A three-stage design method for high tower C55 pumped machine-made sand concrete

Abstract

The present invention relates to the field of building technology, and discloses a three-stage design method for high tower column C55 pumping machine-made sand concrete, wherein the tower column is divided into three stages: a lower tower column, a middle tower column and a "closing section + upper tower column"; wherein the lower tower column is below 40.05-50m, the "closing section + upper tower column" is above 173-180m, and the rest are middle tower columns; the lower tower column adopts a low-glue material and a large amount of mineral admixture to design the concrete mix ratio, so as to reduce the cracking of the lower tower column structure caused by excessive hydration heat; the middle tower column adopts a medium-glue material and a low sand ratio to design the concrete mix ratio, so as to ensure sufficient rigidity and pumpability of the concrete; the "closing section + upper tower column" adopts a high-glue material, a low sand ratio, and a large amount of mineral admixture to design the concrete mix ratio, so as to ensure that the ultra-high pumping of the concrete does not block the pipe and reduce the hydration heat. The present invention solves the cracking and rigidity problems of the concrete while ensuring the pumpability of the C55 machine-made sand concrete.

Description

Technical Field

[0001] The invention relates to the technical field of construction, in particular to a three-stage design method for high tower column C55 pumping machine-made sand concrete. Background Art

[0002] The 270m main tower of the Shenzhen-Zhongshan Channel Bridge is being constructed with C55 pumped concrete made from river sand. However, river sand is a short-term non-renewable resource. With large-scale mining in the past few decades, river sand and gravel are facing the risk of depletion. Under the background of environmental protection, the replacement of river sand with machine-made sand has become an inevitable trend in the development of concrete materials.

[0003] When using machine-made sand to prepare concrete, the following technical problems exist: poor concrete wrapping, insufficient cohesion, and easy pipe blockage during pumping and pouring. After consulting domestic and foreign literature, no successful pumping cases of C55 machine-made sand concrete for the 270m main tower were found. Analysis of the reasons may be due to the poor wrapping of machine-made sand concrete, which is easy to cause pipe blockage.

[0004] Therefore, it is urgent to develop a three-stage design method for high-tower C55 pumped machine-made sand concrete. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a three-stage design method for high tower C55 pumping machine-made sand concrete. The present invention divides the 270-300m high tower into three stages: lower tower (below 40.05-50m), middle tower and "closing section + upper tower" (above 173-180m). The lower tower mainly solves the cracking problem caused by high hydration heat, the middle tower mainly ensures sufficient rigidity and pumpability, and the "closing section + upper tower" mainly solves the pump blockage problem.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A three-stage design method for high tower C55 pumping machine-made sand concrete, characterized by comprising the following steps:

[0008] (1) The tower column is divided into three stages: the lower tower column, the middle tower column and the "closing section + upper tower column"; among them, the lower tower column is below 40.05-50m, the "closing section + upper tower column" is above 173-180m, and the rest are middle tower columns;

[0009] (2) The lower tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using low-cement material and large-volume mineral admixtures; the total cementitious material of the concrete is 460kg / m 3 , of which the fly ash content is 25%, the mineral powder content is 17%, the W / B is 0.31, and the sand ratio is 42%;

[0010] (3) The middle tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using medium-grade cementitious materials and low sand ratio; the total cementitious materials of the concrete are 484kg / m 3 , of which the fly ash content is 20%, the mineral powder content is 15%, W / B is 0.31, and the sand ratio is 38%;

[0011] (4) The “closing section + upper tower column” uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using high-cement material, low sand ratio, and large amount of mineral admixtures; the total cementitious material of the concrete is 510kg / m 3 The fly ash content is 27%, the mineral powder content is 17%, the W / B is 0.30, and the sand rate is 39%.

[0012] Preferably, the design methods of the mix proportion of C55 pumped machine-made sand concrete in step (2), step (3) and step (4) all adopt the provisions of "Code for Design of Ordinary Concrete Mix Proportion" JGJ 55.

