Cementing material for pressure-steaming-free pipe pile and preparation method of cementing material

Abstract

The invention discloses a cementing material for a non-autoclaved tubular pile and a preparation method of the cementing material. The cementing material comprises the following components in percentage by mass: 45-75% of blast furnace water-quenched slag, 5-20% of first-grade fly ash, 5-12% of ferrosilicon fly ash and 15-35% of an early strength agent. According to the gelling material for the pressure-steaming-free pipe pile, the unique physicochemical properties of various solid wastes are fully utilized, the gelling material with high early strength, low hydration heat and small shrinkage is cooperatively prepared, the early strength is high, the pressure autoclaving process (autoclave high-pressure and high-temperature curing at the temperature of about 180 DEG C) is reduced, and the production cost of the pipe pile is remarkably reduced. Meanwhile, the cementing material disclosed by the invention can reduce the use amount of high-grade cement in tubular pile production to the greatest extent, so that not only is the cost reduced, but also the emission of carbon dioxide is indirectly reduced.

Description

Technical Field

[0001] The present invention relates to the technical fields of comprehensive utilization of solid waste and building materials, and particularly to a gelling material for non-pressure-steamed pipe piles and a preparation method thereof. Background Art

[0002] PHC pipe piles have obvious advantages compared with other pipe piles, such as high single-pile bearing capacity, reliable pile driving quality, wide application range, and indirect economic benefits, etc., and are widely used in the construction field. In recent years, with the implementation of the national strategies for promoting environmental protection, energy conservation and emission reduction, not only better quality and strength of PHC pipe piles are required, but also more stringent energy conservation, environmental protection requirements are put forward for PHC pipe piles.

[0003] Nowadays, most PHC pipe pile production enterprises carry out normal-pressure steam curing through a steam pool at about 90 °C, and then carry out high-temperature and high-pressure secondary curing in an autoclave under the conditions of 180 °C and 1 MPa. However, this process has some problems. For example, during the normal-pressure steam curing process, too rapid temperature change will cause cracks in the pile body of PHC pipe piles, thereby reducing the strength of PHC pipe piles. The autoclave consumes a large amount of resources and causes environmental pollution. In addition, the maintenance cost and investment cost required by the autoclave are relatively high.

[0004] In recent years, a large number of studies have been carried out on the non-steam-curing and non-pressure-steaming production technologies of PHC pipe piles at home and abroad. Compared with the traditional high-pressure autoclave technology, the non-high-pressure autoclave production technology can improve the chloride ion penetration resistance, frost resistance and anti-hammering performance of pile concrete, which is beneficial to the construction of the hammer-driven pile sinking method for prestressed high-strength concrete pipe piles. At the same time, the non-high-pressure autoclave production process is also beneficial to reducing the pile-making cost, promoting environmental protection and saving resources. At present, the non-pressure-steaming production process of PHC pipe piles mainly focuses on preferentially selecting raw materials and incorporating admixtures such as fly ash microspheres or silica fume powder. However, this production process still requires a large amount of high-grade cement to be used, with limited carbon reduction effect and high cost. Therefore, pipe pile production enterprises are in urgent need of a new type of low-cost gelling material that can minimize the use of high-grade cement and has good early strength. Summary of the Invention

[0005] Aiming at the technical defects mentioned in the background art, the purpose of the present invention is: one is to provide a gelling material for non-pressure-steamed pipe piles, and the other is to provide a preparation method of this gelling material, so as to improve the early strength of the pipe piles, reduce the shrinkage of pile concrete, omit the autoclave curing process to reduce costs, reduce the use of high-grade cement, and achieve the best carbon reduction effect.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions: A cementitious material for non-steam-cured pipe piles, and the components of the cementitious material are respectively in mass percentages: 45%-75% of blast furnace granulated slag, 5%-20% of first-class fly ash, 5%-12% of ferrosilicon dust removal ash, and 15%-35% of early strength agent.

[0007] As a preferred technical solution: The raw materials of the early strength agent and their mass percentages are: 17% of aluminum ash, 16% of anhydrous sodium sulfate, 22% of coal gangue, 24% of desulfurization ash, 10% of carbide slag, and 11% of iron tailings.

[0008] As a preferred technical solution: In the early strength agent: the mass percentage of Al2O3 in the aluminum ash ≥ 68%; the mass percentage of Na2SO4 in the anhydrous sodium sulfate ≥ 89%; the mass percentage of CaO in the desulfurization ash ≥ 65%.

