An optimized design method and preparation method for high-performance concrete made from manufactured sand

Abstract

This application discloses an optimized design method and preparation method for high-performance concrete made from manufactured sand, comprising the following steps: (1) obtaining the technical indicators of the manufactured sand actually used; (2) determining the concrete mix proportion parameters that meet the concrete strength design; (3) adjusting and determining the actual water consumption per unit volume of concrete based on the water demand ratio of the manufactured sand; (4) determining the water-powder ratio that meets the workability of the concrete mixture, and calculating the volume of powder materials and the total volume of concrete aggregates; (5) determining the volumetric sand ratio of the concrete and calculating the amount of coarse and fine aggregates; (6) determining the actual amount of active admixtures and cement per unit volume of concrete. The concrete mix proportion obtained by this method can significantly improve the performance of high-stone-powder-content manufactured sand concrete, with significant benefits.

Description

Technical Field

[0001] This application relates to the field of building materials technology, and in particular to an optimized design method for high-performance manufactured sand concrete and its preparation method. Background Technology

[0002] With increasingly tight constraints on natural sand resources and growing environmental protection efforts, the replacement of natural sand with manufactured sand has become a common trend in the concrete industry. In 2019, ten national ministries issued the "Opinions on Promoting High-Quality Development of the Manufactured Sand and Gravel Industry," vigorously promoting the development and application of high-performance concrete made from manufactured sand.

[0003] Manufactured sand is rock particles with a diameter of less than 4.75 mm, produced by mechanical crushing, screening, and shaping of parent rock. It is characterized by rough particle surfaces, sharp and angular shapes, and high stone powder content. Currently, the mix design methods for manufactured sand concrete in China mainly refer to the strength-based concrete mix design methods and procedures proposed in the "Specification for Mix Design of Ordinary Concrete" JGJ55-2011. However, manufactured sand is a powder-containing system, and calculating the sand ratio and other mix design parameters by treating the stone powder in the manufactured sand as part of the manufactured sand composition does not consider the impact of excessive stone powder content on the water-cement ratio, sand ratio, and other design parameters of the concrete, as well as its workability, strength, durability, and volume stability.

[0004] Numerous studies and experiments have demonstrated that the above design method leads to the following typical problems with manufactured sand concrete:

[0005] 1. When the stone powder content is too high, the concrete becomes more viscous, and its self-compacting and pumpability deteriorate.

[0006] 2. When the stone powder content is too low, the concrete has poor cohesiveness, is prone to segregation and bleeding, and has poor self-compacting and pumpability.

[0007] 3. It increases the risk of concrete cracking and reduces its durability.

[0008] Therefore, it is urgent to shift from the traditional concrete mix design concept that focuses solely on the relationship between water-cement ratio and strength to one that takes into account the relationship between workability, durability, and volume stability, and to design high-performance concrete mix proportions using manufactured sand in a scientific and reasonable manner. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems of poor self-compactness and pumpability, high risk of cracking, and poor durability of manufactured sand concrete in the prior art. It proposes an integrated design of stone-sand-powder from the perspective of controlling the performance of high-performance manufactured sand concrete by dual constraints of water-cement ratio and water-powder ratio, and provides an optimized design method and preparation method for high-performance manufactured sand concrete.

[0010] The objective of this invention is achieved through the following technical solution.

[0011] A method for optimizing the design of high-performance concrete using manufactured sand includes the following steps:

[0012] (1) According to the method specified in JG / T 568 "Aggregates for High-Performance Concrete", the fineness modulus, stone powder content δ, water requirement ratio X, methylene blue value MB, and stone powder fluidity ratio F of the manufactured sand actually used in the project were tested and determined. F ;

[0013] (2) According to the provisions of the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55, the water consumption M is calculated and determined. w0 And the amount of cementitious materials M b0 ;

[0014] (3) Adjust and determine the actual water consumption M for concrete based on the water demand ratio X of manufactured sand. w The calculation method is as follows:

[0015] M w =M w0 +kM b0 (Equation 1)

[0016] In the formula, M w M represents the adjusted actual water consumption per cubic meter of concrete; w0 The water consumption calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; M b0 The amount of cementitious material calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; k is the water consumption adjustment coefficient, and the value of k is: when the water demand ratio of manufactured sand X≤115%, k is 0; when the water demand ratio of manufactured sand 115%<X≤125%, k is 1%.

