KR20050112311A - Manufacturing method of recycled aggregate from dust of waste concrete and recycled aggregate produced therefrom - Google Patents

Abstract

The present invention is a method for producing recycled aggregates that can be used in construction sites by molding the fine powder generated in the waste concrete crushing / classification process into a molded body at room temperature and then using a modified sulfur coating solution and the recycled aggregate produced therefrom It is about. More specifically, the method of the present invention comprises the steps of providing the waste concrete fine powder, molding the fine powder and cement mixture into a spherical or pellet form at room temperature, drying the molded molded body and using the modified sulfur coating solution Coating the dried formed body.

According to the present invention, by forming and coating the waste fine powder generated from the waste concrete at room temperature, it is possible to produce recycled aggregates having excellent physical properties that can be used again in construction sites, so that the effect of recycling waste resources and minimizing environmental pollution can be expected. have.

Description

Manufacturing Method of Recycled Aggregate Using Waste Concrete Fine Powder and Recycled Aggregate Produced therefrom {Manufacturing Method of Recycled Aggregate from Dust of Waste Concrete and Recycled Aggregate Produced Therefrom}

The present invention relates to a method for producing recycled aggregate using fine powder of waste concrete, and to a recycled aggregate prepared therefrom.

More specifically, the present invention relates to a method for producing recycled aggregates that can be used in construction sites by coating the waste fine powder generated during the waste concrete pulverization / classification process into a molded body at room temperature, and to a recycled aggregate prepared therefrom. will be.

Currently, the amount of waste concrete generated by reconstruction and redevelopment projects is increasing at home and abroad, and in order to recycle the waste concrete, waste fine powder is produced in the process of producing recycled aggregates through the process of grinding, classifying and crushing waste concrete. A large amount of fine powder is generated), but since it is already a fine powder that has undergone carbonation for a long time, the entire powder is discarded since it does not exhibit hydraulic properties capable of exhibiting a certain strength.

Research to recycle such fine powder is being attempted at home and abroad. The developed technologies are as follows.

Fine powder of the melt by way of producing the aggregate by crushing one cooling water maintained the amorphous (Japanese Patent Laid-Open No. 2000-72501), the fine powder at a high temperature above 1300 ℃ by heating for several hours at a temperature about 700 ℃ in CaCO ₃ By restoring hydration by restoring to CaO form, it is possible to use regenerated cement (Korean Patent Publication No. 10-0379697) or cement clinker raw material (Japanese Patent Publication No. 2003-313056) and to fine powders. Disclosed is a method (Japanese Patent Laid-Open No. 2003-2724, Japanese Patent Laid-Open No. Hei 8-151248) for producing aggregate by adding aggregate.

However, the technology up to now requires enormous facility costs in order to perform heat treatment, and even if an expensive admixture is added, the amount of fine powder that can be actually mixed and used in cement is limited.

In addition, in the past, sulfur-concrete was produced by heating and mixing unmodified sulfur (usually sulfur) and aggregate, but it was found to be problematic for long-term durability, and therefore, it was found to be inadequate for quality improvement and commercial use of sulfur concrete.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an excellent recycled aggregate from waste concrete fine powder without adding an expensive admixture and without performing heat treatment at a high temperature.

The present inventors have found that the above object can be achieved by molding the fine powder using a different process at room temperature and then coating the molded body with a modified sulfur coating solution to complete the present invention.

Accordingly, the present invention is a method for producing a recycled aggregate that can be used in construction sites by coating the waste fine powder generated during the waste concrete grinding / classification process at room temperature and using a modified sulfur coating solution and the recycled aggregate produced therefrom to provide.

More specifically, the method for producing recycled aggregate using the fine powder of the present invention

Providing waste concrete fine powder,

Molding the fine powder and cement mixture into a spherical or pellet form at room temperature,

Drying the molded body and

Coating the dried formed body using a modified sulfur coating solution

It includes.

Hereinafter, the present invention will be described in more detail.

First, the step of preparing the starting material by pulverizing the waste concrete may be performed only the grinding / classification of known methods that are conventionally used to recycle the waste concrete, and the washing process may be omitted. That is, it is possible to use the separated fine powder by separating the fine powder, for example, fine powder having a diameter of 0.15 mm or less and aggregates of more than 0.15 mm from the pulverized waste concrete. However, it is not necessary to limit the particle size of the fine powder, which is the starting material of the present invention, as long as the diameter can be formed in the molding machine.

In addition, the fine powder used in the present invention includes not only waste concrete fine powder but also fine powder such as stone powder discharged from a stone processing industry, and any type of fine powder may be used as a raw material in the production of aggregates.

The step of forming the fine powder into a spherical or pellet at room temperature is carried out using an extrusion process or a pelletizer to impart the characteristics as a recycled aggregate because the fine powder itself is carbonated for a long time and is a very hard material. When manufacturing aggregates artificially, in order to express the strength characteristic of aggregates to the maximum value from the viewpoint of material engineering, it must be molded into a spherical shape. For this, there is a method of forming using a pelletizer. The method has a good spherical shape, but in order to increase the production efficiency per unit time, it is more preferable to manufacture a continuous process using an extruder.

