Mix proportion design method of solid waste based artificial aggregate pervious concrete

Abstract

The invention discloses a mix proportion design method of solid waste based artificial aggregate pervious concrete, which comprises the following steps: 1, acquiring related data of artificial aggregate by virtue of a three-dimensional reconstruction technology, 2, calculating the maximum wrapping thickness of the surface of the artificial aggregate according to the required cement paste dosage, and 3, calculating the mix proportion of the artificial aggregate pervious concrete according to the maximum wrapping thickness. And 3, calculating the mix proportion of the artificial aggregate pervious concrete through the constructed mathematical relationship model among the wrapping thickness, the fluidity and the key mix proportion parameters. According to the invention, the accurate mixing proportion of the pervious concrete can be realized, so that the prepared pervious concrete has both water permeability and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of building solid waste materials, and particularly relates to a mix proportion design method for solid waste-based artificial aggregate permeable concrete. Background Art

[0002] With the construction of sponge cities, permeable concrete pavements have received extensive attention. Generally, natural aggregates are commonly used as the skeleton structure of permeable concrete. However, with the introduction of environmental protection policies, the state has begun to restrict the mining of natural sand and gravel aggregates, and the price of sand and gravel aggregates is getting higher and higher. The problem of shortage of construction sand and gravel resources is becoming increasingly prominent. On the other hand, permeable concrete is mainly used in low-traffic areas such as urban roads, landscape gardens, and parking lots. Permeability is its main performance, and the strength requirement is not high. In addition, the failure mode of existing permeable concrete is mainly the failure of the cement paste between aggregates, rather than the failure of the aggregates themselves. Therefore, for permeable concrete, the strength of natural aggregates is excessive.

[0003] The preparation of artificial aggregates generally uses solid waste as raw materials, and the material cost is relatively low, which conforms to the sustainable development strategy. However, its low strength has been restricting its application scope. On the other hand, artificial aggregates have the advantages of adjustable morphology and stable quality. Preparing permeable concrete with solid waste-based artificial aggregates as raw materials can not only avoid the disadvantage of insufficient strength, but also regulate the requirements of its morphology parameters to prepare permeable concrete with excellent permeable performance.

[0004] The permeable concrete aggregates are bonded to each other through the cement paste wrapped on the surface to form a network structure. The aggregates and the cement paste constitute the skeleton structure of the permeable concrete, and the remaining space is its pore structure. Therefore, the mix proportion design process of permeable concrete is different from that of conventional concrete. At present, the common mix proportion design methods for permeable concrete are the empirical method and the volume method. However, both of these methods do not fully consider the wrapping ability of the cement paste and the workability of the mixture. The design of its mix proportion parameters depends on empirical judgment, and it is difficult to effectively balance the mechanical properties and the permeable performance, which limits the further optimization of the performance of permeable concrete. Summary of the Invention

[0005] In order to solve the deficiencies of the above-mentioned existing technologies, the present invention proposes a mix proportion design method for solid waste-based artificial aggregate permeable concrete, hoping to achieve an accurate mix proportion of permeable concrete, so that the prepared permeable concrete can balance the permeable performance and the mechanical properties.

[0006] The present invention adopts the following technical solutions to achieve the above-mentioned invention purpose:

[0007] The mix proportion design method for solid waste-based artificial aggregate permeable concrete of the present invention is characterized by including the following steps:

[0008] Step 1: Obtain data related to artificial aggregates, including: apparent density ρ a , compacted density ρ b , void ratio V under compaction a and total surface area S of artificial aggregates a ;

[0009] Step 2: Determine the designed porosity V according to the requirements of permeable concrete using Equation (1) v :

[0010] (1)

[0011] Step 3: Determine the volume V of cement paste using Equation (2) p ;

[0012] (2)

[0013] Step 4: If all the cement paste of permeable concrete is used to wrap artificial aggregates, the maximum paste thickness CPT on the surface of artificial aggregates can be obtained using Equation (3):

