KR102539627B1 - Composition and making method of cement concrete blocks using recycled aggregates - Google Patents

Abstract

The present invention mainly relates to a cement concrete block composition that can be recycled to replace existing natural aggregate with waste asphalt concrete generated in the crushing process of asphalt concrete road maintenance work and has increased strength, and a method for manufacturing the same.
That is, the present invention relates to a cement concrete block composition using cement, vegetable additives, general aggregate, waste asphalt concrete recycled aggregate, and recycled aggregate including a water reducing agent, and cement containing cement, vegetable additives, general aggregate, waste asphalt concrete recycled aggregate, and water reducing agent. In the concrete block, the vegetable additive is prepared by adding lignocellulose to an acidic solution containing a sulfate-based inorganic compound, an organic solvent, an emulsion-type silicone antifoaming agent, and water, followed by stirring to soften the lignocellulosic particles; preparing a suspension by pulverizing the lignocellulose that has undergone the softening step while being immersed in an acidic solution; It is characterized by a method for producing a vegetable additive contained in a cement concrete block composition using recycled aggregate comprising: neutralizing by adding hydroxide to lignocellulose prepared from the suspension, dehydrating and drying to powder.

Description

Cement concrete block composition and manufacturing method using recycled aggregate {Composition and making method of cement concrete blocks using recycled aggregates}

The present invention is mainly for recycling waste asphalt concrete (hereinafter, waste ascon) generated in the crushing process of asphalt concrete road maintenance work to replace existing natural aggregates, and more specifically, micrometer-sized fine lignocellulose with sulfate A cement concrete block composition made of a compound and a hydroxide, a mixture of hydraulic cement and water at a certain ratio, and then mixing the mixture with recycled aggregate from waste ascon to activate the adhesive force of lignocellulose and increase its strength. and a manufacturing method thereof.

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Most of the aggregates used in mixing hydraulic cement concrete used in civil engineering and construction work are natural aggregates, but due to environmental problems such as natural destruction caused by earth stone extraction, the amount of natural aggregates collected is decreasing, and the trend is to replace them with recycled aggregates.

Asphalt concrete (ascon) road pavement is affected by traffic volume, temperature, climate, etc. after construction and deteriorates gradually, resulting in damage. Accordingly, various maintenance methods are applied, and waste ascon is generated in the crushing work performed when cutting and removing the existing asphalt concrete road. The collected waste asphalt concrete is pulverized into a certain size, passed through a sifting process and washing, and transformed into recycled aggregate, which is mainly used for road construction.

However, the recycled aggregate of waste asphalt concrete has a remarkably low recycling rate. Currently, the compulsory use of recycled aggregate is being strengthened to promote the recycling of construction waste. However, due to concerns over the performance degradation of asphalt roads, recycled aggregate, which is produced annually at about 13 million tons, accounted for 11% of the amount of recycled asphalt ordered in the metropolitan area from 2009 to 2015. doesn't pass

Waste ascon that is not recycled is sometimes buried or used for building and covering soil. In this case, the binder of waste ascon may cause environmental pollution such as soil and underground water pollution. In order to prevent this, a recycling plan has been prepared, but recycling of waste ascon is not active due to the above problems.

In addition, the recycled aggregate of waste asphalt concrete is coated with an asphalt binder having a thickness of about 10 μm on the surface of the aggregate, so it is very difficult to express the strength required for use in hydraulic cement concrete products.

In the prior art 10-2445884, it is difficult to gel the asphalt of the recycled aggregate with emulsified asphalt at room temperature, and only mixing the emulsified asphalt and cement has low adhesive strength and low strength compared to general cement blocks. However, the recycled additive serves to lower the viscosity of the binder coated on the recycled aggregate, which has the disadvantage of lowering the adhesive strength between the oily waste asphalt concrete recycled aggregate and the hydraulic cement paste.

In addition, in the prior art No. 10-0499893, an adhesion enhancer such as SBR Latex, epoxy, acrylic resin, EVA, etc. was used to enhance the adhesion between the waste asphalt concrete aggregate and the hydraulic cement paste, but the adhesion enhancer is an expensive petrochemical product and costs a lot. There is a disadvantage that the economic efficiency is not good by increasing the

In other words, in order to express stable strength by using recycled waste ascon aggregate for cement concrete blocks, a technology to secure adhesion and bonding strength between recycled waste ascon aggregate coated with asphalt binder containing oil and hydraulic cement paste is required. there is.

KR No. 10-0499893 KR No. 10-2445884 KR No. 10-1233807 KR No. 10-1873880

The present invention utilizes recycled aggregate from waste ascon as a concrete block based on hydraulic cement, which is relatively easy to regenerate as recycled aggregate compared to conventional cement concrete. in providing blocks.

The present invention is characterized by a cement concrete block composition using recycled aggregate including cement, vegetable additives, general aggregate, recycled aggregate from waste asphalt concrete, and a water reducing agent.

10 to 25 parts by weight of the cement, 0.1 to 2 parts by weight of vegetable additives, 10 to 75 parts by weight of general aggregate, 10 to 60 parts by weight of waste asphalt concrete recycled aggregate, 0.1 to 1 part by weight of water reducing agent, and 3 to 12.5 parts by weight of water to be characterized

The vegetable additive is characterized in that the solid content of micronized lignocellulose having a particle size of 10 μm to 100 μm is 80% by weight or more.