[0009] As a preferred technical solution: The mass percentage of CaO and SiO2 in the blast furnace granulated slag ≥ 82%.

[0010] As a preferred technical solution: The mass percentage of Al2O3 and SiO2 in the first-class fly ash ≥ 78%.

[0011] As a preferred technical solution: The mass percentage of SiO2 in the ferrosilicon dust removal ash ≥ 90%.

[0012] A preparation method of the cementitious material for non-steam-cured pipe piles as described in any one of claims 1-6, and the specific preparation steps are as follows: Step S1. Mix each component in the early strength agent and put it into a kiln, calcine it in a high-temperature environment of 1300°C - 1350°C for 30 - 45 minutes, and grind the obtained massive early strength agent after calcination until the specific surface area ≥ 480m 2 / kg; Step S2. Grind the blast furnace granulated slag and the first-class fly ash respectively, and the specific surface areas of the two materials after grinding are both ≥ 600m 2 / kg to obtain granulated slag micro powder and fly ash, and set aside; Step S3. Mix the early strength agent obtained in Step S1, the granulated slag micro powder, fly ash and ferrosilicon dust removal ash obtained in Step S2 in proportion and mix them evenly to make a cementitious material for non-steam-cured pipe piles.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. First, the present invention uses various difficult-to-utilize industrial solid wastes such as aluminum ash, sodium sulfate, coal gangue, desulfurized ash, carbide slag, and iron tailings to prepare an early strength agent. The mineral composition of the calcined early strength agent is similar to that of sulfoaluminate cement clinker, which can fully stimulate the early activity of granulated blast furnace slag powder. Therefore, in terms of technical principle, this technology can enable enterprises to reduce the use of high-grade cement in pipe pile concrete while still generating stable hydration products such as calcium silicate hydrate gel and ettringite. The quantity of beneficial hydration products generated by the hydration of granulated blast furnace slag powder is higher than that generated by the hydration of the same amount of cement. In addition, the hydration products of the cementitious system of the present invention are different from those of the cement system. The generated hydration products do not contain a large amount of Ca(OH)2 crystals and are not easily corroded and damaged by external soft water, acids, alkalis, salts, etc., thus enabling the pipe pile concrete to have better durability. The unhydrated fine powder particles aggregate between the aggregate and the slurry, acting as a micro-aggregate, which can improve the state of the weak transition zone between the aggregate and the cementitious material, thereby increasing the early strength of the autoclave-free pipe pile and ensuring its later strength growth.

[0014] 2. The present invention provides a cementitious material for autoclave-free pipe piles for preparing PHC pipe pile concrete. During the production process of PHC pipe piles, the substitution rate of high-grade cement can reach 40%-60%, which can achieve a significant carbon reduction effect and is beneficial to the low-carbon development of enterprises. At the same time, the cementitious system in the present invention can fully exert the activity of granulated blast furnace slag powder, ensuring the early strength of the pipe pile, having low heat of hydration, small shrinkage and being not easy to crack, eliminating the autoclave curing process, greatly reducing the production cost of enterprises, and realizing the high-quality development of enterprises. Detailed Embodiment

[0015] To make the above objects, features, and advantages of the present invention more obvious and understandable, the detailed embodiments of the present invention will be described in detail. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0016] The cementitious material for autoclave-free pipe piles disclosed by the present invention, its components are in mass percentages respectively: granulated blast furnace slag 45%-75%, first-class fly ash 5%-20%, ferrosilicon dust removal ash 5%-12%, early strength agent 15%-35%.

[0017] As a preferred solution, the raw material mass percentages of the early strength agent are: aluminum ash 17%, sodium sulfate 16%, coal gangue 22%, desulfurized ash 24%, carbide slag 10%, iron tailings 11%.

[0018] As another preferred solution: the mass percentage of CaO and SiO2 in blast furnace slag is ≥82%. The mass percentage of Al2O3 and SiO2 in primary fly ash is ≥78%. The mass percentage of SiO2 in ferrosilicon dust removal ash is ≥90%.

[0019] As another preferred solution: the mass percentage of Al2O3 in the aluminum ash in the early strength agent is ≥68%, the mass percentage of Na2SO4 in the sodium sulfate is ≥89%, and the mass percentage of CaO in the desulfurization ash is ≥65%.

