Inactive admixture concrete and mix proportion design method thereof

Abstract

The invention discloses inactive admixture concrete and a mix proportion design method thereof. The method comprises the following steps: collecting machine-made sand tail powder in a dry machine-made sand processing process and measuring performance indexes; the method comprises the following steps: determining the total gelling dosage mj and the dosage mc of each component and a water reducing agent according to the requirements of a structural part on the strength, workability and workability of concrete; correcting and determining the actual water consumption mw based on the slump height required by the construction drawing and the dry water absorption rate of the saturated surface of the machine-made sand tailing powder, and calculating the water-binder ratio w / b; calculating the dosage of coarse and fine aggregates according to a mass method; determining the compressive strength fce of 28-day standard curing mortar according to the cement strength grade fce, g and the surplus coefficient gamma c; calculating the compressive strength fb of the mortar in 28 days according to the influence coefficient of the tail powder; calculating the concrete configuration strength fcu, 0 and the concrete cube compressive strength fcu, k according to the concrete water-binder ratio and the gravel coefficients alpha a and alpha b; and rechecking to obtain the actual required mix proportion. The method has the beneficial effects that the problem of tail powder waste is solved, the concrete performance is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to an inactive admixture concrete and a mix ratio design method thereof. Background Art

[0002] At present, with the vigorous development of infrastructure construction, the constraints of natural sand and gravel resources are tightening and environmental protection is increasingly strengthened, and machine-made sand and gravel have gradually become the main source of sand and gravel for construction. Compared with traditional wet sand making, dry sand making technology is not restricted by water sources and sites, and has the characteristics of high production efficiency and low use cost. However, a large amount of tailing powder will inevitably be produced during the production of machine-made sand and gravel aggregates. It has the characteristics of small particle size and strong adsorption. Whether it can be used in concrete is mainly determined by the methylene blue value (MBV) ≤ 1.4, resulting in the continuous accumulation of some tailing powder (MBV>1.4) during production and processing, which is regarded as waste landfill treatment, not only occupying land resources, but also causing serious damage to the environment. In order to implement the requirements of sustainable development and alleviate ecological pressure, studying the application technology of machine-made sand tailing powder as an inactive admixture in cement concrete is an effective way to develop green concrete and reduce costs and increase efficiency.

[0003] Therefore, it is urgent to provide a non-active admixture concrete and its mix design method that can effectively solve the utilization of tail powder, increase the technical application in concrete engineering, and improve the comprehensive utilization rate. Summary of the invention

[0004] In view of the shortcomings of the prior art mentioned above, the purpose of this application is to provide a concrete mix design method for inactive admixtures, which can effectively solve the problems in the background technology, select a dry production process, use tail powder to replace part of the cement or active admixtures, reduce the cost of concrete use, and improve working performance.

[0005] To achieve the above-mentioned and other related purposes, the present application provides a method for designing a concrete mix ratio of an inactive admixture, which is characterized by comprising:

[0006] Collecting the machine-made sand tailings generated at each dust removal point during the dry-process machine-made sand processing, and measuring the performance indicators of the machine-made sand tailings; the performance indicators include the saturated surface dry water absorption rate, MB value, specific surface area and / or activity index of the machine-made sand tailings;

[0007] According to the requirements of the structural parts for the strength and workability of concrete, the total cementitious amount of cementitious materials is determined. j Then, according to the proportion of cement, fly ash, slag powder, machine-made sand tailings, and water reducer, the cement dosage m is calculated. s , fly ash dosage m f , Slag powder dosage m k , Amount of machine-made sand tailings m eAnd the amount of water reducing agent m c ; The cementitious materials include cement, fly ash, slag powder, and machine-made sand tailings;

[0008] Based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w , and calculate the concrete water-binder ratio w / b:

[0009]

[0010] In the formula, m w The actual water consumption of concrete, unit: kg / m 3 ;

[0011] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0012] Calculate the amount of coarse aggregate m according to the mass method g0 and fine aggregate m s0 Dosage;

[0013] According to cement strength grade f ce,g and the surplus coefficient γ c Determine the compressive strength f of the mortar after 28 days of cement curing ce , unit: MPa:

[0014] f ce =γ c ×f ce,g (2);

[0015] According to the fly ash influence coefficient γ f , mineral powder influence coefficient γ s , tail powder influence coefficient γ h , calculate the compressive strength f of the cementitious material after curing for 28 days b , unit: MPa:

[0016] f b =γ f ×γ s ×γ h ×f ce (3);

[0017] According to the concrete water-binder ratio w / b, select the crushed stone coefficient α a , α b , calculate the concrete configuration strength f cu,0 and the concrete cube compressive strength f cu,k :

[0018]

[0019] f cu,k =f cu,0 γ qN (5);

[0020] In the formula, γ qN is the influence coefficient of maintenance N days, where N is the number of maintenance days;

[0021] According to the strength requirements of the project, the mix ratio corresponding to the mechanical properties is selected, and the accurate total cementitious dosage and the amount of machine-made sand tailings are calculated by interpolation method, and the actual required mix ratio is obtained through re-testing.

[0022] As the preferred embodiment of the present application, the performance index also includes the water demand ratio and the standard consistency water consumption of the machine-made sand tailing powder. The content of clay minerals in the tailing powder can be judged by the MB value. Since the expansive clay minerals have a very large specific surface area, it is easy to adsorb methylene blue dye. The methylene blue value is proportional to the product of the clay content multiplied by the clay specific surface, that is, the larger the methylene blue value, the higher the clay content, and the water consumption and admixture dosage required for mixing concrete are also increased. The specific surface area and water demand ratio determination can also reflect from the side that the tailing powder particles with larger specific surface area have higher reactivity and adsorption capacity, which means that they usually need to add more water or admixture to improve fluidity. The activity index refers to the GB / T1596-2017 specification, and the machine-made sand tailing powder is used to replace fly ash for testing, which can be used to evaluate the active degree of the machine-made sand tailing powder participating in the hydration reaction, and indirectly reflect its strength development law. By measuring the saturated surface dry water absorption rate, the adsorption performance of the machine-made sand tailing powder to water is understood, and the appropriate water-cement ratio of concrete is ensured to ensure the workability and strength durability of the concrete.

