Granite sawing mud-based cementitious material and application thereof

Abstract

The application provides a granite sawing mud-based cementing material and application thereof, and belongs to the technical field of stone processing waste material resource utilization.The raw material of the granite sawing mud-based cementing material comprises granite sawing mud and a composite modifying material; the composite modifying material is composed of cement, lime and fly ash in a mass ratio of (50-70):(15-25):(15-25); and the adding amount of the composite modifying material is 6%-9% of the dry mass of the granite sawing mud.The granite sawing mud is used as the main raw material, so that the solid waste is utilized as a resource; and the granite sawing mud-based cementing material prepared through the modification of the composite modifying material can meet the relevant technical requirements of the filling material of the road subgrade through the hydration of the cement, the separation and consolidation of the lime, and the pozzolanic reaction of the cement, the lime and the fly ash after a series of physical and chemical reactions.

Description

Technical Field

[0001] This invention belongs to the field of stone processing waste resource utilization technology, and in particular relates to a granite sawdust-based cementitious material and its application. Background Technology

[0002] With the growth of transportation demand, road construction projects have also developed rapidly. The materials used in road construction are mostly non-renewable natural resources. In some economically developed areas and important corridors, there has even been a shortage of soil resources.

[0003] Sawdust refers to the cutting residue generated during the production and processing of stone. It is a mixture of stone powder and water. With the continuous mining of granite and other stone resources, natural resources are becoming increasingly scarce, and large amounts of waste sawdust are accumulating. Open-air piles of sawdust are difficult to properly dispose of, causing continuous damage to the ecological environment. The main mineral component of sawdust is quartz, which has low chemical activity. Modifying sawdust using only materials such as calcium hydroxide and cement is still insufficient to meet the needs of engineering fields such as housing construction and road paving.

[0004] Therefore, obtaining a sawdust-based cementitious material that can meet the needs of highway construction would be of great practical significance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a granite sawdust-based cementitious material and its application.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of the present invention:

[0008] A granite sawdust-based cementitious material, wherein the raw materials of the granite sawdust-based cementitious material include granite sawdust and a composite modifier, wherein the composite modifier is composed of cement, lime and fly ash, and the amount of the composite modifier added is 6%-9% of the dry weight of the granite sawdust.

[0009] Preferably, the amount of the composite modified material added is 6% of the dry weight of the granite sawdust.

[0010] Preferably, the composite modified material is composed of cement, lime, and fly ash in a mass ratio of (50-70):(15-25):(15-25). The preparation method of the composite modified material includes the following steps: weighing cement, lime, and fly ash according to the mass ratio, and stirring evenly to obtain the composite modified material.

[0011] More preferably, the composite modified material is composed of cement, lime and fly ash in a mass ratio of 50:25:25.

[0012] Preferably, the granite sawdust has a D50 of 1.64 μm and a pH value between 7.77 and 10.53.

[0013] Preferably, the cement is P·I42.5 silicate cement with a specific surface area of ​​356 m². 2 / kg, 3-day flexural strength 5.5MPa, 3-day compressive strength 26.1MPa; both lime and fly ash are sieved through a 100-mesh sieve, with the fly ash having a specific surface area greater than or equal to 400m². 2 / kg, activity index greater than or equal to 75%, moisture content less than or equal to 3%.

[0014] The composite modified material used in this invention can divide unbonded granite sawdust into many blocks, which are then bonded together. The chemical bonds generated after the hydration reaction of the composite modified material physically encapsulate, adsorb, and solidify the heavy metal ions in the matrix framework, forming a stable structure in the sawdust and achieving effective solidification. The hydration reaction of the granite sawdust also produces various hydrates that adhere to the spaces between the sawdust particles, thus achieving a bonding effect and enhancing strength.

[0015] The second technical solution of the present invention:

[0016] A method for preparing the granite sawdust-based cementitious material includes the following steps:

[0017] (1) Weigh each raw material according to the mass percentage and then press the granite saw mud into a paste.

[0018] (2) Add the composite modified material to the granite sawdust from step (1), stir, and compact to obtain the granite sawdust-based cementitious material.

[0019] Preferably, the curing time in step (1) is 24 hours (one day and night). During the curing process, the granite sawdust needs to be mixed with water to achieve the optimal moisture content.