[0017] (4) Determine the water-to-powder ratio W / P that meets the workability requirements of the concrete mixture based on the design strength grade and stone powder content, and calculate the volume V of the concrete powder material per cubic meter using the following formula. p and the total volume of coarse aggregate V 骨 :

[0018]

[0019]

[0020] V 骨 =1-V w -V p -V a (Equation 4)

[0021] In the formula, W / P is the water-to-powder ratio; V w The volume of water used per cubic meter of concrete after adjustment; ρw V is the apparent density of water. p V is the volume of powder material in a single cubic meter of concrete; 骨 V represents the total volume of concrete aggregate per cubic meter of concrete. a The volume of air introduced into a single cubic meter of concrete is taken as 0.01 to 0.02.

[0022] The W / P ratio was determined using linear interpolation, which included the following steps: when the strength grade of the manufactured sand high-performance concrete was C30, the content of manufactured sand stone powder was 6% to 15%, and the W / P ratio was 1.30 to 1.15.

[0023] When the strength grade of high-performance concrete made from manufactured sand is C35, the content of stone powder in manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.25 to 1.10.

[0024] When the strength grade of high-performance concrete made from manufactured sand is C40, the content of stone powder in the manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.15 to 1.00.

[0025] When the strength grade of high-performance concrete made from manufactured sand is C45, the content of stone powder in manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.05 to 0.95.

[0026] When the strength grade of high-performance concrete made from manufactured sand is C50, the content of stone powder in manufactured sand is 6% to 12%, and the water-to-powder ratio is 0.95 to 0.90.

[0027] When the strength grade of high-performance concrete made from manufactured sand is C55, the content of stone powder in manufactured sand is 6% to 12%, and the water-to-powder ratio is 0.90 to 0.86.

[0028] When the strength grade of high-performance concrete made from manufactured sand is C60, the content of stone powder in manufactured sand is 6% to 10%, and the water-to-powder ratio is 0.86 to 0.82.

[0029] (5) Select the volumetric sand ratio of the concrete based on the design strength grade and stone powder content. The mass of coarse and fine aggregates in a unit volume of concrete is calculated using the following method:

[0030]

[0031]

[0032] In the formula, M s The mass of manufactured sand per cubic meter of concrete; M g The mass of coarse aggregate in a single cubic meter of concrete; ρ s ρ is the apparent density of manufactured sand. g V represents the apparent density of the coarse aggregate. s V is the volume of manufactured sand per cubic meter of concrete;g This represents the volume of coarse aggregate in a single cubic meter of concrete. The volumetric sand ratio is determined based on the design strength grade, the fineness modulus of the manufactured sand, and the stone powder content.

[0033] (6) Adjust the type and dosage of mineral admixtures, and verify that the adjusted concrete water-cement ratio (W / B)′ is less than or equal to the design strength water-cement ratio W / B. Calculate the actual unit volume of reactive admixture M of concrete according to the following formula. f Cement quality M c and admixture mass M a :

[0034] V b =V p -V s (δ-5%) (Equation 8)

[0035]

[0036]

[0037] M f =βM b =βρ b V b (Equation 11)

[0038] M c =(1β)M b =(1β)ρ b V b (Equation 12)

[0039] M a =αM p =αM p =α[M b +ρ s V s (δ-5%)] (Equation 13)

[0040] In the formula: V b ρ is the volume of cementitious materials per cubic meter of concrete; δ is the content of manufactured sand and gravel powder; ρ b β represents the apparent density of the cementitious mixture; β is the mass fraction of mineral admixtures in the cementitious mixture per cubic meter of concrete. When two or more mineral admixtures are used, they can be represented as β1, β2, ..., β1. n The mass fraction of each mineral admixture in the cementitious material is expressed and calculated separately; ρ m ρ is the apparent density of the mineral admixture; c ρ is the apparent density of cement. sM is the apparent density of the manufactured sand; (W / B)′ is the adjusted water-cement ratio of the concrete; W / B is the water-cement ratio that meets the concrete strength design requirements as determined according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; M f M represents the actual amount of active admixture used per cubic meter of concrete; c M represents the actual cement usage per cubic meter of concrete. a This refers to the actual amount of admixture used per cubic meter of concrete; M p M represents the actual amount of powder material used per cubic meter of concrete; b α represents the mass of cementitious materials in a single cubic meter of concrete; α represents the mass percentage of admixtures in the total mass of powder materials in a single cubic meter of concrete.

