Road large-slump premixed concrete mix proportion design method

Abstract

The invention provides a design method for a mix proportion of road large-slump premixed concrete. The design method comprises the following steps: S1, calculating a mean value of 28d flexural-tensile strength of cement concrete for a road large-slump premixed concrete surface layer; s2, calculating a water-cement ratio or a water-binder ratio of the premixed concrete mixture with the large slump; s3, determining the sand ratio of the premixed concrete mixture with the large slump; s4, calculating the use amount of cement in the large-slump premixed concrete mixture; s5, calculating the use amount of water in the large-slump premixed concrete mixture; s6, calculating the use amount of the coarse aggregate and the fine aggregate in the large-slump premixed concrete mixture; s7, the mass ratio of all the materials of the large-slump premixed concrete is obtained, and the mix proportion design is obtained. According to the method, the steps for calculating the mix proportion of the large-slump premixed concrete are defined, the workability and the filling property of the mixture are improved while the durability of the large-slump premixed concrete pavement is guaranteed, and the method has high practicability.

Description

Technical Field

[0001] The present application relates to the field of road engineering, and in particular to a method for designing a mix ratio of premixed concrete for roads with large slump. Background Art

[0002] At present, the current specifications for the slump requirements of cement concrete mixtures for urban road pavements include "Urban Road Quality Acceptance Specifications" (CJJ 1) and "Highway Cement Concrete Pavement Construction Technical Specifications" (JTG / T F30). Both specifications require the slump of concrete mixtures to be 5 to 40 mm; however, in reality, the slump of concrete mixtures for urban road pavements is generally 120 mm to 180 mm, which is quite different from the slump required by the current pavement-related specifications. The current "Ready-mixed Concrete" specification divides the slump into 5 grades (S1, S2, S3, S4, S5) according to the different slump values. The slump of cement concrete mixtures for urban road pavements is between the S3 and S4 grades of ready-mixed concrete.

[0003] The current specifications for the mix design of cement concrete pavement on urban roads include "Standards for Quality Acceptance of Urban Roads" (CJJ 1), "Technical Specifications for Construction of Cement Concrete Pavement on Highways" (JTG / T F30), "Design Code for Mix Ratio of Ordinary Concrete" (JGJ 55), and "Mix Ratio Design of Self-compacting Concrete" (JGJ / T 283). The concrete mix design in "Standards for Quality Acceptance of Urban Roads" (CJJ1) refers to the relevant formula in "Technical Specifications for Construction of Cement Concrete Pavement on Highways" (JTG F30-2003), which has been abolished. The water consumption calculation in the concrete mix design in "Technical Specifications for Construction of Cement Concrete Pavement on Highways" (JTG / T F30-2014) is based on the empirical formula obtained through analysis of the relevant tests of slump of 5 to 40 mm. This formula is not applicable to the concrete mix design with a slump of 120 to 180 mm. The concrete mix design in the "Ordinary Concrete Mix Design Code" (JGJ55-2011) focuses on the concrete structure of building construction, which is different from the characteristics of road concrete and the strength conversion relationship is also different. The concrete mix design in the "Self-compacting Concrete Mix Design" (JGJ / T 283-2012) adopts the absolute volume method, which is different from the mass method used for road concrete.

[0004] At present, there is no clear mix design method for large slump ready-mixed concrete for urban roads. Therefore, it is very necessary to determine the mix design for large slump ready-mixed concrete for urban road pavements. Summary of the invention

[0005] The present application provides a method for designing the mix ratio of premixed concrete with a large slump for roads. The application aims to address the problem that the current specifications lack a concrete mix ratio design method suitable for urban road pavements. The application introduces a functional relationship between the volume of cementitious materials and the amount of cement, provides a method for designing the mix ratio of premixed concrete with a large slump for urban roads, clarifies the calculation steps for the mix ratio of premixed concrete with a large slump, and improves the workability and filling properties of the mixture while ensuring the durability of the premixed concrete pavement with a large slump. The application has strong practicality.

