Method for preparing self-compacting mortar by using calcined muck and residual mud

Abstract

The invention discloses a method for preparing self-compacting mortar by using calcined muck, the self-compacting mortar is prepared from the following components in parts by weight: 73-122 parts of cement, 10-49 parts of muck mixture, 211 parts of fine aggregate, 2-4 parts of water reducing agent and 29-49 parts of water, the most common muck mixture in engineering construction is utilized to partially replace the cement, so that the self-compacting mortar is prepared. Under the condition that the use compressive strength is met, replacement of part of cement is completed through secondary utilization of the muck, and great contribution can be made to energy conservation and emission reduction in the engineering process.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization of construction waste, and more specifically, to a method for preparing self-compacting mortar by utilizing calcined slag and residual mud. Background Art

[0002] With the continuous acceleration of my country's economic development and infrastructure construction, the total amount of construction waste such as construction debris generated during the construction of subways, tunnels and underground multi-story buildings is increasing.

[0003] At present, the general way to deal with these construction waste soils is to use a small amount of it directly as backfill, and the rest is piled up or buried, which not only occupies precious land resources, but also causes serious harm.

[0004] In addition, traditional silicate cement production is a high-energy consumption and high-carbon emission process, and current auxiliary cementitious materials such as fly ash are not fully suitable for sustainable development. Therefore, how to scientifically utilize the large amount of construction waste generated in construction activities is one of the ways to promote the long-term development of the building materials industry and achieve energy conservation and emission reduction strategies.

[0005] However, due to the poor engineering properties of construction waste sludge and poor treatment technology, more effective methods need to be considered to solve the problem of resource utilization of construction waste. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing self-compacting mortar by utilizing calcined slag residue mud.

[0007] The above technical purpose of the present invention is achieved through the following technical scheme: a self-compacting mortar is prepared by utilizing calcined slag mud, and its components include, by weight: 73-122 parts of cement, 10-49 parts of slag mixture, 211 parts of fine aggregate, 2-4 parts of water reducer, and 29-49 parts of water.

[0008] A method for preparing self-compacting mortar using calcined slag mud comprises the following steps:

[0009] S1, drying, drying the construction waste at a temperature of 105°C;

[0010] S2, grinding, putting the dried construction waste into a ball grinder for grinding;

[0011] S3, filtering, passing the ground construction waste soil through a sieve to obtain waste soil residue;

[0012] S4, calcining, calcining the slag and residual mud obtained in S3 at high temperature;

[0013] S5, mixing, mixing the slag mud after calcination in S4 with limestone powder to obtain a slag mixture;

[0014] S6. Mixing: putting the soil mixture, cement, fine aggregate, water reducing agent and water into a mixer, and mixing them evenly to obtain a self-compacting mortar;

[0015] S7, measuring performance, measuring the working performance of the mortar obtained in S6, and preparing the self-compacting mortar.

[0016] The present invention is further configured as follows: S1, drying, drying the construction waste soil at a temperature of 105° C., comprising:

[0017] S1.1. Preliminary drying of construction waste;

[0018] S1.2. Place the construction waste soil that has been preliminarily dried in an electric blower drying oven at a temperature of 105° and dry it until it is completely dry.

[0019] The present invention is further configured as follows: S2, grinding, putting the dried construction waste soil into a ball grinder for grinding, comprising:

[0020] S2.1. Put the completely dry construction waste into a ball grinder and grind for 10-20 minutes.

[0021] The present invention is further configured as follows: S3, filtering, wherein the ground engineering slag is passed through a sieve to obtain slag sludge, comprising:

[0022] S3.1. The ground construction waste soil is passed through a vibrating screen with a screen of 0.15 mm to obtain waste soil sludge.

[0023] The present invention is further configured as follows: S4, calcination, calcining the slag and residual mud obtained in S3 at high temperature, comprising:

[0024] S4.1. Place the slag and residual mud into a box-type resistance furnace for calcination at a temperature of 750 degrees Celsius and a holding time of 2 hours.

[0025] The present invention is further configured as follows: S5, mixing, mixing the slag mud after calcination in S4 with limestone powder to obtain a slag mixture, comprising:

[0026] S5.1. Mix the slag mud and limestone powder in a mass ratio of 2:1 to obtain a slag mixture.