[0020] During the preparation process, the composite modified material is mainly compacted by physical static pressing to reduce the porosity and increase the contact area to improve the initial strength. The increase in strength in the later stage is achieved through the carbonization and secondary hydration reaction between the composite modified material and the saw mud.

[0021] The third technical solution of the present invention:

[0022] The application of the granite sawdust-based cementitious material in road subgrade construction.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] (1) In this invention, granite sawdust is activated and then modified with a composite material consisting of lime, fly ash and cement to prepare a cementitious material. Under the action of external force, the sawdust is compressed, which shortens the spacing between particles, increases the contact area between particles, and increases the friction, thus generating strength and improving its physical and mechanical properties. In addition, the sawdust undergoes a series of physical and chemical reactions, including the hydration of cement, the separation and consolidation of lime, and the pozzolanic reaction when cement, lime and fly ash are mixed, to form hydration products with expansive properties. These hydration products fill the gaps between sawdust particles and bond adjacent particles, giving them better density and thus improving their strength. Furthermore, the sawdust itself is alkaline. After the addition of the composite modified material, it has more negative charges in an alkaline environment. After the curing agent in the sawdust undergoes a hydration reaction, positive ions are generated, which strengthen the connection structure between particles through electrostatic attraction.

[0025] (2) This invention uses granite sawdust as the main raw material, realizing the resource utilization of solid waste. The granite sawdust-based cementitious material prepared can meet the relevant technical requirements of roadbed filling materials. The 7-day compressive strength of the sawdust-based cementitious material specimen can reach 2.0 MPa. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 A comparison chart of the liquid and plastic limits of samples A1-A4;

[0028] Figure 2 A comparison chart of the liquid and plastic limits of samples B1-B4;

[0029] Figure 3 A comparison chart of the liquid and plastic limits of samples C1-C4;

[0030] Figure 4 This is a comparison chart of the liquid and plastic limits of samples D1-D4;

[0031] Figure 5 Images of the compaction test process;

[0032] Figure 6 The compaction curves for samples A1-A4;

[0033] Figure 7 Compaction curves for samples B1-B4;

[0034] Figure 8 Compaction curves for samples C1-C4;

[0035] Figure 9The compaction curves for samples D1-D4;

[0036] Figure 10 This is a diagram illustrating the testing process of an unconfined compression testing machine.

[0037] Figure 11 Comparison of unconfined compressive strength of samples A1-A4;

[0038] Figure 12 Comparison of unconfined compressive strength of samples B1-B4;

[0039] Figure 13 Comparison of unconfined compressive strength of samples C1-C4;

[0040] Figure 14 This is a comparison chart of the unconfined compressive strength of samples D1-D4. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] The granite sawdust used in this embodiment of the invention was collected from a granite quarry in Wulian County, Rizhao City. Testing showed that its pH value was in the range of 7.77–10.53, lower than the corrosivity standard for hazardous waste (pH ≥ 12.5). Its main chemical components were SiO2 and Al2O3, with contents reaching 70.24% and 14.73% respectively. It also contained small amounts of K2O, Na2O, and CaO. The main particle size distribution was below 10 μm, accounting for approximately 90% of the total, with particles below 0.6 μm accounting for 10%. The median particle size D50 was 1.64 μm, indicating a narrow particle size distribution. The maximum dry density was 1.64 g / cm³. 3 .

[0047] All other raw materials used in the embodiments of this invention were obtained through commercial purchase.

[0048] In this embodiment of the invention, the compaction method is physical static compaction, which is a conventional technique in the field and will not be described in detail here.

[0049] The technical solution of the present invention will be further illustrated by the following embodiments.

[0050] Example 1

[0051] (1) Cement, lime and fly ash are mixed evenly in a mass ratio of 70:15:15 to obtain composite modified material F1. Granite sawdust is dried and crushed. Water is added to the dried granite sawdust with a moisture content of 18%. The material is put into a sealed bag and left to sit for 24 hours.

[0052] (2) Add the composite modified material F1 to the granite sawdust from step (1). The amount of composite modified material added is 3% of the dry mass of the granite sawdust. Stir and compact to obtain granite sawdust-based cementitious material, designated A1.

[0053] Example 2

[0054] Same as Example 1, except that the amount of composite modified material F1 added is 6% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated A2.

