Method for designing mix proportion of slag concrete

Abstract

The application discloses a method for designing a mixing proportion of slag concrete, and is based on two factors of strength of the slag concrete, namely, mortar and slag. The strength of the slag is low, and the strength of the mortar is improved to realize the low strength of the slag. The mortar is used in a sufficient amount to sufficiently wrap the slag aggregate, so that the strength of the slag concrete is improved, and the strength of the slag concrete can meet the current construction standard. On one hand, the slag recycled building material is utilized, and on the other hand, the environmental pressure is reduced. The application solves the problem that the slag cannot be directly applied to concrete pouring due to the high porosity and high crushing value of the slag.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of slag recycling, and particularly relates to a slag concrete mix proportion design method. BACKGROUND

[0002] The amount of slag produced by daily household garbage incineration in Shanghai reaches 2000-3000 tons, and the current application direction of such a large amount of slag is mainly road engineering and low-value applications such as small components. With the proposal of the national low-carbon concept, the exploitation of natural sandstone materials is gradually reduced, and how to utilize slag aggregate to prepare C30, C40 and other high-quality concrete materials is becoming increasingly important.

[0003] Due to high-temperature combustion of slag in the incineration plant, the main components of slag include ceramic, masonry fragments, glass, and slag. The surface of slag is rough and irregular in shape, has a high porosity, and the pores are relatively large. The mineral composition of slag is relatively simple, mainly including silicon dioxide, calcium silicate, aluminum silicate, and a small amount of calcium carbonate, calcium oxide, etc., and has stable chemical properties, which can be used to replace traditional sandstone materials for building material resourceization.

[0004] Compared with traditional sandstone materials, slag aggregate has several main deficiencies in physical properties. First, the porosity is high and the water absorption rate is more than 10%. Second, the crushing value of slag is more than 35%, which does not meet the performance requirements of the current national standards “Recycled Coarse Aggregate for Concrete” and “Recycled Fine Aggregate for Concrete and Mortar”, and cannot be directly applied to concrete pouring. SUMMARY

[0005] In order to overcome the defects of the prior art, a slag concrete mix proportion design method is provided to solve the problem that the high porosity and high crushing value of slag cannot be directly applied to concrete pouring.

[0006] To achieve the above-mentioned purpose, a slag concrete mix proportion design method is provided, which includes cement, slag, high-performance water reducing agent, and water. The slag is composed of coarse slag and fine slag. The particle size of the fine slag is less than 5 mm, the particle size of the coarse slag is 5-10 mm, and the weight ratio of the fine slag to the coarse slag is 1:a, wherein the value of a is 1-1.5. The water reduction rate is greater than 30%. The slag concrete mix proportion design method comprises the following steps:

[0007] Determine the weight of the fine slag and the coarse slag in the slag, and the water absorption rate of the fine slag and the coarse slag;

[0008] Based on the design strength x of the slag concrete, determine the slag-binder ratio y of the slag concrete, and the slag-binder ratio y=8.7x.-0.38 ;

[0009] determining a water-cement ratio of the cementitious material based on the water-reducing rate;

[0010] calculating an initial water consumption of the slag concrete based on the weight of the slag, the slag-cement ratio and the water-cement ratio;

[0011] correcting the initial water consumption to obtain a corrected water consumption based on the water absorption rates of the fine slag and the coarse slag and the gradation of the slag, corrected water consumption = initial water consumption + m1 x a1 + m2 x a2, wherein m1 is the weight of the fine slag, m2 is the weight of the coarse slag, a1 is the water absorption rate of the fine slag, and a2 is the water absorption rate of the coarse slag.

[0012] Further, the water-cement ratio is between 0.18 and 0.24.

[0013] Further, the greater the water-reducing rate of the water-reducing agent, the smaller the value of the water-cement ratio.

[0014] Further, when the fineness modulus of the fine slag is less than 2.8, the value of a should be 1.5.

[0015] The slag concrete mix design method of the present application is based on two constituent factors of the strength of the slag concrete, one is the cement paste, and the other is the slag. The low strength of the slag is realized by improving the strength of the cement paste. By ensuring sufficient dosage of the cement paste, the slag aggregate is fully wrapped to improve the strength of the slag concrete, so that the strength of the slag concrete can meet the current construction standard. On the one hand, the slag recycled building materials are utilized, and on the other hand, the environmental pressure is reduced. DETAILED DESCRIPTION

[0016] The present application will be further described below in conjunction with embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application.

[0017] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below in conjunction with embodiments.

[0018] The present application provides a slag concrete mix design method, wherein the slag concrete comprises cement, slag, high-performance water-reducing agent and water.

[0019] The slag is composed of coarse slag and fine slag. The particle size of the fine slag is less than 5 mm. The particle size of the coarse slag is 5-10 mm. The weight ratio of the fine slag to the coarse slag is 1:a, wherein the value of a is preferably 1-1.5. When the fineness modulus of the fine slag is less than 2.8, the value of a should be 1.5.

[0020] The water-reducing rate of the high-performance water-reducing agent should be greater than 30%.

[0021] The method comprises the following steps:

[0022] Specifically, the slag concrete mix proportion design method comprises the following steps:

[0023] S1: measuring the weight of fine slag and coarse slag in the slag, and the water absorption rates of the fine slag and the coarse slag.

[0024] The water absorption rates of the fine slag and the coarse slag are measured according to the Highway Engineering Aggregate Test Regulation JTGE42.

