Slow-setting silicate cement for road base and preparation method thereof

Abstract

The invention discloses a slow-setting silicate cement for road base and a preparation method thereof, belonging to the technical field of cement. The slow-setting silicate cement for road base comprises the following raw materials in weight percentage: 56-59% clinker, 10-14% limestone, 8-12% fly ash, 6-10% granulated blast furnace slag powder, 4-6% desulfurized gypsum, 4-6% phosphogypsum, 0.03-0.04% grinding aid, and 0.05-0.06% retarder. The invention increases the dosage of industrial byproduct desulfurized gypsum and phosphogypsum to increase the linear expansion rate of cement; by adding phosphogypsum and retarder, the effect of extending the setting time of cement is achieved; by controlling the dosage of limestone inactive admixture and fly ash active admixture, and adding strengthening type grinding aid at the same time, the strength of cement is increased and the grinding condition is improved, so that the slow-setting silicate cement for road base has slow-setting micro-expansion characteristics and strength performance indicators meet the standards, and achieves comprehensive resource utilization, reduces cement production costs, and increases corporate benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of cement, and in particular relates to slow-setting silicate cement for road base and a preparation method thereof. Background Art

[0002] Slow-setting silicate cement for road base is a hydraulic cementitious material made by grinding silicate cement clinker, mixed materials with specified dosage, appropriate amount of gypsum and (or) other slow-setting materials. It is a special cement specially used for stabilizing road base, used to stabilize road base and subbase in road engineering construction, with slow-setting micro-expansion characteristics, which greatly prolongs the delayed rolling time of road base construction, compensates for base shrinkage and cracking, and is beneficial to road base construction.

[0003] The retarding materials commonly used in the research and production of retarding silicate cement for road base include phosphogypsum, sulfuric acid slag, sugars and citric acid, etc. These retarding materials are generally waste generated in the production process of local phosphate fertilizer enterprises, sulfuric acid enterprises, paper mills, etc. Some chemical admixtures are also used, such as retarding grinding aids.

[0004] The shrinkage coefficient of cement-based stabilized base is large, and the paved base is prone to cracking. Once the base cracks, it will reflect on the road surface and cause cracking and damage to the road surface. During the road construction process, cracking of the base requires a lot of manpower and material resources to repair and rework, resulting in huge losses. However, the cracking problem of cement-stabilized base has not been effectively solved so far.

[0005] Regarding the problem that cement-stabilized base layers have a large shrinkage coefficient and are prone to shrinkage and cracking, current research and production of slow-setting silicate cement for road base layers focus more on extending the setting time, and research on its expansion performance has not been fully resolved. The expansion performance is crucial for compensating for shrinkage and cracking of cement-stabilized base layers.

[0006] The formula of ordinary Portland cement currently widely produced is: 80% clinker, 5% desulfurized gypsum, 3% limestone, 6% slag, 6% fly ash, and 0.04% grinding aid. Due to the unreasonable proportion of ingredients, the cement's frost resistance, crack resistance, seepage resistance, impact resistance, wear resistance, erosion resistance and other functional properties do not meet the requirements, and it cannot be used as a road base, and the social benefits are not obvious.

[0007] The preparation process of retarded silicate cement for road base is relatively simple and out of touch with the requirements of highway pavement construction. The "Technical Specifications for Highway Pavement Base Construction" (JTG / F20-2015) requires ordinary silicate cement with a strength grade of 32.5 or 42.5, an initial setting time greater than 180 minutes, and a final setting time greater than 360 minutes and less than 600 minutes. As a result, cement companies only produce road base stabilization cement by adding retarders to P·C32.5 cement, which is difficult to meet the requirements of road base construction with retarded micro-expansion characteristics, prolong the delayed rolling time of road base construction, and compensate for base shrinkage and cracking.

[0008] The strength grade of slow-setting silicate cement used in road base is not high, the amount of mixed materials is large, and the high amount of active mixed materials causes material waste. Active mixed materials such as fly ash and slag are scarce in some areas, and excessive active mixed material content makes cement production costs high. The required phosphogypsum has high quality requirements and has a great impact on strength and setting time.