[0027] The present invention is further configured as follows: S6, stirring, putting the slag soil mixture, cement, fine aggregate, water reducing agent and water into a mixer according to a mass ratio, and stirring evenly, including:

[0028] S6.1. The slag soil mixture and cement are mixed to form a gel material, wherein the slag soil mixture accounts for 30%-40% of the total mass of the gel material;

[0029] S6.2. Put the slag soil mixture, cement and fine aggregate into the mixer and stir for 1 min. Pour in 70% of the water and continue stirring for 1 min. Pour in the remaining 30% of the water and the water reducing agent solution and stir for 3 min. Stop stirring for 30 s and finally stir for another 1 min.

[0030] In summary, the present invention has the following beneficial effects:

[0031] The invention uses calcined slag mud as raw material to partially replace ordinary silicate cement, which is beneficial to the resource utilization of construction waste, and has lower resource consumption and environmental impact under calcination conditions and can also form renewable resources.

[0032] The present invention uses calcined slag and residual mud as raw materials, which can directly provide mortar raw materials for subsequent construction of the project and can also reduce emissions caused by garbage disposal, thereby achieving both the effect of meeting on-site use and the effect of energy conservation and emission reduction.

[0033] The present invention uses calcined slag mud as raw material, and after partially replacing ordinary Portland cement, the physical properties of the mortar are slightly improved under the premise of energy saving and emission reduction, and the use strength of the mortar can still be met after replacing a large amount of ordinary Portland cement.

[0034] The method provided by the present invention mixes calcined slag residue mud with limestone powder for use, which saves a large amount of cement while meeting the use strength of the original cement mortar. Tests have shown that the self-compacting cement mortar provided by the present invention has excellent working performance and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a process flow chart of preparing self-compacting mortar using calcined slag and residual mud in an embodiment of the present invention;

[0036] Figure 2 It is a bar chart of the 7d and 28d compressive strength of Example 1 and Comparative Example 1 in the embodiments of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0038] It should be noted that if the terms "first", "second", etc. are involved in the specification and claims of the present invention and the above-mentioned drawings, they are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, if the terms "including" and "having" and any of their variations are involved, it is intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] In addition, in the present invention, the terms "installed", "set", "provided with", "connected", "connected", "socketed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] The following is combined with Figure 1-2 The present invention is described in further detail.

[0042] like Figure 1 and Figure 2 As shown, a self-compacting mortar is prepared by using calcined slag mud. In terms of weight parts, its components include: 73-122 parts of cement, 10-49 parts of slag mixture, 211 parts of fine aggregate, 2-4 parts of water reducing agent, and 29-49 parts of water.

[0043] Most preferred: The best embodiment: 96 parts of cement, 25 parts of slag soil mixture, 211 parts of fine aggregate, 2 parts of water reducer, 48 parts of water, the most preferred 28d compressive strength is 40.5MPa, 90d compressive strength is 46.6MPa, at this time the replacement ratio of the slag soil mixture is 20%, this is the most preferred, its compressive strength except for the 7d compressive test, 28d compressive test and 90d compressive test strength are higher than the compressive strength of pure cement.

[0044] In the self-compacting mortar provided by the present invention, the cement is selected from Yuexiu brand P·O 42.5R cement produced by Guangzhou Zhujiang Cement Co., Ltd., and the cement can be specifically 73 parts by weight, 80 parts by weight, 87 parts by weight, 94 parts by weight, 101 parts by weight, 108 parts by weight, 115 parts by weight, and 122 parts by weight.

[0045] In the self-compacting mortar provided by the present invention, the XRF chemical composition of the slag-soil mixture is shown in Table 1, and the slag-soil mixture may specifically be 10 parts by weight to 49 parts by weight.

[0046] Table 1: Chemical composition analysis data of construction waste soil.

[0047]

[0048] In the self-compacting mortar provided by the present invention, the fine aggregate should meet the requirements of "GB / T14684-2011 Building Sand", and the fine aggregate can specifically be 211 parts by weight.

[0049] In the self-compacting mortar provided by the present invention, the water reducer is a Si ka liquid polycarboxylic acid water reducer, and the water reducer can be specifically 2 parts by weight, 3 parts by weight, or 4 parts by weight, which can be increased or decreased as desired.

[0050] In the self-compacting mortar provided by the present invention, the water may specifically be 29 parts by weight, 39 parts by weight, or 49 parts by weight.

