CN112028537A

CN112028537A - Modified additive suitable for machine-made sand tubular pile concrete

Info

Publication number: CN112028537A
Application number: CN202010838420.2A
Authority: CN
Inventors: 高卫锋; 沈鹏程; 刘平; 沈中华
Original assignee: Zhejiang Wulong Chemical Industrial Stock Co ltd
Current assignee: Zhejiang Wulong Chemical Industrial Stock Co ltd
Priority date: 2020-08-19
Filing date: 2020-08-19
Publication date: 2020-12-04

Abstract

The invention provides a modified additive suitable for machine-made sand pipe pile concrete. The admixture provided by the invention has the effects of improving workability, cohesiveness and water retention of concrete, reducing slump loss and other workability aspects; the additive mother liquor can ensure that the slump retaining performance of the concrete is good, and the strength of the concrete is higher than that of common concrete; the additive can adjust the viscosity of concrete, so that the fresh concrete has good system stability, the phenomena of material collapse, slurry hanging and the like caused by poor stability of a fresh concrete system are reduced, and the surface color difference of the concrete and the appearance of the concrete are improved; on the premise of ensuring that the machine-made sand pipe pile concrete is easy to construct and the strength is not reduced, the using amount of the concrete glue material is reduced by 5-10%, and the machine-made sand pipe pile concrete mixture is prevented from collapsing and hanging slurry.

Description

Modified additive suitable for machine-made sand tubular pile concrete

Technical Field

The invention relates to a modified additive suitable for machine-made sand pipe pile concrete, which can improve workability, cohesiveness, water retention property, and other workability of concrete.

Background

In the era, with the progress of building science, green, environment-friendly and high-strength high-performance concrete is a new development direction of technology, so that the development of a green, environment-friendly and high-performance additive matched with the concrete is urgently needed. The tubular pile concrete is one of high-strength and high-performance concretes, and is expected to keep the leading position in the next 20 years. The water reducing agent used for preparing high-strength concrete in the production of the tubular pile has a plurality of varieties, and naphthalene series in general aliphatic series and sulfonate series are common. The invention uses polycarboxylic acid admixture, and is a novel green environment-friendly admixture.

Under the current situation of higher and higher environmental requirements, the use of polycarboxylic acid products is also a necessary trend. If the aliphatic admixture is used, the color is reddish, and the appearance of the concrete is influenced. Compared with aliphatic and naphthalene series admixtures, the concrete strength and slump retaining effect of the polycarboxylic acid admixture are superior to those of the polycarboxylic acid admixture. The polycarboxylic acid product has more advantages in price under the condition of requiring the same dosage, and more importantly, the polycarboxylic acid product is a green and environment-friendly product.

Disclosure of Invention

The invention provides a modified additive suitable for machine-made sand pipe pile concrete, which comprises, by mass, 35-55% of a polycarboxylic acid water reducing agent, 0.05-0.3% of a polyether defoaming agent, 1-5% of a thickening agent and the balance of water.

In some specific embodiments, the polycarboxylate water reducer is a new generation polycarboxylate water reducer prepared by free radical polymerization of a polyoxyethylene ether macromonomer, an unsaturated acid and a sulfonic acid group monomer, and the new generation polycarboxylate water reducer has a comb-type structure, and polyoxyethylene long chains and high-density sulfonic acid groups with longer length are adopted in molecules, so that the polycarboxylate water reducer has a larger steric hindrance effect and an electrostatic repulsion effect.

In some embodiments, the polyether defoamer is of a structure of a GPE type polyether defoamer, namely, a defoamer synthesized by firstly collecting trione and propylene oxide and then polymerizing the trione and the propylene oxide has a molecular weight of 3000, and the propylene oxide accounts for 10% of the total amount.

In some embodiments, the thickener uses hydroxypropyl methylcellulose as a concrete viscosity adjusting component, and the hydroxypropyl methylcellulose is nonionic cellulose mixed ether prepared by a series of reactions of alkalization treatment of purified cotton and etherification agents of propylene oxide and methyl chloride.

The invention further provides a preparation method of the modified admixture, which comprises the following steps: and respectively putting the polycarboxylic acid water reducing agent, the polyether defoaming agent, the thickening agent and the balance of water into a beaker, adding the polycarboxylic acid water reducing agent, the polyether defoaming agent, the thickening agent and the balance of water while stirring, putting all the materials into the beaker, and uniformly stirring to obtain the modified admixture.

The admixture provided by the invention has the effects of improving workability, cohesiveness and water retention of concrete, reducing slump loss and other workability aspects; the additive mother liquor can ensure that the slump retaining performance of the concrete is good, and the strength of the concrete is higher than that of common concrete; the performance of the concrete is improved by taking a polycarboxylic acid water reducing agent as a water reducing component; the use of the defoaming agent can promote the discharge of large bubbles in the concrete, improve the appearance of the concrete and increase the strength of the concrete; the workability of the concrete can be adjusted by adding the thickening agent, and the working performance of the concrete is improved; the additive can adjust the viscosity of concrete, so that the fresh concrete has good system stability, the phenomena of material collapse, slurry hanging and the like caused by poor stability of a fresh concrete system are reduced, and the surface color difference of the concrete and the appearance of the concrete are improved. The admixture can be widely applied to various concretes with higher requirements on the appearance of the concrete. On the premise of ensuring that the machine-made sand pipe pile concrete is easy to construct and the strength is not reduced, the using amount of a concrete glue material can be reduced by 5-10%, the concrete mixture of the machine-made sand pipe pile is prevented from collapsing and hanging slurry, and the appearance quality of an entity structure and the environmental protection problem in a new era are effectively solved.