[0013] Preferably, the components of the machine-made sand concrete of the lower tower column are: cement, fly ash, mineral powder, machine-made sand, 5-10 mm coarse aggregate, 10-20 mm coarse aggregate, water, and admixtures. The component units are kg / m 3 The mix ratio is: 267:115:78:764:845:211:143:5.52.

[0014] Preferably, the components of the machine-made sand concrete of the middle tower column are: cement, fly ash, mineral powder, machine-made sand, 5-10 mm coarse aggregate, 10-20 mm coarse aggregate, water, and admixtures. The component units are kg / m 3 The mix ratio is: 314:97:73:675:771:330:150:5.81.

[0015] Preferably, the components of the "closing section + upper tower column" machine-made sand concrete are: cement, fly ash, mineral powder, machine-made sand, 5-10mm coarse aggregate, 10-20mm coarse aggregate, water, and admixtures. The component units are kg / m 3 The mix ratio is: 285:140:85:681:373:693:153:6.12.

[0016] Preferably, the tower column is 270m long and is divided into three stages: a lower tower column below 40.05m, a middle tower column 40.05-173.00m and a "closing section + upper tower column" 173.00-270.00m.

[0017] Preferably, the tower column is 300m long and is divided into three stages: a lower tower column of less than 50m, a middle tower column of 50-180m and a "closing section + upper tower column" of 180-300m.

[0018] Preferably, the cement is P.Ⅱ42.5R cement produced by Yingde Conch Co., Ltd.

[0019] Preferably, the fly ash is Class F Grade I ash produced by Shenhua Guangdong Guohua Taishan Power Generation Co., Ltd.

[0020] Preferably, the mineral powder is S95 mineral powder produced by Tangshan Caofeidian Dunshi New Building Materials Co., Ltd.

[0021] Preferably, the machine-made sand is the machine-made sand provided by Jiangmen Xinhui District Biyuan Building Materials Co., Ltd.: the fineness modulus is 2.9, and the stone powder content fluctuates in the range of 1.0% to 3.0%.

[0022] Preferably, the admixture is a polycarboxylate water reducer.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention applies machine-made sand to the construction of 270-300m high towers of bridges for the first time, and proposes a three-stage design method for C55 pumped machine-made sand concrete to address the problems of tower cracking, rigidity and pipe blockage. The present invention divides the 270-300m high tower into three stages: lower tower, middle tower and "closing section + upper tower"; among them, the lower tower is below 40.05-50m, the "closing section + upper tower" is above 173-180m, and the rest are middle towers. The lower tower mainly solves the cracking problem caused by high hydration heat, the middle tower mainly ensures sufficient rigidity and pumpability, and the "closing section + upper tower" mainly solves the pump blockage problem. This design method greatly expands the scope of use of machine-made sand and has significant application value. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with specific embodiments.

[0026] It should be noted that, unless otherwise specified, the raw materials used in the technical solutions provided by the present invention are prepared by conventional means or purchased through commercial channels.

[0027] A three-stage design method for high tower C55 pumping machine-made sand concrete, characterized by comprising the following steps:

[0028] (1) The tower column is divided into three stages: the lower tower column, the middle tower column and the "closing section + upper tower column"; among them, the lower tower column is below 40.05-50m, the "closing section + upper tower column" is above 173-180m, and the rest are middle tower columns;

[0029] (2) The lower tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using low-cement material and large-volume mineral admixtures; the total cementitious material of the concrete is 460kg / m3 The fly ash content is 25%, the mineral powder content is 17%, the W / B is 0.31, and the sand rate is 42%.

[0030] (3) The middle tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using medium-grade cementitious materials and low sand ratio; the total cementitious materials of the concrete are 484kg / m 3 The fly ash content is 20%, the mineral powder content is 15%, the W / B ratio is 0.31, and the sand ratio is 38%.

