Coagulation-based mix proportion design method for road pumping concrete with large slump

Abstract

A cohesive-based high-slump pumped concrete mix design method for road construction is disclosed. This method involves determining the allowable value of the pressure bleeding rate of the concrete; conducting trial mix design based on the design parameters of the concrete pavement and calculating the standard value of the pressure bleeding rate; calculating temperature correction factors and transport time correction factors; adjusting the standard value of the pressure bleeding rate based on these factors to calculate the design value of the pressure bleeding rate; and determining whether the design value of the pressure bleeding rate meets the allowable value. This cohesive-based high-slump pumped concrete mix design method can predict and ensure that the cohesiveness of the prepared concrete meets construction requirements during the mix design stage, thereby guaranteeing concrete quality.

Description

Technical Field

[0001] This application relates to the field of road construction, and more specifically, to a method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness. Background Technology

[0002] Due to constraints related to environmental protection, land use, and economic factors, on-site mixing plants are often not feasible during urban road construction. Therefore, commercially pumped concrete, typically mixed in centralized plants, is commonly used. While pumped concrete is widely used in the construction of cement concrete pavements for urban roads in my country due to its excellent workability, energy efficiency, and environmental friendliness, it has also generated some significant problems, primarily in the following two aspects: First, pumped concrete has high unit water consumption, high cement content, high water-cement ratio, high sand ratio, and high slump, leading to significant heat of hydration and marked drying and thermal shrinkage. This makes the pavement prone to early and severe cracking, resulting in a service life that falls short of the design life. Second, there are no established regulations or standards for the mix design of high-slump pumped concrete. Domestic industry standards only address pavement concrete mix design for concrete with a slump of 5–40 mm, which is insufficient for the construction requirements of pumped cement concrete pavements for urban roads.

[0003] The cohesiveness of pumped concrete is a key performance indicator for pumped concrete in high-slump roads. When the pressure cohesiveness does not meet the requirements, it can easily lead to surface slurry and bleeding in the pumped concrete pavement, weakening the concrete's impermeability and ultimately causing damage to the pavement structure. The cohesiveness of pumped concrete is mainly characterized by the pressure bleeding rate.

[0004] Currently, there is a lack of mix design methods for high-slump pumped concrete for roads based on cohesive control, resulting in the current high-slump pumped concrete for roads falling far short of the construction requirements of urban road surfaces. Summary of the Invention

[0005] The purpose of this application is to provide a cohesive high-slump road pumped concrete mix design method, which can predict and ensure that the cohesiveness of the prepared concrete meets the construction requirements during the concrete mix design stage, thereby ensuring the quality of the concrete.

[0006] This application is implemented as follows:

[0007] This application provides a method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness, which includes the following steps:

[0008] Determine the allowable value of pressure bleeding rate for concrete;

[0009] Based on the design parameters of the concrete pavement, conduct trial mixing design of the concrete pavement mix proportion;

[0010] Calculate the standard value of pressure bleeding rate of concrete based on the design and trial mixing of concrete pavement mix proportions;

[0011] Calculate the temperature correction factor and the transportation time correction factor;

[0012] The design value of the pressure bleeding rate of concrete is calculated by adjusting the standard value of the pressure bleeding rate of concrete based on the temperature correction factor and the transportation time correction factor.

[0013] Determine whether the design value of the pressure bleeding rate of concrete meets the allowable value of the pressure bleeding rate of concrete.

[0014] In some alternative implementations, the design parameters for concrete pavement include the design grade of concrete flexural strength, urban road grade, site temperature, and concrete transport time.

[0015] In some alternative implementations, the permissible values ​​for pressure bleeding rate of concrete are within 30% for expressways, within 35% for arterial roads, within 40% for secondary arterial roads, and within 40% for local roads.

[0016] In some alternative implementation schemes, when designing and testing the mix proportions of the concrete pavement based on the design parameters, the water-cement ratio is 0.44–0.48 and the paste volume is 310–340 L / m³ when the allowable flexural tensile strength of the concrete pavement is 4.5 MPa. 3 The volumetric sand ratio is 42-46%, and the slag powder content is less than 40%; when the allowable flexural tensile strength of the concrete pavement is 5 MPa, the water-cement ratio is 0.4-0.44, and the slurry volume is 320-350 L / m³. 3 The volumetric sand ratio is 40-44%, and the slag powder content is less than 40%.

