CN106186945A - A kind of regeneration concrete and preparation method thereof - Google Patents

Abstract

The invention discloses a recycled concrete and a preparation method thereof. It is prepared from raw materials including cement, water, fine aggregate, recycled coarse aggregate, silicon powder, steel fiber, rubber particles, and a water reducer. The recycled coarse aggregate , The mass ratio of steel fiber to rubber particle is (2.80～3.00):(0.20～0.25):(0.05～0.20). The regenerated concrete of the invention is prepared from components including regenerated coarse aggregate, rubber granules, steel fibers and silicon powder, which improves the mechanical properties of the regenerated concrete while realizing the reuse of waste materials, and has good application prospects.

Description

A kind of recycled concrete and its preparation method

technical field

The invention belongs to the technical field of new building materials, and relates to recycled concrete and a preparation method thereof.

technical background

Recycled concrete technology is a technology that mixes waste concrete in a certain proportion to form recycled coarse aggregate after crushing, cleaning and grading, and partially or completely replaces natural aggregate to prepare concrete. This technology can solve the problems of land occupation and disposal of waste concrete, reduce pollution and save energy. However, there are some defects in recycled coarse aggregate, such as damage caused by the crushing process, large porosity, residual cement base, high water absorption, etc. Due to these defects, recycled coarse aggregate is mostly used in non-structural fields such as paving cushions and making green bricks, which limits its application channels.

Rubber, silica fume and steel fibers can work in harmony in the concrete matrix to form a hybrid effect, which jointly improves the performance of recycled concrete, making it have excellent compression and bending properties, and is suitable for various types of concrete projects. Rubber silica fume steel fiber recycled coarse aggregate concrete not only has a wide range of material sources, but also can expand the application range of recycled coarse aggregate, improve the efficiency of resource recycling and reduce environmental pollution.

Contents of the invention

Aiming at the deficiencies in the prior art above, the present invention provides a recycled concrete and a preparation method thereof. The recycled concrete of the present invention is made from raw materials including recycled coarse aggregate, rubber granules, steel fibers, and silicon powder. It has a good application prospect to improve the mechanical properties of recycled concrete while recycling.

The object of the present invention is achieved through the following technical solutions:

A kind of recycled concrete, prepared from raw materials including cement, water, fine aggregate, recycled coarse aggregate, silicon powder, steel fiber, rubber particles, water reducer, the quality of the recycled coarse aggregate, steel fiber and rubber particle The ratio is (2.80～3.00):(0.20～0.25):(0.05～0.20).

Preferably, the mass ratio of the cement, silica fume and water is 1.00:(0.05-0.15):(0.50-0.55).

Preferably, the mass ratio of the cement to the recycled coarse aggregate is 1.00:(2.80-3.00). Preferably, the recycled coarse aggregate is formed by mixing aggregates with a particle size of 5-10mm and 10-20mm at a ratio of 1:1, which conforms to continuous gradation.

Preferably, the mass ratio of the cement to the fine aggregate is 1.00:(1.80-2.40), and the fine aggregate used in the present invention is not particularly limited.

The rubber granules are rubber granules made from waste tires, preferably with a particle size of 0.85-1.40mm, which play the same role as fine aggregates, can improve the elasticity of concrete, and increase the plastic deformation of concrete.

The silicon powder is silicon powder obtained by recycling industrial dust produced when smelting industrial silicon or silicon-containing alloys. The preferred specific surface area is 20×10 ³ to 23×10 ³ m ² /kg. It can accelerate the hydration process of cement and improve the mechanical properties of concrete. More preferably, the _SiO2 content of the silicon powder is 98.5%, the ignition loss is 2.14%, the water content is 0.3%, the chloride ion content is 0.017%, and the total alkali content is 0.4%.

The steel fibers are cut by ordinary steel plates and pressed into shape, preferably with an aspect ratio of 45-60, more preferably a tensile strength of 600MPa, and a density of 7.82-7.85g/cm ³ ; after being added, they are randomly distributed in the concrete matrix The bridging and tie effects that will be produced can effectively hinder the expansion of micro-cracks and the formation of macro-cracks inside the concrete, and improve the performance of concrete.

