KR20180130392A - recycling concrete mixed with construction wastes - Google Patents

Abstract

The present invention relates to a method for recycling construction wastes. More specifically, the construction wastes which are illegally buried or illegally incinerated due to lack of landfill and strengthened processing regulations are reproduced as aggregates and cement, and fly ash, blast furnace slag, sand, and admixtures are added to the regenerated aggregates and cement to manufacture regenerated concrete. Accordingly, the method for recycling construction wastes has an effect of improving resources and environment due to new aggregate collection.

Description

Recycled concrete mixed with construction wastes.

The present invention relates to a method of recycling construction waste generated at a construction site with aggregate and cement, and recycled construction materials such as concrete using recycled aggregate and cement.

The amount of construction waste in Korea is increasing year by year. In particular, concrete accounts for about 70% of construction waste, about 16% for asphalt and about 8% for ash, and concrete, asphalt and soil have more than 94% It is occupied.

These construction wastes have mainly been disposed of in landfills, but it is difficult to secure landfill sites anymore and they are being disposed through illegal landfill, speculation and incineration by various regulations.

Construction wastes are wastes that are discharged in relation to civil engineering and construction works. They are wastes other than household wastes such as designated wastes such as waste oil and waste paint, and food wastes that workers in the construction site live while they live. Waste materials such as concrete blocks, asphalt concrete blocks , Construction sludge, waste building materials (waste plastics, waste glass, waste bricks, waste styrofoam, etc.)

(Construction materials such as concrete blocks, asbestos blocks, brick pieces, etc.) accompanied by sludge disintegration and dismantling of structures, and industrial wastes, Metals (reinforcing bars, bolts, etc.), glassware, ceramics

(Glass sculptures, tiles, etc.), trees (various kinds of waste wood), and waste plastics. In the case of general waste, waste mattresses, waste curtains, construction waste materials at new construction sites, and trees at new construction sites are included. Such construction wastes are accompanied by a great deal of cost and environmental pollution, because they are disposed of through illegal landfill and incineration due to lack of landfill facilities and strict regulations.

In order to solve such problems, various types of construction waste recycling technologies have been developed. For example, in Korean Patent No. 10-0235319 (published on December 15, 1999), various types of construction waste, The present invention discloses an intermediate treatment method and apparatus for the treatment and recycling of construction waste through a series of processes after collecting the slag, concrete slag, waste wood and asphalt concrete slag, and disclosed in Korean Patent No. 10-0358687 The waste concrete waste and waste asbestos lumps, and various kinds of solid waste such as waste wood, waste vinyl, etc. as well as iron waste and glass are efficiently separated and removed, and the concrete is removed, Discloses a method for recycling construction waste to be recycled as a forming material, and Korean Patent No. 10-047048 No. 6 No. 2005/02/07 discloses an apparatus and a method for producing recycled aggregate by crushing construction waste. In Korean Registered Patent No. 10-0455833 (published on Nov. 10, 2004) Discloses a method and apparatus for regenerating an aggregate using construction waste that can prevent quality deterioration and energy waste in a straight line crushing process.

However, the use of the recycled construction material is still deteriorating in the presentation of such a variety of recycling methods, which may be attributed to the degradation of the properties of recycled construction materials.

The present invention aims to provide a method for recycling construction waste that is illegally reclaimed or incinerated by supplementing the properties of conventional recycled construction materials, thereby contributing to resource saving and environmental improvement.

As described above, the recycled concrete using the construction waste according to the present invention is conventionally illegally buried or incinerated, thereby wasting resources and recycling the construction waste, which has been a cause of environmental pollution, Thereby reducing the costs associated with aggregate production and reducing environmental pollution.

In particular, waste concrete, which accounts for about 70% of construction waste, is provided with a recycling technology that can improve the quality of the waste concrete compared to the conventional method, so that the cost reduction effect on the construction material is very large.