[0014] (3)

[0015] Step 5: Based on the maximum paste thickness CPT, construct a mathematical relationship model between paste thickness and fluidity using Equation (4) to obtain the fluidity F p ;

[0016] (4)

[0017] In Equation (4), e and d represent two fitting coefficients;

[0018] Step 6: Determine the water-binder ratio w / c according to the strength of permeable concrete, cement type and working performance of permeable concrete, where w is the mass of water and c represents the mass of cement;

[0019] Step 7: Based on the fluidity F p and the water-binder ratio w / c, construct a mathematical relationship model between fluidity and admixture dosage using Equation (5) to obtain the admixture dosage :

[0020] (5)

[0021] In Equation (5), a and b represent two fitting coefficients, and thus w / c and are used as the mix proportion of permeable concrete with artificial aggregates.

[0022] An electronic device according to the present invention includes a memory and a processor, characterized in that the memory is used to store a program for supporting the processor to execute the method for designing the mix proportion of artificial aggregate permeable concrete, and the processor is configured to execute the program stored in the memory.

[0023] A computer-readable storage medium according to the present invention, characterized in that when the computer program stored on the computer-readable storage medium is run by a processor, it executes the steps of the method for designing the mix proportion of artificial aggregate permeable concrete.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses solid waste-based artificial aggregates to prepare permeable concrete, which can give play to the advantages of morphology regulation of artificial aggregates. Artificial aggregates with different particle sizes and sphericities are prepared, and the mathematical relationship between the morphology parameters of the overall aggregates and the performance of permeable concrete is established to accurately regulate the performance of permeable concrete.

[0026] 2. Based on the thickness of the paste coating on the surface of the aggregates, the present invention establishes a mathematical model between the coating thickness, fluidity and key mix proportion parameters. The proposed mix proportion design method can make the paste all used for coating on the surface of the aggregates to achieve accurate design of mix proportion parameters.

[0027] 3. The present invention uses solid waste-based artificial aggregates to replace natural aggregates, which not only alleviates the shortage of natural aggregates, but also avoids the disadvantage of poor strength of artificial aggregates, and broadens the application range of solid waste-based artificial aggregates. Description of the Drawings

[0028] Figure 1 It is a relationship diagram of the coating thickness on the surface of artificial aggregates with three different particle sizes and the fluidity of the paste;

[0029] Figure 2 It is a fitting curve diagram of the relationship between the fluidity of cement paste with different water-binder ratios and the admixture dosage. Detailed Embodiments

[0030] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] In this embodiment, a method for designing the mix proportion of solid waste-based artificial aggregate permeable concrete is provided to accurately design the performance of solid waste-based artificial aggregate permeable concrete, and the method includes the following steps:

[0032] Step 1: Use solid waste raw materials to prepare artificial aggregates with different required morphological parameters.

[0033] Prepare artificial aggregates with controllable morphology and good sphericity from solid waste (such as fly ash, recycled fine powder, slag, lime, and other industrial and construction wastes) through the disk granulation method.

[0034] Step 2: Obtain relevant data of the artificial aggregates, including: apparent density ρ a , dense packing density ρ b , void ratio V under dense packing, and total surface area S a ;

[0035] The sphericity SH of the artificial aggregate is an important index to evaluate the degree to which the particle shape approaches an ideal sphere. The sphericity can be characterized by the ratio of the equivalent sphere diameter to the maximum characteristic length of the particle. Its value range is 0 - 1. The closer it is to 1, the closer the aggregate is to an ideal sphere; conversely, the more irregular the aggregate morphology.