[0055] Example 3

[0056] Same as Example 1, except that the amount of composite modified material F1 added is 9% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated A3.

[0057] Example 4

[0058] Same as Example 1, except that the amount of composite modified material F1 added is 12% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated A4.

[0059] Example 5

[0060] (1) Cement, lime and fly ash are mixed evenly in a mass ratio of 60:20:20 to obtain composite modified material F2. Granite saw mud is dried and crushed. Water is added to the dried granite saw mud with a moisture content of 18%. The mud is then put into a sealed bag and left to sit for 24 hours.

[0061] (2) Add the composite modified material F2 to the granite sawdust from step (1). The amount of composite modified material added is 3% of the dry mass of the granite sawdust. Stir and compact to obtain granite sawdust-based cementitious material, designated B1.

[0062] Example 6

[0063] Same as Example 5, except that the amount of composite modified material F2 added is 6% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated B2.

[0064] Example 7

[0065] Same as Example 5, except that the amount of composite modified material F2 added is 9% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated B3.

[0066] Example 8

[0067] Same as Example 5, except that the amount of composite modified material F2 added is 12% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated B4.

[0068] Example 9

[0069] (1) Cement, lime and fly ash are mixed evenly in a mass ratio of 50:25:25 to obtain composite modified material F3. Granite saw mud is dried and crushed. Water is added to the dried granite saw mud at an optimal moisture content of 18%. The mud is then placed in a sealed bag and left to sit for 24 hours.

[0070] (2) Add the composite modified material F3 to the granite sawdust from step (1). The amount of composite modified material added is 3% of the dry mass of the granite sawdust. Stir and compact to obtain granite sawdust-based cementitious material, numbered C1.

[0071] Example 10

[0072] Same as Example 9, except that the amount of composite modified material F3 added is 6% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated C2.

[0073] Example 11

[0074] Same as Example 9, except that the amount of composite modified material F3 added is 9% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated C3.

[0075] Example 12

[0076] Same as Example 9, except that the amount of composite modified material F3 added is 12% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated C4.

[0077] Example 13

[0078] (1) Dry and crush the granite sawdust, add water to the dried granite sawdust at the optimal moisture content of 18%, pack it into a sealed bag, and let it sit for 24 hours. Cement is used as a modifier.

[0079] (2) Add cement to the granite sawdust from step (1). The amount of cement added is 3% of the dry mass of the granite sawdust. Stir and compact to obtain granite sawdust-based cementitious material, designated D1.

[0080] Example 14

[0081] Same as Example 13, except that the amount of cement added is 6% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated D2.

[0082] Example 15

[0083] Same as Example 13, except that the amount of cement added is 9% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated D3.

[0084] Example 16

[0085] Same as Example 13, except that the amount of cement added is 12% of the dry mass of granite sawdust, resulting in granite sawdust-based cementitious material, designated D4.

[0086] Performance testing

[0087] I. Liquid Limit and Plastic Limit Test

[0088] According to the "Specifications for Testing Geotechnical Engineering for Highways" (JTG E40-2007), the combined liquid limit and plastic limit determination method was selected to test the materials prepared in Examples 1-16. The results are shown in Tables 1-4. A comparison chart of the liquid and plastic limits of samples A1-A4 is shown below. Figure 1See the comparison chart of liquid and plastic limits for samples B1-B4. Figure 2 The comparison chart of liquid and plastic limits for C1-C4 samples is shown below. Figure 3 The comparison chart of liquid and plastic limits for samples D1-D4 is shown below. Figure 4 .

[0089] Table 1. Results of Liquid Limit and Plastic Limit Tests (A1-A4)

[0090]

[0091]

[0092] Table 2B1~B4 Liquid Limit and Plastic Limit Test Results Data Table

[0093] Liquid limit (wl) (%) 37.8 38.9 38.4 38.1 Plastic limit (wp) (%) 22.2 22.7 20.3 19.6 Plasticity index lp 15.6 16.3 18.1 18.5

[0094] Table 3. Results of Liquid Limit and Plastic Limit Tests for C1 to C4

[0095] Liquid limit (wl) (%) 38.4 39.3 38.5 38.8 Plastic limit (wp) (%) 20.3 22 23.5 19.85 Plasticity index lp 18.1 17.3 15 18.95

[0096] Table 4 Data of Liquid Limit and Plastic Limit Test Results (D1-D4)

[0097] Liquid limit (wl) (%) 38.2 38.6 38.3 38.6 Plastic limit (wp) (%) 23.9 16.8 12.96 14.95 Plasticity index lp 14.3 21.8 25.3 23.65

[0098] As can be seen from Tables 1-4, the plasticity index increases after the addition of composite modified materials, indicating that the moisture content of sawdust changes more significantly in the plastic state, thus increasing the workability of construction.

