阅读说明：本技术 一种解决混凝土浆体浮黑的方法 (Method for solving blacking of concrete slurry ) 是由 徐勇波 涂凯 杨志华 刘宇贵 左都辉 李�杰 于 2019-12-19 设计创作，主要内容包括：本发明公开了一种解决混凝土浆体浮黑的方法,优选10万分子量的甲基羟丙基纤维素,纤维素占胶凝材料的质量百分比范围为：0.008％～0.015％；压力泌水仪设置稳定持荷压力为2.0MPa、稳定持荷时间为180S；当混凝土拌合物坍落扩展度调整至520～600mm,使用混凝土压力泌水仪检测混凝土的压力泌水率不大于2.6％时,增稠剂可以解决混凝土浆体浮黑问题。本发明通过解决混凝土浆体浮黑,保证了拌合物性能的稳定和结构物的外观质量。(The invention discloses a method for solving the problem of blackness of concrete slurry, which preferably selects 10 ten thousand of methylhydroxypropylcellulose with the mass percentage of cellulose in a gelled material as follows: 0.008 to 0.015 percent; the pressure bleeding instrument is set with stable load holding pressure of 2.0MPa and stable load holding time of 180S; when the slump expansion of the concrete mixture is adjusted to 520-600 mm and the pressure bleeding rate of the concrete detected by using a concrete pressure bleeding instrument is not more than 2.6%, the thickening agent can solve the problem of blackened concrete slurry. The invention ensures the stability of the performance of the mixture and the appearance quality of the structure by solving the problem of blackish appearance of the concrete slurry.)

1. The method for solving the blacking problem of concrete slurry comprises a cementing material and an additive, and is characterized in that: the additive comprises a thickening agent, the slump expansion of the concrete mixture is adjusted to 520-600 mm, and the pressure bleeding rate of the obtained concrete is not more than 2.6%.

2. The method for solving the problem of the blacking of the concrete slurry according to claim 1, wherein: the molecular weight of the thickener is not less than 10 ten thousand, and methyl hydroxypropyl cellulose is preferred.

3. The method for solving the problem of the blacking of the concrete slurry according to claim 1, wherein: the thickening agent accounts for the mass percentage range of the gelled material as follows: 0.008 to 0.015 percent.

4. The method for solving the problem of the blacking of the concrete slurry according to claim 1, wherein: and adjusting the slump expansion degree of the concrete mixture to 520-600 mm.

5. The method for solving the problem of the blacking of the concrete slurry is characterized in that: the pressure bleeding rate of the concrete refers to the percentage of the water yield of each concrete in the total mixing water amount of each concrete under the condition that the concrete mixture is continuously applied with pressure.

6. The method for solving the problem of concrete slurry blackening according to claim 5, wherein: the method also comprises the step of detecting the pressure bleeding rate by using a concrete pressure bleeding instrument, wherein the load holding pressure of the pressure bleeding instrument is set to be 2.0 MPa.

7. The method for solving the problem of concrete slurry blackening according to claim 6, wherein: the load holding time of the pressure bleeding instrument is set to be 180S.

Technical Field

The invention particularly relates to the technical field of building construction, and particularly relates to a method for solving the problem of blackness floating of concrete slurry.

Background

The phenomenon that the coarse aggregate sinks and the black oil floats to the surface of the slurry is called as concrete floating black, and the non-floating black represents that the performance of the concrete is stable, so that the slurry floating black is an important performance characteristic of the working performance of the fresh concrete. The cement clinker is prepared by calcining raw slurry by coal powder in a rotary kiln, and in order to improve the combustion efficiency of the coal powder, an oily substance is added in the combustion process of the coal powder to assist combustion. When the added oil amount is too large or the pulverized coal is not sufficiently combusted, black oil layer substances with different amounts are left on the surface of clinker, and the black oil layer substances have small specific gravity, so that the consistency of cement paste is reduced, and the properties of water retention and coarse aggregate wrapping by the paste are poor, so that the performance of the freshly mixed concrete can not resist floating black. After the cement with the black oil is mixed into concrete, the floating black of the concrete is aggravated along with the increase of pressure and concrete mixture fluidity caused by vibration in construction. The black floating layer and the foam floating layer can be generated on the surface of the structure seriously, and a plurality of bubbles with different sizes such as pore diameter, space and the like can be generated in the structure after hardening, thereby seriously influencing the appearance quality and durability of the structure.

