CN111484298A

CN111484298A - Dry-mixed concrete and preparation method thereof

Info

Publication number: CN111484298A
Application number: CN202010440999.7A
Authority: CN
Inventors: 邱文会; 刘杰; 韦昊奇; 邱润泽; 代志涛; 张浩亮; 王俊; 张欣然
Original assignee: Henan Jinnuo Concrete Co ltd
Current assignee: Henan Jinnuo Concrete Co ltd
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-08-04
Anticipated expiration: 2040-05-22
Also published as: CN111484298B

Abstract

The invention provides dry-mixed concrete which comprises the following components in parts by weight: 38-43 parts of cement, 3-5 parts of fly ash, 88-90 parts of coarse aggregate, 65-67 parts of fine aggregate and 0.043-0.046 part of additive, and provides a preparation method thereof.

Description

Dry-mixed concrete and preparation method thereof

Technical Field

The invention relates to the field of concrete, in particular to dry-mixed concrete and a preparation method thereof.

Background

With the continuous development and improvement of the production technology of the ready-mixed concrete, the competition of the industry also strongly promotes the progress of the concrete technology. At present, the environment protection form is more and more severe, the concrete mixing plant must respond to the heavy pollution weather and stop production, and the construction site cannot carry out normal concrete production construction.

In addition, concrete prepared by a wet method on the market is generally delivered to a construction site through a tank truck after being premixed in a mixing station, and is pumped for pouring, the storage time is short, generally less than 6 hours, and the requirement of the construction site cannot be met, for example, for secondary structures such as a constructional column, when the concrete is used, the section of the constructional column is small, the constructional column is not easy to vibrate, the square amount is small, the pouring time of about 5 sides of one premixed concrete is often more than 6 hours, the concrete has hidden troubles in quality, and therefore, the premixed dry concrete is produced in order to adapt to the change of the market.

Disclosure of Invention

In view of the above problems, a first aspect of the present application provides a dry mix concrete, which comprises the following technical solutions:

the dry-mixed concrete comprises the following components in parts by weight: 38-43 parts of cement, 3-5 parts of fly ash, 88-90 parts of coarse aggregate, 65-67 parts of fine aggregate and 0.043-0.046 part of additive.

The concrete has the advantages of long storage time, good homogeneity, capability of being stored in a building site in advance, free access, pouring operation by adding water and stirring, and excellent comprehensive performance after pouring after detection.

Further, the fineness of the fly ash is 18%, the coarse aggregate and the fine aggregate are prepared from broken stones, wherein the particle size of the coarse aggregate is 5-10mm, the particle size of the fine aggregate is 2-4.0 mm, and the additive comprises a naphthalene-based high-efficiency water reducing agent.

According to the scheme, the particle size of the components is improved, the particle size distribution is optimized, the layering phenomenon in the material transportation and storage processes is greatly reduced, and the homogeneity is good.

Preferably, the naphthalene-based superplasticizer has a water reduction rate of 25%, that is, the naphthalene-based superplasticizer with a water reduction rate of 25% is selected, for example, FDN superplasticizer available from kunming raw concrete admixture, product number 1001.

Further, the water reducing agent comprises 0.13-0.15 part of SAP, 1-2 parts of coupling agent modified and surface roughened steel fiber, 4-6 parts of nano silicon dioxide and 0.044-0.045 part of an additive, wherein the additive comprises a naphthalene water reducing agent and a polycarboxylic acid water reducing agent.

In the scheme, super absorbent resin, namely SAP (super absorbent polymer) and steel fiber are added on the basis of the components, the SAP which is in a net structure by means of polymer chain approaching and crosslinking is in lap joint with coarse aggregate and fly ash with irregular or porous surfaces, and then a coupling agent group on the steel fiber is in lap joint with the SAP to form a large grid structure, so that the stability of material particles is improved, the range of layering of the material components is further reduced, the stability of material transportation and storage is ensured, the homogeneity is improved again, the strength of the poured concrete is stable after the steel fiber is added, the addition of the SAP is beneficial to internal maintenance, the self-shrinkage degree is reduced, the grain grading is further optimized by adding nano silicon dioxide, and the compactness of the system is improved.

In addition, the compound water reducing agent is adopted in the scheme, and the naphthalene water reducing agent and the polycarboxylic acid water reducing agent are compounded, so that the water reducing effect and the slump retaining effect are improved.