[0099] II. Compaction Test

[0100] According to the "Specifications for Testing Geotechnical Engineering for Highways" (JTG E40-2007), the dry soil method and the II.1 heavy compaction test method were used to test the samples prepared in Examples 1-16 (see...). Figure 5 After the samples were compacted, samples were taken to determine the moisture content and dry density. The results are shown in Table 5-8. The compaction curves of samples A1-A4 are shown in Table 5-8. Figure 6 The compaction curves of samples B1-B4 are shown below. Figure 7 The compaction curves of samples C1-C4 are shown in [the original text]. Figure 8 The compaction curves of samples D1-D4 are shown in the figure. Figure 9 .

[0101] Table 5 Compaction Test Results (A1-A4)

[0102]

[0103]

[0104] Table 6 Compaction Test Results (B1-B4)

[0105]

[0106] Table 7 Compaction Test Results for C1 to C4

[0107]

[0108] Table 8 Compaction Test Results (D1-D4)

[0109]

[0110] From Table 4-8 and Figure 6-9 It can be seen that the optimal moisture content of the sawdust-based cementitious materials obtained in Examples 1-16 decreases with the increase of the amount of composite modified material, while the maximum dry density increases with the increase of the content of composite modified material.

[0111] III. Unconfined compressive strength test

[0112] The material was pre-cured according to the optimum moisture content ω obtained from the above compaction test, and the specimen mass was calculated to be 181g based on the maximum dry density. Unconfined compressive strength tests were conducted on the samples prepared in Examples 1-16. The unconfined compressive strength specimens were 39.1mm in diameter and 80mm in height. The compaction degree of the specimens was controlled at 96%. The specimens were formed by static pressing for 1 minute, and then the pressure was released. After molding, the specimens were demolded and then sealed in a sealed bag and placed in a standard curing chamber with a temperature of 14±1℃ and a relative humidity of ≥90% for curing for 1 day, 3 days, and 7 days, respectively.

[0113] When the specimens reached 1 day, 3 days, and 7 days of curing, they were removed and placed on an unconfined compressive strength testing machine for measurement. The testing process is as follows: Figure 10 The test involved applying pressure to the specimen at an axial strain rate of 1% to 3% per minute. Deformation and force values ​​were recorded at strain rates of 0.3% to 0.5%. Once the force reached its maximum value or stabilized, pressure was applied for an additional 60 to 90 seconds before stopping the experiment. The total test duration was 8 minutes. The test results are shown in Table 9-12. A comparison of the unconfined compressive strength of samples A1-A4 is shown in the figure. Figure 11 The comparison chart of unconfined compressive strength of samples B1-B4 is shown below. Figure 12 The comparison chart of unconfined compressive strength of samples C1-C4 is shown below. Figure 13 The comparison chart of unconfined compressive strength of samples D1-D4 is shown below. Figure 14 .

[0114] Table 9A1~A4 Unconfined compressive strength (MPa)

[0115] A1 0.65 0.86 1.34 A2 0.75 0.98 1.99 A3 0.89 1.68 2.44 A4 0.94 1.46 2.39

[0116] Table 10B1~B4 Unconfined compressive strength (MPa)