[0051] It should also be noted in the embodiments provided by the present invention that the water-cement ratio is 0.4, the sand-cement ratio is 1.73, and the amount of water reducing agent is appropriately adjusted to meet the requirements of the self-compacting mortar.

[0052] A method for preparing self-compacting mortar using calcined slag mud comprises the following steps:

[0053] S1. Drying: drying the construction waste at a temperature of 105°C.

[0054] S1.1. Preliminary drying of construction waste;

[0055] S1.2. Place the construction waste soil that has been preliminarily dried in an electric blower drying oven at a temperature of 105° and dry it until it is completely dry.

[0056] S2. Grinding: Grinding the dried construction waste soil in a ball grinder.

[0057] S2.1. Put the completely dry construction waste into a ball grinder and grind for 10-20 minutes.

[0058] S3, filtering, the ground construction waste soil is passed through a sieve to obtain waste soil sludge.

[0059] S3.1. The ground construction waste soil is passed through a vibrating screen with a screen of 0.15 mm to obtain waste soil sludge.

[0060] S4, calcination, calcining the slag and residual mud obtained in S3 at high temperature.

[0061] S4.1. Place the slag and residual mud into a box-type resistance furnace for calcination at a temperature of 750 degrees Celsius and a holding time of 2 hours.

[0062] S5, mixing, mixing the slag mud after calcination in S4 with limestone powder to obtain a slag mixture.

[0063] S5.1. Mix the slag mud and limestone powder in a mass ratio of 2:1 to obtain a slag mixture.

[0064] S6. Mixing: Put the slag soil mixture, cement, fine aggregate, water reducing agent and water into the mixer according to the mass ratio and mix them evenly.

[0065] S6.1. The slag soil mixture and cement are mixed to form a gel material, wherein the slag soil mixture accounts for 30%-40% of the total mass of the gel material;

[0066] S6.2. Put the slag soil mixture, cement and fine aggregate into the mixer and stir for 1 min. Pour in 70% of the water and continue stirring for 1 min. Pour in the remaining 30% of the water and the water reducing agent solution and stir for 3 min. Stop stirring for 30 s and finally stir for another 1 min.

[0067] S7, measuring performance, measuring the working performance of the mortar obtained in S6, and preparing the self-compacting mortar.

[0068] Test The self-compacting mortar prepared by the method of preparing self-compacting mortar by utilizing calcined slag mud was tested by the following process.

[0069] 1. According to EFNARC.Specification and Guidelines for self-compacting concrete.2002. Use flow expansion cylinder and V-funnel to measure the working performance of mortar respectively to meet the requirements of self-compacting mortar.

[0070] 2. According to the provisions of JGJ / T70-2009 "Test Method for Basic Properties of Building Mortar", the self-compacting mortar prepared in the examples and comparative examples was poured into a 70.7 mm cubic mold for molding. Nine mortar test blocks were cast for each example, numbered, and placed in a constant temperature and humidity (temperature 20±1°C, humidity 95%) curing box for one day before demolding. After demolding, the blocks were moved into a standard curing room until the test age.

[0071] Then, the 7d, 28d and 90d compressive strength of the mortar test blocks of the embodiment and the comparative example were measured according to the regulations. Figure 2 shown.

[0072] like Figure 2 As shown, Figure 2 It is a bar graph of the 7d, 28d and 90d compressive strength of the examples and comparative examples. The horizontal axis is the replacement rate, that is, the mass percentage of the mixture of slag mud and limestone powder obtained after calcination in the total cementitious material, and the vertical axis is the compressive strength at different ages.

[0073] Depend on Figure 2 The data results show that with the increase of replacement rate, the 7d compressive strength of mortar shows a downward trend; but with the increase of curing age, the compressive strength is significantly improved. With the increase of curing age, the compressive strength can significantly exceed the compressive strength of pure cement mortar. Figure 2 It can also be seen that in order to increase the amount of energy saving and emission reduction, when the proportion of slag-soil mixture in the gel material is increased, the compressive strength of the mortar is reduced, but it can still meet the use strength of the mortar.