[0023] As the preferred embodiment of this application, the cement dosage m is calculated. s , fly ash dosage m f , Slag powder dosage m k , Amount of machine-made sand tailings m e , water reducing agent dosage m c Follow the following formula:

[0024] m s =β s ×m j (6);

[0025] m f =β f ×m j (7);

[0026] m k =β k ×m j (8);

[0027] me =β w ×m j (9);

[0028] m c =β c ×m j (10);

[0029] In the formula, m s The amount of cement in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0030] m f The amount of fly ash in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0031] m k The amount of slag powder used in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0032] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0033] m c The amount of water reducing agent in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0034] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0035] β s Cement content per cubic meter of concrete mixture, %;

[0036] β f is the fly ash content in each cubic meter of concrete mixture, %;

[0037] β k is the amount of slag powder in each cubic meter of concrete mixture, %;

[0038] β c is the amount of water reducing agent in each cubic meter of concrete mixture, %;

[0039] β w It is the proportion of machine-made sand tailings in each cubic meter of concrete mixture, %.

[0040] As a preferred embodiment of the present application, the mixing ratio of cement, fly ash and slag powder in the cementitious material is 5:3:2.

[0041] As the preferred embodiment of this application, based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w Steps include:

[0042] Based on the slump height required by the construction drawings, determine the amount of water required for concrete m w0 :

[0043] m w0 =m' w0 ×(1-β) (11);

[0044] In the formula, m' w0 The amount of water required for each cubic meter of concrete with a slump of 160 mm, in kg / m 3 ;

[0045] β is the water reduction rate of the water reducing agent, %;

[0046] According to the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w , calculate the water-binder ratio w / b:

[0047] m w =m w0 -m e ×γ w ×δ (12);

[0048]

[0049] In the formula, m w0 To determine the amount of water required for concrete based on the slump height required by the construction drawings, in kg / m 3 ;

[0050] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0051] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0052] γ w is the saturated surface dry water absorption rate of machine-made sand tailings, %;

[0053] δ is the reduction factor;

[0054] As a preferred embodiment of the present application, the dosage of the machine-made sand tailings is 10-20%.

[0055] As the preferred embodiment of this application, when the dosage of machine-made sand tailings is 0-10%, the influence coefficient γ of curing for 28 days is q28 Take 1.05~1.12, the influence coefficient of curing for 90 days γ q90 Take 1.20~1.27;

[0056] When the dosage of machine-made sand tailings is between 20% and 30%, the influence coefficient γ q28 Take 0.94~1.02, the influence coefficient of curing for 90 days γ q90 Take 1.14~1.20.

[0057] As a preferred embodiment of the present application, the mass method is based on the mass of each cubic meter of concrete mixture being equal to the sum of the masses of the constituent materials. The amount of coarse aggregate and fine aggregate can be calculated according to the following set of equations:

[0058] m s +m f +m k +m e =m j (14);

[0059] m j + m g0 + m s0 + m w =m cp (15);

[0060] m s0 =(m cp -m j -m w )×β ss (16);

[0061] m g0 =(m cp -m b0 -m w )×(1-β ss ) (17);

[0062]

[0063] Among them, m cp is the assumed mass of concrete mixture per cubic meter, in kg / m 3 ;

[0064] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0065] m s The amount of cement per cubic meter of concrete mixture, in kg / m3 ;

[0066] m f The amount of fly ash in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0067] m k The amount of mineral powder in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0068] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, in kg / m 3 ;

[0069] m w The amount of water in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0070] m s0 The amount of fine aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0071] m g0 The amount of coarse aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0072] β ss is the sand ratio of concrete mixture, %.

[0073] The present application also provides an inactive admixture concrete prepared according to the inactive admixture concrete mix design method, characterized in that the inactive admixture concrete contains the following raw materials: cementitious material, coarse aggregate, fine aggregate, water reducer and water, the cementitious material is composed of the following components in the following mass ratios: 90 to 250 parts of cement, 54 to 150 parts of fly ash, 36 to 100 parts of slag powder, and 30 to 200 parts of machine-made sand tailings; the amounts of coarse aggregate and fine aggregate are calculated according to the mass method; the solid-reducing dosage of the water reducer is 0.5 to 3% of the amount of the cementitious material; the amount of water is the actual amount of water used after removing the water adsorbed by the machine-made sand tailings on the basis of the water amount of the high-fluidity concrete determined by the concrete slump requirement.

[0074] As a preferred embodiment of the present application, the amount of the gelling material is 300 kg / m 3 、350kg / m 3 , 400kg / m 3 , 450kg / m 3 or 500kg / m 3 .

[0075] As a preferred embodiment of the present application, the machine-made sand tailings are made of diabase, tuff or basalt.

[0076] As a preferred embodiment of the present application, the amount of machine-made sand tailings is 10 to 30% of the total gelling amount.

[0077] As a preferred embodiment of the present application, the particle size of the machine-made sand tailing powder does not exceed 0.075 mm; the saturated surface dry water absorption rate of the machine-made sand tailing powder is greater than 20%, the water demand ratio is greater than 100%, and the specific surface area is greater than 300 cm 2 / g, fluidity ratio <90%, standard consistency water consumption >120mL, MB value ≤6.00g / kg; silicon dioxide content in machine-made sand tailings >45%, alumina content in machine-made sand tailings >10%, 28-day activity index >55%.

