Mix proportion design method and production method of steel slag replacement coarse aggregate concrete

Abstract

The application belongs to the technical field of engineering materials, and particularly relates to a mixing ratio design method and a production method of steel slag replacing coarse aggregate concrete. The application comprises the following steps: determining a replacement rate; obtaining a conversion coefficient; obtaining a calculated strength; obtaining a prepared strength; obtaining a measured value of cement compressive strength; determining a value of an aggregate regression coefficient; obtaining a water-cement ratio; determining a unit water consumption; obtaining a cement consumption; determining a sand rate; obtaining a coarse aggregate consumption; obtaining a steel slag consumption; obtaining a stone consumption; and obtaining a mixing ratio. The application can significantly improve the efficiency of determining the consumptions of components, save the test workload, shorten the test period, and reduce the economic cost. While ensuring that the strength of the concrete product meets the use requirements, the application can quickly achieve the purpose of designing the mixing ratio of the steel slag replacing coarse aggregate concrete under the target strength requirement. The calculation steps involved in the application can provide a reference for the programming of intelligent algorithms of related types.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering materials, and in particular relates to a mix ratio design method and a production method of steel slag-substituted coarse aggregate concrete. Background Art

[0002] Steel slag is an impurity separated from the high-temperature melted liquid charge during the steelmaking process after adding fluxes such as limestone, dolomite, and iron ore, along with slag-forming materials. It is rich in elements such as calcium, iron, and silicon. Because many of the chemical components of steel slag are similar to those of cement clinker, it has great potential for resource utilization. Using steel slag as an admixture in concrete not only reduces concrete production costs and cement usage, but also addresses the environmental pollution issues associated with steel slag.

[0003] Currently, the development and application of steel slag concrete materials involves processing various types of steel slag, based on strict classification management, classified treatment, and graded processing, into steel slag fine powder according to the requirements of high-performance concrete and the different characteristics of each type of steel slag. This is then used to develop steel slag concrete and its finished products. This is disclosed in patent documents such as Chinese Patent Publication No. "CN112851264A," entitled "A High-Temperature Resistant Concrete Based on Iron Tailings and Steel Slag Powder," and Chinese Patent Publication No. "CN101774223B," entitled "A Method for Preparing Steel Fiber Rubber Steel Slag Recycled Aggregate Concrete." As can be seen, existing innovations in the application of steel slag in concrete have mostly focused on the use of steel slag powder as an admixture in concrete, while research on the use of steel slag aggregate as coarse aggregate in concrete and the mix design of concrete using steel slag as a coarse aggregate in concrete is still lacking. The reasons for this are, firstly, the current assessment method for concrete strength at different steel slag coarse aggregate replacement rates is unclear, making it difficult to convert the strength of coarse aggregate using steel slag, thus hindering its application in actual projects; secondly, there is a lack of a clear design process for coarse aggregate concrete using steel slag, which brings difficulties to actual production and application; thirdly, there is a lack of preparation process and method for coarse aggregate concrete using steel slag, resulting in a lack of relevant process for the preparation of coarse aggregate concrete using steel slag, making it difficult to realize the industrial production of coarse aggregate concrete using steel slag. Therefore, this problem needs to be solved urgently. Summary of the Invention

[0004] The purpose of the present application is to overcome the deficiencies of the prior art, provide a mix proportion design method of steel slag replacing coarse aggregate concrete, the present application can significantly improve the efficiency of determining the amount of each component, save the test workload, shorten the test period, reduce the economic cost, while ensuring that the strength of the concrete product meets the use requirements, the mix proportion design purpose of steel slag replacing coarse aggregate concrete under the target strength requirement can be quickly realized; at the same time, the calculation steps involved in the present application can provide reference for intelligent algorithm programming of concrete expert analysis and support system, proportioning design software and the like.