Furthermore, the SAP is polyacrylic acid series super absorbent resin with 70-80 meshes, optimizes the grain composition and is beneficial to lap joint.

Further, the particle size of the nano-silica: 12-14nm, the diameter of the steel fiber is 0.1-0.3mm, and the length is 20-35 mm.

Further, admixture: according to the mass parts, the naphthalene series water reducing agent: the ratio of the polycarboxylic acid water reducing agent to the polycarboxylic acid water reducing agent is 20:7, and the mixing ratio is optimized, so that the effect is improved.

Furthermore, the coupling agent KH550 is used for modifying the steel fiber, so that the cost is low and the effect is good.

Furthermore, water is required to be added when the concrete is formed and poured, the water-cement ratio is less than 0.4, and the performance of the poured and formed concrete is good.

In a second aspect, the present document provides a method of preparing dry mix concrete comprising the steps of

1) Preparing materials of each component;

2) metering the mixture into a stirring device for stirring.

The dry-mixed concrete can be prepared by directly metering and feeding concrete under the components and mixing and stirring, and the preparation method is simple, short in working procedure and low in cost.

For example, in one embodiment, raw materials of cement, fly ash, broken stone and additive required for production are delivered to a production plant area, wherein powdery materials of cement, fly ash and the like are transported to the plant area by adopting a canning vehicle, are blown into a corresponding raw material silo for storage under positive pressure, coarse and fine aggregates are fed from a storage tank, the additive is fed from a hopper, are metered according to the proportion and conveyed to a dry powder concrete mixer, are uniformly mixed, and are transported to a construction site for storage through a powder bulk transport vehicle, namely, the materials are immediately used, and the storage time is up to 60 days.

Drawings

FIG. 1: structure diagram of dry-mixed concrete preparation device.

Detailed Description

The following detailed description of the embodiments of the present invention is provided in order to make the technical solution of the present invention easier to understand and understand.

1. Raw materials: cement: the test results of the cement of the river south Yuzhou Jinxin P.042.5 are as follows:

fly ash: i I-grade ash of Henan Deng Huarun power plant is adopted, and the test results are as follows:

additive: naphthalene series high efficiency water reducing agent (water reducing rate 25%), FDN high efficiency water reducing agent from Kunming Jiasheng concrete admixture company;

a polycarboxylic acid type high-efficiency water reducing agent, TS-4, produced by Jie New materials Co.

Coarse aggregate: the broken stone is adopted as 5-10mm of Henan Yuzhou, and the test result is as follows:

fine aggregate: the crushed stone is prepared by crushing, and the test result is as follows:

2. the preparation method refers to the preparation device shown in figure 1, and the specific operation process is as follows: conveying raw materials such as cement, fly ash, broken stone and an additive required by production to a production plant area, wherein the powdery materials such as the cement, the fly ash and the like are conveyed to the plant area by adopting a canning vehicle, blowing into a corresponding raw material silo at positive pressure for storage, feeding coarse and fine aggregates from a storage tank, feeding the additive from a hopper, metering according to the proportion, controlling and metering by a microcomputer control system, conveying to a dry powder concrete mixer, uniformly stirring, and then conveying to a construction site by a powder bulk transport vehicle for storage.

3. The proportioning design is shown in the following table:

example 1

The dry-mixed concrete is prepared by mixing and stirring according to the preparation method and the proportion, and then the slump and the compression strength of the test block of the test sample are obtained after the dry-mixed concrete is mechanically stirred by adding water, wherein the results are as follows:

example 2

example 3

in the above embodiment, the admixture is a naphthalene-based superplasticizer.

4. Homogeneity test

The dry mixed concrete prepared in the above examples was transported to a construction site by a powder bulk carrier, and then pumped into a closed storage tank, and the dry mixed concrete prepared in each example was placed in 10 tanks, labeled, and tested and averaged after 60 days of storage, as shown in the following table.