[0041] Preferably, the manufactured sand actually used in step (1) is medium sand from Zone II.

[0042] Preferably, the manufactured sand actually used in step (1) meets the following requirements: fineness modulus of 2.6 to 3.0, water requirement ratio of less than or equal to 125%, and stone powder content of greater than or equal to 6%.

[0043] Preferably, when the required strength grade of the manufactured sand high-performance concrete is C30 to C45, the methylene blue MB value of the manufactured sand is less than or equal to 1.4, and the stone powder fluidity ratio is greater than or equal to 100%.

[0044] When the required strength grade of manufactured sand concrete is C50 to C60, the methylene blue MB value of the manufactured sand used should be less than or equal to 1.0, and the stone powder fluidity ratio should be greater than or equal to 110%.

[0045] Preferably, the volumetric sand ratio in step 5) The determination method includes the following steps: when the strength grade of the manufactured sand high-performance concrete is C30 to C35, the volumetric sand ratio is 45% to 43%;

[0046] When the strength grade of the manufactured sand high-performance concrete is C40 to C45, the volumetric sand ratio is 44% to 42%.

[0047] When the strength grade of the manufactured sand high-performance concrete is C50 to C55, the volumetric sand ratio is 43% to 41%.

[0048] When the strength grade of manufactured sand high-performance concrete is C60, the volumetric sand ratio is 42% to 40%.

[0049] Another aspect of this application provides a method for preparing high-performance concrete using manufactured sand, comprising the following steps: obtaining the actual water content M of the concrete according to any one of claims 1 to 5. w Quality of manufactured sand M s Coarse aggregate quality M g , quality of active admixture Mf Cement quality M c and admixture mass M a High-performance concrete made from manufactured sand is obtained by mixing raw materials.

[0050] Preferably, the strength grade of the obtained high-performance concrete made from manufactured sand is C30 to C60, the slump is not less than 200 mm, the spread is not less than 550 mm, and the inverted slump time is not more than 10 s.

[0051] Preferably, when preparing high-performance concrete with manufactured sand, the cement used is P·O42.5 cement.

[0052] Preferably, when preparing high-performance concrete using manufactured sand, the mineral admixtures used are: S75 grade slag powder and Grade II fly ash.

[0053] The beneficial effects that this invention can produce include:

[0054] 1) This application uses 5% stone powder in the manufactured sand as part of the manufactured sand, and more than 5% stone powder as inert powder material, so that the particle size distribution design of the system is more reasonable and can better achieve the close packing of stone-sand-powder particles. Under the premise of ensuring that the 28-day compressive strength of concrete meets the requirements, the amount of cement can be reduced and the workability of concrete can be significantly improved. The spread of concrete is not less than 550mm and the slump time is not greater than 10s, which meets the requirements of self-compacting performance and pumpability.

[0055] 2) This application optimizes the mix proportions of high-performance concrete made from manufactured sand by controlling the mixture properties, mechanical properties, and durability from the perspective of dual constraints on water-cement ratio and water-powder ratio. While significantly improving the self-compacting and pumpability of the manufactured sand high-performance concrete, it effectively improves the durability and volume stability of the concrete. The prepared manufactured sand high-performance concrete exhibits a 56-day reduction in electrical flux of 5%–15% and a reduction in crack area of ​​8%–23%. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the examples in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0057] Technical means not detailed in this application and not used to solve the technical problems of this application are all set according to common general knowledge in the field, and multiple common general knowledge setting methods can be implemented.

[0058] Example

[0059] Unless otherwise specified, all materials and instruments used in the following examples were obtained through commercial channels.