[0017] In some alternative implementations, the following formula is used when calculating the standard value of the pressure bleeding rate of concrete:

[0018] in, V is the water-to-glue ratio. p The volume of the slurry (L / m³) 3 ), β represents the volumetric sand ratio (%), and β represents the slag powder content (%).

[0019] In some alternative implementations, the following formula is used when calculating the temperature correction factor: ξ T -1+0.0052T-2.08×10 -4 T 2 , where ξ T is the temperature correction factor; T is the ambient temperature, °C.

[0020] In some alternative implementations, the following formula is used when calculating the transit time correction factor: In the formula: ξ t t is the time correction factor. i The transit time is in hours (h).

[0021] In some alternative implementations, the following formula is used when calculating the design value of the pressure bleeding rate of concrete:

[0022] In some alternative implementations, determining whether the design value of the pressure bleeding rate of concrete meets the allowable value of the pressure bleeding rate of concrete means that the design value of the pressure bleeding rate is within the allowable range of the pressure bleeding rate. If the design value of the pressure bleeding rate of concrete is not within the allowable range of the pressure bleeding rate of concrete, the above-mentioned design and trial mixing of concrete pavement proportion based on the design parameters of concrete pavement is repeated.

[0023] The beneficial effects of this application are as follows: The cohesive-based high-slump road pumped concrete mix design method provided in this application includes the following steps: determining the allowable value of the concrete pressure bleeding rate; conducting a design trial mix of the concrete pavement based on the design parameters of the concrete pavement; calculating the standard value of the concrete pressure bleeding rate based on the design trial mix of the concrete pavement; calculating the temperature correction coefficient and the transportation time correction coefficient; adjusting the standard value of the concrete pressure bleeding rate based on the temperature correction coefficient and the transportation time correction coefficient to calculate the design value of the concrete pressure bleeding rate; and determining whether the design value of the concrete pressure bleeding rate meets the allowable value of the concrete pressure bleeding rate. The cohesive-based high-slump road pumped concrete mix design method provided in this application can predict and ensure that the cohesiveness of the prepared concrete meets the construction requirements during the concrete mix design stage, thereby ensuring the quality of the concrete. It has the advantages of simple operation and strong applicability, and can be widely promoted and applied in urban road pavement construction. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic flowchart illustrating the mix design method for high-slump road pumped concrete based on cohesiveness, provided in an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Therefore, the following detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The following detailed description of the features and performance of the cohesive-based high-slump road pumped concrete mix design method of this application, in conjunction with embodiments, provides further insight into its characteristics and performance.

[0028] like Figure 1 As shown, this application provides a method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness, which includes the following steps:

[0029] Step 1: Determine the design parameters for the concrete pavement; optionally, the design parameters for the concrete pavement include the design grade of the concrete's flexural strength, the urban road grade, the site temperature, and the concrete transportation time; the concrete transportation time is the time it takes for the concrete to be transported from the concrete mixing plant to the construction site.

[0030] Step 2: Determine the allowable value B of the pressure bleeding rate of concrete. V Optional, allowable value B for pressure bleeding rate of concrete. V The percentages are as follows: expressways within 30%, arterial roads within 35%, secondary arterial roads within 40%, and local roads within 40%.

[0031] Step 3: Conduct trial mix design of the concrete pavement based on the design parameters; optionally, when the allowable flexural tensile strength of the concrete pavement is 4.5 MPa, the water-cement ratio is 0.44–0.48, and the slurry volume is 310–340 L / m³. 3 The volumetric sand ratio is 42-46%, and the slag powder content is less than 40%; when the allowable flexural tensile strength of the concrete pavement is 5 MPa, the water-cement ratio is 0.4-0.44, and the slurry volume is 320-350 L / m³. 3 The volumetric sand ratio is 40-44%, and the slag powder content is less than 40%.

[0032] Step 4: Based on the design and trial mixing of the concrete pavement mix proportions, calculate the standard value B of the concrete pressure bleeding rate. Vk ; Calculate the standard value B of the pressure bleeding rate of concrete. Vk Use the following formula: in, V is the water-to-glue ratio.p The volume of the slurry (L / m³) 3 ), β represents the volumetric sand ratio (%), and β represents the slag powder content (%).