[0006] The technical solution of this application is:

[0007] A method for designing a mix ratio of high-slump ready-mixed concrete for roads comprises the following steps:

[0008] S1, calculate the average value of 28d flexural tensile strength of cement concrete used for road high slump ready-mixed concrete surface layer;

[0009] S2, calculate the water-cement ratio or water-binder ratio of high-slump ready-mixed concrete mixture;

[0010] S3, determine the sand ratio of the high slump ready-mixed concrete mixture;

[0011] S4, calculate the amount of cement in the high slump ready-mixed concrete mixture;

[0012] S5, calculate the amount of water in the high slump ready-mixed concrete mixture;

[0013] S6, calculate the amount of coarse aggregate and fine aggregate in the high slump ready-mixed concrete mixture;

[0014] S7, obtain the mass ratio of each material of the high slump ready-mixed concrete, that is, obtain the mix ratio design.

[0015] As a technical solution of the present application, in step S1, the mean value f of the 28d flexural tensile strength of cement concrete for high slump ready-mixed concrete surface layer is calculated according to the following formula: c :

[0016]

[0017] Where: f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f r is the standard value of design flexural strength, MPa, which is determined according to the design and should not be lower than the requirements of Table 6.2.5 of "Code for Design of Urban Road Pavement" CJJ 169; c vis the coefficient of variation of the bending tensile strength, which should be determined according to statistical data and shall be 0.05 when it is less than 0.05. When there is no statistical data, it can be determined according to the values ​​in Table 3, among which the variation level of expressways and trunk roads should be low, the variation level of secondary trunk roads should not be lower than medium, and the variation level of branches should not be lower than medium; t is the guarantee rate coefficient, which shall be determined according to Table 1; s is the standard deviation of the bending tensile strength test samples, MPa. When there is test data, the test sample standard deviation shall be used. When there is no test data, it can be determined according to the road grade and design bending tensile strength and refer to Table 2.

[0018] Table 1 Guarantee rate coefficient t

[0019]

[0020] Table 2 Standard deviation of flexural strength test samples s

[0021]

[0022] Table 3 Coefficient of variation of flexural strength cv

[0023]

[0024] As a technical solution of the present application, in step S2, the water-cement ratio or water-binder ratio of the high-slump ready-mixed concrete mixture is calculated according to the following formula:

[0025]

[0026] Where: W / C is the water-cement ratio or water-binder ratio; f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f s is the measured 28d flexural strength of cement, MPa;

[0027] Generally speaking, when the standard value of the design flexural strength of concrete is 5.0MPa, the recommended water-cement ratio or water-binder ratio should be 0.38-0.42; when the standard value of the design flexural strength of concrete is 4.5MPa, the recommended water-cement ratio or water-binder ratio should be 0.42-0.46.

[0028] As a technical solution of the present application, in step S3, the sand ratio of the high-slump ready-mixed concrete mixture is determined according to the fineness modulus of the sand and the type of fine aggregate. The medium sand with a fineness modulus of 2.3 to 3.2 can be selected by referring to the following Table 4, and the sand with other fineness moduli should be determined based on experiments.

[0029] Table 4 Sand ratio of cement concrete

[0030]

[0031] As a technical solution of the present application, in step S4, the amount of cement in the high-slump ready-mixed concrete mixture is calculated according to the following formula:

[0032]

[0033] Where: m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; V p is the volume of cementitious material in each cubic meter of high slump ready-mixed concrete mixture, m 3 ; V a is the volume of air introduced into each cubic meter of high slump ready-mixed concrete mixture, m 3 Generally, if there is an antifreeze requirement, the value range of the air-entraining agent is 4.5±0.5%; if there is no antifreeze requirement, the value range of the air-entraining agent is 3±1%; ρ m is the apparent density of mineral admixture, kg / m 3 ; β is the mass fraction of mineral admixture in cementitious materials per cubic meter of high slump ready-mixed concrete mixture, %; ρ c is the apparent density of cement kg / m 3 ρ w is the apparent density of mixing water, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio;

[0034] Under normal circumstances, for the volume of cementitious materials per cubic meter of high-slump ready-mixed concrete mixture, when the standard value of the design flexural strength of concrete is 5.0MPa, the water-cement ratio or water-binder ratio should be 0.30-0.34; when the standard value of the design flexural strength of concrete is 4.5MPa, the water-cement ratio or water-binder ratio should be 0.28-0.32.