In order to achieve the above object, the present invention provides a method for crushing a concrete mass in a size of 50 to 60 cm in the field, crushing a coarse aggregate having a maximum dimension of 25 mm and a coarse aggregate having a maximum dimension of 5 mm to a ratio of 4: 25 to 50% by weight of recycled aggregate produced by removing impurities such as iron contained in the aggregate by using a magnet,

Was ground to a size of 25 mm using a jaw crusher and pre-heated at 200 ° C for 2 hours, pulverized using a ball mill, sieved to a size of 0.15 mm or less, charged into an electric furnace at 700 ° C for 90 minutes, 15 to 45% by weight of recycled cement, 4 to 5% by weight of fly ash, density (g / cm3) of 2.90, specific gravity of 280, and powdery degree of 2 to 10% by weight of recycled cement added to the total weight of cement By weight of the reclaimed cement, 5 to 10% by weight of blast furnace slag having a specific surface area (㎠ / g) of 4,000 to 5,000, 10 to 40% by weight of sand, 10 to 25% by weight of water (H2O) Fly ash, sand, and blast furnace slag are first subjected to dry blending for one minute, and the recycled aggregate, water and water reducing agent are further added to the recycled concrete using the construction waste, which is manufactured through a biping process for 5 to 10 minutes so that the concrete becomes uniform. The main

Hereinafter, the technical configuration will be described in more detail.

The construction materials that are disposed of at construction sites are classified as industrial wastes and general wastes as mentioned above. In the case of industrial wastes, construction waste materials such as sludge (waste bentonite, etc.) and construction waste (concrete blocks, Etc.), metals (reinforcing bars, bolts, etc.), glass and ceramics (glass fragments, tiles, etc.), woods (various kinds of waste wood)

These include wasted mattresses, waste curtains, construction waste in new construction sites, and trees in new construction sites.

The present invention aims to present a method of recycling construction waste by regenerating such waste construction materials as aggregate and cement, and manufacturing recycled concrete using the recycled concrete as recycled concrete. First, the regeneration of aggregate will be described.

Recycled aggregate has not been used effectively with poor quality such as high absorption rate and abrasion rate compared with natural aggregate. It is pointed out that the recycled aggregate concrete also has a problem in practical use because its performance in compressive strength and other concrete properties is lower than that of concrete using natural aggregate. As such, the recycled aggregate concrete

The reason for the deterioration in performance compared with the crit is that the existing studies show that the deterioration of the aggregate quality due to the mortar and other impurities adhering to the aggregate surface and the deterioration of the rigidity of the aggregate itself due to the impact applied to the waste concrete during the manufacturing of the recycled aggregate Etc. In order to improve the quality of the recycled aggregate itself, it is necessary to increase the process of sorting the aggregate during the manufacturing process of the aggregate, to improve the quality of the aggregate through the manufacturing process such as improvement of the crushing method, It is necessary to improve the quality thereof and to improve the quality by processing the aggregate itself. The thus-regenerated aggregate is used in an amount of 25 to 50% by weight based on the electrolytic compounding amount used in the concrete production, There is a problem that the workability of the concrete is poor, and when it exceeds 50% by weight

The recycled aggregate is preferably used in an amount of 25 to 50% by weight based on the electrolytic compounding amount used in the production of concrete. The cement is prepared by mixing the waste concrete with 25 mm Crushed to a size of 0.15 mm or less and heated at 700 ° C for 90 minutes in an electric furnace to heat the cement to a total weight of the cement, 2% by weight to 10% by weight. The addition of the above-

This is to solve the sudden action of raw cement.

The regenerated cement thus produced has a density (g / cm 3) of 3.15 and a powder degree of 2,300 to 2,500 cm 2 / g. Generally, ordinary Portland cement has a high powdery figure of about 3,300 cm 2 / g. This high degree of hydration helps to improve the initial strength of the cured product, but it can be a disadvantage in hydration heat. In a normal small building, the influence of hydration heat of the cement is not so great, and heat is easily released to the outside, which does not adversely affect the structure, but it can cause a serious problem in a large structure. In the case of large structures, thermal stress is generated inside the structure because heat is not released to the outside. As a result, cracks are generated in the structure. Therefore, instead of Portland cement having a high powder degree of about 3,300 cm 2 / g, Gt; / g / cm < 2 > / g. Specifically, the hydration heat of the cement having a powder degree of 2,300 cm 2 / g for 48 hours was 41.7 cal / g, and the powdery degree of the common portland cement was about 3,300 cm 2 / g. Which is about 15% lower than 49.1 cal / g. follow

It is preferable to use cement having a degree of powder of 2,300 to 2,500 cm 2 / g in order to prevent wide utilization and cracking of the structure.