[0036] In this embodiment, artificial aggregates with good sphericity and an aggregate particle size of 4.75 - 9.5 mm are selected for the test. The apparent density ρ of the artificial aggregates is obtained through the graduated cylinder method and the bulk density and void ratio test a实 , dense packing density ρ b实 , void ratio V under dense packing a实 ;

[0037] Based on the artificial aggregate morphology analysis program independently written in Matlab, three-dimensional reconstruction is performed on the digital images of the aggregates obtained by scanning to obtain the surface area S of any aggregate, and the average surface area of the sample aggregates is tested. When it tends to a stable value, the sample aggregates can represent the total sample, and the total surface area S of the total sample a实 is calculated by "average surface area per single particle × total number of particles".

[0038] Step 3: According to the requirements of permeable concrete, determine the design void ratio V using Equation (1) v :

[0039] (1)

[0040] In this embodiment, based on the parameters ρ a实 and ρ b实 obtained in Step 2, substitute them into Equation (1) to calculate the design void ratio V v实 which is 18%.

[0041] Step 4: Use Equation (2) to determine the volume V of the cement paste p ;

[0042] (2)

[0043] Combining the parameters in Step 2 and Step 3, calculate the volume V of the cement paste p实 .

[0044] Step 5: If all the cement paste of the permeable concrete is used to wrap the artificial aggregate, the maximum paste thickness CPT on the surface of the artificial aggregate can be obtained by using Equation (3):

[0045] (3)

[0046] The wrapping thickness CPT is an important index parameter, and its function is to build a bridge between the fluidity of the paste and the mix ratio parameters.

[0047] The wrapping thickness of the artificial aggregate can be obtained through the vibrating table test. The specific steps are as follows: 1. Add a certain mass of silica fume, cement, admixture and water to the mixing pot and stir evenly. 2. Weigh m1 of the artificial aggregate and pour it into the mixer, and mix the aggregate with the cement paste until the paste completely wraps the aggregate. 3. Place the aggregate wrapped with the paste in the sieve; fix the sieve on the vibrating table and let the vibrating table vibrate several times until the cement paste no longer drops. 4. Collect the artificial aggregate wrapped with the paste and weigh its mass m2. The wrapping thickness of the artificial aggregate can be calculated according to Equation (6).

[0048] (6)

[0049] In Equation (6), ρ is the density of the cement paste (g / cm 3 ).

[0050] Furthermore, assuming that all the cement paste of the permeable concrete is used to wrap the artificial aggregate, the maximum wrapping thickness CPT on the surface of the artificial aggregate can be obtained by using Equation (3) 实 .

[0051] Step 6: Based on the maximum paste thickness CPT, use Equation (4) to construct a mathematical relationship model between the paste thickness and the fluidity, so as to obtain the fluidity F p ;

[0052] (4)

[0053] In Equation (4), e and d represent two fitting coefficients.

[0054] Group the artificial aggregates according to the particle size d and the sphericity SH, which can give full play to the advantages of the adjustable morphology of the artificial aggregates. And adjust the aggregate gradation and void ratio V as needed a , the dense packing density ρ b, establish the mathematical relationship between the morphological parameters of the overall aggregate and the performance of the permeable concrete, and achieve precise control of the performance of the permeable concrete.

[0055] In this embodiment, it is necessary to prepare two other groups of artificial aggregates with a relatively high sphericity (≥0.95) and particle sizes of 9.5 - 13.2 mm and 13.2 - 16 mm, and the ratio of the three groups of artificial aggregates is 1:1:1. Measure the total surface area S of the three groups of artificial aggregates respectively a1 、S a2 、S a3 , and the test method is the same as that in step 2. Use the three groups of artificial aggregates to test the wrapping thickness of the artificial aggregates and the fluidity of the paste on the aggregate surface, and fit the test results to obtain formula (4), and the fitting curve is as Figure 1 shown.

[0056] Based on the maximum paste thickness CPT 实 , use the mathematical relationship model of the paste thickness and fluidity constructed by formula (2) to back-calculate the fluidity F of the cement paste that meets the wrapping requirements p实 , and its value is 130 mm.

[0057] The mix ratio parameters calculated in the above steps are shown in Table 1.