[0009] The patent publication number is CN 109503006 A, and the invention name is a slow-setting silicate cement for road base and production method. The disclosed cement formula is 45-55% clinker, 3-11% desulfurized gypsum, 3-11% limestone, 4-8% slag, 25-35% fly ash, and 0.8% grinding aid. The amount of grinding aid reaches 0.8%, which exceeds the national standard for the amount of liquid grinding aid added to cement: it cannot exceed 0.5% of the cement mass. In addition, the amount of fly ash in the cement active admixture is as high as 25-35%. The large amount of active admixture and the high price of fly ash make the production cost of cement high.

[0010] In summary, combined with reducing the amount of active mixed materials, comprehensively utilizing industrial waste slag and reducing cement production costs, a slow-setting silicate cement for road base with slow-setting micro-expansion characteristics and excellent and stable performance has been researched and developed. Summary of the invention

[0011] In view of the above problems, the present invention provides a slow-setting silicate cement for road base, which increases the linear expansion rate of cement by increasing the dosage of industrial by-products desulfurized gypsum and phosphogypsum; prolongs the setting time of cement by adding phosphogypsum and retarders; controls the dosage of limestone inactive admixtures and fly ash active admixtures, and adds strengthening grinding aids to improve the strength of cement and the grinding condition, so that the slow-setting silicate cement for road base finally has slow-setting micro-expansion characteristics and meets various strength performance indicators, while achieving comprehensive resource utilization, reducing cement production costs and increasing enterprise benefits.

[0012] The present invention is achieved through the following technical solutions:

[0013] A slow-setting silicate cement for road base comprises the following raw materials in percentage by weight: 56-59% clinker, 10-14% limestone, 8-12% fly ash, 6-10% granulated blast furnace slag powder, 4-6% desulfurized gypsum, 4-6% phosphogypsum, 0.03-0.04% grinding aid, and 0.05-0.06% retarder;

[0014] The quality control requirements for the raw materials are:

[0015] Clinker: f-CaO≤1.5%, SO 3 ≤1.0%, 3-day and 28-day compressive strengths are ≥28.0MPa and ≥57.0MPa respectively;

[0016] Limestone: CaCO 3 52~90%,Al 2 O 3 0.1~2.5%, particle size ≤25mm;

[0017] Desulfurized gypsum: pH ≥ 5.0, Cl - ≤0.5%;

[0018] Phosphogypsum: pH value ≥8.0, the setting time is longer than that of natural gypsum, with the final setting time being ≥120min and ≤300min.

[0019] The retarded silicate cement for road base comprises the following raw materials in percentage by weight: 58.3% clinker, 13% limestone, 10% fly ash, 8% granulated blast furnace slag powder, 5.5% desulfurized gypsum, 5.2% phosphogypsum, 0.03% grinding aid and 0.05% retarder.

[0020] Furthermore, the grinding aid is any one of ammonium acetate, triethanolamine, ammonium acetate, propylene glycol, ethylene glycol, capric acid, and cyclohexane acid, or a combination of two or more thereof.

[0021] Furthermore, the retarder is any one of polyhydroxy compounds, hydroxycarboxylates and their derivatives, and high-sugar lignin sulfonates, or a combination of two or more thereof.

[0022] Furthermore, the total amount of admixture components in the slow-setting silicate cement for the road base is ≥ 32%, SO 3 : 4.8~5.5%, f-CaO≤0.8%, MgO≤3.5%, 45um fineness≤15%.

[0023] Furthermore, the slow-setting silicate cement used for the road base has a 7-day antenna expansion rate ≥ 0.10%, a 28-day antenna expansion rate ≤ 0.35%, a 7-day compressive strength ≥ 16.0 MPa, a 28-day compressive strength ≥ 36.0 MPa, an initial setting time ≥ 300 min, a final setting time ≥ 360 min and ≤ 500 min, an internal irradiation index IRa ≤ 0.4, an external irradiation index IR ≤ 0.4, an autoclave stability of 0.04%, and both the boiling method and the immersion method stability are qualified.

[0024] A method for preparing the above-mentioned slow-setting silicate cement for road base comprises the following steps:

[0025] (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system;

[0026] (2) Measuring and batching: The clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum in the batching warehouse are metered and batched according to the weight percentage of the raw materials through the metering system;

[0027] (3) Grinding: The measured ingredients are transported into the cement mill and the cement mill is started for grinding;

[0028] (4) Adding grinding aids and retarders: While the ingredients are being ground, the amount of grinding aids and retarders added is controlled by a metering pump and evenly added to the cement mill from the point of incorporation. After the grinding process is completed, a cement product is obtained;

[0029] (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

[0030] Furthermore, in step (3), the stirring speed of the grinding process is 1200 to 2000 rpm, and the stirring time is 2.5 to 8 hours.