In one embodiment of the present invention, the molding process is carried out using an extruder, and the cement is mixed with water in the fine powder and extruded, and then a cutter, for example, a compressed air cutter, is attached to the end of the extruder die to extrude the extrudate. Cut to a constant size. At this time, an additive may be added to improve the fluidity of the fine powder and cement during the extrusion process, and preferred examples of the additive include, but are not limited to, plastic clay, fly ash, methylcellulose, water glass, and the like. In addition, the cut extrudate may be rolled in a pelletizer, molded into a completely spherical shape, and then dried.

When cement is mixed with the fine powder with water, the mixing ratio of fine powder to cement is 90:10 to 10:90, and water is determined according to the fine powder particle size and distribution and the amount of cement added, for example, based on the total amount of the total compound. 20 to 50% by weight.

The cut molded body is dried and retains latent heat while moving into a conveyor belt maintained at about 120 ° C to 140 ° C so as to preheat the cut molded body in advance to a predetermined temperature, so that the coating conditions are uniform. The coating is performed while passing through the coating reactor installed at the end of the furnace line.

The molded article is coated using a coating solution such as water glass, colloidal silica sol, modified sulfur, etc. In the present invention, modified sulfur was prepared and used. The sulfur used to prepare the sulfur coating liquid may be powdered, flaked or molten sulfur, but may be prepared by adding oligomers or the like to sulfur discharged as a byproduct during petroleum refining.

Specifically, reformed sulfur can be produced according to a known method using sulfur discharged as a by-product from a domestic refinery and cyclopentadiene oligomer and reagent-grade dicyclopentadiene (DCPD) discharged as a by-product from a petrochemical plant. Can be.

According to one embodiment of the invention, the cyclopentadiene oligomer and dicyclopentadiene are mixed at a volumetric volume of 50:50, and 5% of the mixture based on 100% by volume of sulfur is sulfur and high temperature, for example 120 ° C. The modified sulfur is synthesized by mixing and reacting in a reactor kept at a constant temperature from 180 ° C., and the reformed sulfur solution is cooled to room temperature and stored in a flake state. have. In the coating operation, the coating liquid is used while maintaining the temperature of 120 ° C. to 150 ° C., in consideration of the melting temperature of the sulfur and the working fluidity, preferably in a thermostat that can maintain a constant temperature of about 130 ° C.

The molten reformed sulfur bath is installed at the end of the conveyor line, the coating is made while passing the molded body having a latent heat as the drying is completed into the chamber.

The coating time is preferably about 10 minutes in terms of economical efficiency, but may be arbitrarily determined in consideration of the porosity and diameter of the spherical body.

The coated molded body is manufactured as a recycled aggregate capable of exhibiting elasticity and initial strength that can be raised without breaking even when hardened to the ground in about 5 minutes.

The recycled aggregate according to the present invention may be used as coarse aggregate, or may be used in the form of fine aggregate used with coarse aggregate. When used as coarse aggregate, the aggregate size is about 5 to 20 mm is suitable, and when used as fine aggregate with coarse aggregate, 5 mm or less is preferable. However, even in the field where recycled aggregates are used up to now, there is no case of verifying the long-term durability due to the use of recycled aggregates, so it is necessary to limit the size to the aggregates used for each use because it is a situation that a certain amount of recycled aggregates and natural aggregates are used together. There is no.

Hereinafter, the present invention will be described in more detail with reference to Examples.

<Examples 1 to 3>

A fine concrete with a diameter of 0.15 mm or less was obtained from a waste concrete recycling company, and the fine powder was blended with cement in an amount as shown in Table 1, which was 37% of Example 1 based on the total amount of the formulation, In the case of 34% and in the case of Example 3, 30% of water was added and mixed, and then injected into a twin screw extruder (product of oil company) through a hopper and extrusion was performed. The extruded mixture was cut to a size of about 10 mm using a compressed air cutter attached to the die end.

Three holes for 6,000 ml are installed in a thermostatic chamber (silicone oil is used as a fruit) that maintains a constant temperature by using a PID method (the center hole is a German IKA impeller equipped with a 45/50 joint, and the other hole is 24/40). A condenser for the joint was inserted and the last hole was composed of an oligomer and a hole into which DCPD was injected.

4,000 g of industrial powdered sulfur was added to the reactor, and then dissolved in a liquid phase at 130 ° C while gradually raising the temperature. Cyclopentadiene was stirred with an impeller in a blender. 100 cc of oligomer was added in about 5-10 minutes. Subsequently, after about 10 minutes, DCPD 100 ㏄ was added thereto, and the stirring was performed while maintaining the reaction temperature at 140 ° C, noting that the liquid temperature rose from 130 ° C to about 145 ° C by exothermic reaction. . After about 4 hours, a little viscous viscosity occurred, and the reaction was terminated. If the temperature of the reaction solution rises to about 160 ° C., the color of the reaction solution turns black and at the same time, the viscosity rises and hardens, causing damage to the reactor.