[0060] Example 1: Optimization Design Method for Mix Proportion of High-Performance Concrete with Mechanized Sand

[0061] (1) According to the method specified in JG / T 568 "Aggregates for High-Performance Concrete", the fineness modulus, stone powder content δ, water requirement ratio X, and stone powder fluidity ratio F of the manufactured sand actually used in the project were tested and determined. F According to the methods specified in GB / T 14684 "Sand for Construction", the methylene blue (M) content of the manufactured sand actually used in the project was tested and determined. B value;

[0062] (2) In accordance with the provisions of the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55, the mix proportion parameters of the concrete were preliminarily calculated and determined: water consumption (m³) w0 and cementitious material dosage m b0 ;

[0063] (3) Adjust and determine the actual water consumption of concrete (M) based on the water demand ratio X of manufactured sand. w The calculation method is as follows:

[0064] M w =M w0 +kM b0 (Equation 1)

[0065] In the formula, M w M represents the adjusted actual water consumption per cubic meter of concrete; w0 The water consumption calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; M b0 The amount of cementitious material calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; k is the water consumption adjustment coefficient, and the value of k is: when the water demand ratio of manufactured sand X≤115%, k is 0; when the water demand ratio of manufactured sand 115%<X≤125%, k is 1%.

[0066] (4) Determine the water-to-powder ratio (W / P) to meet the workability requirements of the concrete mixture based on the design strength grade and stone powder content, and calculate the volume of powder material per cubic meter of concrete using the following formula (V). p ) and total volume of coarse aggregate (V 骨 ):

[0067]

[0068]

[0069] V 骨 =1-V w0 -V p -V a(Equation 4)

[0070] In the formula, W / P is the water-to-powder ratio; V w The volume of water used per cubic meter of concrete after adjustment; ρ w V is the apparent density of water. p V is the volume of powder material in a single cubic meter of concrete; 骨 Va is the total volume of concrete aggregate per cubic meter of concrete. 为 The volume of air introduced into a single cubic meter of concrete is taken as 0.01 to 0.02.

[0071] The W / P ratio was determined using linear interpolation, which included the following steps: when the strength grade of the manufactured sand high-performance concrete was C30, the content of manufactured sand stone powder was 6% to 15%, and the water-to-powder ratio was 1.25 to 1.05.

[0072] When the strength grade of high-performance concrete made from manufactured sand is C35, the content of manufactured sand powder is 6% to 15% and the water-powder ratio is 1.15 to 1.0; when the strength grade of high-performance concrete made from manufactured sand is C40, the content of manufactured sand powder is 6% to 15% and the water-powder ratio is 1.05 to 0.9.

[0073] When the strength grade of high-performance concrete made from manufactured sand is C45, the content of stone powder in manufactured sand is 6% to 15%, and the water-to-powder ratio is 0.95 to 0.85.

[0074] When the strength grade of high-performance concrete made from manufactured sand is C50, the content of stone powder in manufactured sand is 6% to 12%, and the water-to-powder ratio is 1.1 to 1.05.

[0075] When the strength grade of high-performance concrete made from manufactured sand is C55, the content of stone powder in the manufactured sand is 6% to 12%, and the water-to-powder ratio is 1.05 to 1.0.

[0076] When the strength grade of high-performance concrete made from manufactured sand is C60, the content of stone powder in manufactured sand is 6% to 10%, and the water-to-powder ratio is 1.0 to 0.97.

[0077] (5) Select the volumetric sand ratio of the concrete based on the design strength grade and stone powder content. The mass of coarse and fine aggregates in a unit volume of concrete is calculated using the following method:

[0078]

[0079]

[0080] In the formula, M s The mass of manufactured sand per cubic meter of concrete; M g The mass of coarse aggregate in a single cubic meter of concrete; ρ s ρ is the apparent density of manufactured sand. gV represents the apparent density of the coarse aggregate. s V is the volume of manufactured sand per cubic meter of concrete; g This represents the volume of coarse aggregate in a single cubic meter of concrete. The volumetric sand ratio φ is determined based on the design strength grade, the fineness modulus of the manufactured sand, and the stone powder content. The method for determining the volumetric sand ratio φ includes the following steps: when the strength grade of the manufactured sand high-performance concrete is C30–C35, the volumetric sand ratio is 45%–43%; when the strength grade is C40–C45, the volumetric sand ratio is 44%–42%; when the strength grade is C50–C55, the volumetric sand ratio is 43%–41%; and when the strength grade is C60, the volumetric sand ratio is 42%–40%.