[0035] As a technical solution of the present application, in step S5, the amount of water in the high-slump ready-mixed concrete mixture is calculated according to the following formula:

[0036]

[0037] Where: m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio; γ is the measured water reduction rate of the admixture dosage used, %;

[0038] Generally speaking, when the standard value of the design flexural tensile strength of concrete is 5.0MPa, the maximum unit water consumption is 165kg; when the standard value of the design flexural tensile strength of concrete is 4.5MPa, the maximum unit water consumption is 175kg.

[0039] As a technical solution of the present application, in step S6, the amount of coarse aggregate and fine aggregate in the high-slump ready-mixed concrete mixture is calculated according to the following conditions, and the unit mass of the high-slump ready-mixed concrete mixture can be 2400-2450 kg / m 3 :

[0040] When there is no admixture in the high slump ready-mixed concrete mixture, the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0041] m s +m g +m c +m w =m cp ;

[0042]

[0043] Where: m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ; S p is the sand ratio of high slump ready-mixed concrete mixture;

[0044] When slag powder or silica fume is added to the high slump ready-mixed concrete mixture, the mass of slag powder or silica fume is calculated by the equal substitution method, and the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0045]

[0046] m s +m g +m c +m k +m w =m cp ;

[0047] Where: S p is the sand ratio of the large slump ready-mixed concrete mixture; m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m k The mass of slag powder or silica fume in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ;

[0048] In general, the amount of slag powder added does not exceed 30%, and the amount of silica fume added does not exceed 10%;

[0049] When fly ash is added to high-slump ready-mixed concrete, the mass of fly ash is calculated using the excess substitution method, and the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0050] In general, the maximum amount of fly ash added is: Type I Portland cement should not be greater than 30%, Type II Portland cement should not be greater than 25%; road Portland cement should not be greater than 20%, and the total amount of fly ash added should be finally determined through tests;

[0051] Select the mass percentage f of fly ash replacing cement and adjust various materials:

[0052] The total mass of fly ash is calculated using the following formula in the excess substitution method:

[0053] m f =m c ×f×k;

[0054] Where: m f is the total mass of fly ash; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient. Generally, k for Class I fly ash is 1.1-1.4, k for Class II fly ash is 1.3-1.7, and k for Class III fly ash is 1.5-2.0;

[0055] The excess fly ash mass is calculated using the following formula:

[0056] m f1 =m c ×f×(k-1);

[0057] Where: m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient. Generally, k for Class I fly ash is 1.1-1.4, k for Class II fly ash is 1.3-1.7, and k for Class III fly ash is 1.5-2.0;

[0058] The adjusted cement mass is calculated using the following formula:

[0059] m c0 =m c ×(1-f);

[0060] Where: m c0 is the mass of cement after adjustment; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement;

[0061] The quality of sand after adjustment:

[0062]

[0063] m s0 +m g +m c0 +m f +m w =m cp ;

[0064] Where: m s0 is the mass of adjusted sand in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ρ f is the apparent density of fly ash, kg / m 3 ρ s is the apparent density of fine aggregate, kg / m 3 ;mg is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c0 The mass of adjusted cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m f is the mass of fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 .

[0065] Beneficial effects of this application:

[0066] The present application provides a method for designing the mix ratio of large-slump premixed concrete for roads. Based on the problem of the lack of a method for designing the mix ratio of large-slump premixed concrete, the application proposes a design step for the mix ratio of large-slump premixed concrete, introduces the functional relationship between the volume of cementitious materials and the amount of cement, clarifies the calculation formula of each component material of large-slump premixed concrete, and improves the workability and filling property of the mixture while ensuring the durability of the large-slump premixed concrete pavement. The application has strong practicality and solves the problem that there is no evidence for the design of the mix ratio of large-slump premixed concrete. The mix ratio design method determined in the present application can be directly used for design, and the mass ratio of each component material can be quickly obtained, which has a very large engineering practical value. At the same time, the steps in the present application are simple, the formula is clear in meaning, and the application has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the drawings required for use in the implementation methods will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0068] Figure 1 A schematic flow chart of a method for designing a mix ratio of high-slump ready-mixed concrete for roads provided in an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0070] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0071] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0072] Example:

