio of the river sand and the manufactured sand fine aggregates, the combined fine aggregate concrete of the river sand and the manufactured sand is mixed. After the concrete specimens are cured under standard conditions for 28 days, the test for detecting the compressive strength, splitting tensile strength, and elastic modulus is carried out to study the influence law of the mass ratio of the river sand and the manufactured sand on the mechanical properties of concrete.

[0092] The change curves of the compressive strength and splitting tensile strength of concrete under different mass ratios of natural river sand and manufactured sand are shown in Appendix Figure 8 and Appendix Figure 9 . Under the same mix ratio conditions, the compressive strength of concrete is significantly affected by the type and proportion of its fine aggregate. The incorporation of natural river sand fine aggregate can effectively improve the compressive strength of concrete. For example, when the mass ratio of natural river sand to manufactured sand is 1:1, the compressive strength of concrete increases by 12.80% compared to when the mass ratio is 0:1.

[0093] Based on the above experiments on fine powder content and the influence of the ratio of river sand to manufactured sand on the mechanical properties of concrete, a design example of the mix ratio of C50 limestone manufactured sand concrete is carried out in combination with the actual engineering requirements.

[0094] In the examples and experimental examples of the present invention, Examples 1-3 are the preferred examples of the present invention, and are compared with Experimental Examples 1-6 to illustrate the working performance advantages of the present invention. For clarity, the mass ratios of the components in the aggregate and inorganic binder in each example and experimental example are shown in Table 4.

[0095] Table 4 Mix ratio table of river sand and limestone manufactured sand C50 concrete (kg / m 3 )

[0096]

[0097] In Experimental Example 1, Experimental Example 2 and Example 1, the proportion of manufactured sand and river sand is different, and the remaining materials are the same. The manufactured sand in Experimental Example 1 is 193.5 kg / m 3 , and the manufactured sand in Experimental Example 2 is 322.5 kg / m 3 .

[0098] In Experimental Example 3, Experimental Example 4 and Example 2, the proportion of manufactured sand is different, and the dosage of the remaining materials is the same. The manufactured sand in Experimental Example 3 is 205.2 kg / m 3 , and the manufactured sand in Experimental Example 4 is 342.0 kg / m 3 .

[0099] In Experimental Example 5, Experimental Example 6 and Example 3, the proportion of manufactured sand is different, and the proportion of the remaining materials is the same. The manufactured sand in Experimental Example 5 is 215.7 kg / m 3 , and the manufactured sand in Experimental Example 6 is 359.5 kg / m 3 .

[0100] The water-cement ratio of JP1-JP3 is 0.28, the cement is 532 kg / m 3 ; the crushed stone is 1098 kg / m 3 , the water is 149 kg / m 3 , and the admixture is 6.384 kg / m 3; The water-cement ratio of JP4-JP6 is 0.31, and the cement is 481 kg / m 3 ; The crushed stone is 1116 kg / m 3 , and the admixture is 5.770 kg / m 3 ; The water-cement ratio of JP7-JP9 is 0.34, and the cement is 438 kg / m 3 ; The crushed stone is 1098 kg / m 3 , and the admixture is 5.256 kg / m 3 .

[0101] The main basis for testing the workability and mechanical properties of concrete is the "Test Regulations for Cement and Cement Concrete in Highway Engineering" (JTG 3420-2020). The compressive strength of C50 concrete in the experiment is shown in Table 5 below.

[0102] Table 5 Compressive Strength of C50 Concrete with Limestone Manufactured Sand and River Sand (MPa)

[0103] Number JP1 JP2 JP3 JP4 JP5 JP6 JP7 JP8 JP9 7d 58.4 60.0 56.6 54.7 56.8 51.5 48.2 53.5 47.1 28d 68.3 70.2 65.8 63.5 66.3 60.8 54.3 57.6 54.4

[0104] As can be seen from Table 5, the 28-day concrete strengths of the mix proportions numbered JP1 and JP2 can both meet the requirement of the trial-mix strength of 59.9 MPa, but the over-strength is relatively large and the economy is poor. Although the 28-day concrete strengths of the mix proportions numbered JP3 and JP4 can meet the trial-mix strength, there are problems such as poor workability. The 28-day strengths of the mix proportions numbered JP7, JP8, and JP9 do not meet the trial-mix strength requirements.

[0105] Based on the 7-day and 28-day compressive strengths of concrete with a mixing ratio of 30%:70%, 40%:60%, and 50%:50% of limestone manufactured sand and river sand under different water-binder ratios are shown in Figure 10. The compressive strength of the concrete with a standard age of 28 days and the short-age 7-day compressive strength are the best when the mixing ratio of manufactured sand and river sand is 40%:60%.