[0078] As a preferred embodiment of the present application, the cementitious material includes fixed cement, fly ash, mineral powder, and machine-made sand tailings, wherein the mixing ratio of the cement, fly ash, and mineral powder is 5:3:2.

[0079] As a preference of the present application, the fine aggregate is artificial sand (also known as machine-made sand) with a fineness modulus of 2.5 to 3.0.

[0080] As a preferred embodiment of the present application, the coarse aggregate is continuously graded crushed stone with a particle size range of 5 to 31.5 mm.

[0081] As a preference of the present application, the cement is PO 42.5 ordinary silicate or silicate cement.

[0082] As a preferred embodiment of the present application, the fly ash is selected from Class F II fly ash, with a water requirement ratio of ≤105% and a fineness of ≤30%.

[0083] As a preferred embodiment of the present application, the slag powder is S95 grade slag powder, with a 28-day activity index ≥95% and a fluidity ratio ≥95%.

[0084] As a preferred embodiment of the present application, the dosage of the admixture is 1.2% of the amount of machine-made sand tailings incorporated into the cementitious material.

[0085] As a preferred embodiment of the present application, the amount of the gelling material is 300 kg / m 3 、350kg / m 3 , 400kg / m 3 , 450kg / m 3 or 500kg / m 3 ; The sand rate β ss Adjust according to the amount of cementitious materials, including:

[0086] When the total gelling amount m j =300kg / m 3When the sand rate β ss 44%

[0087] When the total gelling amount m j =350kg / m 3 When the sand rate β ss 43%

[0088] When the total gelling amount m j =400kg / m 3 When the sand rate β ss 41%

[0089] When the total gelling amount m j =450kg / m 3 When the sand rate β ss 40%;

[0090] When the total gelling amount m j =500kg / m 3 When the sand rate β ss It is 39%.

[0091] As the preferred embodiment of this application, m cp The value is 2380kg / m 3 .

[0092] As a preferred embodiment of the present application, the solid content of the water reducing agent is 1.3% of the amount of the cementitious material.

[0093] This application uses dry-process machine-made sand processing, which requires crushing the sand and gravel raw materials to produce machine-made sand tailings, which escape into the environment at various dust removal points. In traditional processes, these fine powders are basically useless as by-products of machine-made sand processing, which not only causes waste of resources but also leads to a bad environment. This application will use a dust removal system to set up dust removal points at the crushing outlet, screening machine and other places where dust is easily generated, and use the blower to centrally recover the machine-made sand tailings with a particle size of less than 0.075 mm. The machine-made sand tailings recovered by the pulse induced draft dust removal system mostly contain fine clay particles, which have the characteristics of small particle size and strong adsorption. They can be used as an inactive admixture to replace part of the cement or active admixture in concrete, reduce production costs, and improve the workability of concrete.

[0094] Compared with the prior art, the beneficial effects of this application are:

[0095] 1. The present invention uses dry-process machine-made sand tailings as admixtures, which can realize resource recycling and reduce the cost of concrete production. Through experiments, it is found that the machine-made sand tailings have certain volcanic ash activity and filling benefits, and can be used as a concrete supplementary cementitious material. With the increase of the admixture, the strength is reduced, but it can fully cover the concrete with different strength requirements.

[0096] 2. The mechanical properties of the concrete prepared by adding 10% to 20% tailings to replace the cementitious material are basically the same, and the workability is also improved. Based on this, the present invention adopts dry-process machine-made sand tailings as concrete admixtures, and by adjusting the blending ratio with fly ash mineral powder, the prepared cementitious material can have higher volcanic ash activity, thereby ensuring the mechanical properties and durability of the concrete.

[0097] 3. This application utilizes the tailings of dry-process machine-made sand production as an admixture, which can replace part of the cement and active admixtures while realizing the utilization of various solid waste resources, thereby reducing the cost of raw materials and improving the working performance of concrete, and has a strong value for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 It is a flow chart of the mix ratio design method of the present invention;

[0099] Figure 2 The present invention is 300kg / m 3 The amount of cementitious materials used to prepare the compressive strength of concrete;

[0100] Figure 3 The present invention is 350kg / m 3 The amount of cementitious materials used to prepare the compressive strength of concrete;

[0101] Figure 4 The present invention is 400kg / m 3 The amount of cementitious materials used to prepare the compressive strength of concrete;

[0102] Figure 5 The present invention is 450kg / m 3 The amount of cementitious materials used to prepare the compressive strength of concrete;

[0103] Figure 6 The present invention is 500kg / m 3 The amount of cementitious material used to prepare the compressive strength of concrete. DETAILED DESCRIPTION

[0104] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application.

[0105] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0106] In addition, it should be understood that one or more method steps mentioned in this application do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in this application does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of implementation of this application. Changes or adjustments in their relative relationships shall also be regarded as the scope of implementation of this application without substantial changes in the technical content.

[0107] The present application provides a method for designing a concrete mix ratio of an inactive admixture, comprising:

[0108] S1 collects the machine-made sand tailings produced at each dust removal point in the dry process of machine-made sand processing and whose particle size does not exceed 0.075 mm, and determines the performance index of the machine-made sand tailings; the performance index includes the saturated surface dry water absorption rate, MB value, specific surface area and / or activity index of the machine-made sand tailings;

[0109] The particle size of the machine-made sand tailing powder does not exceed 0.075 mm; the saturated surface dry water absorption rate of the machine-made sand tailing powder is greater than 20%, the water demand ratio is greater than 100%, and the specific surface area is greater than 300 cm 2 / g, fluidity ratio <90%, standard consistency water consumption >120mL, MB value ≤6.00g / kg; silicon dioxide content in machine-made sand tailings >45%, alumina content in machine-made sand tailings >10%, 28-day activity index >55%.