[0025] S2: determining the slag-binder ratio y of the slag concrete based on the design strength x of the slag concrete, the slag-binder ratio y = 8.7x -0.38 .

[0026] The slag-binder ratio is the mass ratio of the slag to the cement binder. The slag-binder ratio y = mass of slag : mass of cement binder.

[0027] S3: determining the water-cement ratio of the cement binder based on the water-reducing rate and the net paste fluidity of the cement binder.

[0028] Specifically, the greater the water-reducing rate of the water-reducing agent, the smaller the water-cement ratio. The water-cement ratio is between 0.18 and 0.24.

[0029] S4: calculating the initial water consumption of the slag concrete based on the weight of the slag, the slag-binder ratio and the water-cement ratio.

[0030] S5: correcting the initial water consumption to obtain the corrected water consumption based on the water absorption rates of the fine slag and the coarse slag and the gradation of the slag, the corrected water consumption = initial water consumption + m1 x alpha1 + m2 x alpha2, wherein m1 is the weight of the fine slag, m2 is the weight of the coarse slag, alpha1 is the water absorption rate of the fine slag, and alpha2 is the water absorption rate of the coarse slag.

[0031] The following slag concrete with a design strength of C50 is taken as an example to specifically illustrate the slag concrete mix proportion design method.

[0032] The maximum particle size of the slag is 10 mm, and the fineness modulus of the fine slag is 2.7. The water absorption rate of the fine slag is 13%, the water absorption rate of the coarse slag is 7%, the water-reducing rate of the high-performance water-reducing agent is 30%, and the target strength of the prepared concrete is C50. The mix proportion design is as follows:

[0033] The weight ratio of the fine slag to the coarse slag is determined to be 1:1.4. If the weight of the fine slag is set to be 1 kg, then the weight of the coarse slag is 1.4 kg.

[0034] According to the water-reducing rate 30% of the high-performance water-reducing agent, the water-cement ratio is preliminarily determined to be 0.20.

[0035] The design strength of the slag concrete is C50, and according to the slag-binder ratio y=8.7x -0.38 The slag-binder ratio y is 1.97, and the corresponding cement binder material amount is 1.22 kg.

[0036] According to the preliminary water-cement ratio of 0.2, the initial water consumption is 0.244 kg.

[0037] According to the water absorption rate of the fine slag of 13% and the water absorption rate of the coarse slag of 7%, the corrected water consumption = 0.244+1*0.13+1.4*0.07 = 0.472 kg.

[0038] According to the existing slag level, the calculated fine-coarse slag ratio is 1:1.4, the weight of the fine slag is 1 kg, the weight of the coarse slag is 1.4 kg, the binder material amount is 1.22 kg, and the water consumption is 0.472 kg when the water-reducing rate of the water-reducing agent is 30%.

[0039] The slag concrete mixing ratio design method of the application is based on two constituent factors of the strength of the slag concrete, one is the mortar, and the other is the slag. The low strength of the slag is realized by improving the mortar strength. The mortar amount is ensured to be sufficient to realize full wrapping of the slag aggregate and to improve the strength of the slag concrete, so that the strength of the slag concrete can meet the current construction standard. On the one hand, the slag recycled building material is utilized, and on the other hand, the environmental pressure is reduced.

[0040] The above description is only the preferred embodiment of the application and the explanation of the applied technical principles. It should be understood by those skilled in the art that the application range involved in the application is not limited to the technical solutions formed by the specific combination of the above technical features, and also covers other technical solutions formed by the combination of the above technical features or equivalent features without departing from the application concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the application (but not limited to) having similar functions.

Claims

1. A method for mix proportion design of slag concrete, characterized in that, The slag concrete comprises cement, slag, high-performance water reducing agent and water, the slag is composed of coarse slag and fine slag, the particle size of the fine slag is less than 5 mm, the particle size of the coarse slag is 5-10 mm, the weight ratio of the fine slag to the coarse slag is 1:a, wherein the value of a is 1-1.5, the water-reducing rate of the high-performance water reducing agent is greater than 30%, and the slag concrete mix proportion design method comprises the following steps: determining the weight of the fine slag and the coarse slag in the slag, and the water absorption rate of the fine slag and the coarse slag; determining a slag binder ratio y of the slag concrete based on the design strength x of the slag concrete, the slag binder ratio y = 8.7x -0.38 ; determining the water-cement ratio of the cement binder based on the water-reducing rate; calculating the initial water consumption of the slag concrete based on the weight of the slag, the slag-binder ratio and the water-cement ratio; correcting the initial water consumption to obtain the corrected water consumption based on the water absorption rate of the fine slag and the coarse slag and the gradation of the slag, corrected water consumption = initial water consumption + m1*alpha1 + m2*alpha2, wherein m1 is the weight of the fine slag, m2 is the weight of the coarse slag, alpha1 is the water absorption rate of the fine slag, and alpha2 is the water absorption rate of the coarse slag.

2. The method of claim 1, wherein the method is characterized by: The water-cement ratio is between 0.18 and 0.

24.

3. The method of claim 2, wherein the method is characterized by: The greater the water-reducing rate of the high-performance water reducing agent, the smaller the value of the water-cement ratio.

4. The method of claim 1, wherein the method is characterized by: When the fineness modulus of the fine slag is less than 2.8, the value of a should be 1.5.