Highway bridge high-pier slip-form concrete and preparation method thereof

Abstract

The present application relates to the field of bridge construction technology, especially relates to a kind of highway bridge high pier slipform concrete and preparation method thereof.Slipform concrete includes the following mass fraction components: cement 360-390 parts, fly ash 40-60 parts, natural sand 660-700 parts, gravel 1100-1200 parts, water 155-170 parts, polycarboxylic acid water reducing agent 4.6-5.5 parts, thixotropic agent 0.2-4 parts and early strength agent 0.08-2.1 parts.The present application limits the amount of each component within a reasonable range of values, so that each component can achieve better synergies, better improve the overall performance of slipform concrete, so as to obtain a suitable flow, appropriate slump retention, also with good plasticity and higher early strength and other multiple effects of slipform construction of concrete suitable for highway bridge high pier.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a slipform concrete for high piers of highway bridges and its preparation method. Background Technology

[0002] Slipform construction technology, due to its advantages such as fast construction speed, high degree of mechanization, good structural integrity, small footprint, and reusability, has been increasingly applied to the construction of high piers for highway bridges. According to the slipform construction requirements of a certain highway high pier, the slump of the slipform concrete should be controlled at 180mm-200mm, with a slump retention time of 2 hours, a demolding strength of 0.2MPa-0.4MPa, a slipform height of 300mm per run, and a daily slipform height of 2-5m. Polycarboxylate superplasticizers have a high water reduction rate. With the widespread application of polycarboxylate superplasticizers, concrete typically exhibits high fluidity and poor plasticity retention, severely affecting the construction progress and quality of slipform construction. Therefore, formulating a slipform concrete that meets the workability requirements of the concrete while also possessing good plasticity retention and high early strength is of great significance. Summary of the Invention

[0003] To address the above technical problems, this invention proposes a slipform concrete for high piers of highway bridges and its preparation method.

[0004] According to a first aspect of the present invention, the present invention provides a slipform concrete for high piers of highway bridges, comprising the following components in parts by weight: 360-390 parts cement, 40-60 parts fly ash, 660-700 parts natural sand, 1100-1200 parts crushed stone, 155-170 parts water, 4.6-5.5 parts polycarboxylate superplasticizer, 0.2-4 parts thixotropic agent, and 0.08-2.2 parts early strength agent.

[0005] In the above-mentioned scheme, a slipform concrete for high piers of highway bridges includes cement, fly ash, natural sand, crushed stone, water, polycarboxylate superplasticizer, thixotropic agent, and early-strength agent. By adding polycarboxylate superplasticizer and thixotropic agent, the slipform concrete possesses both the fluidity and slump retention required for construction, as well as good plasticity retention. The addition of early-strength agent allows the slipform concrete to reach the appropriate demolding strength according to the construction schedule, improving construction efficiency without adversely affecting later strength. The slipform concrete of this invention, by limiting the dosage of each component within a reasonable range, allows for better synergistic effects among the components, thus improving the overall performance of the slipform concrete. This results in a concrete suitable for slipform construction of high piers of highway bridges, possessing multiple benefits such as suitable fluidity, appropriate slump retention, good plasticity retention, and high early strength.

[0006] To further improve the overall performance of slipform concrete, the following components are included in parts by weight: 360 parts cement, 50 parts fly ash, 690 parts natural sand, 1150 parts crushed stone, 160 parts water, 4.9 parts polycarboxylate superplasticizer, 0.2 to 4 parts thixotropic agent, and 0.08 to 2.1 parts early strength agent.

[0007] Further, the polycarboxylate superplasticizer comprises the following components in parts by weight: 200-250 parts of polycarboxylate superplasticizer mother liquor, 160-200 parts of polycarboxylate slump-retaining mother liquor, 1-10 parts of air-entraining agent, 1-5 parts of defoamer, and 535-638 parts of water; preferably, the polycarboxylate superplasticizer comprises the following components in parts by weight: 200 parts of polycarboxylate superplasticizer mother liquor, 180 parts of polycarboxylate slump-retaining mother liquor, 2 parts of air-entraining agent, 2 parts of defoamer, and 616 parts of water. The air-entraining agent can be AE-II or K. 12 Defoamers such as ATS-71 can be silicone-based or polyether-based.