[0031] (4) The “closing section + upper tower column” uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using high-cement material, low sand ratio, and large amount of mineral admixtures; the total cementitious material of the concrete is 510kg / m 3 The fly ash content is 27%, the mineral powder content is 17%, the W / B is 0.30, and the sand rate is 39%.

[0032] The design methods of the C55 pumped machine-made sand concrete mix ratio in step (2), step (3) and step (4) all adopt the provisions of "Code for Design of Ordinary Concrete Mix Ratio" JGJ 55.

[0033] As one of the preferred solutions of the present invention: the tower column is 270m long and is divided into three stages: a lower tower column below 40.05m, a middle tower column 40.05-173.00m and a "closing section + upper tower column" 173.00-270.00m.

[0034] As another preferred embodiment of the present invention, the tower column is 300 m long and is divided into three stages: a lower tower column of less than 50 m, a middle tower column of 50 to 180 m, and a "closing section + upper tower column" of 180 to 300 m.

[0035] The present invention sets Example 1 and Comparative Examples 1-2:

[0036] in:

[0037] The cement is P.Ⅱ42.5R cement produced by Yingde Conch Co., Ltd.;

[0038] The fly ash was Class F Grade I produced by Shenhua Guangdong Guohua Taishan Power Generation Co., Ltd.;

[0039] The mineral powder is S95 mineral powder produced by Tangshan Caofeidian Dunshi New Building Materials Co., Ltd.

[0040] The machine-made sand is provided by Jiangmen Xinhui District Biyuan Building Materials Co., Ltd.: the fineness modulus is 2.9, and the stone powder content fluctuates in the range of 1.0% to 3.0%;

[0041] The 5-10mm coarse aggregate is 5-10mm crushed stone produced by Gucheng Mining Development Investment Co., Ltd.;

[0042] The 10-20mm coarse aggregate is 10-20mm crushed stone produced by Gucheng Mining Development Investment Co., Ltd.;

[0043] The admixture is polycarboxylate water reducer provided by Guangdong Qiangshi Building Materials Technology Co., Ltd.;

[0044] The mixing water is groundwater.

[0045] Example 1

[0046] The three-stage design method for C55 pumped machine-made sand concrete for the 270m high tower column of Zhongshan Xiangshan Bridge includes the following steps:

[0047] (1) The 270m main tower is divided into three stages: the lower tower column below 40.05m, the middle tower column 40.05-173.00m and the "closing section + upper tower column" 173.00-270.00m.

[0048] (2) Design technology route for C55 pumped machine-made sand concrete for lower tower column (0-40.05m): To reduce the risk of cracking of lower tower column structure due to excessive heat of hydration of concrete, the concrete mix ratio of lower tower column is designed by using low-cement material and high-volume mineral admixture. The total cementitious material of concrete is 460kg / m 3 , of which fly ash content is 25%, mineral powder content is 17%, W / B is 0.31, and sand content is 42%. By reducing the total amount of cementitious materials and increasing the amount of mineral admixtures, the hydration heat of concrete can be effectively reduced. The mix ratio is shown in Table 1, and the concrete performance results are shown in Table 2.

[0049] Table 1 Mix ratio of C55 pumped machine-made sand concrete for the lower tower of Xiangshan Bridge (kg / m 3 )

[0050]

[0051] Table 2 Performance results of C55 pumped machine-made sand concrete for the lower tower of Xiangshan Bridge

[0052]

[0053] (3) Design technology route for C55 pumped machine-made sand concrete for the middle tower column (40.05-173.00m): The design goal of this stage is to ensure sufficient rigidity and pumpability of the concrete. The concrete mix ratio is designed by using medium-grade cementitious materials and low sand ratio. The total cementitious material of the concrete is 484kg / m 3 The fly ash content is 20%, the mineral powder content is 15%, the W / B is 0.31, and the sand ratio is adjusted from 42% of the lower column to 38%. The mix ratio is shown in Table 3, and the concrete performance results are shown in Table 4.

