CN107117909B - A kind of reactive powder concrete mixed with fly ash and preparation method thereof - Google Patents

Abstract

The invention discloses a reactive powder concrete doped with fly ash and a preparation method thereof. The active powder concrete doped with fly ash is composed of the following materials in parts by mass: 1 part of cement, 1.1 parts of quartz sand, 0.21-0.28 part of silica fume, 0.07-0.14 part of fly ash, 0.1 part of steel fiber, 0.1 part of minor component, 0.2 part of water and 0.015 part of water reducing agent; stirring, vibrating, forming, removing mould and high-temperature curing. The invention is characterized in that industrial waste residue fly ash is doped as an active component, and the novel active powder concrete is prepared by high-temperature curing, has the advantages of high strength, good workability, low cost, environmental protection, simple preparation method and the like, is suitable for popularization and application in practical engineering, and conforms to the strategic concept of green sustainable development in China.

Description

A kind of reactive powder concrete mixed with fly ash and preparation method thereof

technical field

The invention relates to the technical field of building materials, in particular to a reactive powder concrete mixed with fly ash and a preparation method thereof.

Background technique

Reactive powder concrete is an ultra-high performance concrete with high strength, high toughness, high durability and low porosity. The principle of its configuration is to reduce the internal defects (microcracks and pores) of the material to a minimum by removing coarse aggregates, improving the activity and fineness of the components, thereby obtaining higher mechanical properties and high durability. Its basic constituent materials are: cement, fine quartz sand, ground quartz powder, silica fume, superplasticizer, steel fiber, etc. Due to the high cost of some components, the popularization and application of reactive powder concrete in practical engineering is restricted to a certain extent. On the other hand, slag such as fly ash is one of the industrial waste residues with the largest emissions. At present, the annual emission in my country has reached more than 150 million tons. The treatment and utilization of slag such as fly ash has caused widespread concern. focus on. Since the beginning of the 21st century, with the development of high-performance concrete technology, it has been found that when preparing high-performance concrete, appropriate admixtures must be added. Improve the workability of concrete, improve the pumpability of concrete, reduce the creep of concrete, reduce the heat of hydration, save a lot of cement and fine aggregate and many other advantages.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a reactive powder concrete mixed with fly ash and a preparation method thereof, which can reduce the production cost of reactive powder concrete and solve the problem of environmental pollution caused by fly ash.

In order to achieve above-mentioned goal, the present invention adopts following technical scheme:

An active powder concrete mixed with fly ash is composed of the following materials in parts by mass: 1 part of cement, 1.1 part of quartz sand, 0.21-0.28 part of silica fume, 0.07-0.14 part of fly ash, 0.1 part of steel fiber, and small group Divide 0.1 part, 0.2 part of water and 0.015 part of water reducing agent.

The cement is Portland cement with the grade of 52.5, the fineness of the cement is 10 m ² /kg, the initial setting time is greater than or equal to 45 minutes, and the final setting time is less than or equal to 600 minutes.

The particle size of the quartz sand is 0.4mm-0.6mm, and the content of SiO ₂ is more than 99.6%.

The silica fume has an average particle size of 0.1-0.2 μm, a specific surface area of >20 m ² /g, a water demand ratio of <120%, and a loss on ignition of 1.45.

The steel fiber is a copper-plated smooth flat steel fiber, with a diameter of 0.22 mm, a length of 12-15 mm, and a tensile strength of more than 2300 MPa.

The fly ash is off-white powder with an average particle size of 6.34 μm and a loss on ignition of 0.4.

The group is divided into gray powder, and the main components are polyester fiber, swelling agent and latex protein.

The water reducing agent is tan powder, and the water reducing rate is ≥25%.

The invention also discloses a method for preparing the reactive powder concrete mixed with fly ash, which specifically includes the following steps:

(1) Mixing: After weighing the raw materials according to the mixing ratio, first pour the cement, quartz sand, silica fume, and fly ash into the mixer, and then sieve the steel fibers into the mixer evenly through the steel sieve, and dry mixing 4 Finally, mix the water with the superplasticizer and the small components, evenly pour it into the mixer, and stir for 6 to 8 minutes before discharging.

(2) Vibration molding: put the active powder concrete material into the steel mold at one time, and use a spatula to slightly vibrate along the inner wall of the mold when charging, and make the mixture higher than the upper mouth of the mold, and place the mold on a vibrating table to vibrate for molding. , until the concrete surface is grout.

(3) Demolition: After the test piece is poured, it is covered with wet sawdust immediately, and it is placed in the standard curing room for curing for 36 hours before demoulding.

(4) High temperature curing: Put the test piece after removing the mold into the HW-30 constant temperature cement concrete curing box, and after curing at a constant temperature of 75 ℃ for 48 hours, take out the test piece and put it into the standard curing room.