[0031] Furthermore, in step (4), the flow rate of the grinding aid and retarder added into the metering pump is controlled to be 120 to 180 L / h.

[0032] Furthermore, in step (4), the grinding aid and retarder are added dropwise from the grinding head of the cement mill to the position inside the mill.

[0033] In the present invention, grinding aids and retarders are both admixtures, and the addition amounts of grinding aids and retarders account for 0.03-0.04% and 0.05-0.06% of the total weight percentage of the ingredients (clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum) in the cement mill, respectively.

[0034] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0035] 1. The present invention is based on the requirement that silicate cement used for road base should have slow setting and micro expansion characteristics. The micro expansion source of cement is mainly SO 3 , SO 3 Affects the retarding effect of cement, while SO 3 It is mainly provided by desulfurized gypsum and phosphogypsum. Therefore, by adding appropriate amounts of desulfurized gypsum and phosphogypsum, the addition amount of both is 4-6%, the purpose of delaying the cement setting time and increasing the linear expansion rate can be achieved, so that the cement has micro-expansion characteristics in the early stage without affecting the structure of the cement.

[0036] 2. The present invention simultaneously controls the pH value of phosphogypsum and the effect of extending the setting time and retarding the setting. By controlling the pH value of phosphogypsum to be ≥8.0, the soluble phosphorus content in the phosphogypsum is reduced, so that the phosphogypsum can better play a controlling role, and the setting time is extended to a final setting of ≥120min and ≤300min compared with natural gypsum, which can better control the setting time of cement. The present invention also adds 0.05-0.06% of retarder, which can appropriately extend the setting time of cement, so as to achieve the purpose of stabilizing the setting time of cement and the 7-day expansion rate of the antenna, so that the structure of the cement material is not destroyed and the performance is not deteriorated.

[0037] 3. In the present invention, since the amount of gypsum added is large and inactive, in order to avoid affecting the structure and performance of the cement material, the amount of inactive admixture limestone added needs to be reduced. Therefore, the amount of limestone added is controlled at 10-14%, and 0.03-0.04% of strengthening grinding aid is added to ensure that the grinding fineness and strength of the cement meet the standards, thereby preparing a slow-setting silicate cement for road base with excellent and stable performance.

[0038] 4. The cement of the present invention is mixed with a large amount of industrial byproducts, desulfurized gypsum and phosphogypsum, and the total amount of gypsum is 8-12% of the cement mass, making full use of industrial waste and reducing the exploitation of natural resources. At the same time, low-priced limestone inactive admixtures are mixed, the amount of limestone mixed is 10-14%, and the high-priced fly ash active admixture is less mixed, the amount of fly ash mixed is 8-12%, while the amount of fly ash mixed in the prior art (25-35%) is reduced by more than 13%, reducing the material waste caused by the high amount of active admixtures. The present invention saves cement clinker resources and comprehensively utilizes industrial waste slag, achieving the purpose of comprehensive resource utilization, energy conservation and emission reduction. Compared with the prior art, the cost of cement raw materials is reduced by about 20.78%, effectively reducing the cost of cement production and increasing corporate benefits.

[0039] 5. The strength grade of the slow-setting silicate cement of the present invention is 32.5, which meets the strength grade requirements of cement in the "Technical Specifications for Highway Pavement Base Construction" (JTG / F20-2015). The component materials in the slow-setting silicate cement of the present invention are ≥32%, SO 3: 4.8~5.5%, f-CaO≤0.8%, MgO≤3.5%, 45um fineness≤15%, 7-day expansion rate of slow-setting silicate cement ≥0.10%, 28-day expansion rate ≤0.35%, 7-day compressive strength ≥16.0MPa, 28-day compressive strength ≥36.0MPa, initial setting time ≥300min, final setting time ≥360min and ≤500min, internal irradiation index IRa≤0.4, external irradiation index IR≤0.4, autoclave stability 0.04%, boiling method and immersion method stability are both qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a process flow chart of slow-setting silicate cement for road base. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below by way of examples. These examples are only used to illustrate the present invention and do not limit the protection scope of the present invention.