[0081] (6) Adjust the type and dosage of mineral admixtures, and verify that the adjusted concrete water-cement ratio (W / B)′ is not greater than the design strength water-cement ratio (W / B). Calculate the actual unit volume of reactive admixture (M) of concrete according to the following formula. f Cement quality (M) c ) and admixture mass (M a ):

[0082] V b =V p -V s (δ-5%) (Equation 8)

[0083]

[0084]

[0085] M f =βM b =βρ b V b (Equation 11)

[0086] M c =(1β)M b =(1β)ρ b V b (Equation 12)

[0087] M a =αM p =αM p =α[M b +ρ s V s (δ-5%)] (Equation 13)

[0088] In the formula: V b ρ is the volume of cementitious materials per cubic meter of concrete; δ is the content of manufactured sand and gravel powder; ρ bβ represents the apparent density of the cementitious mixture; β is the mass fraction of mineral admixtures in the cementitious mixture per cubic meter of concrete. When two or more mineral admixtures are used, they can be represented as β1, β2, ..., β1. n The mass fraction of each mineral admixture in the cementitious material is expressed and calculated separately; ρ m ρ is the apparent density of the mineral admixture; c ρ is the apparent density of cement. s The apparent density of the manufactured sand is (W / B)′; the adjusted water-cement ratio of the concrete is (W / B)′; M is the apparent density of the manufactured sand. f M represents the actual amount of active admixture used per cubic meter of concrete; c M represents the actual cement usage per cubic meter of concrete. a This refers to the actual amount of admixture used per cubic meter of concrete; M p M represents the actual amount of powder material used per cubic meter of concrete; b α represents the mass of cementitious materials in a single cubic meter of concrete; α represents the mass percentage of admixtures in the total mass of powder materials in a single cubic meter of concrete.

[0089] Comparative Example 1

[0090] The concrete mix proportions were determined according to the method specified in JGJ 55 of the "Specification for Mix Proportion Design of Ordinary Concrete".

[0091] The following raw materials from a certain batching plant were selected, and the parameters for concrete mix design were determined according to the methods of Example 1 and Comparative Example 1, respectively.

[0092] The design target value for concrete slump is (220±20) mm, and the air content of concrete is 1% to 2%.

[0093] The density of the P·O 42.5 cement used is 3.10 g / cm³. 3 The 3-day compressive strength is 26.0 MPa, and the 28-day compressive strength is 46.5 MPa.

[0094] The density of the Class II fly ash used is 2.4 g / cm³. 3 The water requirement ratio is 99%, the loss on ignition is 2.8%, the 7-day activity index is 63%, and the 28-day activity index is 74%.

[0095] The density of the S75 slag powder used is 2.9 g / cm³. 3 The mortar fluidity ratio is 99%, the 7-day activity index is 56%, and the 28-day activity index is 78%.

[0096] The coarse aggregate used is continuously graded crushed stone with a particle size of 5mm to 25mm and an apparent density of 2.7g / cm³. 3 The crushing index was 10.6%, the needle-like and flaky content was 1.4%, and the mud content was 0.15%.

[0097] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of more than 30% and a solid content of 12%.

[0098] The water used is tap water with a density of 1.0 g / cm³. 3 .

[0099] The 1# to 12# fine aggregates used are manufactured sand, medium sand from Zone II, with a fineness modulus of 2.6 to 3.0 and an apparent density of 2.7 g / cm³. 3 The water requirement ratio is less than or equal to 125%, and the stone powder content is greater than or equal to 6%. Specific performance indicators are shown in Table 1.

[0100] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the content of manufactured sand and stone powder used in the comparative examples and embodiments is obtained by artificial control. Stone powder in the manufactured sand is first screened out and then added in proportion.

[0101] The relevant performance indicators of the manufactured sand used in the comparative examples and embodiments are listed in Table 1.

[0102] Table 1. Relevant performance indicators of the manufactured sand used in the comparative examples and embodiments.

[0103]

[0104]

[0105] The concrete mix proportions for the comparative example are shown in Table 2. The concrete mix proportion parameters and proportions for the embodiment determined by the design method of this patent are shown in Tables 3 and 4, respectively.