[0054] Table 3 Mix ratio of C55 pumped machine-made sand concrete for the middle tower of Xiangshan Bridge (kg / m 3 )

[0055]

[0056] Table 4 Performance results of C55 pumped machine-made sand concrete used in the middle tower of Xiangshan Bridge

[0057]

[0058] (4) "Closing section + upper tower column" (173.00-270.00m) uses C55 pumped machine-made sand concrete design technology route: This stage aims to ensure that concrete pumping does not block the pipe and reduce the hydration heat. The concrete mix ratio is designed by using high-cement material, low sand ratio, and large amount of mineral admixture. The total cementitious material of the concrete is 510kg / m 3 The fly ash content is 27%, the mineral powder content is 17%, W / B is 0.30, and the sand ratio is 39%. The mix ratio is shown in Table 5, and the concrete performance results are shown in Table 6.

[0059] Table 5 Mix ratio of C55 pumped machine-made sand concrete for the "closing section + upper tower" of Xiangshan Bridge (kg / m 3 )

[0060]

[0061] Table 6 Performance results of C55 pumped machine-made sand concrete for the "closing section + upper tower" of Xiangshan Bridge

[0062]

[0063] Example 1 shows:

[0064] The concrete mix ratio is designed by using low-binder and large-volume mineral admixtures, which can effectively reduce the temperature rise of the lower tower column structure. The concrete working performance meets the pumpability requirements and the strength meets the C55 strength grade requirements. It has certain technical and economic rationality and significant social and economic benefits.

[0065] Designing the concrete mix ratio using medium-sized adhesive and low sand ratio can effectively improve the pumpability of the concrete in the middle tower column, and the concrete elastic modulus is also improved to a certain extent. The strength meets the C55 strength grade requirements, which has certain technical and economic rationality and significant social and economic benefits.

[0066] Designing the concrete mix ratio by using high adhesive, low sand ratio and large amount of mineral admixture can effectively improve the pumpability of the concrete of the "closing section + upper tower column", and the concrete temperature is also reduced, the elastic modulus is also guaranteed, and the strength meets the C55 strength grade requirements. It has certain technical and economic rationality and significant social and economic benefits.

[0067] The C55 machine-made sand concrete designed with this technical route was applied to Zhongshan Xiangshan Bridge. Practice has shown that this concrete design technology is feasible and effective.

[0068] Comparative Example 1

[0069] The three-stage design method for C55 pumped machine-made sand concrete with a 270m high tower includes the following steps:

[0070] Steps (1) to (3) are the same as in Example 1;

[0071] In step (4), the mix ratio of C55 pumped machine-made sand concrete for the “closing section + upper tower column” (173.00-270.00 m) is shown in Table 7, and the concrete performance results are shown in Table 8.

[0072] Table 7 Mix ratio of C55 pumped machine-made sand concrete for the "closing section + upper tower" of Xiangshan Bridge (kg / m 3 )

[0073]

[0074] Table 8 Performance results of C55 pumped machine-made sand concrete for the "closing section + upper tower column" of Xiangshan Bridge

[0075]

[0076] By comparing Example 1 with Comparative Example 1, it can be seen that water consumption has a key influence on ultra-high pumping. Increasing the water consumption by 3kg per cubic meter of concrete can effectively reduce the cohesiveness of the concrete and greatly improve the pumpability of C55 machine-made sand concrete. When the tower column concrete in Example 1 (i.e., the "closing section + upper tower column" in Comparative Example 1) is used to pump the "closing section + upper tower column", the 12.5mm pump pipe will be blocked or the pipe clamp will break, and the on-site construction cannot proceed smoothly.

[0077] Comparative Example 2

[0078] The three-stage design method for C55 pumped machine-made sand concrete with a 270m high tower includes the following steps:

[0079] Step (1) is the same as in Example 1;

[0080] In step (2): the mix ratio of C55 pumped machine-made sand concrete for the lower tower column (0-40.05 m) is shown in Table 9, and the concrete performance results are shown in Table 10.

[0081] Steps (3)-(4) are the same as in Example 1.