[0042] In the following embodiments:

[0043] Raw material quality control requirements are:

[0044] Clinker: f-CaO≤1.5%, SO 3 ≤1.0%, 3-day and 28-day compressive strengths are ≥28.0MPa and ≥57.0MPa respectively;

[0045] Limestone: CaCO 3 52~90%,Al 2 O 3 0.1~2.5%, particle size ≤25mm;

[0046] Desulfurized gypsum: pH ≥ 5.0, Cl - ≤0.5%;

[0047] Phosphogypsum: pH value ≥8.0, setting time is longer than that of natural gypsum, with final setting ≥120min and ≤300min;

[0048] Grinding aids and retarders are in liquid form.

[0049] The composition of clinker, granulated blast furnace slag powder and fly ash is shown in Table 1:

[0050] Loss on ignition (%) <![CDATA[SiO 2 (%)]]> <![CDATA[Al 2 THE 3 (%)]]> <![CDATA[Fe 2 THE 3 (%)]]> CaO(%) MgO(%) <![CDATA[SO 3 (%)]]> f-CaO(%) Clinker 0.05～0.3 16～25 4～6 0.1～4.5 49～68 0.9～3.5 0.4～1.0 0.2～1.5 Slag powder 0～1.0 23～42 12～26 0.1～1.8 30～43 6～14 0.1～0.6 ___ Fly ash 0.3～15 35～62 18～25 3.0～10.8 5.0～11.5 0.2～3.5 0.1～3.5 0～0.8

[0051] Example 1

[0052] A method for preparing slow-setting silicate cement for road base comprises the following steps:

[0053] (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system;

[0054] (2) Measuring and batching: The ingredients in the batching warehouse are measured and batched through the metering system according to 58.3% clinker, 13% limestone, 10% fly ash, 8% granulated blast furnace slag powder, 5.5% desulfurized gypsum, and 5.2% phosphogypsum;

[0055] (3) Grinding: The measured ingredients are transported into the cement mill, and the cement mill is started for grinding. The stirring speed is 1600 rpm and the stirring time is 6 hours.

[0056] (4) Adding grinding aids and retarders: While grinding the ingredients, the amount of ammonium acetate and high-sugar lignin sulfonate added is controlled by a metering pump, so that the added amounts account for 0.03% and 0.05% of all the ingredients in the cement mill, respectively. The flow rate controlled by the metering pump is 130 L / h. The addition point is the position where the cement mill is directly added from the grinding head to the inside of the mill. After the grinding process is completed, a retarded silicate cement product for road base is obtained;

[0057] (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

[0058] Example 2

[0059] A method for preparing slow-setting silicate cement for road base comprises the following steps:

[0060] (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system;

[0061] (2) Measuring and batching: The ingredients in the batching warehouse are measured and batched through the metering system according to 59% clinker, 14% limestone, 12% fly ash, 6% granulated blast furnace slag powder, 5% desulfurized gypsum, and 4% phosphogypsum;

[0062] (3) Grinding: The measured ingredients are transported into the cement mill, and the cement mill is started for grinding. The stirring speed is 1200 rpm and the stirring time is 2.5 h.

[0063] (4) Adding grinding aids and retarders: While grinding the ingredients, the addition amount of acetamide and polyol is controlled by a metering pump, so that the addition amount accounts for 0.04% and 0.06% of all the ingredients in the cement mill, respectively. The flow rate controlled by the metering pump is 120L / h. The addition point is the position where the cement mill is directly added from the grinding head to the inside of the mill. After the grinding process is completed, a retarded silicate cement product for road base is obtained;

[0064] (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

[0065] Example 3

[0066] A method for preparing slow-setting silicate cement for road base comprises the following steps:

[0067] (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system;

[0068] (2) Measuring and batching: The ingredients in the batching warehouse are measured and batched through the metering system according to 56% clinker, 10% limestone, 8% fly ash, 10% granulated blast furnace slag powder, 4% desulfurized gypsum, and 6% phosphogypsum;

[0069] (3) Grinding: The measured ingredients are transported into the cement mill, and the cement mill is started for grinding. The stirring speed is 1500 rpm and the stirring time is 5 h.