[0106] Table 2 Concrete mix proportion parameters obtained from Comparative Example 1

[0107]

[0108] Table 3 Concrete mix proportion parameters obtained by the method in Example 1

[0109]

[0110]

[0111] Table 4 shows the mix proportions of the concrete obtained by the method provided in Example 1.

[0112]

[0113] Table 4 shows the fly ash mass (M) according to the method provided in Example 1. f1 ) and slag powder quality (M f2 The sum of these two values ​​represents the actual amount of active admixture used per cubic meter of concrete, M. f The cement mass is Mc; the fly ash mass (M) f1), Slag powder quality (M) f2 The mass of cement is Mc, and the sum of the masses of cementitious materials is M. b Water is the actual amount of water used in concrete (M). w The mass of crushed stone is the mass of coarse aggregate per cubic meter of concrete, M. g The mass of manufactured sand is M, which is the mass of coarse aggregate per cubic meter of concrete. s .

[0114] According to the method in JGJ 55 of the "Specification for Mix Proportion Design of Ordinary Concrete", concrete samples S-1 to S-12 and D-1 to D-12 were prepared based on the mix proportions in Tables 2 and 4, respectively.

[0115] The workability, mechanical properties, chloride ion penetration resistance, and early crack resistance of concrete samples prepared according to the mix proportions of Comparative Example 1 and Example 1 were tested according to the methods specified in GB / T 50080 "Standard for Test Methods of Performance of Ordinary Concrete Mixture", GB / T 50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and GB / T 50082 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The test results are shown in Table 5.

[0116] Table 5. Test results of concrete performance prepared in Comparative Example 1 and Example 1

[0117]

[0118] As shown in Table 5, compared with the comparative samples D-1 to D-12, the concrete S-1 to S-12 obtained by the method of this application, under the premise of ensuring that the 28-day compressive strength of the concrete meets the design requirements, have the following workability: S-1 to S-12 have good workability, while D1 to D-12 have problems such as edge micro-bleeding, poor cohesion, and relatively viscous concrete. This indicates that the mix proportion obtained by the method provided in this application can effectively improve the workability of the obtained concrete, and there are no technical problems pointed out in the comparative samples. It effectively solves the above-mentioned problems of concrete obtained by existing methods.

[0119] The 56-day electrical flux of the concrete samples obtained by the method provided in this application is lower than that of the concrete samples obtained by the corresponding comparative method, indicating that the chloride ion penetration resistance of the concrete prepared according to the mix proportion provided in this application is significantly improved.

[0120] The unit crack area of ​​the concrete samples obtained by the method provided in this application is smaller than that of the concrete samples obtained by the corresponding comparative method, indicating that the volume stability of the concrete prepared by the mix proportion provided in this application is significantly improved.

[0121] The high-performance concrete (S-1 to S-12) made from manufactured sand obtained by the method provided in this application all have a spread of not less than 550 mm and an inverted slump time of not more than 10 s. This indicates that the concrete samples can significantly improve the efficiency and quality of concrete construction. The increased spread of the concrete indicates a significant improvement in the self-compacting property of the obtained concrete; the reduced inverted slump time indicates an improvement in the pumpability of the concrete obtained by the method provided in this application. Furthermore, the obtained concrete meets the self-compacting performance requirements of "Technical Specification for Application of Self-Compacting Concrete" JGJ / T 283 and the pumpability requirements of "Technical Specification for Concrete Pumping Construction" JGJ / T10.

[0122] Meanwhile, this invention fully considers the stone powder content and characteristics in manufactured sand, and optimizes the mix proportion from the perspective of controlling the mixture performance, mechanical properties, and durability of high-performance concrete made from manufactured sand using both water-cement ratio and water-powder ratio constraints. Based on significantly improving the self-compacting and pumpability of high-performance concrete made from manufactured sand, the prepared S-1 to S-12 high-performance concretes show a 56-day electrical flux reduction of 5% to 15% and a crack area reduction of 8% to 23% compared to the comparative examples D-1 to D-12 concretes. This demonstrates that the mix proportion obtained by the method provided in this application can effectively improve concrete performance.