[0008] In the above scheme, adding an appropriate amount of air-entraining agent and defoamer to the polycarboxylate high-performance water-reducing agent can make the concrete have a good appearance when it is demolded.

[0009] Furthermore, the early strength agent comprises one or both of nano-CSH nucleus early strength agent and triethanolamine.

[0010] In the above scheme, by selecting a suitable type of early strength agent, the slipform concrete can reach the appropriate demolding strength according to the construction schedule requirements, thereby improving construction efficiency and having no adverse effect on the later strength.

[0011] To achieve a better and more suitable demolding strength, the molar ratio of calcium to silicon in the nano-CSH nucleation early strength agent is further (1-2):1, preferably 1.5:1; and / or the median particle size of the nano-CSH nucleation early strength agent is 100nm-200nm, preferably 150nm.

[0012] Further, the early strength agent comprises a nano-CSH nucleus early strength agent and triethanolamine; preferably, the weight ratio of the nano-CSH nucleus early strength agent to the triethanolamine is (1.3-2.1):(0.08-0.25).

[0013] Furthermore, the thixotropic agent comprises one or more of attapulgite, polyacrylamide, hydroxypropyl methylcellulose ether, and magnesium aluminum silicate.

[0014] In the above scheme, by selecting a suitable type of thixotropic agent, it can achieve a better synergistic effect with polycarboxylate superplasticizer, better meet the requirements of fluidity and slump retention during construction, and at the same time have good plasticity retention.

[0015] Furthermore, the crushed stone has a continuous gradation of 5–31.5 mm.

[0016] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described slipform concrete, comprising the following steps:

[0017] Mix cement, fly ash, natural sand, crushed stone and thixotropic agent evenly to obtain mixture one;

[0018] Mix water, polycarboxylate superplasticizer and early strength agent evenly to obtain mixture two;

[0019] Under stirring conditions, mixture 2 is added to mixture 1 and forcibly stirred until homogeneous to obtain the slipform concrete.

[0020] Furthermore, the forced stirring time is 1-2 minutes, preferably 1.5 minutes.

[0021] The beneficial effects of this invention are:

[0022] A type of slipform concrete for high piers of highway bridges includes cement, fly ash, natural sand, crushed stone, water, polycarboxylate superplasticizer, thixotropic agent, and early strength agent. By limiting the dosage of each component within a reasonable range, the components can achieve better synergistic effects, thereby improving the overall performance of the slipform concrete. This results in concrete with multiple advantages, including suitable fluidity, appropriate slump retention, good plasticity retention, and high early strength, making it suitable for slipform construction of high piers of highway bridges. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 The demolding diagram of the slipform concrete of Embodiment 2 of the present invention in actual application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] For any techniques or conditions not specified in the embodiments and comparative examples, the techniques or conditions described in the literature in this field, or the product instructions, shall be followed. Instruments and other equipment whose manufacturers are not specified can be purchased from reputable suppliers. All chemical raw materials used in this invention are readily available in the domestic chemical market.

[0027] Example 1

[0028] This embodiment provides a slipform concrete for high piers of highway bridges, the composition of which is shown in Table 1 below. Among the raw materials used in Table 1, the polycarboxylate superplasticizer comprises the following components: 200 parts polycarboxylate superplasticizer mother liquor, 180 parts polycarboxylate slump-maintaining mother liquor, 2 parts air-entraining agent, 2 parts defoamer, and 616 parts water. The polycarboxylate superplasticizer mother liquor is a pale yellow liquid with a solid content of 50%, the polycarboxylate slump-maintaining mother liquor is a pale yellow, slow-release type with a solid content of 40%, and the air-entraining agent is K. 12 The defoamer is an organosilicon defoamer.

[0029] Thixotropic agents: attapulgite (A), polyacrylamide (B) (molecular weight 8 million), hydroxypropyl methylcellulose ether (C) (molecular weight 150,000), magnesium aluminum silicate (D).

[0030] Early strength agents: Nano-CSH nucleation early strength agent (E), triethanolamine (F). The preparation method of the nano-CSH nucleation early strength agent is as follows: using PCE as the base solution, calcium nitrate tetrahydrate as the calcium source, and sodium silicate pentahydrate as the silicon source, the mixture is added dropwise at 60℃ under a nitrogen atmosphere for 3 hours, and a nano-CSH suspension with a calcium-to-silicon molar ratio of 1.5 is synthesized by co-precipitation. The median particle size of the nano-CSH nucleation early strength agent is 150 nm.

