CN1323975C - Efficient corrosion inhibifing water reducing and plasticity keeping agent for steel pipe concrete - Google Patents

Abstract

The invention relates to a retarding high-efficiency water-reducing and plastic-retaining agent for steel tube concrete. The slow-setting high-efficiency water-reducing and plastic-retaining agent for steel tube concrete is characterized in that it is a water agent compounded by polycarboxylate water-reducing agent, sodium gluconate, and zinc sulfate, with a solid content of 30-36%; The solid mass ratio of polycarboxylate water reducer, sodium gluconate, and zinc sulfate is: polycarboxylate water reducer: sodium gluconate: zinc sulfate = 87-94.5%: 5-10%: 0.5-3%, each The sum of the components is 100%. The retarding high-efficiency water-reducing and plastic-preserving agent of the present invention has the advantages of low air-entrainment, high water-reducing rate, and good plastic-retaining performance. It can effectively improve the fluidity and workability of freshly mixed steel pipe concrete, and significantly improve the construction performance of steel pipe concrete pumping. , reduce the air content of concrete, improve the debonding phenomenon between the steel pipe wall and concrete, improve the strength and durability of steel pipe concrete, and increase the bearing capacity of steel pipe concrete structures.

Description

Slow-setting high-efficiency water-reducing and plastic-retaining agent for steel tube concrete

technical field

The invention belongs to the category of concrete admixtures, and in particular relates to a retarding, high-efficiency, water-reducing and plastic-retaining agent for steel tube concrete.

Background technique

Due to its outstanding advantages and characteristics, the CFST structure has broad application prospects in modern high-rise buildings and long-span arch bridges. The construction technology of concrete-filled steel tubes mostly adopts the pumping jacking method, so special requirements are put forward for the working performance and hardening performance indicators of concrete-filled steel tubes: firstly, the concrete is required to have good pumpability and operability (the initial setting time must meet the requirements of concrete The time required for pumping jacking and the slump loss of fresh concrete in a long period of time should be small); second, the concrete is required to have suitable compensation shrinkage performance and certain self-compacting performance to ensure that the concrete and steel pipe It has good bonding and integrity, and participates in the force bearing together; third, the core concrete should have early strength characteristics and appropriate rigidity to ensure that when pouring concrete filled steel pipes sequentially, especially the truss arch ribs composed of multiple steel pipes Alignment of ribs in process.

When designing the mix ratio of concrete-filled steel tubes, it is usually used to add a certain amount of concrete water-reducing agent (or composite admixture) to prepare concrete-filled steel tubes that meet the requirements of the pumping construction process. At present, naphthalene-based high-efficiency water reducers are mainly used to compound plastic-retaining ingredients such as sodium gluconate, or naphthalene-based and sulfamate-based water-reducers are used to prepare concrete filled steel tubes. The amount of air-entraining admixture used in concrete filled steel pipe concrete has a great influence on the bond between the steel pipe wall and concrete. The admixture mixed in the preparation of concrete has a large amount of air-entraining, which leads to an excessive amount of gas introduced into the concrete. During the pumping and jacking construction of steel pipe concrete, the introduced gas is very easy to be absorbed by the pumping pressure and the concrete itself. Under the action of gravity, it is adsorbed on the inner wall of the steel pipe and enriched to form a layer of gas film, which offsets the expansion of the core concrete and easily causes the steel pipe wall to debond from the concrete. Usually, the air content of steel pipe concrete is 2.3%-3.0%. When the air content of the core concrete is 2.3%, the pumping pressure of the concrete during the construction process can reach 10MPa, when the air content of the core concrete is 2.3%. Under the action of self-weight, 0.2%-0.5% of the concrete volume will be enriched at the inner wall of the steel pipe. Calculated at the minimum value of 0.2%, a circular gap with a width of 0.5mm will be formed between the concrete and the inner wall of the steel pipe. Therefore, the expansion rate of the core concrete is required to be at least greater than 10×10 ^-4 to ensure that no debonding occurs. In the vicinity of the vault of the steel pipe arch, the phenomenon of air adsorption and enrichment caused by concrete gravity settlement and pumping pressure is more serious, so the probability of debonding is greater, thereby reducing the integrity of the steel pipe concrete structure and deteriorating its structural mechanical properties. In addition, sulfamic acid water reducers are easy to cause concrete to bleed, and the concrete slump made with naphthalene water reducers has a large loss over time, and it is difficult to prepare high-performance steel pipe expansion concrete that meets the construction requirements.