Detailed Description

The polycarboxylate water reducing agent of the following embodiment is a new generation polycarboxylate water reducing agent prepared by polymerizing polyoxyethylene ether macromonomer, unsaturated acid and sulfonic monomer through free radicals;

the polyether defoamers of the following examples adopt the structure of a polyether defoamer of the "GPE" type.

Example 1

Weighing 58.15% by mass of clear water, 40.0% by mass of a polycarboxylic acid water reducing agent, 1.5% by mass of hydroxypropyl methyl cellulose and 0.05% by mass of a polyether defoaming agent, respectively putting into a beaker, stirring and adding all the materials in sequence when putting, and uniformly stirring to obtain the additive for improving the concrete performance of the machine-made sand when the pipe pile concrete is applied.

Example 2

Weighing 56.65 percent by mass of clear water, 40.0 percent by mass of polycarboxylic acid water reducing agent, 3 percent by mass of hydroxypropyl methylcellulose and 0.05 percent by mass of polyether defoaming agent, respectively putting into a beaker, stirring and adding all the materials in sequence when putting into the beaker, and uniformly stirring to obtain the additive for improving the concrete performance when the machine-made sand is applied to the pipe pile concrete.

Example 3

Weighing 53.45 mass percent of clear water, 45.0 mass percent of polycarboxylic acid water reducing agent, 1.5 mass percent of hydroxypropyl methyl cellulose and 0.05 mass percent of polyether defoaming agent, respectively putting the clear water, the hydroxypropyl methyl cellulose and the polyether defoaming agent into a beaker, stirring and adding the materials while putting the materials, putting all the materials in sequence, and uniformly stirring the materials to obtain the additive for improving the concrete performance of the machine-made sand in the application of the pipe pile concrete.

Comparative example

Weighing 60.0 mass percent of clear water and 40.0 mass percent of I-type polycarboxylate superplasticizer, respectively putting the clear water and the I-type polycarboxylate superplasticizer into a beaker, and uniformly stirring to obtain a comparative additive.

Test examples

The concrete water reducing rate and the setting time difference of the additives in the examples 1 to 3 and the comparative examples are tested according to the GB8076-2008 concrete additive standard, a concrete standard test block is simultaneously manufactured, the surface appearance of the concrete test block is observed after the concrete standard test block is hardened, the test cement is the reference cement, and the addition amount of the additives is 1.8 percent of the mass of the cement.

TABLE 1 concrete mix proportion (unit: kg)

TABLE 2 concrete Performance test results for different admixtures

Test specimen	The water reduction rate%	7d strength	28d strength	Workability
					Example 1	30	25.5Mpa	33Mpa	Good effect
Example 2	29.2	25.0Mpa	31.7Mpa	The concrete has higher viscosity
					Example 3	33	28.5Mpa	37.8Mpa	Good effect
Comparative example	29.0	24.1Mpa	31.2Mpa	Poor or bleeding

From the test results in table 2, it can be seen that the additive for improving concrete performance of machine-made sand in pipe pile concrete application prepared by the present invention has the characteristics of improving concrete workability and improving concrete strength in addition to excellent water reducing rate performance, compared with the currently used additive in the market (comparative example).

The admixture provided by the invention has the effects of improving workability, cohesiveness and water retention of concrete, reducing slump loss and other workability aspects; can improve the strength of concrete, is a composite multifunctional additive, and improves the performance of the concrete by taking a polycarboxylic acid water reducing agent as a water reducing component. The method has the advantages of adjusting the viscosity of the concrete, ensuring that the fresh concrete has good system stability, reducing the phenomena of material collapse, slurry hanging and the like caused by poor stability of the fresh concrete system, and improving the surface color difference of the concrete and the appearance of the concrete. Can be widely applied to various concretes with higher requirements on the appearance of the concrete. On the premise of ensuring that the machine-made sand pipe pile concrete is easy to construct and the strength is not reduced, the using amount of a concrete glue material can be reduced by 5-10%, the concrete mixture of the machine-made sand pipe pile is prevented from collapsing and hanging slurry, the appearance quality of an entity structure is effectively improved, and the environment-friendly problem in the new era is solved.

Claims

1. The modified additive suitable for machine-made sand pipe pile concrete is characterized by comprising, by mass, 35% -55% of a polycarboxylic acid water reducing agent, 0.05% -0.3% of a polyether defoaming agent, 1% -5% of a thickening agent and the balance of water.

2. The modified admixture according to claim 1, wherein the polycarboxylic acid water reducing agent is prepared by radical polymerization of a polyoxyethylene ether macromonomer, an unsaturated acid and a sulfonic acid group monomer.

3. The modified admixture as claimed in claim 1, wherein the polyether defoamer is GPE type polyether defoamer.

4. The modified admixture of claim 1 wherein the thickener employs hydroxypropyl methylcellulose as a concrete viscosity adjusting component.

5. The method for preparing a modified admixture according to any one of claims 1 to 4, characterized in that it comprises the steps of: and respectively putting the polycarboxylic acid water reducing agent, the polyether defoaming agent, the thickening agent and the balance of water into a beaker, adding the polycarboxylic acid water reducing agent, the polyether defoaming agent, the thickening agent and the balance of water while stirring, putting all the materials into the beaker, and uniformly stirring to obtain the modified admixture.