[0031] The crushed stone has a continuous gradation of 5–31.5 mm. The cement used is PO 42.5 cement.

[0032] The method for preparing slipform concrete includes the following steps:

[0033] Cement, fly ash, natural sand, crushed stone, and thixotropic agent are mixed evenly in a forced mixer to obtain mixture one;

[0034] Mix water, polycarboxylate superplasticizer and early strength agent evenly to obtain mixture two;

[0035] Under stirring conditions, mixture 2 is added to mixture 1 and forcibly stirred for 1.5 minutes to obtain the slipform concrete.

[0036] Table 1

[0037]

[0038]

[0039] Performance tests were conducted on the slipform concrete of Examples 1-10 and Comparative Examples 1-6. The performance indicators were based on GB / T50080—2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures"; GB / T 50081—2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete"; and GB / T50113-2019 "Technical Standard for Slipform Engineering". The test results are shown in Table 2 below. Figure 1 This is a demolding diagram of the slipform concrete of Embodiment 2 of the present invention in actual application. Figure 1 It can be seen that after the concrete is demolded, it has a hardness when pressed by hand and can leave a fingerprint. The surface is smooth and there is no flow or cracking.

[0040] Table 2

[0041]

[0042]

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A slipform concrete method for high piers of highway bridges, characterized in that, The composition includes the following components in parts by weight: 360-390 parts cement, 40-60 parts fly ash, 660-700 parts natural sand, 1100-1200 parts crushed stone, 155-170 parts water, 4.6-5.5 parts polycarboxylate superplasticizer, 0.2-4 parts thixotropic agent, and 0.08-2.2 parts early strength agent; The early strength agent comprises a nano-CSH nucleation early strength agent and triethanolamine; the weight ratio of the nano-CSH nucleation early strength agent to the triethanolamine is (1.3-2.1):(0.08-0.25); the calcium-silicon molar ratio of the nano-CSH nucleation early strength agent is (1-2):1; the median particle size of the nano-CSH nucleation early strength agent is 100nm-200nm; the thixotropic agent comprises one or more of attapulgite, polyacrylamide, hydroxypropyl methylcellulose ether, and magnesium aluminum silicate. The polycarboxylate superplasticizer comprises the following components in parts by weight: 200-250 parts of polycarboxylate superplasticizer mother liquor, 160-200 parts of polycarboxylate slump retainer mother liquor, 1-10 parts of air-entraining agent, 1-5 parts of defoamer, and 535-638 parts of water.

2. The slipform concrete according to claim 1, characterized in that, The components include the following parts by weight: 360 parts cement, 50 parts fly ash, 690 parts natural sand, 1150 parts crushed stone, 160 parts water, 4.9 parts polycarboxylate superplasticizer, 0.2-4 parts thixotropic agent, and 0.08-2.1 parts early strength agent.

3. The slipform concrete according to claim 1, characterized in that, The polycarboxylate superplasticizer comprises the following components in parts by weight: 200 parts polycarboxylate superplasticizer mother liquor, 180 parts polycarboxylate slump retainer mother liquor, 2 parts air-entraining agent, 2 parts defoamer, and 616 parts water.

4. The slipform concrete according to claim 1, characterized in that, The molar ratio of calcium to silicon in the nano-CSH nucleation early strength agent is 1.5:1; and / or, the median particle size of the nano-CSH nucleation early strength agent is 150 nm.

5. The slipform concrete according to claim 1, characterized in that, The crushed stone has a continuous gradation of 5~31.5mm.

6. The method for preparing slipform concrete according to any one of claims 1-5, characterized in that, Includes the following steps: Mix cement, fly ash, natural sand, crushed stone and thixotropic agent evenly to obtain mixture one; Mix water, polycarboxylate superplasticizer and early strength agent evenly to obtain mixture two; Under stirring conditions, mixture 2 is added to mixture 1 and forcibly stirred until homogeneous to obtain the slipform concrete.

7. The preparation method according to claim 6, characterized in that, The forced stirring time is 1-2 minutes.

8. The preparation method according to claim 7, characterized in that, The forced stirring time is 1.5 minutes.

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