Contents of the invention

In view of the above main problems, the object of the present invention is to provide a slow-setting, high-efficiency, water-reducing and plastic-retaining agent for concrete-filled steel tubes with low air-entrainment and high water-reducing rate, which can effectively improve the fluidity and workability of freshly mixed steel tube concrete , Significantly improve the concrete-filled steel pipe concrete pumping construction performance, reduce the air content of concrete, improve the debonding phenomenon between the steel pipe wall and concrete, improve the strength and durability of steel pipe concrete, and increase the bearing capacity of steel pipe concrete structures.

In order to achieve the above purpose, the technical solution of the present invention is: using the characteristics of high water-reducing rate and low air-entraining capacity of polycarboxylic acid, compounding retarding and plastic-retaining components, and preparing WUT-G, a special retarding and high-efficiency water-reducing and plastic-retaining agent for steel pipe concrete . It is characterized in that: it is a water agent compounded by polycarboxylate water reducer, sodium gluconate and zinc sulfate, with a solid content of 30-36%; among them, polycarboxylate water reducer, sodium gluconate and zinc sulfate The solid mass ratio is: polycarboxylate water reducer: sodium gluconate: zinc sulfate = (87-94.5)%: (5-10)%: (0.5-3)%, the sum of each component is 100%. After being used for the preparation of steel pipe concrete, it can significantly improve the working performance of concrete, reduce the air content of concrete, make the air content of concrete ≤ 1.5%, reduce the debonding of steel pipe and concrete caused by gas adhesion on the inner wall of steel pipe, and improve the performance of steel pipe concrete. strength and bearing capacity.

The preparation method of the slow-setting high-efficiency water-reducing and plastic-retaining agent for steel tube concrete comprises the following steps: 1). The selection of polycarboxylate water-reducing agent: the average molecular weight of the polymer is 11000-15000, and at the same time, in order to ensure that WUT-G The amount of air-entraining is very small, the number of polyoxyethylene groups (ie, EO addition number) as one of the side chains in the molecular structure of the polycarboxylic acid used is greater than 60, and the molar ratio of carboxylic acid groups to ester groups in the molecule (m/n) 1.9-2.1 to ensure the adaptability of WUT-G to cement. 2). Accurately weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate and water according to the ratio, dissolve sodium gluconate, zinc sulfate and water in sequence in the weighed polycarboxylate superplasticizer, and stir thoroughly Mix it evenly to get the product with a solid content of 30-36%. According to the different proportions of raw materials in WUT-G, the optimal dosage in different strength grades of steel pipe expansive concrete is different: the dosage in C50 steel pipe concrete is 0.9%-1.3%, and the dosage in C60 steel pipe concrete is 1.2%-1.6%. , its performance index is tested according to GB8076-1997, and the results are shown in Table 1 below:

Table 1 Properties of concrete mixed with WUT-G Water reduction % Bleeding rate% Gas content% Coagulation time difference/min compressive strength ratio initial setting final set 7d 28d ≥30 ≤95 ≤1.5 +360 - ≥128 ≥116

The high-efficiency retarding water-reducing and plastic-retaining agent WUT-G has the advantages of low air-entrainment and high water-reducing rate. The air content can improve the debonding phenomenon between the steel pipe wall and the concrete, improve the strength and durability of the steel pipe concrete, and increase the bearing capacity of the steel pipe concrete structure.

Experimental research shows that for a concrete-filled steel tube arch bridge with a diameter of 1m and a span of 200-300m, the construction pumping pressure is 10-20MPa, and when the air content of the core concrete is less than 1.5%, the amount of air adsorbed on the steel tube wall only accounts for 1% of the concrete volume. 0.02%-0.05%, based on the maximum value of 0.05%, the annular gap formed at the steel pipe wall is 0.13mm, so the steel pipe concrete with an expansion rate of 3×10 ^-4 developed through the optimization design of the mix ratio can completely solve the problem of the steel pipe wall. debonding from concrete.

Detailed ways

Example 1:

1). Selection of polycarboxylate superplasticizer: The polyoxyethylene group (ie, EO addition number) as one of the side chains in the molecular structure is 68, and the molar ratio of carboxylic acid group to ester group in the molecule (m /n) is a polycarboxylate water-reducer of 2, and its average molecular weight is 11400; 2). According to polycarboxylate water-reducer: sodium gluconate: zinc sulfate=94.5%: 5%: 0.5% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve them, and adjust the solid content of the solution to 33% by adding water. % and mix evenly to get the product. A certain amount of this product is mixed into the C50 concrete filled steel tube with the mix ratio shown in Table 2 below to obtain a concrete filled steel tube material with good mechanical properties and working properties. The concrete raw materials are: P.O 42.5 cement produced by Huaxin Cement Co., Ltd., Class I fly ash of Yangluo Power Plant, Wuhan Iron and Steel Haoyuan UEA-H expansion agent, 5-25mm continuous graded broken basalt, fineness modulus of 2.6-2.7 Sand in the Ba River. The experimental results are shown in Table 2:

Table 2 Implementation results of C50 steel tube concrete mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength/MPa Concrete air content/% 0h 1.5h 3 hours 5h 415:53:63.5:162:740:905 1.0 63 23.5 21.5 20 15 60.8 1.3 440:60:60:170:610:1120 1.0 60 twenty three 21.5 19.5 14 69 1.5 460:60:60:190:669:1004 0.9 61 23.5 twenty one 20 14 64 1.4

Example 2:

1). Selection of polycarboxylate superplasticizer: The polyoxyethylene group (ie, EO addition number) as one of the side chains in the molecular structure is 68, and the molar ratio of carboxylic acid group to ester group in the molecule (m /n) is a polycarboxylate water-reducer of 2, and its average molecular weight is 11400; 2). According to polycarboxylate water-reducer: sodium gluconate: zinc sulfate=90%: 8%: 2% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve them, and adjust the solid content of the solution to 33% by adding water. % and mix evenly to get the product. A certain amount of this product is mixed into the C50 concrete filled steel tube with the mix ratio shown in Table 3 to obtain a concrete filled steel tube material with good mechanical properties and working properties. The concrete raw materials are: P.O 42.5 cement produced by Huaxin Cement Co., Ltd., Class I fly ash of Wuhan Huadian Industrial Co., Ltd., Jingmen Jinshi company EA concrete expansion agent, Yangxin 5-20mm continuous graded crushed stone, Bahe fineness mold The number is 2.6-2.8 medium sand. The experimental results are shown in Table 3:

Table 3 Implementation results of C50 steel tube concrete mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength MPa Concrete air content/% 0h 1.5h 3 hours 5h 415:55:65:165:748:952 1.1 64 twenty four 22.5 twenty one 16 62.1 1.4 430:60:65:170:617:1098 1.1 62 twenty three twenty two 20.5 15 65.3 1.4 460:60:65:188:692:1038 1.0 61.5 twenty three twenty one 20.5 15 64 1.3

Example 3:

1). Selection of polycarboxylate superplasticizer: the number of polyoxyethylene groups (ie, EO addition number) as one of the side chains in the molecular structure is 68, and the molar ratio of carboxylic acid groups to ester groups in the molecule (m /n) is a polycarboxylate water-reducer of 2, and its average molecular weight is 11400; 2). According to polycarboxylate water-reducer: sodium gluconate: zinc sulfate=87%: 10%: 3% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve them, and adjust the solid content of the solution to 33% by adding water. % and mix evenly to get the product. A certain amount of this product is mixed into the C50 steel tube concrete with the mix ratio shown in Table 4 to obtain a steel tube concrete material with good mechanical properties and working properties. The concrete raw materials are: P.O 42.5 cement produced by Huaxin Cement Co., Ltd., Class I fly ash of Wuhan Huadian Industrial Co., Ltd., Jingmen Jinshi company EA concrete expansion agent, Yangxin 5-20mm continuous graded crushed stone, Bahe fineness mold The number is 2.6-2.8 medium sand. The experimental results are shown in Table 4:

Table 4 Implementation results of C50 concrete filled steel pipe mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength/MPa Concrete air content/% 0h 1.5h 3 hours 5h 410:55:65:160:719:993 1.3 63 23.5 twenty two twenty one 19 60.1 1.3 430:60:65:170:617:1098 1.2 64 twenty three 21.5 20.5 18 66 1.3 460:60:65:185:684:986 1.1 60 twenty three twenty two 20.5 18 65.7 1.4

Example 4:

1). Selection of polycarboxylate superplasticizer: The number of polyoxyethylene groups (ie, EO addition number) as one of the side chains in the molecular structure is 61, and the molar ratio of carboxylic acid groups to ester groups in the molecule (m /n) is a polycarboxylate water reducer of 1.9, and its average molecular weight is 11000; 2). According to polycarboxylate water reducer: sodium gluconate: zinc sulfate=94.5%: 5%: 0.5% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve them, and adjust the solid content of the solution to 30% by adding water. % and mix evenly to get the product. A certain amount of this product is mixed into the C60 concrete filled steel tube with the mix ratio shown in Table 5 to obtain a concrete filled steel tube material with good mechanical properties and working properties. The concrete raw materials are: P.O 52.5 cement produced by Huaxin Cement Co., Ltd., Class I fly ash, concrete expansion agent of Wuhan Sanyuan Company, Yichang 5-25mm continuous graded crushed stone, Yichang Qingjiang fineness modulus of 2.6-2.8 sand. The experimental results are shown in Table 5:

Table 5 Implementation results of C60 concrete filled steel pipe mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength MPa Concrete air content/% 0h 1.5h 3 hours 5h 460:70:60:180:660:1010 1.6 61 twenty four 22.5 twenty one 19.5 73.1 1.4 470:70:55:185:625:1010 1.6 62 23.5 21.5 20 18 79.3 1.4

Example 5:

1). Selection of polycarboxylate superplasticizer: the number of polyoxyethylene groups (ie, EO addition number) as one of the side chains in the molecular structure is 68, and the molar ratio of carboxylic acid groups to ester groups in the molecule (m /n) is a polycarboxylate water-reducer of 2.1, and its average molecular weight is 15000; 2). According to polycarboxylate water-reducer: sodium gluconate: zinc sulfate=90%: 8%: 2% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve, and add water to adjust the solid content of the solution to 36 % and mix evenly to get the product. A certain amount of this product is mixed into the C60 concrete filled steel tube with the mix ratio shown in Table 6 to obtain a concrete filled steel tube material with good mechanical properties and working properties. The raw materials of concrete are the same as above-mentioned example 4, and the experimental results are shown in Table 6:

Table 6 Implementation results of C60 concrete filled steel pipe mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength/MPa Concrete air content/% 0h 1.5h 3 hours 5h 450:60:60:175:660:1010 1.4 64 twenty four 22.5 twenty one 18.5 72.9 1.5 460:70:55:180:655:1050 1.4 62 twenty three twenty two 20.5 18 76 1.4

Example 6:

1). Selection of polycarboxylate superplasticizer: the number of polyoxyethylene groups (ie, EO addition number) as one of the side chains in the molecular structure is 68, and the molar ratio of carboxylic acid groups to ester groups in the molecule (m /n) is a polycarboxylate water-reducer of 2, and its average molecular weight is 11400; 2). According to polycarboxylate water-reducer: sodium gluconate: zinc sulfate=87%: 10%: 3% solid mass proportioning is accurate Weigh polycarboxylate superplasticizer, sodium gluconate, zinc sulfate, add sodium gluconate and zinc sulfate in sequence to the weighed polycarboxylate superplasticizer and stir to fully dissolve them, and adjust the solid content of the solution to 33% by adding water. % and mix evenly to get the product. A certain amount of this product is mixed into the C60 concrete filled steel tube with the mix ratio shown in Table 7 to obtain a concrete filled steel tube material with good mechanical properties and working properties. The raw materials of concrete are the same as those in Application Example 4, and the experimental results are shown in Table 7:

Table 7 Implementation results of C60 concrete filled steel pipe mixed with WUT-G Cement: fly ash: expansion agent: water: sand: gravel (kg/m ³ ) WUT-G content/% Expansion/cm Slump/cm 28d Strength/MPa Concrete air content/% 0h 1.5h 3 hours 5h 450:70:60:175:625:1020 1.2 60 twenty three 21.5 20 18 72 1.4 440:70:55:172:649:1014 1.2 61.5 twenty three twenty two 21.5 18.5 75.6 1.3

Claims (3)

1. be used for the efficient corrosion inhibifing water reducing and plasticity keeping agent of concrete filled steel tube, it is characterized in that: it is the aqua that is composited by polycarboxylate water-reducer, Sunmorl N 60S, zinc sulfate, and solid content is 30-36%; Wherein the solid masses proportioning of polycarboxylate water-reducer, Sunmorl N 60S, zinc sulfate is: polycarboxylate water-reducer: Sunmorl N 60S: zinc sulfate=87-94.5%: 5-10%: 0.5-3%, the each component sum is 100%.

2. the efficient corrosion inhibifing water reducing and plasticity keeping agent that is used for concrete filled steel tube according to claim 1, it is characterized in that: the molecular-weight average of described polycarboxylate water-reducer is at 11000-15000, in the used poly carboxylic acid molecular structure as the polyoxyethylene radix of one of side chain greater than 60, and the mol ratio of carboxylic acid group and ester group is 1.9-2.1 in the molecule.

3. the application that is used for the efficient corrosion inhibifing water reducing and plasticity keeping agent of concrete filled steel tube as claimed in claim 1 is characterized in that: volume is 0.9%-1.3% in the C50 concrete filled steel tube, and volume is 1.2%-1.6% in the C60 concrete filled steel tube.