The raw materials for the preparation of the renewable concrete also include a water reducer, and there are no special requirements for the actual amount and type of substance.

The invention uses the synergistic effect and hybrid effect of rubber particles, silicon powder and steel fibers in the concrete matrix to jointly improve the mechanical properties of recycled concrete, making it have excellent compression and bending properties, suitable for various concrete projects, rubber Granules, silicon powder, steel fiber and recycled coarse aggregate are all recycled materials with a wide range of sources, which can improve the efficiency of resource recycling, reduce environmental pollution, and expand the application range of recycled coarse aggregate.

The present invention further provides a preparation method for recycled concrete, comprising the steps of:

Mix and stir the recycled coarse aggregate, steel fiber and rubber particles, add silica fume, cement and fine aggregate and then mix, then add water reducer and water to mix to obtain recycled concrete slurry, which is cured and maintained to obtain renewable concrete slurry. concrete. The curing and curing conditions are not particularly limited.

The present invention has the following beneficial effects:

(1) The present invention utilizes the high elasticity of rubber, the volcanic ash of silica fume and the micro-filling effect and the bridging and knotting effect of steel fibers to comprehensively improve the mechanical properties of recycled concrete;

(2) The rubber granules used in the present invention are processed from waste tires and have a wide range of sources. They are tough materials with high elasticity, which can ease various stresses inside the concrete, reduce the generation and development of primary cracks inside the concrete, and better Improve the energy absorption and energy dissipation capacity of concrete;

(3) the silicon powder used in the present invention is the waste material that smelting industry silicon produces, and source is extensive, has extremely strong pozzolanic performance, can produce the Ca(OH) unfavorable to intensity with cement hydration _2Reaction generates CSH gel, accelerates cement The hydration process can not only reduce the use of cement, but also reduce the strength loss caused by the defects of recycled coarse aggregate and the addition of rubber, and improve the mechanical properties of concrete, such as compressive resistance and bending toughness;

(4) The bridging and tie effect produced by the chaotic distribution of steel fibers in the concrete matrix can improve the crack resistance of concrete and obtain better toughness and ductility;

(5) The present invention combines the characteristics of the above materials, can significantly improve the performance of recycled concrete, turn waste into treasure, and recycle and reuse, which is conducive to promoting the reasonable and extensive application of recycled coarse aggregate in actual construction projects, Save social resources and reduce environmental pollution.

detailed description

The present invention can be further illustrated by the following examples, but the examples are not intended to limit the protection scope of the present invention.

The preparation method of the regenerated concrete slurry in the embodiment 1 and 2 of the present invention is: take the regenerated coarse aggregate of two kinds of particle size ranges and mix, then mix with steel fiber, rubber particle and put into the mixer and stir for 90 seconds, then silicon powder, Add cement and fine aggregate to the mixer and stir for 90 seconds to fully mix evenly, then mix the water reducer and water and add to the mixer and stir for 180 seconds to obtain recycled concrete slurry.

Prepare contrasting concrete: mix natural coarse aggregates in two particle size ranges, mix them with steel fibers and put them in a mixer for 90 seconds, then add cement and fine aggregates into the mixer and mix them for 90 seconds to fully mix them evenly. Then mix the water reducing agent with water and add to the mixer and stir for 180 seconds to obtain the natural concrete slurry for comparison.

The consumption of rubber particle, silicon powder, steel fiber, regenerated coarse aggregate, fine aggregate, cement, water and water-reducing agent in embodiment 1, 2 and natural coarse aggregate, fine aggregate, steel fiber, The amount of cement, water and water reducer is shown in Table 1. The data in the table is the material amount per unit volume of recycled concrete (unit: kg/m ³ ).

Table 1

Note: The additional water is to consider the characteristics of the high water absorption rate of the recycled aggregate. In order to keep the water-cement ratio of the concrete unchanged, the additional water calculated by 2% of the mass of the recycled aggregate is added.