[0110] Specifically, the machine-made sand tailings in the embodiments of the present application can be made of diabase (HLY) in Huzhou, Zhejiang Province, tuff (NHY) in Jingning, and basalt (XWY) in Lishui.

[0111] The saturated surface dry water absorption rates of the three machine-made sand tailings are 22.7% (HLY), 20.0% (NHY), and 23.2% (XWY).

[0112] The water demand ratios of the three machine-made sand tailings are 107.3% (HLY), 103.4% (NHY), and 105.2% (XWY), respectively.

[0113] The specific surface areas of the three machine-made sand tailings are 447 cm2 / g (HLY), 384 cm2 / g (NHY), and 311 cm2 / g (XWY), respectively.

[0114] The activity indexes of the three machine-made sand tailings were 61.1% (HLY), 62.8% (NHY), and 57.8% (XWY), respectively.

[0115] The methylene blue values ​​(also known as MB values) of the three machine-made sand tailings are 3.25 g / kg (HLY), 1.50 g / kg (NHY), and 6.00 g / kg (XWY), respectively.

[0116] The chemical composition of the three machine-made sand tailings is mainly composed of silicon dioxide SiO 2 、Alumina Al 2 O 3 , calcium oxide CaO and iron oxide Fe 2 O 3 Composition, among which volcanic ash active oxide (SiO 2 +A1 2 O 3 ) can react with Ca(OH) 2 The reaction generates calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH), which provide support for the later strength growth. The specific content is shown in Table 1.

[0117] Table 1 Chemical composition of machine-made sand tailings

[0118] Sample type <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> CaO <![CDATA[Fe 2 THE 3 ]]> <![CDATA[K 2 The]]> <![CDATA[Na 2 The]]> MgO <![CDATA[TiO 2 ]]> Diabase 55.03 15.66 9.99 8.75 4.79 2.03 1.78 1.2 tuff 68.98 11.91 3.73 4.37 6.74 2.55 0.72 0.47 Basalt 45.75 12.12 11.25 20.17 2.24 1.79 4.25 2.44

[0119] S2 Determine the total cementitious amount of cementitious materials m according to the requirements of the structural parts for concrete strength and workability. j Then, according to the proportion of cement, fly ash, slag powder, machine-made sand tailings, and water reducer, the cement dosage m is calculated. s , fly ash dosage m f , Slag powder dosage m k , Amount of machine-made sand tailings m e And the amount of water reducing agent m c ; The cementitious materials include cement, fly ash, slag powder, and machine-made sand tailings:

[0120] m s =β s ×m j (6);

[0121] m f =β f ×m j (7);

[0122] m k =β k ×m j (8);

[0123] m e =β w×m j (9);

[0124] m c =β c ×m j (10);

[0125] In the formula, m s The amount of cement in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0126] m f The amount of fly ash in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0127] m k The amount of slag powder used in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0128] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0129] m c The amount of water reducing agent in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0130] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0131] β s Cement content per cubic meter of concrete mixture, %;

[0132] β f is the fly ash content in each cubic meter of concrete mixture, %;

[0133] β k is the amount of slag powder in each cubic meter of concrete mixture, %;

[0134] β c is the amount of water reducing agent in each cubic meter of concrete mixture, %;

[0135] β w It is the proportion of machine-made sand tailings in each cubic meter of concrete mixture, %.

[0136] Since cast-in-place piles have high requirements for concrete workability, for low-grade concrete, high-volume tail powder β w For the early-age strength structural parts where columns and beams need to rebound and detect the carbonization depth, β-carbon can be added in time. w0-10% tail powder improves the pore structure and increases strength. Therefore, this application uses the total gelling amount m j =400kg / m 3 For example, the mixing ratio of cement, fly ash and slag powder is 5:3:2, and the mixing ratio of machine-made sand tailing powder is β w The water reducing agent dosage is 20%, c Calculated as 1.3%, that is, the cement content β s 40%, fly ash content β f 24%, mineral powder content β k is 16%, and the amount of machine-made sand tailing powder is 20%, then the amount of machine-made sand tailing powder is m e =400×20%=80kg / m 3 ; Cement dosage m s =400×80%×(5 / 10)=160kg / m 3 ; Fly ash dosage m f =400×80%×(3 / 10)=96kg / m 3 ; Slag powder dosage m k =400×80%×(2 / 10)=64kg / m 3 ; Water reducing agent dosage m c =400×1.3%=4.2kg / m 3 .

[0137] S3 Based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w , and calculate the concrete water-binder ratio w / b:

[0138]

[0139] In the formula, m w The actual water consumption of concrete, unit: kg / m 3 ;

[0140] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0141] Calculate the amount of coarse aggregate m according to the mass method g0 and fine aggregate m s0 Dosage;

[0142] Based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w Steps include:

[0143] S31 Determine the amount of water required for concrete based on the slump height required by the construction drawings. w0 :

[0144] m w0 =m' w0 ×(1-β) (11);

[0145] In the formula, m' w0 The amount of water required for each cubic meter of concrete with a slump of 160 mm, in kg / m 3 ;

[0146] β is the water reduction rate of the water reducer, %;

[0147] Specifically, the water consumption m is determined according to the slump requirements of the construction concrete in the design drawings. w0 The maximum nominal particle size of the crushed stone is 31.5 mm, and the water consumption for a slump of 90 mm is 205 kg / m 3 Based on, increase 5kg / m for every 20mm increase in slump 3 The slump of high-fluidity concrete mixture is required to be no less than 160mm, that is, the amount of water required for concrete with a slump of 160mm is m' w0 222.5kg / m 3 Based on, but the water reduction rate of high-performance water reducer β is not less than 25%, then the actual water consumption per cubic meter of high-flow concrete is m w =m' w0 (1-β)=222.5×(1-25%)≈166.9kg / m 3 .