[0020] The preparation process of the present invention is described in detail below with specific examples. Example 1

[0021] The method for preparing the gelling material for the pressure-free steaming pipe pile of the present invention comprises the following specific steps: Step S1. Mix the components of the early strength agent according to the above predetermined proportions and put them into a kiln for calcination at 1300°C for 30 minutes. Grind the block early strength agent obtained after calcination until the specific surface area is ≥480m 2 / kg.

[0022] Step S2: Grind the blast furnace slag and primary fly ash separately, and the specific surface area of the two raw materials after grinding is ≥600m 2 / kg, to obtain water-quenched slag powder and fly ash.

[0023] Step S3. The early strength agent obtained in step S1, the water-quenched slag powder obtained in step S2, fly ash and ferrosilicon dust removal ash are mixed in a mass percentage of 30:45:15:10 to finally prepare a cementitious material for pressure-free steaming pipe piles. Example 2

[0024] The method for preparing a gelling material for pressure-free steaming pipe piles in the present invention comprises the following specific steps: Step S1. Mix the components of the early strength agent in proportion and put them into a kiln for calcination at 1350°C. Grind the block early strength agent obtained after calcination until the specific surface area is ≥480m 2 / kg.

[0025] Step S2: Grind the blast furnace slag and primary fly ash separately, and the specific surface area of the two raw materials after grinding is ≥600m 2 / kg, to obtain water-quenched slag powder and fly ash.

[0026] Step S3. The early strength agent obtained in step S1, the water-quenched slag powder obtained in step S2, fly ash and ferrosilicon dust removal ash are mixed in a mass percentage of 25:55:10:10 to finally prepare a cementitious material for pressure-free steaming pipe piles. Example 3

[0027] The method for preparing the gelling material for the pressure-free steaming pipe pile of the present invention comprises the following specific steps: Step S1. Mix the components of the early strength agent in proportion and put them into a kiln for calcination at 1320°C. Grind the block early strength agent obtained after calcination to a specific surface area of ≥480m 2 / kg.

[0028] Step S2: Grind the blast furnace slag and primary fly ash separately, and the specific surface area of the two raw materials after grinding is ≥600m 2 / kg, to obtain water-quenched slag powder and fly ash.

[0029] Step S3. The early strength agent obtained in step S1, the water-quenched slag powder obtained in step S2, fly ash and ferrosilicon dust removal ash are mixed in a mass percentage of 20:65:5:10 to finally prepare a cementitious material for pressure-free steaming pipe piles. Example 4

[0030] The method for preparing the gelling material for pressure-free steaming pipe piles of the present invention has the following specific steps.

[0031] Step S1. Mix the components of the early strength agent in proportion and put them into a kiln for calcination at 1300-1350°C. Grind the block early strength agent obtained after calcination until the surface area is ≥480m 2 / kg.

[0032] Step S2: Grind the blast furnace slag and primary fly ash separately, and the specific surface area of the two raw materials after grinding is ≥600m 2 / kg, to obtain water-quenched slag powder and fly ash.

[0033] Step S3. The early strength agent obtained in step S1, the water-quenched slag powder obtained in step S2, fly ash and ferrosilicon dust removal ash are mixed in a mass percentage of 15:75:5:5 to finally prepare a cementitious material for pressure-free steaming pipe piles.

[0034] Experimental comparison demonstration The cementitious materials obtained in Examples 1-4 were used to prepare concrete according to the following mix ratio: cement 180 kg / m 3 , cementitious material 240 kg / m 3 , sand 660kg / m 3 , stone 1320 kg / m 3 , water 115 kg / m 3 , polycarboxylate high efficiency water reducing agent 6.05 kg / m 3 .

[0035] Comparative Example 1 Prepare ordinary concrete according to the following mix proportions. The concrete mix proportion is as follows: cement 420 kg / m 3 , sand 660 kg / m 3 , gravel 1320 kg / m 3 , water 115 kg / m 3 , polycarboxylate superplasticizer 6.05 kg / m 3 .

[0036] Comparative Example 2 Prepare concrete with the cementitious material obtained in Example 4 according to the following mix proportions. The concrete mix proportion is as follows: cement 170 kg / m 3 , cementitious material 250 kg / m 3 , sand 660 kg / m 3 , gravel 1320 kg / m 3 , water 115 kg / m 3 , polycarboxylate superplasticizer 6.05 kg / m 3 .