[0117] B1 0.66 0.99 1.41 B2 0.79 1.31 2.19 B3 0.89 1.13 2.22 B4 0.75 0.88 2.32

[0118] Table 11 Unconfined compressive strength (MPa) of C1 to C4

[0119] C1 0.48 0.77 1.13 C2 0.75 1.35 2.17 C3 0.71 1.26 2.21 C4 0.74 1.35 2.22

[0120] Table 12 Unconfined compressive strength (MPa) of D1 to D4

[0121] D1 1.07 1.23 1.71 D2 1.21 1.57 2.36 D3 1.44 2.21 3.38 D4 1.91 2.99 4.10

[0122] From Tables 9-12 and Figure 11-14 It can be seen that when cement is added alone as a composite modifier, the compressive strength of sawdust specimens cured for 7 days continuously increases with the increase of cement content. With the same proportion of composite modifier added, the compressive strength of sawdust specimens continuously increases with the increase of composite material content. To ensure the strength and water stability of sawdust, the composite materials added to the sawdust material are mainly cement-based. However, increasing the cement content will increase the cost of clay-based cementitious materials, and sawdust specimens may exhibit shrinkage and cracking. Under long-term damp or water-exposed conditions, its compressive strength and other properties may decrease, thus affecting its curing effect.

[0123] The sawdust specimens with composite modified materials have higher strength. Under certain conditions, the higher the dosage, the better the effect. Among them, the sawdust-based cementitious material specimens made with 6% cement, 6% F2 modified composite material, 6% F2 composite modified material and 9% F1 composite material have a 7-day compressive strength of 2.0 MPa.

[0124] IV. Unconfined compressive strength test under immersion water

[0125] Experimental procedure:

[0126] The test results are shown in Tables 13-16.

[0127] Table 13A1~A4 Unconfined compressive strength (MPa) under water immersion

[0128]

[0129]

[0130] Table 14B1~B4 Unconfined compressive strength (MPa) under water immersion

[0131] B1 0.79 1.01 B2 1.11 1.55 B3 1.03 1.62 B4 0.78 1.60

[0132] Table 15 Unconfined compressive strength (MPa) of C1~C4 materials after immersion in water

[0133] C1 0.67 0.85 C2 1.05 1.59 C3 1.06 1.63 C4 1.05 1.65

[0134] Table 16 Unconfined compressive strength (MPa) of D1~D4 after immersion in water

[0135] D1 0.73 1.26 D2 1.23 1.96 D3 1.90 2.63 D4 2.80 3.60

[0136] As can be seen from the experimental results in Table 13-16, the physical and mechanical properties of the sawdust specimens were significantly improved after modification with composite modified materials, meeting the technical requirements for engineering applications. The composite modified materials mainly use chemical bonds generated after hydration reaction to physically encapsulate, adsorb, and solidify the heavy metal ions in the matrix skeleton structure, enabling the sawdust to form a stable structure and thus achieve an effective solidification effect.

[0137] Based on the above performance test results, cement and composite modifiers (cement, lime, fly ash) were selected as the modification materials for sawdust to improve its activity. According to the experimental analysis, when composite modifiers were used for treatment, the strength of the sawdust specimens increased continuously with the increase of the modifier dosage and the age. However, when a certain age was reached, the strength increase of the specimens became slow. The optimal addition amount of composite modifiers was determined to be 6% of the dry weight of granite sawdust.

[0138] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A granite sawdust-based cementitious material, characterized in that, The raw materials of the granite sawdust-based cementitious material include granite sawdust and composite modified materials. The composite modified materials are composed of cement, lime and fly ash in a mass ratio of (50-70):(15-25):(15-25). The amount of composite modified materials added is 6%-9% of the dry mass of granite sawdust. The granite sawdust has a D50 of 1.64 μm, and 90% of the particles are smaller than 10 μm. The pH value is between 7.77 and 10.

53. The preparation method of the granite sawdust-based cementitious material includes the following steps: (1) Weigh each raw material according to the mass percentage, and let the granite saw mud sit for 24 hours; (2) Add the composite modified material to the granite sawdust from step (1), stir, and compact to obtain the granite sawdust-based cementitious material.

2. The granite sawdust-based cementitious material according to claim 1, characterized in that, The amount of the composite modified material added is 6% of the dry weight of the granite sawdust.

3. The granite sawdust-based cementitious material according to claim 1, characterized in that, The composite modified material is composed of cement, lime and fly ash in a mass ratio of 50:25:

25.

4. The granite sawdust-based cementitious material according to claim 1, characterized in that, The cement is P·I42.5 silicate cement, and the specific surface area of ​​the fly ash is greater than or equal to 400 m². 2 / kg, activity index greater than or equal to 75%, moisture content less than or equal to 3%.

5. The application of the granite sawdust-based cementitious material according to any one of claims 1-4 in road subgrade construction.

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