[0073] Please refer to Figure 1 In the embodiment of the present application, a method for designing the mix ratio of premixed concrete with large slump for roads is provided, and a newly built trunk road is taken as an example for specific description:

[0074] In the newly built trunk road, the mass of concrete mixture per cubic meter is 2450kg / m 3 The design flexural strength is not less than 5.0MPa. The mix ratio design is carried out using machine-made sand and concrete pavement without admixtures. The specific design method is:

[0075] S1, calculate the mean 28d flexural strength of the large slump ready-mixed concrete surface layer according to the following formula, where the coefficient of variation of flexural strength c v Take 0.075, the guarantee rate coefficient t is 0.46, and the standard deviation s of the bending tensile strength test sample is 0.4, and the calculation is:

[0076]

[0077] Where: f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f r is the standard value of design flexural strength, MPa, which is determined according to the design and should not be lower than the requirements of Table 6.2.5 of "Code for Design of Urban Road Pavement" CJJ 169; c vis the coefficient of variation of bending tensile strength, which should be determined according to statistical data and taken as 0.05 when it is less than 0.05. If there is no statistical data, it can be determined according to the values ​​in Table 3. The variation level of expressways and trunk roads should be low, the variation level of secondary trunk roads should not be lower than medium, and the variation level of branches should not be lower than medium. t is the guarantee rate coefficient, which is taken according to Table 1. s is the standard deviation of the bending tensile strength test sample, MPa. If there is test data, the standard deviation of the test sample should be used. If there is no test data, it can be determined according to the road grade and the design bending tensile strength and refer to Table 2.

[0078] Table 1 Guarantee rate coefficient t

[0079]

[0080] Table 2 Standard deviation of flexural strength test samples s

[0081]

[0082] Table 3 Coefficient of variation of flexural strength cv

[0083]

[0084] S2, calculate the water-cement ratio or water-binder ratio of high slump ready-mixed concrete mixture according to the following formula:

[0085]

[0086] Where: W / C is the water-cement ratio or water-binder ratio; f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f s is the measured 28d flexural strength of cement, MPa;

[0087] It should be noted that, in general, when the standard value of concrete design flexural strength is 5.0MPa, the water-cement ratio or water-binder ratio should be 0.38-0.42; when the standard value of concrete design flexural strength is 4.5MPa, the water-cement ratio or water-binder ratio should be 0.42-0.46;

[0088] S3, determine the sand ratio of the high slump ready-mixed concrete mixture according to the following Table 4:

[0089] It should be noted that the sand ratio of the high slump ready-mixed concrete mixture is determined according to the fineness modulus of the sand and the type of fine aggregate. The medium sand with a fineness modulus of 2.3 to 3.2 can be selected according to the following Table 4. For sands with other fineness moduli, they should be determined according to tests:

[0090] Table 4 Sand ratio of cement concrete

[0091]

[0092] Specifically, in this embodiment, machine-made sand is used, the fineness modulus of the sand is 2.6, and the sand ratio is determined to be 38% according to Table 4;

[0093] S4, calculate the amount of cement for high slump ready-mixed concrete mixture according to the following formula:

[0094] The volume of the cementitious material is determined according to the following Table 5. The proposed volume of the cementitious material is 0.32, and the water-cement ratio W / C is 0.42 as calculated in S2. The amount of the cementitious material used can be calculated as 390.91 kg according to the following formula;

[0095]

[0096] Where: m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; V p is the volume of cementitious material in each cubic meter of high slump ready-mixed concrete mixture, m 3 ; V a is the volume of air introduced into each cubic meter of high slump ready-mixed concrete mixture, m 3 Generally, if there is an antifreeze requirement, the value range of the air-entraining agent is 4.5±0.5%; if there is no antifreeze requirement, the value range of the air-entraining agent is 3±1%; ρ m is the apparent density of mineral admixture, kg / m 3 ; β is the mass fraction of mineral admixture in cementitious materials per cubic meter of high slump ready-mixed concrete mixture, %; ρ c is the apparent density of cement kg / m 3 ρ w is the apparent density of mixing water, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio;