[0058] Table 1 shows the calculation process parameters of the artificial aggregate permeable concrete

[0059]

[0060] Step 7: Determine the water-binder ratio w / c according to the strength of the permeable concrete, the type of cement, and the workability of the permeable concrete, where w is the mass of water and c represents the mass of cement;

[0061] In this embodiment, according to the strength of the permeable concrete, the type of cement, and the workability of the permeable concrete, select the water-binder ratio w / c 实 to be 0.30.

[0062] Step 8: Based on the fluidity F p and the water-binder ratio w / c, use formula (5) to construct a mathematical relationship model between the fluidity and the admixture dosage, so as to obtain the admixture dosage :

[0063] (5)

[0064] In formula (5), a and b represent two fitting coefficients, so that w / c and are used as the mix ratio of the artificial aggregate permeable concrete.

[0065] Equation (5) is the fitting result obtained through systematic fluidity tests under the cementitious materials and admixture system used in this experiment. The fitting curve is as shown in Figure 2 . When the cementitious material system is changed, a new fitting model can also be established by the same method. Therefore, when the fluidity of the cement paste is known and the water-binder ratio is fixed, the admixture dosage can be calculated using Equation (5). In this experiment, the cementitious materials were cement: silica fume = 95%: 5%.

[0066] Based on the fluidity F p实 and the water-binder ratio w / c 实 , a mathematical relationship model between the fluidity and the admixture dosage was constructed using Equation (5), and thus the admixture dosage 实 was found to be 1%;

[0067] Furthermore, the theoretical mix proportion of the artificial aggregate pervious concrete obtained by this mix proportion design method is shown in Table 2.

[0068] Table 2 shows the theoretical mix proportion of the artificial aggregate pervious concrete

[0069]

[0070] For the above steps, it is necessary to first determine the dosage of the artificial aggregate, and then, based on the relevant data of the aggregate and the target porosity V v , determine the paste dosage V p . Then, according to the constructed mathematical relationship model, key mix proportion parameters such as the water-binder ratio w / c and the admixture dosage are calculated inversely.

[0071] The compressive strength of the pervious concrete prepared according to the above method reached 10.5 MPa, the permeability coefficient was 3.2 mm / s, the measured porosity was 20.2%, and the deviation of the designed porosity was small, verifying the scientificity and feasibility of the mix proportion design method of the present invention.

Claims

1. A mix proportion design method for solid waste-based artificial aggregate permeable concrete, characterized in that, It includes the following steps: Step 1: Obtain data related to artificial aggregates, including: apparent density ρ a , dense packing density ρ b , void ratio V under dense packing a and total surface area S of artificial aggregates a ; Step 2: Determine the design porosity V according to the requirements of permeable concrete using Equation (1) v :[[]]END]] (1) Step 3: Determine the volume V of the cement paste using Equation (2) p ; (2) Step 4: If all the cement paste of the permeable concrete is used to wrap the artificial aggregate, the maximum paste thickness CPT on the surface of the artificial aggregate is obtained by using Equation (3): (3) Step 5: Based on the maximum paste thickness CPT, use Equation (4) to construct a mathematical relationship model between the paste thickness and the fluidity, so as to obtain the fluidity F p ; (4) In Equation (4), e and d represent two fitting coefficients; Step 6: Determine the water-binder ratio w / c according to the strength of the permeable concrete, the type of cement, and the workability of the permeable concrete, where w is the mass of water and c represents the mass of cement; Step 7: Based on the fluidity F p and the water-binder ratio w / c, use Equation (5) to construct a mathematical relationship model between the fluidity and the admixture dosage, so as to obtain the admixture dosage : (5) In formula (5), a and b represent two fitting coefficients, so that with w / c and serve as the mix proportion of the permeable concrete with artificial aggregates.

2. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program for supporting the processor to execute the mix proportion design method of the artificial aggregate permeable concrete described in Claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is run by the processor, it executes the steps of the mix proportion design method of the artificial aggregate permeable concrete described in Claim 1.

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