[0148] S32 According to the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w :

[0149] m w =m w0 -m e ×γ w ×δ (12);

[0150]

[0151] In the formula, m w0 To determine the amount of water required for concrete based on the slump height required by the construction drawings, in kg / m 3 ;

[0152] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0153] mj It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0154] γ w is the saturated surface dry water absorption rate of machine-made sand tailings, %;

[0155] δ is the reduction factor.

[0156] Specifically, in this embodiment, basalt is taken as an example, and the saturated surface dry water absorption rate γ of the measured machine-made sand tailing powder is w It is 23.2%, which needs to be multiplied by the reduction coefficient δ. In this embodiment, the reduction coefficient δ is 0.7 (30% surface floating water, 70% powder open pore water). The water absorption rate of basalt tail powder is γ w =23.2%×0.7=16.3%. Similarly, the water absorption rate of tuff tail powder is γ w 14%; water absorption rate of diabase tail powder γ w It is 15.89%.

[0157] If the added machine-made sand tailings are basalt tailings, the actual water consumption of concrete is m w =m w0 -m e ×γ w , that is 166.9-80×0.163=153.86kg / m 3 ; The theoretical water-cement ratio of concrete is w / b = 166.9 / 400≈0.42; The actual water-cement ratio is w / b = 153.86 / 400≈0.38.

[0158] S4 Calculate the amount of coarse aggregate m according to the mass method g0 and fine aggregate m s0 Dosage;

[0159] The mass method is based on the mass of each cubic meter of concrete mixture being equal to the sum of the masses of the constituent materials. The amount of coarse aggregate and fine aggregate can be calculated according to the following equations:

[0160] m s +m f +m k +m e =m j (14);

[0161] m j + m g0 + m s0 + m w =m cp (15);

[0162] m s0 =(m cp -mj -m w )×β ss (16);

[0163] m g0 =(m cp -m b0 -m w )×(1-β ss ) (17);

[0164]

[0165] Among them, m cp is the assumed mass of concrete mixture per cubic meter, in kg / m 3 ;

[0166] m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ;

[0167] m s The amount of cement per cubic meter of concrete mixture, in kg / m 3 ;

[0168] m f The amount of fly ash in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0169] m k The amount of mineral powder in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0170] m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, in kg / m 3 ;

[0171] m w The amount of water in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0172] m s0 The amount of fine aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0173] m g0 The amount of coarse aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ;

[0174] β ss is the sand ratio of concrete mixture, %.

[0175] Specifically, 400kg / m3 Take the total cementitious dosage and 20% admixture of machine-made sand dust as an example, the concrete mixture is assumed to have a mass of 2380kg / m 3 , the total amount of coarse aggregate and fine aggregate is:

[0176] m g0 +m s0 =m cp -m j -m w =2380-400-166.9=1818.1kg / m 3 .

[0177] Calculated based on a sand ratio of 41%, then:

[0178] Fine aggregate dosage m s0 =(m cp -m j -m w )×β ss =1818.1×41%=745.42kg / m 3 ;

[0179] Coarse aggregate dosage m g0 =(m cp -m j -m w )×(1-β ss )=1818.1×59%=1072.68kg / m 3 .

[0180] S5 is based on the cement strength grade f in Table 2 ce,g and the surplus coefficient γ c Determine the compressive strength f of the mortar after 28 days of cement curing ce , unit: MPa:

[0181] f ce =γ c ×f ce,g (2).

[0182] Table 2 shows the cement strength grade f ce,g and the surplus coefficient γ c Correspondence table

[0183]

[0184] This application takes the surplus coefficient γ of the cement strength grade value c =1.16, cement strength grade is f ce,g Taking 42.5Mpa as an example, the compressive strength of cement mortar at 28d is: ce =γ c f ce,g=49.3MPa.

[0185] S6 According to the requirements of JGJ 55-2011 "Ordinary Concrete Mix Design Code", the fly ash influence coefficient γ can be obtained by looking up the table f , Mineral powder influence coefficient γ s , tail powder influence coefficient γ h , calculate the compressive strength f of the cementitious material after curing for 28 days b , unit: MPa:

[0186] f b =γ f ×γ s ×γ h ×f ce (3).

[0187] Specifically, from Table 3, we can see that the influence coefficient γ of fly ash with a dosage of 24% is f =0.81, the influence coefficient of slag powder with a dosage of 16% γ s =1, and the tail powder influence coefficient γ with a dosage of 20% h =0.8, then the compressive strength of cementitious material 28d mortar is f b =γ f γ s γ h f ce ≈31.9MPa.

[0188] Table 3 Tail powder influence coefficient γ f Table of relationship with dosage

[0189]

[0190] S7 Select the crushed stone coefficient α according to the concrete water-binder ratio w / b in Table 4 a , α b , calculate the concrete configuration strength f cu,0 and the concrete cube compressive strength f cu,k :

[0191]

[0192] f cu,k =f cu,0 γ qN (5);

[0193] In the formula, γ qN is the impact coefficient of maintenance N days, where N is the number of maintenance days.

[0194] Specifically, according to the concrete water-binder ratio w / b in Table 4, select the crushed stone coefficient α a , α b , after calculation, fcu,0 =(0.53×31.9) / 0.38-0.53×0.2×31.9≈41.11MPa.

[0195] Table 4 Relationship between coarse aggregate type and crushed stone coefficient

[0196]

[0197] Since tail powder has low activity, it is only used as filler in the early stage and does not participate in hydration reaction. With the change of tail powder dosage and total amount of cementation, the strength changes. Therefore, the age influence coefficient γ needs to be considered in the concrete strength design. q , that is, f cu,k =f cu,0 γ q The total amount of cementitious agent in this mix design is m j =400kg / m 3 The design value of the cube compressive strength of concrete with 20% admixture cured for 28 days is 41.11×1.05≈43.2MPa; the design value of the cube compressive strength of concrete with 90 days of curing is 41.11×1.22≈50.2MPa.