The prior solution is to ensure the coal powder to be fully combusted by a single heat source and ensure the stable production quality of clinker, but has the defects of high energy consumption, low production efficiency and high cost.

Disclosure of Invention

In order to solve the technical problems, the invention provides a simple method for solving the problem of blackness of concrete slurry, and overcomes the defects of high energy consumption, low production efficiency and high cost caused by the blackness of the concrete slurry in the prior art.

The invention is realized by the following technical scheme.

The invention provides a method for solving the blackening problem of concrete slurry, wherein the cement concrete raw material comprises a cementing material and an additive, the cementing material comprises cement and the additive, the additive comprises a thickening agent, and when a concrete pressure bleeding instrument is used for detecting the pressure bleeding rate of the concrete, the thickening agent can solve the blackening problem of the concrete when the pressure bleeding rate of the obtained concrete is not more than 2.6 percent.

The molecular weight of the thickener is not less than 10 ten thousand, and methyl hydroxypropyl cellulose is preferred.

The thickening agent accounts for the mass percentage range of the gelled material as follows: 0.008 to 0.015 percent.

And adjusting the slump expansion degree of the concrete mixture to 520-600 mm.

The pressure bleeding rate of the concrete refers to the percentage of the water yield of each concrete in the total mixing water amount of each concrete under the condition that the concrete mixture is continuously applied with proper pressure.

When the concrete pressure bleeding instrument is used for detecting the pressure bleeding rate, the load holding pressure of the pressure bleeding instrument is set to be 2.0 MPa.

When the concrete pressure bleeding instrument is used for detecting the pressure bleeding rate, the load holding time of the pressure bleeding instrument is set to be 180S.

The invention has the beneficial effects that: by adopting the technical scheme of the invention, the floating black of the concrete is solved by adding the thickening agent in the process of preparing the concrete; the problem of floating black of concrete is solved, so that the appearance quality and durability of a structure are ensured, and the service life of a building can reach the expected service life; and secondly, clinker is not required to be calcined by a separate heat source during cement preparation, so that the production cost of the cement is reduced, the floating black cement is effectively and reasonably applied, and the application range of the floating black cement in engineering is enlarged.

Detailed Description

The technical solutions of the present invention are further described below, but it should be apparent to those skilled in the art that several variations and modifications can be made without departing from the inventive concept of the present invention, and these are within the scope of the present invention.

When the slurry is blackened during production and stirring of concrete, the performance of the slurry for wrapping the coarse aggregate is poor, the coarse aggregate is easy to accumulate in the flowing process of the concrete, the workability of the concrete is poor, and a foam laitance layer can be generated when the blackness is serious; the concrete can resist the generation of slurry blackening by improving the performance of the concrete, namely the blackening of the concrete can be solved by using the methylhydroxypropylcellulose with the molecular weight of 10 ten thousand. The methyl hydroxypropyl cellulose can increase the consistency of cement paste, improve the viscosity of water, and increase the cohesiveness, the wrapping property and the water-retaining property of concrete, so that the performance of the concrete can reach the state of resisting the occurrence of floating black.

Raw material mass (kg/m) of pressure bleeding test sample³) And the mass ratio of the cement:

the preparation method of the pressure bleeding sample comprises the following steps: after the raw materials are measured, firstly adding the aggregate, the cement and the fly ash into a stirrer, uniformly stirring, adding water and a liquid water reducing agent until the materials are uniformly stirred, and stirring for 120S.

Adjusting the slump expansion degree of the concrete mixture to 520-600 mm; the pressure bleeding instrument is used for measuring the pressure bleeding rate of the concrete, the load holding pressure of the pressure bleeding instrument is set to be 2.0MPa, and the load holding time is set to be 180S during the test; the mass percentage range of the thickening agent in the gelled material is as follows: 0.008 to 0.015 percent; preferably, methyl hydroxypropyl cellulose is added, wherein the methyl hydroxypropyl cellulose with the molecular weight of 10 ten thousand is added according to the mass percentage of 0-0.015 percent in the gel material; the test comparison confirms that: when the mass percentage of the methylhydroxypropylcellulose in the gelled material is 0.008% -0.015%, the pressure bleeding rate of the mixture is not more than 2.6%, no floating black appears on the surface of the slurry, the working performance of the mixture meets the construction requirements, and the detection results are shown in table 1.