The recycled cement is used in an amount of 15 to 45% by weight with respect to the amount of electrolytic compound used in the production of concrete. When the recycled cement is used in an amount less than 15% by weight, the durability is poor. The recycled cement is preferably used in an amount of 15 to 45% by weight based on the electrolytic compounding amount used in the concrete production. The fly ash has a spherical shape of the artificial pozzolan As the powder, the main component is silica (SiO2), alumina (Al2O3)

, Ferric oxide (Fe2O3), and the like. However, when used in concrete, the soluble silica contained in the fly ash slowly bonds with the calcium hydroxide (Ca (OH) 2) generated at the hydration of the cement at room temperature to form insoluble curing Only materials with the potential to produce large quantities of material

Represents a pozzolanic reaction, and has a composition ratio of carbon 62.16%, hydrogen 0.85%, oxygen 1.56%, nitrogen 0.41%, combustible sulfur 0.47% and ash 34.55%.

 The fly ash used in the present invention is generated when coal is incinerated in a thermal power plant at a high temperature of 1,400 to 1,500 DEG C. The fly ash has a density (g / cm3) of 2.19 and a powder degree (cm2 / g) of 3,740. When the amount of the fly ash is less than 4% by weight based on the total amount of the blending, the strength and durability of the fly ash are inferior. The blast furnace slag fine powder has a density (g / cm < 3 & 2.90, a specific gravity of 280 or more, and a powder degree (㎠ / g) of 4,201, wherein the molten slag produced in the blast furnace during the manufacture of pig iron is quenched by cold air or cold water,

Lag fine powder, and the crystal state and quality of the product are changed according to the treatment method, and they are classified into slowly cooled slag, semi-quenched slag and quenched slag. As for the applications according to the classification, ) And semicrystalline slag are used for blast furnace cement (cement admixture), for ground improvement, for concrete

The blast furnace slag is an amorphous structure that is mostly glassy and the vitreous slag is composed of various minerals contained in the structure. The slag of the blast furnace slag is used as the aggregate, and the quenched slag is used as lightweight concrete aggregate and lightweight embedding material. The blast furnace slag powder is used in an amount of 5 to 10% by weight based on the total blend ratio of the concrete, and the blast furnace slag powder is used in an amount of 5 to 10% by weight. The sand has a density (g / cm3) of 2.5 to 2.8, a water absorption (%) of 0.2 to 2.8, a weight loss (%) of 5 to 70, and a compressive strength Strength (MPa) 80 to 3

(G / cm < 3 >) of 2.5-3.0, density (g / cm3) of 2.7-3.0, absorption rate (%) of 0.3-0.9, abrasion loss (%) of 5-30, compressive strength (MPa) (G / cm3) of 2.6 to 3.0, a water absorption (%) of 0.3 to 1.5, a wear rate (%) of 6 to 19 and a compressive strength (MPa) of 70 to 00, Density (g / cm3) of 2.7 to 3.2, water absorption (%) of 0.5 to 1.3, wear loss (%) of 8 to 27, compressive strength (MPa) of 8 to 21, ) 14

And at least one kind of igneous rock selected from among 0 to 360 basalt rocks is crushed sand having a particle size of 0.1 to 0.6 mm and a round or cubic shape and is used in a range of 10 to 40% When it is less than 10% by weight, there is a problem of poor compression strength and durability, and even when it is used in excess of 40% by weight

It is preferable to use the crushed sand in a range of 10 to 40% by weight based on the total amount of the crushed sand. The particle size of the sand is determined by the workability of the concrete, the strength of the hardened concrete, density, abrasion resistance, water tightness, durability And concrete can be manufactured with a small amount of unit cement, and the amount of unit cement is decreased, so that drying shrinkage and hydration

Heat can be reduced to reduce cracking. As a concrete example, sand having a particle size of 0.15 to 0.30 mm affects fluidity and workability of concrete, and sand having a particle size of 0.3 to 0.6 mm affects air entraining property. Therefore, in order to improve the strength, density and durability of the hardened concrete, crushed sand having a particle size of 0.15-0.6 mm

And the sand mold increases the concrete property, and the fluidity of the rounded or cubic shape is increased and the filling property is increased. When the shape is out of the above range, for example,

 The friction between the aggregates increases as they are formed, which reduces the fluidity and fillability of the concrete, thereby deteriorating the workability.