[0106] It can also be seen from Figure 10 that as the water-binder ratio increases, the dosage of the gel material decreases, which will instead reduce the compressive strength of the concrete.

[0107] Table 6 Workability Table of C50 Concrete with Limestone Manufactured Sand and River Sand

[0108] Experimental group Number Manufactured sand: River sand Slump / mm Spread / mm Experiment 1 JP1 30％:70％ 190 475 Example 1 JP2 40％:60％ 180 465 Experiment 2 JP3 50％:50％ 165 460 Experiment 3 JP4 30％:70％ 195 495 Example 2 JP5 40％:60％ 190 485 Experiment 4 JP6 50％:50％ 165 470 Experiment 5 JP7 30％:70％ 200 525 Example 3 JP8 40％:60％ 195 500 Experiment 6 JP9 50％:50％ 160 490

[0109] As can be seen from Table 6, under the condition of constant water-binder ratio, the slump and spread of the fresh concrete both decrease with the increase of the dosage of limestone manufactured sand; when the proportion of river sand in the fine aggregate is relatively large, it can be seen that the workability of the fresh concrete is good. When the ratio of limestone manufactured sand to river sand is 40%:60%, the slump and spread of the fresh concrete are both good, and it has good workability.

[0110] According to the experimental results of the present invention, when the mixing ratio of limestone manufactured sand to river sand in Mixing Ratio No. JP5 is 40%:60%, the workability and mechanical properties of the concrete can meet the design indexes. Considering the dosage of the gel material and ensuring the strength of the concrete, Mixing Ratio No. JP5 with a water-cement ratio of 0.31 is preferably selected for construction.

[0111] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A high-strength concrete containing machine-made sand-river sand, comprising aggregate and inorganic binder, characterized in that: The aggregate includes fine aggregate and coarse aggregate, the fine aggregate includes limestone machine-made sand and river sand, the coarse aggregate is crushed stone, and the inorganic binder includes cement, water, and a water reducer, wherein the mass fraction of each component is 1740-1844 parts of aggregate, including 258-288 parts of limestone machine-made sand, 387-432 parts of river sand, 1095-1124 parts of crushed stone, 586-684 parts of inorganic binder, including 146-150 parts of water, 5-6 parts of a water reducer, and 435-528 parts of cement.

2. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: The limestone machine-made sand has a fine powder content of 5-15%, and a sieve size of the fine powder is 0.08 mm.

3. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: The crushing index of the limestone machine-made sand is 22%, the fineness modulus is 2.9, most of the particles are needle-shaped long particles with many edges and corners, large specific surface area, strong adsorption capacity for water, and the slump and expansion values ​​are smaller than river sand.

4. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: The river sand has a fineness modulus of 2.7, a particle shape close to spherical, a smooth surface, good fluidity, and a natural stacking gap ratio smaller than that of machine-made sand. The river sand is mainly composed of translucent quartz particles with SiO2 as the main component and has good compatibility with cement.

5. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: Coarse aggregate crushed stone has a particle size of 10-25mm 1 # and 5-10mm 2 # Composition, 1 # Crushed stone is 90%, 2 # The crushed stone is 10%.

6. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: The water reducer is a PH-HPC-H type polycarboxylic acid high-performance retarding water reducer with a water reduction rate of 28% and an air content of 3.0%.

7. The high-strength concrete containing machine-made sand-river sand according to claim 1, characterized in that: The crushing index of the coarse aggregate is <20%.

8. The method for preparing high-strength concrete containing machine-made sand-river sand according to any one of claims 1 to 7, characterized in that: The steps include: Step 1: Mechanically crush and screen the limestone and classify it according to the size of the machine-made sand required for the experiment; Step 2: Weigh the required limestone machine-made sand, river sand, and coarse aggregate crushed stone according to the mass ratio; Step 3: Mix limestone machine-made sand, river sand and crushed stone in proportion, add 2 / 3 of water, and stir with a concrete mixer for 3-5 minutes until the mixture is evenly mixed without segregation to obtain aggregate; Step 4: Mix the remaining water with the aggregate and cement prepared in step 3, add a water reducing agent and mix well, place in a mold, and use a press to press at a compaction degree of 98% and a loading rate of 1 mm / min until the upper and lower pressure columns are pressed into the mold, and maintain the pressure for more than 2 minutes. Demould 2-6 hours after molding to obtain a concrete part; Step 5: After the concrete is poured, it is cured at standard temperature and humidity; Step 6: After the concrete reaches a certain curing time, remove the mold and test its physical and mechanical properties.

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