[0074] Table 2: Detailed proportion of slag and residual mud

[0075] cement(%) Calcined slag residue (%) Limestone powder (%) Example 1 90 7 3 Example 2 85 10 5 Example 3 80 14 6 Example 4 70 20 10 Example 5 60 27 13 Comparative Example 1 100 0 0

[0076] The ratio of calcined slag mud to limestone powder in Table 2 follows the conventional 2:1 ratio to control the single variable experiment.

[0077] Example 1: Replacement rate of soil mixture in gel material 10%

[0078] The compressive strength of the mortar at 28 days was higher than that of the control, and the comprehensive compressive strength increased by 2%;

[0079] The compressive strength of the mortar at 90d is higher than that of the control example, and the comprehensive compressive strength is increased by 2%.

[0080] Example 2: Replacement rate of soil mixture in gel material 15%

[0081] The compressive strength of the mortar at 28 days was higher than that of the control, and the comprehensive compressive strength decreased by 3%;

[0082] The compressive strength of the mortar at 90d is higher than that of the control example, and the comprehensive compressive strength is increased by 3%.

[0083] Example 3: Replacement rate of soil mixture in gel material 20%

[0084] The compressive strength of the mortar at 28 days was lower than that of the control, and the comprehensive compressive strength decreased by 5%;

[0085] The compressive strength of the mortar at 90d is higher than that of the control example, and the comprehensive compressive strength is increased by 2%.

[0086] Example 4: Replacement rate of slag soil mixture in gel material 30%

[0087] The compressive strength of the mortar at 28 days was lower than that of the control, and the comprehensive compressive strength decreased by 8%;

[0088] The 90d data of mortar is not included in the test results due to unstable data.

[0089] Example 5: Replacement rate of soil mixture in gel material 40%

[0090] The compressive strength of the mortar at 28 days was lower than that of the comparative example, with a decrease of 12% in the comparative compressive strength;

[0091] The compressive strength of the mortar at 90d was lower than that of the comparative example, and the comprehensive compressive strength decreased by 11%.

[0092] It can be seen from the results of the examples and comparative examples that the present invention provides a method for preparing self-compacting mortar using calcined slag mud, and calcined slag mud and limestone powder can be used to replace cement as raw materials for self-compacting mortar, and when the replacement rate is as high as 30-40%, it can still meet the performance requirements of cement mortar. In this way, the slag mud obtained after the treatment of engineering slag can be replaced by a large amount of energy saving and emission reduction, and the energy consumption in the subsequent treatment process of construction slag can be greatly reduced.

[0093] Summary and comparison of strength after replacement:

[0094] The 28d compressive strength test results: Example 1 increased by 2%, Example 2 decreased by 3%, Example 3 decreased by 5%, Example 4 decreased by 8%, and Example 5 decreased by 12%;

[0095] The 90d compressive strength test results: Example 1 increased by 2%, Example 2 increased by 3%, Example 3 increased by 2%, Example 4 decreased by 5%, and Example 5 decreased by 11%;

[0096] In addition, the fluidity test of the self-compacting mortar found that as the amount of calcined slag residue increased, the fluidity of the mortar would be affected, especially when the replacement rate was high (>40%).

[0097] Under the premise of meeting the compressive strength requirement, the construction waste soil material can be utilized as a resource. It is recommended that the waste soil mixture accounts for 30%-40% of the total mass of the cementitious material to achieve maximum energy saving and reduction without affecting the use strength of the mortar.

[0098] Self-compacting concrete (SCC) does not require vibration during pouring. It can fill densely reinforced formwork under the action of its own gravity alone, maintaining good uniformity and non-segregation characteristics.

[0099] In order to meet the requirements of fluidity, self-compacting mortar uses a larger amount of cementitious materials than ordinary mortar.

[0100] The preparation method provided by the invention mainly uses calcined slag mud as raw material, partially replaces ordinary Portland cement, and is beneficial to the resource utilization of construction waste.

[0101] At the same time, while ensuring the excellent working performance and mechanical properties of self-compacting mortar, the processing cost of construction waste is reduced, the amount of cement in the mortar is reduced, emissions and carbon reduction are achieved, and it has good economic and environmental benefits.

[0102] The slag mud contains mineral components such as kaolinite, which can be converted into metakaolin through high-temperature calcination, thereby improving the activity of the material.