Compared with the prior art, adopting the formula of the reactive powder concrete mixed with fly ash according to the present invention will have the following beneficial effects due to the addition of fly ash:

Further improve the fluidity and workability of the slurry, thereby reducing the viscosity, reducing the bubbles introduced during stirring and vibration due to high viscosity, and improving the compactness of the matrix;

Fly ash does not participate in hydration in the early stage, so in the whole cementitious component, although the water-binder ratio is small, considering that fly ash is not hydrated in the early stage, the water/cement ratio is not low, which is beneficial to cement. in early hydration;

When the matrix has formed a structure with sand, fly ash particles and partially unhydrated cement particles as the skeleton and wraps the hydration products, then the surface hydration of the fly ash particles can further fill and compact;

Adding fly ash to replace part of silica fume can also reduce the total cost and improve the performance-price ratio;

The application of industrial waste residues into concrete can effectively solve the problem of massive accumulation of fly ash and reduce environmental pollution, which is conducive to the realization of green and sustainable development in my country.

The preparation method of the present invention has a simple preparation process and improves the problem of uniform dispersion of multiple components. In particular, the steel fibers are evenly screened into the mixer through a steel screen during stirring, which can well avoid the formation of "steel fibers" in the mixture. agglomeration" phenomenon.

Under high temperature curing conditions, the pozzolanic effect of the active material is stimulated, the content of Ca(OH) ₂ is reduced to a certain extent, C-S-H gel is formed, the microstructure of the interface area is improved, the density of the slurry is improved, and the Compressive and flexural strength of reactive powder concrete.

The present invention is characterized in that a new type of active powder concrete is prepared by adding industrial waste slag fly ash as an active component after high temperature curing, and has the advantages of high strength, good workability, low cost, environmental protection and simple preparation method. It is suitable for promotion and application in practical projects, and is in line with the strategic concept of green and sustainable development in my country.

Detailed ways

The specific embodiments of the present invention will be described with reference to examples.

Example 1:

An active powder concrete mixed with fly ash is composed of the following materials in parts by mass: 1 part of cement, 1.1 part of quartz sand, 0.28 part of silica fume, 0.07 part of fly ash, 0.1 part of steel fiber, and 0.1 part of small components, 0.2 part of water, 0.015 part of water reducing agent;

The cement is Portland cement with the grade of 52.5, the fineness of the cement is 10 m ² /kg, the initial setting time is greater than or equal to 45 minutes, and the final setting time is less than or equal to 600 minutes.

The particle size of the quartz sand is 0.4 mm, and the content of SiO ₂ is more than 99.6%.

The silica fume has an average particle size of 0.1 μm, a specific surface area of >20 m ² /g, a water demand ratio of <120%, and a loss on ignition of 1.45.

The steel fiber is a copper-plated smooth flat steel fiber, with a diameter of 0.22 mm, a length of 12-15 mm, and a tensile strength of more than 2300 MPa.

The fly ash is off-white powder with an average particle size of 6.34 μm and a loss on ignition of 0.4.

The group is divided into gray powder, and the main components are polyester fiber, swelling agent and latex protein.

The water reducing agent is tan powder, and the water reducing rate is ≥25%.

The concrete steps of the method for the above-mentioned reactive powder concrete mixed with fly ash are:

(1) Mixing: After weighing the raw materials according to the mixing ratio, first pour the cement, quartz sand, silica fume, and fly ash into the mixer, and then sieve the steel fibers into the mixer evenly through the steel sieve, and dry mixing 4 Finally, mix the water with the superplasticizer and the small components, evenly pour it into the mixer, and stir for 6 minutes before discharging.

(2) Vibration molding: put the active powder concrete material into the steel mold at one time, and use a spatula to slightly vibrate along the inner wall of the mold when charging, and make the mixture higher than the upper mouth of the mold, and place the mold on a vibrating table to vibrate for molding. , until the concrete surface is grout.

(3) Demolition: After the test piece is poured, it is covered with wet sawdust immediately, and it is placed in the standard curing room for curing for 36 hours before demoulding.

(4) High temperature curing: Put the test piece after removing the mold into the HW-30 constant temperature cement concrete curing box, and after curing at a constant temperature of 75 ℃ for 48 hours, take out the test piece and put it into the standard curing room.

The obtained fly ash reactive powder concrete has a compressive strength of 131.8Mpa and a flexural strength of 25.43Mpa.

Example 2:

An active powder concrete mixed with fly ash is composed of the following materials in parts by mass: 1 part of cement, 1.1 part of quartz sand, 0.21 part of silica fume, 0.14 part of fly ash, 0.1 part of steel fiber, 0.1 part of small components, 0.2 part of water, 0.015 part of water reducing agent;

The cement is Portland cement with the grade of 52.5, the fineness of the cement is 10 m ² /kg, the initial setting time is greater than or equal to 45 minutes, and the final setting time is less than or equal to 600 minutes.