[0070] (4) Adding grinding aids and retarders: While grinding the ingredients, the addition amount of propylene glycol and high-sugar lignin sulfonate is controlled by a metering pump, so that the addition amount accounts for 0.03% and 0.05% of all the ingredients in the cement mill, respectively. The flow rate controlled by the metering pump is 150L / h. The addition point is the position where the cement mill is directly added from the grinding head to the inside of the mill. After the grinding process is completed, a retarded silicate cement product for road base is obtained;

[0071] (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

[0072] Example 4

[0073] A method for preparing slow-setting silicate cement for road base comprises the following steps:

[0074] (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system;

[0075] (2) Measuring and batching: The ingredients in the batching warehouse are measured and batched through the metering system according to 57% clinker, 14% limestone, 9% fly ash, 9% granulated blast furnace slag powder, 6% desulfurized gypsum, and 5% phosphogypsum;

[0076] (3) Grinding: The measured ingredients are transported into the cement mill, and the cement mill is started for grinding. The stirring speed is 2000 rpm and the stirring time is 8 hours.

[0077] (4) Adding grinding aids and retarders: While grinding the ingredients, the amount of triethanolamine and polyol added is controlled by a metering pump, so that the added amounts account for 0.03% and 0.05% of all the ingredients in the cement mill, respectively. The flow rate controlled by the metering pump is 160 L / h. The adding point is the position where the cement mill is directly added from the grinding head to the inside of the mill. After the grinding process is completed, a retarded silicate cement product for road base is obtained;

[0078] (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

[0079] The road base prepared in Examples 1-4 was tested for composition using slow-setting silicate cement, and the results are shown in Table 2 below.

[0080] Table 2 Composition and content of slow-setting silicate cement for road base of Examples 1-3

[0081]

[0082]

[0083] The road base prepared in Examples 1-4 was tested for performance using slow-setting silicate cement. The test method was as follows: the specific test method was carried out in accordance with the standard GB / T1346-2011 "Test Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency", the stability immersion method was carried out in accordance with the standard "JC / T1099-2009 Calcium Sulphoaluminate Modified Portland Cement", the autoclave stability was carried out in accordance with the standard "GB / T750-1992 Test Method for Autoclave Stability of Cement", the fineness was carried out in accordance with the standard "GB / T1345-2005 Test Method for Cement Fineness", the cement strength was carried out in accordance with the standard "GB / T17671-1999 Test Method for Strength of Cement Mortar (ISO Method)", and the expansion rate test was carried out in accordance with the standard "JC / T313-2009 Test Method for Expansion Rate of Expansive Cement".

[0084] The test results are shown in Table 3 below.

[0085] Table 3 Performance parameters of slow-setting silicate cement for road base of Examples 1-4

[0086]

[0087] It can be seen from Table 2 and Table 3 that the component materials in the slow-setting silicate cement for the road base of the present invention are ≥ 32%, SO 3: 4.8-5.5%, f-CaO≤0.8%, MgO≤3.5%, 45um fineness≤15%, 7-day expansion rate of slow-setting silicate cement ≥0.10%, 28-day expansion rate ≤0.35%, 7-day compressive strength ≥16.0MPa, 28-day compressive strength ≥36.0MPa, initial setting time ≥300min, final setting time ≥360min and ≤500min, autoclave stability 0.04%, boiling method and immersion method stability are both qualified.

[0088] Table 4 Cost of slow-setting silicate cement for road base of Example 1-4 (calculated based on the preparation of one ton of cement)

[0089]

[0090] As shown in Table 4, the cost of the retarded silicate cement for road base of the present invention is about 180.6 yuan / ton, and the cement cost is low. Patent Publication No. CN 109503006 A discloses a retarded silicate cement for road base and a production method, and the cement formula disclosed in Example 2 of its specification is: 50% clinker, 7% desulfurized gypsum, 7% limestone, 6% slag, 30% fly ash, and 0.8% grinding aid. The raw material cost calculated by producing one ton of cement is 227.96 yuan. Compared with the raw material cost of the cement production, the raw material cost of the cement of the present invention is reduced by about 20.78%, indicating that the present invention can effectively reduce the cost of cement production and increase the benefits of enterprises.