[0123] Furthermore, this invention uses 5% of the stone powder content in the manufactured sand as manufactured sand, and the portion of stone powder exceeding 5% is included in the powder material. The particle size distribution design of the system is more reasonable, which can better achieve the compact packing of particles, reduce the amount of cement, and thus effectively improve the workability of concrete and avoid bleeding or poor cohesion.

[0124] As shown in Tables 2 and 4, compared with comparative examples D-1 to D-12, the cement content of S-1 to S-12 high-performance concrete made with manufactured sand using the method provided in this application is reduced by 5% to 11%, which can reduce production costs while improving performance, and generate significant social, environmental, technical and economic benefits.

[0125] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing the design of high-performance concrete using manufactured sand, characterized in that, Includes the following steps: (1) According to the method specified in JG / T 568 "Aggregates for High-Performance Concrete", the fineness modulus, stone powder content δ, water requirement ratio X, methylene blue value MB, and stone powder fluidity ratio F of the manufactured sand actually used in the project were tested and determined. F ; (2) According to the provisions of the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55, the water consumption M is calculated and determined. w0 And the amount of cementitious materials M b0 ; (3) Adjust and determine the actual water consumption M for concrete based on the water demand ratio X of manufactured sand. w The calculation method is as follows: M w =M w0 +kM b0 (Equation 1) In the formula, M w M represents the adjusted actual water consumption per cubic meter of concrete; w0 The water consumption calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; M b0 The amount of cementitious material calculated according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; k is the water consumption adjustment coefficient, and the value of k is: when the water demand ratio of manufactured sand X≤115%, k is 0; when the water demand ratio of manufactured sand 115%<X≤125%, k is 1%. (4) Determine the water-to-powder ratio W / P that meets the workability requirements of the concrete mixture based on the design strength grade and stone powder content, and calculate the volume V of the concrete powder material per cubic meter using the following formula. p and the total volume of coarse aggregate V 骨 : V 骨 = 1 - V w -V p -V a (Equation 4) In the formula, W / P is the water-to-powder ratio; V w The volume of water used per cubic meter of concrete after adjustment; ρ w V is the apparent density of water. p V is the volume of powder material in a single cubic meter of concrete; 骨 V represents the total volume of concrete aggregate per cubic meter of concrete. a The volume of air introduced into a single cubic meter of concrete is taken as 0.01 to 0.

02. The W / P ratio was determined using linear interpolation, which included the following steps: when the strength grade of the manufactured sand high-performance concrete was C30, the content of manufactured sand stone powder was 6% to 15%, and the W / P ratio was 1.30 to 1.

15. When the strength grade of high-performance concrete made from manufactured sand is C35, the content of stone powder in manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.25 to 1.

10. When the strength grade of high-performance concrete made from manufactured sand is C40, the content of stone powder in the manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.15 to 1.

00. When the strength grade of high-performance concrete made from manufactured sand is C45, the content of stone powder in manufactured sand is 6% to 15%, and the water-to-powder ratio is 1.05 to 0.

95. When the strength grade of high-performance concrete made from manufactured sand is C50, the content of stone powder in manufactured sand is 6% to 12%, and the water-to-powder ratio is 0.95 to 0.

90. When the strength grade of high-performance concrete made from manufactured sand is C55, the content of stone powder in manufactured sand is 6% to 12%, and the water-to-powder ratio is 0.90 to 0.

86. When the strength grade of high-performance concrete made from manufactured sand is C60, the content of stone powder in manufactured sand is 6% to 10%, and the water-to-powder ratio is 0.86 to 0.