[0005] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0006] A mix proportion design method of steel slag replacing coarse aggregate concrete, characterized in that it comprises the following steps:

[0007] S1. Determine the replacement rate m of steel slag replacing coarse aggregate;

[0008] S2. Obtain the conversion coefficient ξ of steel slag replacing coarse aggregate concrete and ordinary concrete from the following formula s :

[0009] ξ s = 0.2518m-0.0215;

[0010] S3. Obtain the calculated strength f of steel slag replacing coarse aggregate concrete from the following formula cu,sk :

[0011] f cu,sk =(1-ξ s )f cu,s ;

[0012] Wherein:

[0013] f cu,s is the standard value of the compressive strength of the target concrete;

[0014] S4. Obtain the preparation strength f of steel slag replacing coarse aggregate concrete from the following formula cu,so :

[0015] f cu,so =f cu,sk +tM;

[0016] Wherein:

[0017] t takes 1.645;

[0018] M is the standard deviation of the target concrete strength;

[0019] S5. Obtain the measured value f of the compressive strength of cement from the following formula ce :

[0020] fce =γ c ·f ce,k ;

[0021] in:

[0022] γ c is the redundancy factor of cement strength value;

[0023] f ce，k is the cement strength grade value;

[0024] S6. Determine the aggregate regression coefficient α A and α B The value of

[0025] S7. The water-cement ratio (W / C) of concrete with steel slag replacing coarse aggregate is obtained from the following formula:

[0026]

[0027] S8. Determine the unit water consumption W0;

[0028] S9. The cement dosage C0 is obtained by the following formula:

[0029]

[0030] S10. Determine the sand ratio;

[0031] S11. Obtain the amount of coarse aggregate from the following formula:

[0032]

[0033] in:

[0034] S0 is the amount of sand used;

[0035] G0 is the amount of coarse aggregate;

[0036] ρ c is the cement density;

[0037] ρ m is the density of water;

[0038] ρ 0S is the apparent density of sand;

[0039] ρ 0G is the apparent density of coarse aggregate;

[0040] α is the percentage of air content in concrete;

[0041] S P is the sand ratio;

[0042] S12. The slag dosage Z1 is obtained by the following formula:

[0043] Z1=G0·m;

[0044] S13. Obtain the stone dosage Z2 by the following formula:

[0045] Z2=G0·(1-m);

[0046] S14. It can be seen that the mix ratio of concrete with steel slag replacing coarse aggregate is:

[0047] C0:W0:S0:Z1:Z2.

[0048] Preferably, in step S4, t=1.645.

[0049] Preferably, in step S6, when the coarse aggregate is crushed stone, α A =0.46,α B =0.07; when the coarse aggregate is pebbles, α A =0.48,α B =0.33.

[0050] Preferably, in step S11, when no air-entraining admixture is used, α=1.

[0051] Preferably, a production method, which applies the mix ratio design method of replacing coarse aggregate concrete with steel slag, is characterized in that:

[0052] Sa according to the slag to replace the coarse aggregate concrete mix ratio, determine the weight of cement, water, slag, sand and gravel required for preparing concrete;

[0053] Sb. Weigh the materials according to the required weight and add cement, steel slag, sand, and gravel to the mixer in sequence and stir for 2 to 3 minutes;

[0054] Sc. After the materials are evenly mixed, add mixing water and water reducer, and continue stirring for 3 to 5 minutes to form a slurry; wait until the slurry is completely fluidized in the mixer to obtain the required slurry for replacing coarse aggregate concrete with steel slag.

[0055] Preferably, the cement is ordinary Portland cement with a grade of PO 42.5.

[0056] Preferably, the steel slag is converter slag produced by a hot stuffing process, and the steel slag particles have a particle size of 5 to 10 mm and 10 to 20 mm after being selected by a mechanical screening method, and the flaky particles are removed; the converter slag uses old slag that has been piled for more than one year, with a crushing value of no more than 30%, a free calcium oxide content of no more than 3%, a mud content of no more than 0.5%, and a water absorption rate of no more than 1%.

[0057] Preferably, the sand is ordinary medium sand with a fineness modulus of 2.3 to 3.0.

[0058] Preferably, the stone is 5-20 mm continuously graded limestone, with a mud content of no more than 0.5% and a water absorption rate of no more than 1%.

[0059] Preferably, the mixing water is neutral natural water; the water reducer is a polycarboxylic acid high-efficiency water reducer, and the water reduction rate is not less than 30%.

[0060] The beneficial effects of the present invention are:

[0061] 1) Through the above scheme, the present invention not only proposes a simplified calculation method for the compressive strength of concrete under different steel slag coarse aggregate replacement rates, and realizes the rapid prediction of the compressive strength of concrete with steel slag replaced with coarse aggregate; it also solves the mix ratio design problem of concrete with steel slag replaced with coarse aggregate under target strength requirements, and realizes the specific application design of concrete with steel slag replaced with coarse aggregate.