The cut molded body was moved into the conveyor belt maintained at about 130 ° C. and passed through the inside of the coating reactor installed at the end of the conveyor line while retaining latent heat. The reactor includes the coating solution prepared above, which is maintained at about 130 ° C., and is coated while passing for about 10 minutes, followed by cooling at room temperature to obtain a recycled aggregate.

<Example 4>

A molded product was prepared in the same manner as in Example 2, but the coating was performed with a coating time of 1 minute.

Example 5

A molded product was prepared in the same manner as in Example 2, but the coating was performed with a coating time of 5 minutes.

<Example 6>

A molded product was prepared in the same manner as in Example 2, but the coating was performed with a coating time of 30 minutes.

<Test Example>

In order to measure the physical properties of the recycled aggregate prepared in the above example, the density, water absorption and compressive strength were measured.

Absorption rate is a constant weight that no longer loses weight when weighed after drying, that is, the weight of the dry aggregate is set to dry weight until it becomes a constant weight, impregnated with tap water for one day, and then taken out, and the surface of the aggregate is gently wiped with a damp towel. The weight measured afterwards was measured as the impregnating weight, which was calculated by converting the amount of water into the aggregate through the dried aggregate surface. Density is measured by volume ratio to weight. After measuring the dry aggregate weight until the weight is measured, it is measured by the principle of water buoyancy in the cylinder, which may cause slight deviation from underwater measurement.

Compressive strength test pieces were mixed at the mixing ratio of cement 1: fine aggregate (waste recycled aggregate) 2: recycled aggregate 2, and 100 mm diameter x 200 mm cylindrical concrete specimens were prepared in KSF 2403 (Method for Producing Concrete Strength Test Specimens). It produced according to. The prepared concrete specimens were cured in a constant temperature and humidity chamber maintained at 23 ° C. and 90% relative humidity for 1 day, and then demolded.Then, the specimens were cured in tap water maintained at about 20 ° C. and then tested for KSF2405 (compressive strength test on concrete). ) Was measured for 28 days using a universal testing machine (UTM).

The measurement results are shown in Table 1 below.

Fine powder (wt%) Cement (wt.%) Coating time (minutes) Density (gr / cm 3) Absorption rate (%) Compressive strength (kg / ㎠) Visual inspection Example 1 90 10 10 1.91 0.59 450 Good Example 2 80 20 10 2.07 0.51 510 Good Example 3 70 30 10 2.14 0.44 540 Good Example 4 80 20 One 1.85 0.85 310 usually Example 5 80 20 5 1.90 0.62 506 Good Example 6 80 20 30 2.01 0.52 520 Good

As can be seen from Table 1, it can be seen that the physical properties are greatly improved after the fine powder is prepared from the recycled aggregate than the fine powder state.

The density and water absorption measured by the present inventors in the state of collecting the fine powder were 1.42 and 26.39%, respectively, after coating with recycled aggregates according to Examples 1 to 6 to 1.85 to 2.14 and 0.85% to 0.44%, respectively. Improvements were made. In particular, the absorption rate is almost 1% or less, which is almost the same as the general crushed stone.

The density value shows a typical phenomenon that increases as the amount of cement increases, which means that the recycled aggregate can be adjusted according to the use. Compressive strength results are also proportional to the amount of cement, but the change is not large. The visual inspection observed by the neck side was generally good, but only in the case of Example 4, where the coating time was 1 minute, the surface was not smooth, and the reaction was still less.

The optimum condition considering productivity seems to be economical after extruding by adding 10% of cement to 90% by weight of fine powder. The coating time may be properly adjusted since the porosity, diameter and productivity of the spherical body should be taken into consideration.

According to the present invention, by forming and coating the waste fine powder generated from the waste concrete at room temperature, it is possible to produce recycled aggregates having excellent physical properties that can be used again in construction sites, so that the effect of recycling waste resources and minimizing environmental pollution can be expected. have.

1 is a process chart showing a manufacturing method of the present invention.

Claims (6)

Providing waste concrete fine powder, Molding the fine powder and cement mixture into a spherical or pellet form at room temperature, Drying the molded body and Coating the dried formed body using a modified sulfur coating solution To include, using the fine powder to produce a recycled aggregate. The process of claim 1, wherein the modified sulfur coating solution is prepared by reacting a cyclopentadiene oligomer and a dicyclopentadiene mixture with sulfur. The process of claim 1 comprising adding plastic clay, fly ash, methylcellulose and / or waterglass to the fine powder and cement mixture for improved flowability. The method of claim 1, wherein the molding is extrusion molding. The process of claim 1 wherein the mixing ratio of fine powder to cement is from 90:10 to 10:90. Recycled aggregate produced by the method of claim 1.