[0097] Table 5 Volume of cementitious materials per cubic meter of high slump ready-mixed concrete mixture

[0098] Standard value of concrete design flexural strength (MPa) 5.0 4.5 <![CDATA[Volume of cementitious material (m 3 )]]> 0.32～0.36 0.30～0.34

[0099] It should be noted that, in general, for the volume of cementitious materials per cubic meter of high slump ready-mixed concrete mixture, when the standard value of concrete design flexural tensile strength is 5.0MPa, the water-cement ratio or water-binder ratio should be 0.30-0.34; when the standard value of concrete design flexural tensile strength is 4.5MPa, the water-cement ratio or water-binder ratio should be 0.28-0.32;

[0100] S5. Calculate the amount of water for high slump ready-mixed concrete mixture according to the following formula:

[0101]

[0102] Where: m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio; γ is the measured water reduction rate of the admixture dosage used, %;

[0103] It should be noted that, in general, when the standard value of concrete design flexural tensile strength is 5.0MPa, the maximum unit water consumption is 165kg, and when the standard value of concrete design flexural tensile strength is 4.5MPa, the maximum unit water consumption is 175kg;

[0104] S6, the amount of coarse aggregate and fine aggregate in the high slump ready-mixed concrete mixture is calculated according to the following conditions. The unit mass of the high slump ready-mixed concrete mixture can be 2400~2450kg / m 3 :

[0105] (1) When there is no admixture in the high slump ready-mixed concrete mixture, the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0106] m s +m g +m c +m w =m cp ;

[0107]

[0108] Where: m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m g is the mass of coarse aggregate in each cubic meter of concrete, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ; S p is the sand ratio of high slump ready-mixed concrete mixture;

[0109] Calculated from the above formula: m s =720kg,m g =1174.91kg;

[0110] Thus, the mass ratio of each material of high-slump ready-mixed concrete is obtained, that is, the mix ratio design of high-slump concrete is obtained:

[0111] m s :m g :m c :m w =720:1174.91:391.91:164.18;

[0112] (2) When slag powder or silica fume is added to the large slump ready-mixed concrete mixture, the mass of the slag powder or silica fume is calculated by the equal replacement method. Generally, the slag powder content does not exceed 30%, and the silica fume content does not exceed 10%; therefore, in this embodiment, the slag content is 30%;

[0113] Among them, the volume of cementitious material is determined according to Table 5, the proposed volume of cementitious material is 0.32, and the water-binder ratio is 0.42 calculated according to step 2;

[0114] According to the following formula, the amount of cementitious material can be calculated as 387.18 kg:

[0115]

[0116] Where: m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; V p is the volume of cementitious material in each cubic meter of high slump ready-mixed concrete mixture, m 3 ; V a is the volume of air introduced into each cubic meter of high slump ready-mixed concrete mixture, m 3 ρ m is the apparent density of mineral admixture, kg / m 3 ; β is the mass fraction of mineral admixture in cementitious materials per cubic meter of high slump ready-mixed concrete mixture, %; ρ c is the apparent density of cement kg / m 3 ρ w is the apparent density of mixing water, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio;

[0117] The amount of water required for high slump ready-mixed concrete mixture is calculated according to the following formula:

[0118]

[0119] Where: m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;mc is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio; γ is the measured water reduction rate of the admixture dosage used, %;

[0120] From the above, it can be calculated that the amount of water used in the high slump ready-mixed concrete mixture is 162.62 kg;

[0121] When adding slag powder or silica fume, the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0122]

[0123] m s +m g +m c +m k +m w =m cp ;

[0124] Where: S p is the sand ratio of the large slump ready-mixed concrete mixture; m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m k The mass of slag powder or silica fume in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ;

[0125] Calculated: m s =721.98kg, m g =1174.91kg, m k =116.23kg;

[0126] Thus, the mass ratio of each material of high-slump ready-mixed concrete is obtained, that is, the mix ratio design of high-slump concrete is obtained:

[0127] m s :m g :m c :m k:m w =721.98:1177.98:271.2:116.23:162.62;

[0128] (3) When fly ash is added to high-slump ready-mixed concrete, the mass of fly ash is calculated using the excess substitution method, and the amount of coarse aggregate and fine aggregate is calculated according to the following formula:

[0129] It should be noted that, under normal circumstances, the maximum amount of fly ash added is: Type I Portland cement should not be greater than 30%, Type II Portland cement should not be greater than 25%, and road Portland cement should not be greater than 20%. The total amount of fly ash added should be finally determined through experiments.