[0082] Table 9 Mix ratio of C55 pumped machine-made sand concrete for the lower tower of Xiangshan Bridge (kg / m 3 )

[0083]

[0084] Table 10 Performance results of C55 pumped machine-made sand concrete used in the lower tower column of Xiangshan Bridge

[0085]

[0086] By comparing Example 1 with Comparative Example 2, it can be seen that reducing the total amount of cementitious materials and increasing the amount of mineral admixtures are effective ways to reduce the temperature rise of concrete. By designing the concrete mix ratio of the lower tower column with low cementitious materials and large amounts of mineral admixtures, the temperature rise of concrete can be effectively reduced, and the temperature of concrete can be reduced by 12.7°C. If the 1d concrete elastic modulus is 20GPa, the elastic tensile stress generated inside the concrete can be effectively reduced by 2.5MPa. This plays a positive role in reducing the cracking of the large-volume concrete structure of the lower tower column.

[0087] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A three-stage design method for high tower C55 pumping machine-made sand concrete, characterized in that: The following steps are involved: (1) The tower columns are divided into three stages: lower tower columns, middle tower columns and "closing section + upper tower columns"; among them, the lower tower columns are below 40.05-50m, the "closing section + upper tower columns" are above 173-180m, and the rest are middle tower columns; (2) The lower tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using low-cement material and high-volume mineral admixtures; the total cementitious material of the concrete is 460kg / m 3 , of which the fly ash content is 25%, the mineral powder content is 17%, W / B is 0.31, and the sand ratio is 42%; (3) The middle tower column uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by using medium-grade cementitious materials and low sand ratio; the total cementitious materials of the concrete are 484kg / m 3 , of which the fly ash content is 20%, the mineral powder content is 15%, W / B is 0.31, and the sand ratio is 38%; (4) The "closing section + upper tower column" uses C55 pumped machine-made sand concrete, and the concrete mix ratio is designed by adopting a method of high binder, low sand ratio, and large amount of mineral admixtures; the total cementitious material of the concrete is 510kg / m3, of which the fly ash content is 27%, the mineral powder content is 17%, the W / B ratio is 0.30, and the sand ratio is 39%.

2. A three-stage design method for high tower C55 pumped machine-made sand concrete according to claim 1, characterized in that: The components of the machine-made sand concrete of the lower tower column are: cement, fly ash, mineral powder, machine-made sand, 5-10mm coarse aggregate, 10-20mm coarse aggregate, water, and admixtures. The component unit is kg / m 3 The mix ratio is: 267:115:78:764:845:211:143:5.

52.

3. A three-stage design method for high tower C55 pumping machine-made sand concrete according to claim 1, characterized in that: The components of the machine-made sand concrete of the middle tower column are: cement, fly ash, mineral powder, machine-made sand, 5-10mm coarse aggregate, 10-20mm coarse aggregate, water, and admixtures. The unit of components is kg / m 3 The mix ratio is: 314:97:73:675:771:330:150:5.

81.

4. A three-stage design method for high tower C55 pumped machine-made sand concrete according to claim 1, characterized in that: The components of "closing section + upper tower column" machine-made sand concrete are: cement, fly ash, mineral powder, machine-made sand, 5-10mm coarse aggregate, 10-20mm coarse aggregate, water, admixtures, and the component unit is kg / m 3 The mix ratio is: 285:140:85:681:373:693:153:6.

12.

5. A three-stage design method for high tower C55 pumping machine-made sand concrete according to claim 1, characterized in that: The tower column is 270m long and is divided into three stages: lower tower column below 40.05m, middle tower column 40.05-173.00m and "closing section + upper tower column" 173.00-270.00m.

6. A three-stage design method for high tower C55 pumped machine-made sand concrete according to claim 1, characterized in that: The tower column is 300m long and is divided into three stages: a lower tower column of less than 50m, a middle tower column of 50-180m and a "closing section + upper tower column" of 180-300m.

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