[0091] The present invention adds a large amount of industrial waste slag desulfurization gypsum and phosphogypsum when preparing cement, and at the same time adds low-priced limestone inactive admixtures, and adds less expensive fly ash active admixtures, thereby reducing material waste caused by high dosage of active admixtures, saving cement clinker resources, and comprehensively utilizing industrial waste slag, achieving the purpose of comprehensive resource utilization, energy conservation and emission reduction, while reducing cement production costs and increasing corporate benefits.

Claims

1. A slow-setting silicate cement for road base, characterized in that: The invention comprises the following raw materials in weight percentage: 56-59% clinker, 10-14% limestone, 8-12% fly ash, 6-10% granulated blast furnace slag powder, 4-6% desulfurized gypsum, and 4-6% phosphogypsum; based on the raw materials as 100%, the invention also comprises 0.03-0.04% of a grinding aid and 0.05-0.06% of a retarder; the grinding aid is any one of ammonium acetate, triethanolamine, propylene glycol, ethylene glycol, decanoic acid, and cyclohexane acid, or a combination of two or more thereof; The quality control requirements for the raw materials are: Clinker: f-CaO≤1.5%, SO3≤1.0%, 3-day and 28-day compressive strength ≥28.0 MPa and ≥57.0 MPa respectively; Limestone: CaCO3 52-90%, Al2O3 0.1-2.5%, particle size ≤25 mm; Desulfurized gypsum: pH ≥ 5.0, Cl - ≤0.5%; Phosphogypsum: pH value ≥8.0, setting time is longer than that of natural gypsum, with final setting ≥120 min and ≤300 min; The slow-setting silicate cement used for the road base has a 7-day antenna expansion rate ≥ 0.10%, a 28-day antenna expansion rate ≤ 0.35%, a 7-day compressive strength ≥ 16.0 MPa, a 28-day compressive strength ≥ 36.0 MPa, an initial setting time ≥ 300 min, a final setting time ≥ 360 min and ≤ 500 min, an internal irradiation index IRa ≤ 0.4, an external irradiation index IR ≤ 0.4, an autoclave stability of 0.04%, and both the boiling method and the immersion method stability are qualified.

2. The slow-setting silicate cement for road base according to claim 1, characterized in that: The invention comprises the following raw materials in weight percentage: 58.3% clinker, 13% limestone, 10% fly ash, 8% granulated blast furnace slag powder, 5.5% desulfurized gypsum, and 5.2% phosphogypsum; based on the raw materials being 100%, the invention also comprises 0.03% grinding aid and 0.05% retarder.

3. The slow-setting silicate cement for road base according to claim 1, characterized in that: The retarder is any one or two of hydroxycarboxylate and its derivatives, and high-sugar lignin sulfonate.

4. The slow-setting silicate cement for road base according to claim 1, characterized in that: The total content of mixed material components in the slow-setting silicate cement for the road base is ≥32%, SO3: 4.8-5.5%, f-CaO≤0.8%, MgO≤3.5%, and 45μm fineness≤15%.

5. A method for preparing slow-setting silicate cement for road base as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Batching and storage: clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum are transported to the batching warehouse through the conveying system; (2) Measuring and batching: The clinker, limestone, fly ash, granulated blast furnace slag powder, desulfurized gypsum and phosphogypsum in the batching warehouse are measured and batched according to the weight percentage of the raw materials through the metering system; (3) Grinding process: transport the measured ingredients into the cement mill and start the cement mill for grinding process; (4) Adding grinding aids and retarders: While the ingredients are being ground, the amount of grinding aids and retarders added is controlled by a metering pump and evenly added to the cement mill from the point of incorporation. After the grinding process is completed, the cement product is obtained. (5) Cement packaging: The obtained cement products are packaged in cement bulk machines and packaging machines.

6. The method for preparing slow-setting silicate cement for road base according to claim 5, characterized in that: In step (3), the stirring speed of the grinding process is 1200 to 2000 rpm, and the stirring time is 2.5 to 8 h.

7. The method for preparing slow-setting silicate cement for road base according to claim 5, characterized in that: In step (4), the flow rate controlled by the grinding aid and retarder metering pump is 120 to 180 L / h.

8. The method for preparing slow-setting silicate cement for road base according to claim 7, characterized in that: In step (4), the grinding aid and retarder are added dropwise from the grinding head of the cement mill to the position inside the mill.

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