[0033] Step 5: Calculate the temperature correction factor and the transportation time correction factor; the following formula is used to calculate the temperature correction factor: ξ T = 1 + 0.0052T - 2.08 × 10 -4 T 2 , where ξ T Here is the temperature correction factor; T is the ambient temperature, in °C. The following formula is used to calculate the transportation time correction factor: In the formula: ξ t t is the time correction factor. i The transit time is in hours (h).

[0034] Step Six: Adjust the standard value B of the pressure bleeding rate of concrete based on the temperature correction factor and the transportation time correction factor. Vk Calculate the design value B of the pressure bleeding rate of concrete. VD ; Calculate the design value B of the pressure bleeding rate of concrete. VD Use the following formula:

[0035] Step 7: Determine the design value B of the pressure bleeding rate of concrete. VD Does it meet the allowable value B for pressure bleeding rate of concrete? V Determine whether the design value of the pressure bleeding rate of concrete meets the allowable value B for the pressure bleeding rate of concrete. V This refers to the design value B of the pressure-induced water leakage rate. VD Within the permissible pressure-induced water leakage rate B V Within the range; when the design value B of the concrete pressure bleeding rate VD Not within the allowable value B for pressure bleeding rate of concrete V If the condition is within the specified range, repeat step three and continue the design and trial mixing of the concrete pavement mix after modifying the design parameters of the concrete pavement.

[0036] This application provides a cohesive-based mix design method for high-slump pumped concrete for urban roads, addressing the gap in current pavement design methods regarding the cohesiveness index of high-slump pumped concrete. Through extensive experience and statistical analysis, a formula for calculating the pressure bleeding rate of concrete is derived and corrected using construction temperature and concrete transport time. The final calculated design value of the pressure bleeding rate is compared with the allowable value specified for construction. This allows for prediction and assurance that the cohesiveness of the prepared concrete meets construction requirements during the mix design stage, guaranteeing concrete quality at the material source and avoiding or reducing defects such as laitance and bleeding in pumped concrete pavements caused by insufficient cohesiveness of high-slump pumped concrete, which weakens the concrete's impermeability and leads to surface damage to the pavement structure. The cohesive-based mix design method for high-slump pumped concrete provided in this application has the advantages of simple operation and strong applicability, and can be widely promoted and applied in urban road pavement construction.

[0037] Example 1

[0038] This application provides a method for designing mix proportions of high-slump road pumped concrete based on cohesiveness, which includes the following steps;

[0039] Step 1: Determine the design parameters for the concrete pavement. Consider a newly constructed main road in a city, requiring a continuously reinforced concrete surface layer with a flexural tensile strength of 5.0 MPa. The construction site temperature is 30℃, and the concrete transport time is 0.5 hours.

[0040] Step 2: Determine the allowable value B for the pressure bleeding rate of the concrete. V The proportion of main roads is within 35%.

[0041] Step 3: Conduct trial mix design of high-slump concrete based on the design parameters for the concrete pavement. The mix design parameters are: water-cement ratio of 0.44 and paste volume of 320 L / m³. 3 The volumetric sand ratio is 44%, and the slag powder content is 30% (all cementing materials are by mass).

[0042] Step 4: Calculate the standard value B of pressure-induced water leakage rate. Vk for:

[0043]

[0044] Step 5: Calculate the temperature correction factor and the transportation time correction factor; where the temperature correction factor ξ T For: ξ T =1 + 0.0052T - 2.08 × 10 -4 T 2-1 + 0.0052 × 30 - 2.08 × 10 -4 ×30 2 -0.969; Transit time correction factor ξ t for:

[0045] Step 6: Adjust the standard value B of the pressure bleeding rate of concrete based on the temperature correction factor and the transportation time correction factor. Vk Calculate the design value B of the pressure bleeding rate of concrete. VD for:

[0046]

[0047] Step 7: Determine whether the design value of the pressure bleeding rate of the concrete meets the allowable value B of the pressure bleeding rate of the concrete. V This refers to the design value B of the pressure-induced water leakage rate. VD Within the permissible pressure-induced water leakage rate B V Within the range, B Vd -33.96∈[B V = [0.35]. Therefore, the design value of the pressure bleeding rate meets the requirements of the allowable pressure bleeding rate.

[0048] Example 2

[0049] This application provides a method for designing mix proportions of high-slump road pumped concrete based on cohesiveness, which includes the following steps;

[0050] Step 1: Determine the design parameters for the concrete pavement. Consider a newly constructed secondary arterial road in a city, requiring a surface concrete layer with a flexural strength of 5.0 MPa. The construction site temperature is 25℃, and the concrete transportation time is 1 hour.