[0103] When kaolinite is calcined at low temperature, some organic matter and physically adsorbed water in kaolin gradually separate. When calcined to 500-900℃, kaolin is dehydroxylated, the crystal structure is destroyed, it becomes amorphous, the layered structure collapses, the specific surface area increases, and the activity is relatively improved. The kaolin calcined at this temperature stage is metakaolin.

[0104] When the calcination temperature of kaolinite reaches 1000℃, kaolinite forms an aluminum-silicon spinel structure, and when the calcination temperature reaches above 1100℃, it undergoes a mullite transformation.

[0105] For high-temperature calcination methods, different calcination temperatures and holding times are adopted, as shown in the following table, and the possible temperatures and holding times are optimally selected.

[0106] Table 3: Calcination time selection table

[0107] Calcination temperature (℃) Insulation time (h) Activity index (%) 1 700 1.5 78 2 700 2.0 79 3 700 2.5 75 4 750 1.5 81 5 750 2.0 86 6 750 2.5 79

[0108] Refer to the activity index test method in GB / T 1596-2017 "Fly ash used in cement and concrete".

[0109] Therefore, it is proposed to "calcine the slag residue in a box-type resistance furnace at a calcination temperature of 750 degrees Celsius and a holding time of 2 hours" to maximize the activity of the material.

[0110] It should be noted that all features disclosed in this specification, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any manner.

[0111] In addition, the above specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention description and its drawings are illustrative and do not constitute a limitation of the claims. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. A self-compacting mortar prepared by using calcined slag and residual mud, wherein the components include, in parts by weight: Cement 73-122 parts, slag soil mixture 10-49 parts, fine aggregate 211 parts, water reducing agent 2-4 parts, water 29-49 parts.

2. The method for preparing self-compacting mortar using calcined slag residue according to claim 1, characterized in that: 。 3. A method for preparing self-compacting mortar using calcined slag mud as claimed in any one of claims 1 to 2, characterized in that: S1, drying, drying the construction waste at a temperature of 105°C; S2, grinding, putting the dried construction waste into a ball grinder for grinding; S3, filtering, passing the ground construction waste soil through a sieve to obtain waste soil residue; S4, calcining, calcining the slag and residual mud obtained in S3 at high temperature; S5, mixing, mixing the slag mud after calcination in S4 with limestone powder to obtain a slag mixture; S6. Mixing: putting the soil mixture, cement, fine aggregate, water reducing agent and water into a mixer, and mixing them evenly to obtain a self-compacting mortar; S7, measuring performance, measuring the working performance of the mortar obtained in S6, and preparing the self-compacting mortar.

4. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S1. Drying: Dry the construction waste at a temperature of 105°C, including: S1.

1. Preliminary drying of construction waste; S1.

2. Place the construction waste soil that has been preliminarily dried in an electric blower drying oven at a temperature of 105° and dry it until it is completely dry.

5. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S2. Grinding: putting the dried construction waste into a ball grinder for grinding, including: S2.

1. Put the completely dry construction waste into a ball grinder and grind for 10-20 minutes.

6. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S3, filtering, passing the ground construction waste through a sieve to obtain waste mud, including: S3.

1. The ground construction waste soil is passed through a vibrating screen with a screen of 0.15 mm to obtain waste soil sludge.

7. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S4, calcining, calcining the slag and residual mud obtained in S3 at high temperature, including: S4.

1. Place the slag and residual mud into a box-type resistance furnace for calcination at a temperature of 750 degrees Celsius and a holding time of 2 hours.

8. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S5, mixing, mixing the slag and residual mud after calcination in S4 with limestone powder to obtain a slag mixture, including: S5.

1. Mix the slag mud and limestone powder in a mass ratio of 2:1 to obtain a slag mixture.

9. The method for preparing self-compacting mortar using calcined slag mud according to claim 3, characterized in that: S6. Mixing: Put the soil mixture, cement, fine aggregate, water reducing agent and water into the mixer according to the mass ratio and mix them evenly, including: S6.

1. The slag soil mixture and cement are mixed to form a gel material, wherein the slag soil mixture accounts for 30%-40% of the total mass of the gel material; S6.

2. Put the slag soil mixture, cement and fine aggregate into the mixer and stir for 1 min. Pour in 70% of the water and continue stirring for 1 min. Pour in the remaining 30% of the water and the water reducing agent solution and stir for 3 min. Stop stirring for 30 s and finally stir for another 1 min.

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