[0198] Table 5 Tail powder dosage and influence coefficient γ q28 Relationship table

[0199] Tail powder dosage <![CDATA[28-day influence coefficient γ q28 > <![CDATA[90-day impact coefficient γ q90 > 0～10％ 1.05～1.12 1.20～1.27 20～30％ 0.94～1.02 1.14～1.20

[0200] Since the total amount of gelling agent varies, the age influence coefficient is given in an interval range. When the amount of gelling agent is low, the upper limit value should be taken, and when the amount of gelling agent is high, the lower limit value should be taken. The dosage exceeding the amount in the table should be determined through experiments.

[0201] S8 selects the mix ratio corresponding to the mechanical properties according to the strength requirements of the project, and calculates the accurate total cementitious dosage and the amount of machine-made sand tailings by interpolation, and re-tests to obtain the actual required mix ratio.

[0202] Embodiments 1 to 4

[0203] A concrete mix design method for inactive admixtures, with a total cementitious content of 300 kg / m 3 For example, the total design density is 2385kg / m 3 , determine the water consumption 166.9kg / m 3 , cement, fly ash, mineral powder dosage = 5:3:2, machine-made sand tailings replace the total cementitious materials in the proportion of 0%, 10%, 20%, 30%. Due to the low total cementitious dosage, in order to reduce the exposed stones and improve the workability of concrete, the sand ratio is appropriately increased to 44%; the dosage of coarse aggregate and fine aggregate is calculated according to the mass method, among which the coarse aggregate is crushed stone, and the dosage is 1074.14kg / m 3The fine aggregate is machine-made sand (also called artificial sand) with a dosage of 843.96 kg / m 3 ; The solid content of water reducer is calculated as 1.3% of the amount of cementitious material; The amount of water is the actual amount of water after removing the amount of water adsorbed by machine-made sand tailings from the amount of water used for high-flow concrete determined by the concrete slump requirement. The concretes prepared with the inactive admixtures in the proportion table are numbered N300-0, N300-1, N300-2 and N300-4, and the amounts of each component in the concrete are shown in Table 6.

[0204] Table 6 Amount of each component in concrete mix

[0205]

[0206] Implementation cases 5 to 8

[0207] A concrete mix design method for inactive admixtures, with a total cementitious content of 350 kg / m 3 For example, the total design density is 2385kg / m 3 , determine the water consumption 166.9kg / m 3 , cement, fly ash, mineral powder dosage = 5:3:2, the tailings replace the total cementitious materials in the proportion of 0%, 10%, 20%, 30%, the sand ratio is set to 43%; the amount of coarse aggregate and fine aggregate is calculated according to the mass method, among which the coarse aggregate is crushed stone, and the amount is 1064.82kg / m 3 The fine aggregate is machine-made sand (also called artificial sand) with a dosage of 803.28 kg / m 3 The solid content of water reducing agent is calculated as 1.3% of the amount of cementitious material. The concretes prepared with the inactive admixtures in the proportion table are numbered N350-0, N350-1, N350-2 and N350-4.

[0208] Table 7 Amount of each component in concrete mix

[0209]

[0210] Implementation Cases 9-12

[0211] A concrete mix design method for inactive admixtures, with a total cementitious content of 400 kg / m 3 For example, the total design density is 2385kg / m 3 , determine the water consumption 166.9kg / m 3 , cement, fly ash, mineral powder dosage = 5:3:2, the tailings replace the total cementitious materials in the proportion of 0%, 10%, 20%, 30%, the sand ratio is set to 41%; the amount of coarse aggregate and fine aggregate is calculated according to the mass method, among which the coarse aggregate is crushed stone, and the amount is 1072.68kg / m 3The fine aggregate is machine-made sand (also called artificial sand) with a dosage of 745.42 kg / m 3 The solid content of water reducing agent is calculated as 1.3% of the amount of cementitious material. The concretes prepared with the inactive admixtures in the proportion table are numbered N400-0, N400-1, N400-2 and N400-4.

[0212] Table 8 Amount of each component in concrete mix

[0213]

[0214] Implementation Cases 13-16

[0215] A concrete mix design method for inactive admixtures, with a total cementitious content of 450 kg / m 3 For example, the total design density is 2385kg / m 3 , determine the water consumption of 166.9kg / m 3 , cement, fly ash, mineral powder dosage = 5:3:2, the tailings replace the total cementitious materials in the proportion of 0%, 10%, 20%, 30%, the sand ratio is set to 40%; the amount of coarse aggregate and fine aggregate is calculated according to the mass method, among which the coarse aggregate is crushed stone, and the amount is 1060.86kg / m 3 The fine aggregate is machine-made sand (also called artificial sand) with a dosage of 707.24 kg / m 3 The solid content of water reducing agent is calculated as 1.3% of the amount of cementitious material. The concretes prepared with the inactive admixtures in the proportion table are numbered N450-0, N450-1, N450-2 and N450-4.

[0216] Table 9 Amount of each component in concrete mix

[0217]

[0218]

[0219] Implementation Cases 17-20

[0220] A concrete mix design method for inactive admixtures, with a total cementitious content of 500 kg / m 3 For example, the total design density is 2385kg / m 3 , determine the water consumption of 166.9kg / m 3 , cement, fly ash, mineral powder dosage = 5:3:2, the tailings replace the total cementitious materials in the proportion of 0%, 10%, 20%, 30%, the sand ratio is set to 39%; the amount of coarse aggregate and fine aggregate is calculated according to the mass method, among which the coarse aggregate is crushed stone, and the amount is 1048.04kg / m 3The fine aggregate is machine-made sand (also called artificial sand) with a dosage of 670.06 kg / m 3 The solid content of water reducing agent is calculated as 1.3% of the amount of cementitious material. The concretes prepared with the inactive admixtures in the proportion table are numbered N500-0, N500-1, N500-2 and N500-4.