[0051] Step 2: Determine the allowable value B for the pressure bleeding rate of the concrete. V The proportion of secondary arterial roads is within 35%.

[0052] Step 3: Conduct trial mix design of high-slump concrete based on the design parameters for the concrete pavement. The mix design parameters are: water-cement ratio of 0.46 and paste volume of 320 L / m³. 3 The volumetric sand ratio is 45%, and the slag powder content is 20% (all cementing materials are by mass).

[0053] Step 4: Calculate the standard value B of pressure-induced water leakage rate. Vk for:

[0054]

[0055] Step 5: Calculate the temperature correction factor and the transportation time correction factor; where the temperature correction factor ξ TFor: ξ T = 1 + 0.0052T - 2.08 × 10 -4 T 2 = 1 + 0.0052 × 25 - 2.08 × 10 -4 ×25 2 =1; Transportation time correction factor ξ t for:

[0056] Step 6: Adjust the standard value B of the pressure bleeding rate of concrete based on the temperature correction factor and the transportation time correction factor. Vk Calculate the design value B of the pressure bleeding rate of concrete. VD for:

[0057]

[0058] Step 7: Determine whether the design value of the pressure bleeding rate of the concrete meets the allowable value B of the pressure bleeding rate of the concrete. V This refers to the design value B of the pressure-induced water leakage rate. VD Within the permissible pressure-induced water leakage rate B V Within the range, B Vd =39.13∈[B v = [0.40]. Therefore, the design value of the pressure bleeding rate meets the requirements of the allowable pressure bleeding rate.

[0059] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness, characterized in that, It includes the following steps: Determine the allowable value of pressure bleeding rate for concrete; Based on the design parameters of the concrete pavement, conduct trial mixing design of the concrete pavement mix proportion; The standard value of the pressure bleeding rate of concrete was calculated based on the design trial mix of the aforementioned concrete pavement proportion. The following formula was used to calculate the standard value of the pressure bleeding rate of concrete: ； in, This refers to the water-to-glue ratio. The volume of the slurry is expressed in L / m³. 3 , β is the volumetric sand ratio, %; β is the slag powder content, %; Calculate the temperature correction factor and the transit time correction factor; the following formula is used to calculate the temperature correction factor: ,in, Here, T is the temperature correction factor; T is the ambient temperature, in °C; the following formula is used to calculate the transportation time correction factor: In the formula: This is a time correction factor. For transportation time, h; The design value of the pressure bleeding rate of concrete is calculated by adjusting the standard value of the pressure bleeding rate of concrete based on the temperature correction factor and the transportation time correction factor; the following formula is used to calculate the design value of the pressure bleeding rate of concrete: ; Determine whether the design value of the pressure bleeding rate of the concrete meets the allowable value of the pressure bleeding rate of the concrete.

2. The method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness according to claim 1, characterized in that, The design parameters for the concrete pavement include the design grade of concrete flexural strength, urban road grade, site temperature, and concrete transportation time.

3. The method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness according to claim 1, characterized in that, The permissible values ​​for the pressure bleeding rate of concrete are within 30% for expressways, within 35% for main roads, within 40% for secondary roads, and within 40% for branch roads.

4. The method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness according to claim 1, characterized in that, When designing and testing the concrete pavement mix proportions based on the aforementioned design parameters, when the allowable flexural tensile strength of the concrete pavement is 4.5 MPa, the water-cement ratio is 0.44~0.48, and the slurry volume is 310~340 L / m³. 3 The volumetric sand ratio is 42-46%, and the slag powder content is less than 40%; when the allowable flexural tensile strength of the concrete pavement is 5MPa, the water-cement ratio is 0.4-0.44, and the slurry volume is 320-350L / m³. 3 The volumetric sand ratio is 40-44%, and the slag powder content is less than 40%.

5. The method for designing mix proportions of high-slump pumped concrete for roads based on cohesiveness according to claim 1, characterized in that, Determining whether the design value of the pressure bleeding rate of the concrete meets the allowable value of the pressure bleeding rate of the concrete means that the design value of the pressure bleeding rate is within the allowable range of the pressure bleeding rate. When the design value of the pressure bleeding rate of the concrete is not within the allowable range of the pressure bleeding rate of the concrete, the above-mentioned design and trial mixing of the concrete pavement mix proportion based on the design parameters of the concrete pavement is repeated.

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