[0062] In actual operation, the technical solution of the present invention consists of two parts: a strength conversion formula and a mix ratio design calculation. For the strength conversion formula, the conversion coefficient is calculated by the replacement rate of steel slag replacing coarse aggregate. Then, based on the conversion coefficient, the design strength of the concrete with steel slag replacing coarse aggregate is converted into the calculated strength, and then the calculated strength is converted into the mix strength. For the mix ratio design calculation part, the design is carried out based on the calculated mix strength to obtain the mix ratio of the concrete with steel slag replacing coarse aggregate, that is, the ratio of water, cement, sand, gravel, and steel slag. This ratio can then be used to accurately and quickly determine the component amounts of water, cement, sand, gravel, and steel slag without the need for experiments or a small amount of verification experiments.

[0063] Thus, the present invention can significantly improve the efficiency of determining the dosage of each component, save experimental workload, shorten the test cycle, and reduce economic costs. While ensuring that the strength of the finished concrete product meets the use requirements, it can quickly achieve the purpose of designing the mix ratio of steel slag replacing coarse aggregate concrete under the target strength requirements.

[0064] At the same time, the calculation steps involved in the present invention can provide a reference for the compilation of intelligent algorithms such as concrete expert analysis and support systems and mix design software.

[0065] 2) Furthermore, based on the above scheme, the present invention also provides a production method to clarify the specific preparation process of steel slag replacing coarse aggregate concrete, providing a basic guarantee for the production and manufacturing of steel slag replacing coarse aggregate concrete. DETAILED DESCRIPTION

[0066] For ease of understanding, the specific structure and working mode of the present invention are further described below:

[0067] In the process of relevant mix design, firstly, the design strength of the steel slag replacing coarse aggregate concrete which needs to be prepared is determined, the design strength is converted into calculation strength according to the strength conversion formula of the steel slag replacing coarse aggregate concrete and the ordinary concrete provided in the application. Secondly, the calculation strength of the steel slag replacing coarse aggregate concrete is converted into preparation strength by using the formula considering the strength guarantee rate requirement of the concrete. Finally, the parameters such as the measured value of the cement compressive strength, the aggregate regression coefficient, the water-cement ratio, the unit water consumption, the sand ratio, the sand consumption, the stone consumption and the steel slag consumption are determined in turn according to the specification requirements and the test data. The value of the aggregate regression coefficient can be set by reference according to the shape and performance of the aggregate, and the unit water consumption can be set by reference according to the type of the coarse aggregate, the maximum particle size and the design requirement of the slump value.

[0068] In order to further explain the application, the steel slag replacing coarse aggregate concrete with the preparation strength grade of C50 is taken as an example to carry out the mix design of the steel slag replacing coarse aggregate concrete, so as to demonstrate the specific embodiment of the application.

[0069] Example 1

[0070] Target concrete: the steel slag replacing coarse aggregate concrete test piece with the design strength grade of C50 is prepared, the strength guarantee rate is required to be 95%, the construction requires the slump of 35mm-50mm, and the mechanical stirring and mechanical vibration are adopted.

[0071] The material specifications adopted are as follows:

[0072] Cement: ordinary portland cement, the strength grade is 42.5, the cement density is 3.00g / cm 3 , and the cement surplus coefficient is 1.08;

[0073] Sand: river sand, the gradation is qualified, the apparent density is 2650kg / m 3 , and the water content is 1%;

[0074] Stone: gravel, the particle size is 5mm-20mm, the gradation is qualified, and the apparent density is 2700kg / m 3 ;

[0075] Water: tap water.

[0076] At this time:

[0077] According to the concrete strength grade of C50, the standard value of the compressive strength of the target concrete f cu,s is 50MPa;

[0078] According to the strength guarantee rate of 95%, t=1.645;

[0079] According to the cement strength grade of 42.5, f ce,k=42.5MPa;

[0080] Since the cement surplus coefficient is 1.08, we know that γ c =1.08;

[0081] The density of cement is 3.00g / cm 3 , we know that ρ c =3.00g / cm 3 ;

[0082] The apparent density of sand is 2650kg / m 3 , we know that ρ 0S =2.65g / cm 3 ;

[0083] The apparent density of the stone is 2700kg / m 3 , we know that ρ 0G =2.7g / cm 3 ;

[0084] Density of water ρ m =1g / cm 3 ;

[0085] When the coarse aggregate is stone and the stone is crushed stone, α A =0.46,α B =0.07.