[0221] Table 10 Amount of each component in concrete mix

[0222]

[0223] The compressive strength test of concrete cube specimens was carried out in accordance with GB / T 50081-2019 “Standard for Test Methods for Physical and Mechanical Properties of Concrete”. The specific results are shown in Table 11.

[0224] Table 11 Concrete compressive strength test results

[0225]

[0226]

[0227] The addition of tail powder leads to an increase in fine particles in the admixture, which increases the contact area with water and significantly improves the workability of concrete. As the amount of tail powder continues to increase, the amount of water required for concrete also increases. If the amount of water remains unchanged, the concrete will be too viscous, which increases the amount of admixture, that is, the amount of admixture increases in different cementitious dosage mix ratios.

[0228] It can be seen from Table 11 that after adding tail powder, the 28d strength of some concretes is higher than that without tail powder. When the tail powder content reaches 10%, the strength reaches the peak value. Then, as the tail powder content continues to increase, the strength of the machine-made sand concrete gradually decreases. This is because the addition of tail powder fills the voids in the concrete, increases the density of the concrete, and makes up for the defect of poor grading of machine-made sand, thereby improving the strength of the concrete. That is, when the tail powder content is less than 10%, its filling effect is more obvious and contributes more to the strength.

[0229] When the gelling dosage is from 300 to 500 kg / m 3 When the strength changes, the strength from 15MPa to 60MPa is basically fully covered, meeting the strength range of daily conventional structural concrete. At the same time, under the premise of ensuring the same strength, the large amount of tail powder in the case of high cementitious dosage (N450-3) is far more cost-effective than the low cementitious and low tail powder dosage (N350-1). As shown in Table 12, the amount of cement, fly ash, slag powder and other materials is almost the same. It is worth noting that the tail powder dosage of (N450-3) is increased by 100kg / m compared with (N350-1). 3This move not only realizes the reuse of machine-made sand tailings, but also brings into play the characteristics of the tailings while saving resources and protecting the environment, greatly reducing the cost of concrete production and ensuring the mechanical properties of concrete.

[0230] Table 12

[0231]

[0232] Therefore, the present invention utilizes dry-process machine-made sand tailings as an admixture, which can not only realize resource recycling but also reduce the cost of concrete production. Through experiments, it is found that the tailings have certain volcanic ash activity and filling benefits, and can be used as a supplementary cementitious material for concrete. Although the strength decreases with the increase of the dosage, it can fully cover the concrete with different strength requirements. According to the applicant's research, the mechanical properties of the concrete prepared by adding 10% to 20% of the tailings to replace the cementitious material are basically the same, and the workability is also improved. Based on this, the present invention adopts dry-process machine-made sand tailings as a concrete admixture, and by adjusting the blending ratio with fly ash powder, the prepared cementitious material can have a higher volcanic ash activity, thereby ensuring the mechanical properties and durability of the concrete.

[0233] In summary, a method for designing concrete mix proportions with inactive admixtures utilizes tailings from dry-process machine-made sand production as an admixture. It can replace part of cement and active admixtures while realizing the utilization of multiple solid waste resources, thereby reducing the cost of raw materials and improving the working performance of concrete. It has a strong value for promotion and application.

[0234] The above examples are for the purpose of illustrating the embodiments disclosed in the present application and should not be construed as limiting the present application. In addition, the various modifications listed herein and the changes in the methods and compositions in the application are obvious to those skilled in the art without departing from the scope and spirit of the present application. Although the present application has been specifically described in conjunction with a variety of specific preferred embodiments of the present application, it should be understood that the present application should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the application should be included in the scope of the present application.

Claims

1. A method for designing a concrete mix ratio of an inactive admixture, characterized in that: include: Collect the machine-made sand tailings with a particle size not exceeding 0.075 mm generated at each dust removal point during the dry machine-made sand processing, and measure the performance indicators of the machine-made sand tailings; the performance indicators include the saturated surface dry water absorption rate, MB value, specific surface area and / or activity index of the machine-made sand tailings; According to the requirements of the structural parts for the strength and workability of concrete, the total cementitious amount of cementitious materials is determined. j Then, according to the proportion of cement, fly ash, slag powder, machine-made sand tailings, and water reducer, the cement dosage m is calculated. s , fly ash dosage m f , Slag powder dosage m k , Amount of machine-made sand tailings m e And the amount of water reducing agent m c ; The cementitious materials include cement, fly ash, slag powder, and machine-made sand tailings; Based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w , and calculate the concrete water-binder ratio w / b: In the formula, m w The actual water consumption of concrete, unit: kg / m 3 ; m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ; Calculate the amount of coarse aggregate m according to the mass method g0 and fine aggregate m s0 Dosage; According to cement strength grade f ce,g and the surplus coefficient γ c Determine the compressive strength f of the mortar after 28 days of cement curing ce , unit: MPa: f ce =c c ×f ce,g (2); According to the fly ash influence coefficient γ f , Mineral powder influence coefficient γ s , tail powder influence coefficient γ h , calculate the compressive strength f of the cementitious material after curing for 28 days b , unit: MPa: f b =c f ×c s ×c h ×f ce (3); According to the concrete water-binder ratio w / b, select the crushed stone coefficient α a , α b , calculate the concrete configuration strength f cu,0 and the concrete cube compressive strength f cu,k : f cu,k =f cu,0 c qN (5); In the formula, γ qN is the influence coefficient of maintenance N days, where N is the number of maintenance days; According to the strength requirements of the project, the mix ratio corresponding to the mechanical properties is selected, and the accurate total cementitious dosage and the amount of machine-made sand tailings are calculated by interpolation method, and the actual required mix ratio is obtained through re-testing.