TABLE 1 test results in concrete pressurized bleeding Chamber

When the pressure bleeding rate is not more than 2.6 percent, the thickening agent solves the problem of concrete blackness.

Further, it is preferable that the thickener is methylhydroxypropylcellulose; the thickening agent accounts for the mass percent of the gelled material and comprises the following components: 0.008 to 0.015 percent.

The pressure bleeding rate of the concrete can be calculated by the following formula:

wherein:

ρ: the pressure bleeding rate of the concrete;

W₀: when the concrete is used, the water yield of each concrete is equal to pressure water yield and pressure water yield divided by pressure water yield sample mass X and the concrete volume weight of each concrete;

w: total water usage for each mix used to make the concrete;

the effect of the thickener in solving the floating black in concrete will be described in examples 1, 2, 3 and 4, in which structures 12 meters long are cast at a time. The thickening agent is not added in the embodiment 1, the thickening agent accounting for 0.006 percent of the mass of the gelled material is added in the embodiment 2, the thickening agent accounting for 0.008 percent of the mass of the gelled material is added in the embodiments 3 and 4, and the methyl hydroxypropyl cellulose with the molecular weight of 10 ten thousand is used as the thickening agent. Concrete samples with proper quality are respectively intercepted through an embodiment 1, an embodiment 2, an embodiment 3 and an embodiment 4, a concrete pressure bleeding instrument is used for detecting the pressure bleeding rate of the concrete samples, the stable load holding pressure of the concrete pressure bleeding instrument is set to be 2.0MPa, the pressurizing load holding time is set to be 180S, and the bleeding performance detection results are shown in a table 2. The concrete samples of examples 1, 2, 3 and 4 were tested for workability, and the results are shown in table 3.

TABLE 2 concrete sample bleeding Performance test results

Remarking: in the embodiment of the patent, the design volume weight of the mixture ratio is 2360Kg/m³The total mixing water consumption in the concrete is 168Kg/m³。

TABLE 3 concrete sample construction site working performance test results

By testing the bleeding performance and the working performance of the example 1, the example 2, the example 3 and the example 4 and observing the floating black of the mixture and the structure of the construction site, the following results are summarized:

① example 1, when the admixture is not added with methylhydroxypropylcellulose with molecular weight of 10 ten thousand, blackening occurs at the beginning of pouring, the performance of slurry wrapping coarse aggregate is poor, the blackening amount of concrete is increased along with the increase of vibration pressure and the increase of fluidity of mixture, the pressure bleeding rate of the concrete is detected to be 5.3 percent and more than 2.6 percent, and the surface of the hardened and formed concrete has a black oil layer and more large bubbles.

② example 2, when the admixture is added with 10 ten thousand molecular weight methylhydroxypropylcellulose, the mixing amount is 0.006%, the consistency of the slurry is improved, the performance of the slurry wrapping coarse aggregate is improved, in the pouring process, along with the increase of vibration pressure and the fluidity of the mixture, a small part of slurry surface appears black floating, the pressure bleeding rate of the concrete is detected to be 3.3%, which is still more than 2.6%, and after the concrete is hardened and formed, the large bubbles on the surface are obviously reduced.

③ example 3 and example 4, when the admixture is added with 10 ten thousand of methylhydroxypropylcellulose with the molecular weight of 0.008 percent, the workability and cohesiveness of the concrete can meet the requirements, the pressure bleeding rate of the concrete is detected to be 2.0-2.6 percent and not more than 2.6 percent, no floating black is generated during the pouring process until the concrete is hardened, the appearance quality of the structure after the concrete is hardened and formed is good, and no foam floating slurry layer is generated.

In conclusion, the thickener accounts for 0.008-0.015 percent of the mass of the cementing material, and the concrete mixing amount of the thickener is based on the condition that the pressure bleeding rate of the concrete is not more than 2.6 percent, so that the problem of the blackening of the concrete is solved.