[0037] Comparative Example 3 Prepare concrete with the cementitious material obtained in Example 4 according to the following mix proportions. The concrete mix proportion is as follows: cement 160 kg / m 3 , cementitious material 260 kg / m 3 , sand 660 kg / m 3 , gravel 1320 kg / m 3 , water 115 kg / m 3 , polycarboxylate superplasticizer 6.05 kg / m 3 .

[0038] Put the raw materials in the concrete mixer and stir them evenly in Examples 1 - 4 and Comparative Examples 1 - 3. Pour them into a 100 mm × 100 mm × 100 mm mold under the conditions of temperature 20 ± 5°C and relative humidity not less than 60%, and vibrate and form them on a concrete vibrating table. Test their relevant properties; place the prepared concrete test blocks in an autoclave for curing, with the curing temperature of 85°C ± 2°C, demold after curing for 5 h, and then continue to place them in a constant temperature and humidity curing box with a curing temperature of 20°C ± 2°C and relative humidity not less than 95% until the age of 3 d and 28 d. Test the compressive strength of the concrete and test the chloride ion permeability of the concrete at 28 d. The above test results are shown in Table 1:

[0039] As can be seen from Table 1, the gelling material for non-steam-cured pipe piles of the present invention has an obvious improvement effect on the workability, strength and durability of non-steam-cured pipe pile concrete. The specific dosage can be adjusted according to the concrete design parameters. The above specific embodiments are only preferred, but not a limitation on the implementation mode.

[0040] In summary, the gelling material for non-steam-cured pipe piles provided by the present invention can largely replace the use of high-grade cement in the production of PHC pipe piles, achieving a good carbon reduction effect, and at the same time can improve the compressive strength and durability of pipe piles. The advantages of the gelling material of the present invention compared with high-grade cement and other types of admixtures sold on the market are lower raw material costs, high early strength, and the elimination of the steam curing process can greatly reduce the production costs of enterprises. At the same time, a variety of industrial solid wastes are effectively recycled, which has an obvious beneficial effect on the ecological environment.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A cementitious material for prestress-free autoclaved pipe piles, characterized in that, The components of the cementitious material are as follows by mass percentage: granulated blast furnace slag 45% - 75%, Class I fly ash 5% - 20%, ferrosilicon dust removal ash 5% - 12%, early strength agent 15% - 35%; The raw materials of the early strength agent and their mass percentages are: aluminum ash 17%, anhydrous sodium sulfate 16%, coal gangue 22%, desulfurized ash 24%, carbide slag 10%, iron tailings 11%.

2. The cementitious material for prestress-free autoclaved pipe piles according to claim 1, wherein: In the early strength agent: the mass percentage of Al2O3 in aluminum ash ≥ 68%; the mass percentage of Na2SO4 in anhydrous sodium sulfate ≥ 89%; the mass percentage of CaO in desulfurized ash ≥ 65%.

3. The gelling material for prestress-free autoclaved pipe piles according to claim 1, characterized in that: The mass percentage of CaO and SiO2 in the granulated blast furnace slag ≥ 82%.

4. The gelling material for non-autoclaved pipe piles according to claim 1, wherein: The mass percentage of Al2O3 and SiO2 in the Class I fly ash ≥ 78%.

5. The cementitious material for prestress-free autoclaved pipe piles according to claim 1, characterized in that: The mass percentage of SiO2 in the ferrosilicon dust removal ash ≥ 90%.

6. A preparation method of a gelling material for non-autoclaved pipe piles as described in any one of claims 1-5, characterized in that, The specific preparation steps are as follows: Step S1. Mix the components of the early strength agent and put them into a kiln. Calcinate them in a high-temperature environment of 1300°C - 1350°C for 30 - 45 minutes. Grind the obtained massive early strength agent after calcination until the specific surface area is ≥ 480 m 2 / kg; Step S2. Grind the blast furnace granulated slag and the first-class fly ash separately. The specific surface areas of the two materials after grinding are both ≥ 600 m 2 / kg to obtain granulated slag micro-powder and fly ash, and reserve them for use; Step S3. Mix the early strength agent obtained in step S1, the ground granulated blast furnace slag obtained in step S2, fly ash and ferrosilicon dust removal ash in proportion and mix them thoroughly to make a cementitious material for non-autoclaved pipe piles.

Images