2. A method for designing a concrete mix ratio of inactive admixtures according to claim 1, characterized in that: Calculate the cement consumption m s , fly ash dosage m f , Slag powder dosage m k , Amount of machine-made sand tailings m e , water reducing agent dosage m c Follow the following formula: m s =b s ×m j (6); m f =b f ×m j (7); m k =b k ×m j (8); m e =b w ×m j (9); m c =b c ×m j (10); In the formula, m s The amount of cement in each cubic meter of concrete mixture, unit: kg / m 3 ; m f The amount of fly ash per cubic meter of concrete mixture, unit: kg / m 3 ; m k The amount of slag powder used in each cubic meter of concrete mixture, unit: kg / m 3 ; m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ; m c The amount of water reducing agent in each cubic meter of concrete mixture, unit: kg / m 3 ; m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ; β s Cement content per cubic meter of concrete mixture, %; β f is the fly ash content in each cubic meter of concrete mixture, %; β k is the amount of slag powder in each cubic meter of concrete mixture, %; β c is the amount of water reducing agent in each cubic meter of concrete mixture, %; β w It is the proportion of machine-made sand tailings in each cubic meter of concrete mixture, %.

3. The method for designing a concrete mix ratio of an inactive admixture according to claim 1, characterized in that: The mixing ratio of cement, fly ash and slag powder in the cementitious material is 5:3:

2.

4. The method for designing a concrete mix ratio of an inactive admixture according to claim 1, characterized in that: Based on the slump height required by the construction drawings and the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w Steps include: Based on the slump height required by the construction drawings, determine the amount of water required for concrete m w0 : m w0 =m' w0 ×(1-β) (11); In the formula, m' w0 The amount of water required for each cubic meter of concrete with a slump of 160 mm, in kg / m 3 ; β is the water reduction rate of the water reducing agent, %; According to the dry water absorption rate of the saturated surface of the machine-made sand tailings, the water consumption of the concrete mixture is corrected to determine the actual water consumption m w : m w =m w0 -m e ×γ w ×δ (12); In the formula, m w0 To determine the amount of water required for concrete based on the slump height required by the construction drawings, in kg / m 3 ; m e The amount of machine-made sand tailings in each cubic meter of concrete mixture, unit: kg / m 3 ; m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ; γ w is the saturated surface dry water absorption rate of machine-made sand tailings, %; δ is the reduction factor.

5. The method for designing a concrete mix ratio of an inactive admixture according to claim 1, characterized in that: The mixing amount of the machine-made sand tailing powder is 10-30%.

6. The method for designing a concrete mix ratio of an inactive admixture according to claim 4, characterized in that: When the dosage of machine-made sand tailings is between 0% and 10%, the influence coefficient γ q28 Take 1.05~1.12, the influence coefficient of curing for 90 days γ q90 Take 1.20~1.27; When the dosage of machine-made sand tailings is between 20% and 30%, the influence coefficient γ q28 Take 0.94~1.02, the influence coefficient of curing for 90 days γ q90 Take 1.14~1.

20.

7. The method for designing a concrete mix ratio of an inactive admixture according to claim 1, characterized in that: The mass method is based on the mass of each cubic meter of concrete mixture being equal to the sum of the masses of the constituent materials. The amount of coarse aggregate and fine aggregate can be calculated according to the following equations: m s +m f +m k +m e =m j (14); m j +m g0 +m s0 +m w =m cp (15); m s0 =(m cp -m j -m w )×β ss (16); m g0 =(m cp -m b0 -m w )×(1-β ss ) (17); Among them, m cp is the assumed mass of concrete mixture per cubic meter, in kg / m 3 ; m j It is the total cementitious amount per cubic meter of concrete mixture, in kg / m 3 ; m s The amount of cement per cubic meter of concrete mixture, in kg / m 3 ; m f The amount of fly ash in each cubic meter of concrete mixture, unit: kg / m 3 ; m k The amount of mineral powder in each cubic meter of concrete mixture, unit: kg / m 3 ; m e The amount of machine-made sand dust per cubic meter of concrete mixture, in kg / m 3 ; m w The amount of water in each cubic meter of concrete mixture, unit: kg / m 3 ; m s0 The amount of fine aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ; m g0 The amount of coarse aggregate in each cubic meter of concrete mixture, unit: kg / m 3 ; β ss is the sand ratio of concrete mixture, %.

8. An inactive admixture concrete prepared according to the inactive admixture concrete mix design method according to any one of claims 1 to 7, characterized in that: The invention comprises the following raw materials: cementitious material, coarse aggregate, fine aggregate, water reducing agent and water, wherein the cementitious material is composed of the following components in the following mass ratio: 90 to 250 parts of cement, 54 to 150 parts of fly ash, 36 to 100 parts of slag powder and 30 to 200 parts of machine-made sand tailings; the amounts of coarse aggregate and fine aggregate are calculated according to the mass method; the solid content of the water reducing agent is 0.5 to 3% of the amount of the cementitious material; the amount of water is the actual amount of water after deducting the water adsorbed by the machine-made sand tailings from the water content of the large-flowability concrete determined by the concrete slump requirement.

9. The inactive admixture concrete according to claim 8, characterized in that: The particle size of the machine-made sand tailing powder does not exceed 0.075 mm; the saturated surface dry water absorption rate of the machine-made sand tailing powder is greater than 20%, the water demand ratio is greater than 100%, and the specific surface area is greater than 300 cm 2 / g, fluidity ratio <90%, standard consistency water consumption >120mL, MB value ≤6.00g / kg; silicon dioxide content in machine-made sand tailings >45%, alumina content in machine-made sand tailings >10%, 28-day activity index >55%.

10. The inactive admixture concrete according to claim 8, characterized in that: The amount of machine-made sand tailings is 10-30% of the total gelling amount.

Images