The particle size of the quartz sand is 0.6 mm, and the content of SiO ₂ is more than 99.6%.

The silica fume has an average particle size of 0.2 μm, a specific surface area of >20 m ² /g, a water demand ratio of <120%, and a loss on ignition of 1.45.

The steel fiber is a copper-plated smooth flat steel fiber, with a diameter of 0.22 mm, a length of 12-15 mm, and a tensile strength of more than 2300 MPa.

The fly ash is off-white powder with an average particle size of 6.34 μm and a loss on ignition of 0.4.

The group is divided into gray powder, and the main components are polyester fiber, swelling agent and latex protein.

The water reducing agent is tan powder, and the water reducing rate is ≥25%.

The concrete steps of the method for the above-mentioned reactive powder concrete mixed with fly ash are:

(1) Mixing: After weighing the raw materials according to the mixing ratio, first pour the cement, quartz sand, silica fume, and fly ash into the mixer, and then sieve the steel fibers into the mixer evenly through the steel sieve, and dry mixing 4 minutes, and finally mix the water with the superplasticizer and small components, evenly pour it into the mixer, and stir for 8 minutes before discharging.

(2) Vibration molding: put the active powder concrete material into the steel mold at one time, and use a spatula to slightly vibrate along the inner wall of the mold when charging, and make the mixture higher than the upper mouth of the mold, and place the mold on a vibrating table to vibrate for molding. , until the concrete surface is grout.

(3) Demolition: After the test piece is poured, it is covered with wet sawdust immediately, and it is placed in the standard curing room for curing for 36 hours before demoulding.

(4) High temperature curing: Put the test piece after removing the mold into the HW-30 constant temperature cement concrete curing box, and after curing at a constant temperature of 75 ℃ for 48 hours, take out the test piece and put it into the standard curing room.

The obtained fly ash reactive powder concrete has a compressive strength of 142.7Mpa and a flexural strength of 23.58Mpa.

The above embodiments merely illustrate the basic principles, main features and advantages of the present invention, and do not limit the present invention in any form. All technical solutions obtained by those skilled in the art by means of equivalent replacement and equivalent replacement within the spirit and principles of the present invention are within the protection scope of the present invention.

Claims (2)

1. A reactive powder concrete mixed with fly ash is characterized in that it is made up of the following materials by mass: 1 part of cement, 1.1 part of quartz sand, 0.21 to 0.28 part of silica fume, 0.07 to 0.14 part of fly ash, 0.1 part of part steel fiber, 0.1 part small part, 0.2 part water and 0.015 part water reducing agent; The cement is Portland cement with the grade of 52.5, the fineness of the cement is 10 m ² /kg, the initial setting time is ≥ 45 min, and the final setting time is ≤ 600 min; The particle size of the quartz sand is 0.4mm-0.6mm, and the content of SiO ₂ is more than 99.6%; The silica fume has an average particle size of 0.1-0.2 μm, a specific surface area >20 m ² /g, a water demand ratio <120%, and a loss on ignition of 1.45; The steel fiber is a copper-plated smooth flat steel fiber, with a diameter of 0.22 mm, a length of 12-15 mm, and a tensile strength of more than 2300 MPa; The fly ash is gray-white powder with an average particle size of 6.34 μm and a loss on ignition of 0.4; The small component is gray powder, and the main components are polyester fiber, swelling agent and latex protein; The water reducing agent is tan powder, and the water reducing rate is ≥25%. 2. the preparation method of the reactive powder concrete mixed with fly ash according to claim 1 is characterized in that concrete steps are: (1) Weigh each raw material by mass: 1 part of cement, 1.1 part of quartz sand, 0.21 to 0.28 part of silica fume, 0.07 to 0.14 part of fly ash, 0.1 part of steel fiber, 0.1 part of small part, 0.2 part of water and 0.015 part of water reducing agent; (2) After weighing according to step (1), first pour cement, quartz sand, silica fume and fly ash into the mixer, then sieve the steel fibers into the mixer evenly through a steel sieve, and dry stirring for 4 minutes , and finally mix the water with the superplasticizer and small components, evenly pour it into the mixer, and stir for 6 to 8 minutes before discharging; (3) The active powder concrete material obtained in step (2) is loaded into the steel mold at one time, and the inner wall of the mold is slightly vibrated with a spatula during charging, and the mixture is raised above the upper mouth of the mold, and the mold is placed on a vibrating table to vibrate. Forming, continuing until the concrete surface is grout; (4) Immediately after the pouring of the test piece is completed, it is covered with wet sawdust, and it is placed in the standard curing room for curing for 36 hours and then demolded; (5) Put the specimen after removing the mold into the HW-30 constant temperature cement concrete curing box, and after curing at a constant temperature of 75 ℃ for 48 hours, take out the specimen and put it into the standard curing room.