The water (H2O) is used in an amount of 10 to 25% by weight based on the total mixing ratio of the concrete. When it is used in an amount of less than 10% by weight, the workability of the concrete deteriorates and the durability is poor. The water resistance is preferably 10 to 25% by weight based on the total amount of the concrete.

The water reducing agent is used in an amount of from 0.5 to 1% by weight based on the total amount of the concrete. When the water reducing agent is used in an amount less than 0.5% by weight, dispersion stability and fluidity are poor. When the water reducing agent is used in an amount exceeding 1% The over-expansion and condensation may be excessively delayed, and therefore, the water reducing agent may be added in an amount of 0.5 to 1

The concrete is composed of three components of cement, aggregate, and water, and is used in large quantities in construction and civil engineering. However, the above three components are difficult to meet a wide range of concrete applications. Therefore, an admixture is used to solve this problem, and recently, among the admixtures, a high-performance AE water reducing agent is used. The use of such a water reducing agent is intended to increase the fluidity of the concrete by dispersing the cement particles. The effect of the water reducing agent is to reduce the unit water amount required to produce the concrete having the desired kneading agent, As the water reducing agent, there are polycarboxylic acid type, melamine type and naphthalene type.

Examples of the polycarboxylic acid-based component include a polycarboxylic acid polymer, a polycarboxylic acid polymer compound, a crosslinked polymer, and a polycarboxylic acid group-containing polycarboxylic acid multi-component polymer having a sulfonic acid group. Examples of the melamine-based component include melamine sulfonic acid and modified lignin, A methylmelamine condensate and a water-soluble special polymer. Examples of the naphthalene-based component include naphthalene alcohol

Formalin condensates, special surfactants (such as modified ligninsulfonic acid), naphthalenesulfonic acid formalin condensates and reactive polymers.

The higher the specific surface area of the cement, the higher the adsorption amount of the dispersant and the lower the flowability of the mortar. The more the adsorbed amount of the dispersant to the cement is, the less the amount of the dispersing agent contributing to the fluidity. The solubility of gypsum in the solution was determined by the addition of the semi-gypsum, poorly soluble anhydrite,

The amount of adsorbed dispersant increases with decreasing solubility of gypsum in cement

The technical composition according to the mixing ratio of the recycled concrete using the construction waste as described above will be described in more detail through examples.

Recycled aggregate - Example 1

The waste concrete was crushed to a size of 60 cm at the site, and then crushed to a ratio of 4: 1 using a crusher to a coarse aggregate having a maximum dimension of 25 mm and a residual aggregate having a size of 5 mm or less. The crusher used for the crushing of the waste concrete uses a force such as compression, shearing, bending, impact and friction as a basic principle, and in particular, to produce a recycled aggregate , It is preferable to use a crusher having excellent friction action during crushing because it is important to remove the mortar attached to the aggregate surface. For this reason, in the present invention, a jaw crusher is used, and waste concrete having a large particle size is first crushed to a size of 60 cm by using the crusher, and then second crushed again to obtain a coarse aggregate having a maximum dimension of 25 mm, Is crushed to have a 4: 1 ratio.

The average particle size of the recycled aggregate has a particle size distribution of 0 to 5.0 mm and the foreign materials (mortar, stone materials, red brick, glass, tile, ascon, plastic, Flooring, wood, insulation, hardware, etc.) are removed by visual identification or iron is removed using a magnet.

Recycled Cement - Example 2

The waste concrete was pulverized to a size of 25 mm using a jaw crusher and pre-heated at 200 ° C. for 2 hours, pulverized using a ball mill, sieved to a size of 0.15 mm or less, and charged into an electric furnace at 700 ° C. for 90 minutes After the heat treatment, 96 kg of cement and 4 kg of dihydrate are added to produce. The reason for putting this high-

For delaying condensation due to rapid hydration reaction with water.

When the recycled cement was compared with the conventional cement, the content of CaO, SiO2, Al2O3, Fe2O3, and MgO decreased by about 10 to 15%, while the content of SO3 was slightly increased, Of MgO and 1.9% of SO3, respectively

Claims (2)

Wherein the blast furnace slag has a density (g / cm3) of 2.90, a specific gravity of 280, and a powder degree (㎠ / g) of 4,000 to 5,000. The method of claim 1, wherein the sand is a granite having a density (g / cm3) of 2.5 to 2.8, a water absorption rate (%) of 0.2 to 2.8, a wear loss (%) of 5 to 70,