82. (5) Select the volumetric sand ratio of the concrete based on the design strength grade and stone powder content. The mass of coarse and fine aggregates in a unit volume of concrete is calculated using the following method: In the formula, M s The mass of manufactured sand per cubic meter of concrete; M g The mass of coarse aggregate in a single cubic meter of concrete; ρ s ρ is the apparent density of manufactured sand. g V represents the apparent density of the coarse aggregate. s V is the volume of manufactured sand per cubic meter of concrete; g This represents the volume of coarse aggregate in a single cubic meter of concrete. The volumetric sand ratio is determined based on the design strength grade, the fineness modulus of the manufactured sand, and the stone powder content. (6) Adjust the type and dosage of mineral admixtures, and verify that the adjusted concrete water-cement ratio (W / B)′ is less than or equal to the design strength water-cement ratio W / B. Calculate the actual unit volume of reactive admixture M of concrete according to the following formula. f Cement quality M c and admixture mass M a : V b = V p - V s (δ - 5%) (Equation 8) M f =βM b =water b V b (formula 11) M c =(1-β)M b =(1-β)ρ b V b (formula 12) M a = αM p = αM p = α[M b + ρ s V s (δ - 5%)] (Equation 13) In the formula: V b ρ is the volume of cementitious materials per cubic meter of concrete; δ is the content of manufactured sand and gravel powder; ρ b β represents the apparent density of the cementitious mixture; β is the mass fraction of mineral admixtures in the cementitious mixture per cubic meter of concrete. When two or more mineral admixtures are used, they can be represented as β1, β2, ..., β1. n The mass fraction of each mineral admixture in the cementitious material is expressed and calculated separately; ρ m ρ is the apparent density of the mineral admixture; c ρ is the apparent density of cement. s M is the apparent density of the manufactured sand; (W / B)′ is the adjusted water-cement ratio of the concrete; W / B is the water-cement ratio that meets the concrete strength design requirements as determined according to the "Specification for Mix Proportion Design of Ordinary Concrete" JGJ 55; M f M represents the actual amount of active admixture used per cubic meter of concrete; c M represents the actual cement usage per cubic meter of concrete. a This refers to the actual amount of admixture used per cubic meter of concrete; M p M represents the actual amount of powder material used per cubic meter of concrete; b α represents the mass of cementitious materials in a single cubic meter of concrete; α represents the mass percentage of admixtures in the total mass of powder materials in a single cubic meter of concrete.

2. The optimized design method for high-performance concrete using manufactured sand according to claim 1, characterized in that, In step (1), the actual manufactured sand used in the project is medium sand from Zone II.

3. The optimized design method for high-performance concrete using manufactured sand according to claim 1, characterized in that, The manufactured sand used in step (1) meets the following requirements: fineness modulus of 2.6 to 3.0, water requirement ratio of less than or equal to 125%, and stone powder content of greater than or equal to 6%.

4. The optimized design method for high-performance concrete using manufactured sand according to claim 1, characterized in that, When the required strength grade of the manufactured sand high-performance concrete is C30 to C45, the methylene blue MB value of the manufactured sand used is less than or equal to 1.4, and the stone powder fluidity ratio is greater than or equal to 100%. When the required strength grade of manufactured sand concrete is C50 to C60, the methylene blue MB value of the manufactured sand used should be less than or equal to 1.0, and the stone powder fluidity ratio should be greater than or equal to 110%.

5. The optimized design method for high-performance concrete using manufactured sand according to claim 1, characterized in that, Step 5) Volumetric sand ratio The determination method includes the following steps: when the strength grade of the manufactured sand high-performance concrete is C30 to C35, the volumetric sand ratio is 45% to 43%; When the strength grade of the manufactured sand high-performance concrete is C40 to C45, the volumetric sand ratio is 44% to 42%. When the strength grade of the manufactured sand high-performance concrete is C50 to C55, the volumetric sand ratio is 43% to 41%. When the strength grade of manufactured sand high-performance concrete is C60, the volumetric sand ratio is 42% to 40%.

6. A method for preparing high-performance concrete using manufactured sand, characterized in that, Includes the following steps: The method according to any one of claims 1 to 5 obtains the actual water content M of concrete. w Quality of manufactured sand M s Coarse aggregate quality M g , quality of active admixture M f Cement quality M c and admixture mass M a High-performance concrete made from manufactured sand is obtained by mixing raw materials.

7. The preparation method according to claim 6, characterized in that, The resulting high-performance concrete made from manufactured sand has a strength grade of C30 to C60, a slump of not less than 200 mm, a spread of not less than 550 mm, and an inverted slump time of not more than 10 seconds.

8. The preparation method according to claim 6, characterized in that, When preparing high-performance concrete with manufactured sand, the cement used is P·O42.5 cement.

9. The preparation method according to claim 6, characterized in that, When preparing high-performance concrete using manufactured sand, the mineral admixtures used are: S75 grade slag powder and Grade II fly ash.

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