[0086] The specific steps are as follows:

[0087] S1. Determine the replacement rate of steel slag for coarse aggregate m = 0.4;

[0088] S2 is obtained by the following formula to obtain the conversion coefficient ξ of steel slag replacing coarse aggregate concrete and ordinary concrete s :

[0089] ξ s =0.2518m-0.0215=0.2518×0.4-0.0215=0.0792;

[0090] S3. The calculated strength f of concrete with steel slag replacing coarse aggregate is obtained from the following formula: cu,sk :

[0091] f cu,sk =(1-ξ s )f cu,s =(1-0.0792)×50=46.04MPa;

[0092] S4. The strength of concrete prepared by replacing coarse aggregate with steel slag is obtained as follows: cu,so :

[0093] f cu,so =fcu,sk +tM=46.04+1.645×6=55.91MPa;

[0094] in:

[0095] M is the standard deviation of target concrete strength, which is taken as 6MPa according to the target concrete strength table;

[0096] S5. The measured value of cement compressive strength f is obtained from the following formula ce :

[0097] f ce =γ c ·f ce,k =1.08×42.5=45.9MPa;

[0098] S6. Determine the aggregate regression coefficient α A and α B The value of

[0099] When replacing the coarse aggregate here, the steel slag replaces the crushed stone, so the relevant aggregate regression coefficient is taken according to the crushed stone; As mentioned above, when the coarse aggregate is crushed stone, α A and α B They are 0.46 and 0.07 respectively.

[0100] S7. The water-cement ratio (W / C) of concrete with steel slag replacing coarse aggregate is obtained from the following formula:

[0101]

[0102] S8. Determine the unit water consumption W0; based on the concrete slump and Vebe consistency and the maximum particle size of the gravel and other indicators obtained by looking up the table, take W0 = 185kg;

[0103] S9. The cement dosage C0 is obtained by the following formula:

[0104]

[0105] S10. Determine the sand ratio S P , according to the water-cement ratio and the maximum particle size of pebbles and gravel, the sand rate S is obtained by looking up the table. P Take 35%;

[0106] S11. Obtain the amount of coarse aggregate from the following formula:

[0107]

[0108] When no air-entraining admixture is added, α is set to 1;

[0109] At this point, we know:

[0110]

[0111] So: S0 = 598 kg, G0 = 1111 kg;

[0112] S12. The slag dosage Z1 is obtained by the following formula:

[0113] Z1=G0·m=1111×0.4=444.5kg;

[0114] S13. Obtain the stone dosage Z2 by the following formula:

[0115] Z2=G0·(1-m)=1121×(1-0.4)=666.5kg.

[0116] Integrating the above values, it can be seen that the mix ratio of concrete with steel slag replacing coarse aggregate is: C0:W0:S0:Z1:Z2=1:0.37:1.19:0.88:1.33.

[0117] On the basis of the above-mentioned Example 1, the value of the steel slag replacement rate m is changed, and the calculations of Examples 2, 3, 4, 5, 6 and 7 are performed to obtain the actual amount of each component of the coarse aggregate concrete replaced by the corresponding steel slag.

[0118] The final mix ratios of the steel slag-replaced coarse aggregate concrete of Examples 1 to 7 and the amounts of each component are shown in Table 1:

[0119] Table 1

[0120]

[0121] The components in the above-mentioned embodiments were used in the preparation method of the present invention to prepare slurries. The slurries were used to prepare test blocks according to the method specified in GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Concrete". After curing for 28 days, the compressive strength of the prepared steel slag replaced coarse aggregate concrete test blocks was tested. The compressive strength test values ​​of the steel slag replaced coarse aggregate concrete test blocks obtained by using the components in the amounts of Examples 1 to 7 are shown in Table 2:

[0122] Table 2

[0123]

[0124]

[0125] Through the compressive strength test, it can be concluded that the strength of the concrete samples obtained by replacing the coarse aggregate concrete with the steel slag obtained by the present invention is greater than or equal to the target value, that is, it meets the use requirements.