[0130] Select the mass percentage f of fly ash replacing cement and adjust various materials:

[0131] The total mass of fly ash is calculated using the following formula in the excess substitution method:

[0132] m f =m c ×f×k=390.91×0.3×1.2=140.73kg;

[0133] Where: m f is the total mass of fly ash; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient. Generally, k for Class I fly ash is 1.1-1.4, k for Class II fly ash is 1.3-1.7, and k for Class III fly ash is 1.5-2.0;

[0134] The excess fly ash mass is calculated using the following formula:

[0135] m f1 =m c ×f×(k-1)=390.91×0.3×(1.2-1)=23.45kg;

[0136] Where: m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient. Generally, k for Class I fly ash is 1.1-1.4, k for Class II fly ash is 1.3-1.7, and k for Class III fly ash is 1.5-2.0;

[0137] The adjusted cement mass is calculated using the following formula:

[0138] m c0 =m c ×(1-f)=390.91×(1-0.3)=273.64kg;

[0139] Where: m c0 is the mass of cement after adjustment; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement;

[0140] The quality of sand after adjustment:

[0141]

[0142] Where: m s0 is the mass of adjusted sand in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ;m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ρ f is the apparent density of fly ash, kg / m 3 ρ s is the apparent density of fine aggregate, kg / m 3 ;

[0143] The mass ratio of each material of high-slump ready-mixed concrete is obtained, that is, the mix ratio design of high-slump concrete is obtained:

[0144] m s0 :m g :m c0 :m f :m w =692.08:1179.65:7273.64:140.73:163.9.

[0145] In summary, the present application provides a method for designing the mix ratio of large-slump premixed concrete for roads. Based on the problem of the lack of a method for designing the mix ratio of large-slump premixed concrete, the application proposes a design step for the mix ratio of large-slump premixed concrete, introduces the functional relationship between the volume of cementitious materials and the amount of cement, clarifies the calculation formula for each component of large-slump premixed concrete, and improves the workability and filling properties of the mixture while ensuring the durability of large-slump premixed concrete pavement. The application has strong practicality and solves the problem that there is no evidence for the design of large-slump premixed concrete mix ratio. The mix ratio design method determined in the present application can be directly used for design, and the mass ratio of each component material can be quickly obtained, which has great engineering practical value. At the same time, the steps in the present application are simple, the formulas are clear in meaning, and the application has strong practicality.

[0146] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for designing the mix ratio of premixed concrete for roads with large slump, characterized in that: The following steps are involved: S1, calculate the average value of 28d flexural tensile strength of cement concrete used for road high slump ready-mixed concrete surface layer; S2, calculate the water-cement ratio or water-binder ratio of high-slump ready-mixed concrete mixture; S3, determine the sand ratio of the high slump ready-mixed concrete mixture; S4, calculate the amount of cement in the high slump ready-mixed concrete mixture; S5, calculate the amount of water in the high slump ready-mixed concrete mixture; S6, calculate the amount of coarse aggregate and fine aggregate in the high slump ready-mixed concrete mixture; S7, obtain the mass ratio of each material of the high slump ready-mixed concrete, that is, obtain the mix ratio design.

2. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S1, the mean value f of the 28d flexural tensile strength of cement concrete for high slump ready-mixed concrete surface layer is calculated according to the following formula: c : Where: f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f r is the standard value of design flexural strength, MPa; c v is the coefficient of variation of flexural strength; t is the guarantee rate coefficient; s is the standard deviation of the flexural strength test samples, MPa.

3. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S2, the water-cement ratio or water-binder ratio of the high-slump ready-mixed concrete mixture is calculated according to the following formula: Where: W / C is the water-cement ratio or water-binder ratio; f c The average 28d flexural strength of cement concrete for the surface layer, MPa; f s It is the measured 28d flexural strength of cement, MPa.

4. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S3, the sand ratio of the high-slump ready-mixed concrete mixture is determined according to the fineness modulus of the sand and the type of fine aggregate: When the fineness modulus of medium sand is 2.3-2.6, the proportion of natural sand is 34%-38%, and the proportion of artificial sand or mixed sand is 36%-40%; when the fineness modulus of medium sand is 2.6-2.9, the proportion of natural sand is 36%-40%, and the proportion of artificial sand or mixed sand is 38%-42%; when the fineness modulus of medium sand is 2.9-3.2, the proportion of natural sand is 38%-42%, and the proportion of artificial sand or mixed sand is 40%-44%.

5. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S4, the amount of cement in the high-slump ready-mixed concrete mixture is calculated according to the following formula: Where: m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; V p is the volume of cementitious material in each cubic meter of high slump ready-mixed concrete mixture, m 3 ; V a is the volume of air introduced into each cubic meter of high slump ready-mixed concrete mixture, m 3 ; ρ m is the apparent density of mineral admixture, kg / m 3 ; β is the mass fraction of mineral admixture in cementitious materials per cubic meter of concrete, %; ρ c is the apparent density of cement kg / m 3 ; ρ w is the apparent density of mixing water, kg / m 3 ; W / C is the water-cement ratio or water-cement ratio.

6. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S5, the amount of water in the high-slump ready-mixed concrete mixture is calculated according to the following formula: Where: m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; W / C is the water-cement ratio or water-binder ratio; γ is the measured water reduction rate of the admixture dosage used, %.

7. The method for designing the mix ratio of high-slump ready-mixed concrete for roads according to claim 1, characterized in that: In step S6, the amounts of coarse aggregate and fine aggregate in the high-slump ready-mixed concrete mixture are calculated according to the following conditions: When there is no admixture in the high slump ready-mixed concrete mixture, the amount of coarse aggregate and fine aggregate is calculated according to the following formula: m s +m g +m c +m w =m cp ; Where: m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ; S p is the sand ratio of high slump ready-mixed concrete mixture; When slag powder or silica fume is added to the high slump ready-mixed concrete mixture, the mass of slag powder or silica fume is calculated by the equal substitution method, and the amount of coarse aggregate and fine aggregate is calculated according to the following formula: m s +m g +m c +m k +m w =m cp ; Where: S p is the sand ratio of the large slump ready-mixed concrete mixture; m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m k The mass of slag powder or silica fume in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m cp is the mass of high slump ready-mixed concrete mixture per cubic meter, kg / m 3 ; When fly ash is added to high-slump ready-mixed concrete, the mass of fly ash is calculated using the excess substitution method, and the amount of coarse aggregate and fine aggregate is calculated according to the following formula: Select the mass percentage f of fly ash replacing cement and adjust various materials: The total mass of fly ash is calculated using the following formula in the excess substitution method: m f =m c ×f×k; Where: m f is the total mass of fly ash, kg / m 3 ;m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient; The excess fly ash mass is calculated using the following formula: m f1 =m c ×f×(k-1); Where: m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; k is the excess substitution coefficient; The adjusted cement mass is calculated using the following formula: m c0 =m c ×(1-f); Where: m c0 is the mass of cement after adjustment; m c is the mass of cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; f is the mass percentage of cement; The quality of sand after adjustment: m s0 +m g +m c0 +m f +m w =m cp ; Where: m s0 is the mass of adjusted sand in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m s is the mass of fine aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m f1 The mass of excess fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; ρ f is the apparent density of fly ash, kg / m 3 ; ρ s is the apparent density of fine aggregate, kg / m 3 ;m g is the mass of coarse aggregate in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m c0 The mass of adjusted cement in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m f is the mass of fly ash in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m w is the mass of water in each cubic meter of high slump ready-mixed concrete mixture, kg / m 3 ; m cp is the mass of the mixture per cubic meter of high slump ready-mixed concrete, kg / m 3 .

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