	Cementitious material	Coarse aggregate	Fine aggregate	Whether or not to meet the relevant requirements
					10 tank top	+0.7％	-1.3％	-0.8％	Conform to
9 tank top	+0.6％	-1.5％	-1.2％	Conform to
					8 tank top	+0.7％	-1.0％	-1.1％	Conform to
7 tank top	+0.2％	-1.2％	-1.0％	Conform to
					6 tank top	+0.2％	+0.5％	+0.6％	Conform to
5 tank top	+0.12％	+0.8％	+0.3％	Conform to
					4 tank top	-0.1％	+1.1％	+0.5％	Conform to
3 tank top	-0.3％	+1.5％	+0.9％	Conform to
					2 tank top	-0.32％	+1.6％	+1.1％	Conform to
1 tank top	-0.8％	+1.2％	+1.2％	Conform to

5. The proportioning design is as follows, and the admixture in the following examples is a compound type, naphthalene series water reducing agent: 20:7 of polycarboxylic acid water reducing agent, wherein SAP is polyacrylic acid super absorbent resin, 70-80 meshes, and the particle size of nano silicon dioxide is as follows: 12-14nm, the diameter of the steel fiber is 0.2mm, the length of the steel fiber is 30mm, and the steel fiber with the roughened surface is soaked in KH550 for 1h for modification treatment.

Example 4

example 5

example 6

6. homogeneity test

	Cementitious material	Coarse aggregate	Fine aggregate	Whether or not to meet the relevant requirements
					10 tank top	+0.2％	-0.24％	-0.3％	Conform to
9 tank top	+0.24％	-0.1％	-0.2％	Conform to
					8 tank top	+0.1％	-0.23％	-0.2％	Conform to
7 tank top	+0.1％	-0.15％	-0.1％	Conform to
					6 tank top	+0.15％	+0.2％	+0.2％	Conform to
5 tank top	+0.12％	+0.23％	+0.3％	Conform to
					4 tank top	-0.1％	+0.2％	+0.3％	Conform to
3 tank top	-0.2％	+0.27％	+0.16％	Conform to
					2 tank top	-0.23％	+0.4％	+0.3％	Conform to
1 tank top	-0.3％	+0.2％	+0.2％	Conform to

7. Summary of the invention

As can be seen from the table course, the dry-mixed concrete in the examples 1 to 3 has good homogeneity, long storage time and the performance meeting the requirements of C series concrete.

Examples 4-6 the addition of SAP, steel fiber and silica further enhanced the homogeneity of the dry-mix concrete, and the water-to-gel ratio decreased, the compressive strength increased significantly with water addition, the slump loss decreased, and after the addition of SAP, a decrease in the number of large capillary pores of the concrete slurry, especially large capillary pores between 200nm and 400nm, and a more dense concrete was observed in the compressive strength test.

The above is, of course, only a specific application example of the present invention, and the scope of the present invention is not limited in any way. All the technical solutions formed by equivalent transformation or equivalent replacement fall within the protection scope of the present invention.

Claims

1. The dry-mixed concrete is characterized by comprising the following components in parts by weight: 38-43 parts of cement, 3-5 parts of fly ash, 88-90 parts of coarse aggregate, 65-67 parts of fine aggregate and 0.043-0.046 part of additive.

2. The dry-mixed concrete according to claim 1, wherein the pulverized fuel ash has a fineness of 18%, the coarse aggregate and the fine aggregate are prepared from crushed stones, the particle size of the coarse aggregate is 5-10mm, the particle size of the fine aggregate is 2mm-4.0mm, and the additive comprises a naphthalene-based superplasticizer.

3. The dry mix concrete according to claim 1, wherein the naphthalene based superplasticizer has a water reduction rate of 25%.

4. The dry mix concrete according to claim 1, further comprising 0.13-0.15 parts of SAP, 1-2 parts of coupling agent modified and surface roughened steel fibers, 4-6 parts of nano silica, 0.044-0.045 parts of additives, including a naphthalene based water reducer and a polycarboxylic acid based water reducer.

5. The dry mix concrete according to claim 4, wherein the SAP is a polyacrylic acid-based super absorbent resin, 70-80 mesh.

6. The dry mix concrete according to claim 4, wherein the nano silica particle size: 12-14nm, the diameter of the steel fiber is 0.1-0.3mm, and the length is 20-35 mm.

7. The dry mix concrete according to claim 4, wherein the admixture: according to the mass parts, the naphthalene series water reducing agent: 20:7 of polycarboxylic acid water reducing agent.

8. Dry mix concrete according to claim 4, characterized in that the steel fibres are modified with a coupling agent KH 550.

9. A dry mix concrete according to any one of claims 1 to 8 wherein water is added to form the concrete for casting, the water to binder ratio being < 0.5.

10. The preparation method of the dry-mixed concrete is characterized by comprising the following steps

1) Preparing materials of each component;

2) metering the mixture into a stirring device for stirring.