[0126] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, but also encompasses the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that fall within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0127] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0128] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A mix design method for concrete with steel slag replacing coarse aggregate, characterized in that The following steps are involved: S1. Determine the replacement rate m of slag for coarse aggregate; S2 is obtained by the following formula to obtain the conversion coefficient ξ of steel slag replacing coarse aggregate concrete and ordinary concrete s : x s =0.2518m-0.0215; S3. The calculated strength f of concrete with steel slag replacing coarse aggregate is obtained from the following formula: cu,sk : f cu,sk =(1-ξ s )f cu,s ; in: f cu,s is the standard value of compressive strength of target concrete; S4. The strength of concrete prepared by replacing coarse aggregate with steel slag is obtained as follows: cu,so : f cu,so =f cu,sk +tM; in: t is 1.645; M is the standard deviation of target concrete strength; S5. The measured value of cement compressive strength f is obtained from the following formula ce : f ce =c c ·f ce,k ; in: γ c is the redundancy factor of cement strength value; f ce，k is the cement strength grade value; S6. Determine the aggregate regression coefficient α A and α B The value of S7. The water-cement ratio (W / C) of concrete with steel slag replacing coarse aggregate is obtained from the following formula: S8. Determine the unit water consumption W0; S9. The cement dosage C0 is obtained by the following formula: S10. Determine the sand ratio S P ; S11. Obtain the amount of coarse aggregate from the following formula: in: S0 is the amount of sand used; G0 is the amount of coarse aggregate; ρ c is the cement density; ρ m is the density of water; ρ 0S is the apparent density of sand; ρ 0G is the apparent density of coarse aggregate; α is the percentage of air content in concrete; S P is the sand ratio; S12. The slag dosage Z1 is obtained by the following formula: Z1=G0·m; S13. Obtain the stone dosage Z2 by the following formula: Z2=G0·(1-m); S14. It can be seen that the mix ratio of concrete with steel slag replacing coarse aggregate is: C0:W0:S0:Z1:Z2.

2. The mix design method for concrete using steel slag instead of coarse aggregate according to claim 1, characterized in that: In step S6, when the coarse aggregate is crushed stone, α A =0.46,α B =0.07; when the coarse aggregate is pebbles, α A =0.48,α B =0.

33.

3. The mix design method for concrete using steel slag instead of coarse aggregate according to claim 1, characterized in that: In the step S11, when no air-entraining admixture is used, α=1.

4. A production method, which uses the mix design method for steel slag-replacing coarse aggregate concrete as described in claim 1, 2, or 3, characterized in that: Sa according to the slag to replace the coarse aggregate concrete mix ratio, determine the weight of cement, water, slag, sand and gravel required for preparing concrete; Sb. Weigh the materials according to the required weight and add cement, steel slag, sand, and gravel to the mixer in sequence and stir for 2 to 3 minutes; Sc. After the materials are evenly mixed, add mixing water and water reducer, and continue stirring for 3 to 5 minutes to form a slurry; wait until the slurry is completely fluidized in the mixer to obtain the required slurry for replacing coarse aggregate concrete with steel slag.

5. The production method according to claim 4, characterized in that: The cement is ordinary Portland cement with a grade of PO 42.

5.

6. The production method according to claim 4, characterized in that: The steel slag is converter slag produced by a hot stuffing process, and the steel slag particles with particle sizes of 5 to 10 mm and 10 to 20 mm are selected by mechanical screening, and flaky particles are removed; the converter slag is old slag that has been piled up for more than one year, with a crushing value of no more than 30%, a free calcium oxide content of no more than 3%, a mud content of no more than 0.5%, and a water absorption rate of no more than 1%.

7. The production method according to claim 4, characterized in that: The sand is ordinary medium sand with a fineness modulus of 2.3 to 3.

0.

8. The production method according to claim 4, characterized in that: The stone is limestone with a continuous gradation of 5 to 20 mm, a mud content of no more than 0.5%, and a water absorption rate of no more than 1%.

9. The production method according to claim 4, characterized in that: The mixing water is neutral natural water; the water reducer is a polycarboxylic acid high-efficiency water reducer, and the water reduction rate is not less than 30%.

Images