The parameter index of the various materials that embodiment 1, 2 and comparative examples use are as follows:

(1) Cement: Ordinary Portland cement of Shijing brand 42.5R grade;

(2) Fine aggregate: use continuously graded natural fine aggregate, which is medium-coarse river sand with a specific gravity of 2.69 and a fineness modulus of 2.52;

(3) Natural coarse aggregate: natural coarse aggregate with a particle size between 5mm-10mm and 10mm-20mm respectively, with a mass ratio of 1:1, which conforms to continuous gradation;

(4) Regenerated coarse aggregate: produced by Shenzhen Lvfa Pengcheng Environmental Protection Technology Co., Ltd., which are recycled coarse aggregates with particle sizes ranging from 5mm to 10mm and 10mm to 20mm. The mass ratio is 1:1, which conforms to continuous gradation. The water absorption rate is 2%, remove sundries such as glass, sawdust, bricks, etc., wash with clean water, and dry naturally for use.

(5) Rubber particles: the particle size is 0.85-1.40mm, the density is 1.05g/cm ³ , and the melting point is 170°C;

(6) Silicon powder: produced by Chengdu Donglanxingke Co., Ltd., with SiO ₂ content of 98.5%, ignition loss of 2.14%, specific surface area of 22.99×10 ³ m ² /kg, moisture content of 0.3%, and chloride ion content 0.017%, total alkalinity is 0.4%;

(7) Steel fiber: The shear wave fiber provided by Guangzhou Jinyue New Material Co., Ltd. is cut by ordinary steel plate and pressed into shape. The length is 32mm, the aspect ratio is 45, the tensile strength is 600MPa, and the density is 7.82 g/cm ³ , melting point is 1538°C;

(8) Water reducing agent: produced by Jiangmen Qiangli Building Materials Technology Co., Ltd., Guangdong Province, the model is QL-PC5.

Pour the concrete slurry prepared in the above-mentioned Examples 1, 2 and Comparative Example into a standard mold and vibrate it compactly with a vibrator, cover it with a plastic film, remove the mold after curing for 24 hours, and pour it indoors to make the strength stable. Water curing for 28 days, and then stand outside for 90 days to obtain 1-3# concrete specimens for testing, and use a material compression testing machine to perform a uniaxial compression load test on a standard cylinder of φ150mm×300mm to test the axial center of the obtained concrete The compressive strength and modulus of elasticity are the flexural strength of the concrete obtained through the three-point bending test of the small beam of 100mm×100mm×515mm by a full-digital electro-hydraulic servo dynamic and static testing machine. The data are shown in Table 2.

Table 2

As can be seen from the data in the table, the recycled concrete prepared by the present invention is relative to the concrete of comparative examples. Silica fume can enhance the compressive strength of recycled concrete, and can obtain higher compressive strength than natural concrete when the rubber content is low. Both powder and rubber can improve the toughness of concrete, and the fracture toughness is higher than that of natural concrete. The effect of rubber incorporation is particularly significant, and the fracture energy increases significantly with the increase of rubber content.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than limit the protection scope of the present invention. Those skilled in the art should understand that several inferences or equivalent replacements can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims (7)

1. A recycled concrete, prepared from raw materials including cement, water, fine aggregate, recycled coarse aggregate, silicon powder, steel fiber, rubber particles, water reducing agent, the recycled coarse aggregate, steel fiber and rubber particle The mass ratio is (2.80～3.00):(0.20～0.25):(0.05～0.20). 2. The recycled concrete according to claim 1, characterized in that, the mass ratio of the cement, silica fume and water is 1.00:(0.05～0.15):(0.50～0.55). 3. The recycled concrete according to claim 1, characterized in that, the mass ratio of the cement to the recycled coarse aggregate is 1.00:(2.80-3.00). 4. The recycled concrete according to claim 1, characterized in that, the mass ratio of the cement to the fine aggregate is 1.00:(1.80-2.40). 5. The recycled concrete according to any one of claims 1-4, characterized in that, the rubber particles have a particle size of 0.85-1.40mm. 6. The recycled concrete according to any one of claims 1-4, characterized in that the specific surface area of the silica fume is 20×10 ³ -23×10 ³ m ² /kg. 7. The preparation method of the reclaimed concrete as described in any one of claim 1-4 is that regenerated coarse aggregate, steel fiber and rubber particle are mixed and stirred, stir after adding silica fume, cement and fine aggregate, then add reducing The water agent and water are mixed to obtain recycled concrete slurry, and after curing and curing, renewable concrete is obtained.