In the cement concrete block containing cement, vegetable additives, general aggregate, recycled ascon aggregate, and water reducing agent, the vegetable additive is added to an acidic solution containing a sulfate-based inorganic compound, an organic solvent, an emulsion-type silicone antifoaming agent, and water. Softening the lignocellulosic particles by adding cellulose and stirring it; preparing a suspension by pulverizing the lignocellulose that has undergone the softening step while being immersed in an acidic solution; It is characterized by a method for producing a vegetable additive contained in a cement concrete block composition using recycled aggregate comprising: neutralizing by adding hydroxide to lignocellulose prepared from the suspension, dehydrating and drying to powder.

The cement concrete block using the regenerated aggregate of the present invention is coated with hydraulic cement and aged asphalt by cross-linking the cellulose component of fine-sized lignocellulose and lignin component, which are vegetable additives, on the surface of the aged asphalt binder covering the regenerated asphalt concrete aggregate. Adhesion between recycled aggregates is activated so that the strength required as a conventional hydraulic cement concrete structure is stably expressed, and waste ascon, which is discarded, can be applied to cement concrete blocks, which has the effect of increasing economic feasibility.

1 is a view of one embodiment showing that a mixture containing vegetable additives is combined with recycled aggregate of waste asphalt concrete by a cement concrete block composition using recycled aggregate according to the present invention.
Figure 2 is a block diagram showing a manufacturing process of vegetable additives contained in the cement concrete block composition using recycled aggregate according to the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail. And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present invention, a hydraulic cement concrete block is formed by utilizing aggregate pulverized from discarded asphalt concrete, but the concrete block according to the present invention is an asphalt concrete regenerated aggregate covered with a cement paste and an asphalt binder as a vegetable additive based on lignocellulose. It is to ensure durability and commonality by activating the adhesive force between the concrete blocks and improving the binding force inside the concrete block.

In the present invention, when composing a cement concrete block using recycled aggregate, 10 to 25 parts by weight of cement, 0.1 to 2 parts by weight of vegetable additives, 10 to 75 parts by weight of general aggregate, 10 to 60 parts by weight of recycled aggregate from waste asphalt concrete, 0.1 part by weight of water reducing agent to 1 part by weight and 3 to 12.5 parts by weight of water.

The cement includes any one or more of ordinary Portland cement, medium heat Portland cement, early strength Portland cement, low heat Portland cement, sulfate-resistant Portland cement, white Portland cement, blast furnace slag cement, pozzolan cement, and fly ash cement, and If the content of cement is less than 10 parts by weight, bonding strength is lowered and durability is lowered, and if it exceeds 25 parts by weight, internal binding force due to material separation and interlocking of aggregates is reduced and durability is lowered.

The vegetable additive is based on lignocellulosic cement concrete, which enhances the compressive strength by activating the adhesive force between the asphalt concrete regenerated aggregate composed of cement paste and asphalt binder to improve the bonding force inside the concrete block made of the cement concrete mixture. have a block

It is preferable to use 0.1 to 2 parts by weight of these vegetable additives, and if less than 0.1 parts by weight, the strength of the concrete block is reduced due to insufficient bonding strength between cement particles and recycled aggregate particles of waste asphalt concrete, and if it exceeds 2 parts by weight, the cement concrete mixture During manufacturing, the viscosity increases and workability deteriorates.

The vegetable additive preferably has a solid content of 80% by weight or more of micronized lignocellulose having a particle size of 10 μm to 100 μm. When the solid content of the micronized lignocellulose is less than 80% by weight, the amount of additives used in manufacturing the concrete block increases, which is uneconomical.

The water reducing agent is a material that improves fluidity by forming a repulsive force between cement particles when preparing a cement concrete mixture, and may use a polycarboxylic acid-based, lignin-based, naphthalene-based, melamine-based water reducing agent, etc., 0.1 based on 100 parts by weight of the cement concrete mixture. to 1 part by weight is preferably used.

The general aggregate refers to materials such as sand or gravel used in cement concrete blocks.

The waste ascon recycled aggregate is produced by collecting, crushing and classifying waste ascon generated in the road crushing process using a breaker, a road cutting machine, a heating cutter, etc. at a road maintenance site at a waste intermediate treatment company.

At this time, the waste asphalt that is brought in to the waste intermediate treatment company is generally subjected to on-site crushing by a breaker or grinding machine, and most waste asphalt is crushed by a grinding machine in consideration of workability and transportation efficiency In small-scale pipeline repair work, asphalt pavement sofa repair, or in sections where it is difficult to enter the road cutting machine, it is crushed into chunks using a breaker and then transported.

The maximum particle diameter of waste asphalt concrete generated according to the crushing method before being brought in to the intermediate treatment company is very different. do.

When the waste asphalt concrete is crushed to a thickness of 13.2 mm or more in the additional crushing and classification process, the content of the aggregate in the form of large particles is increased by combining small aggregates with an asphalt binder. Since these types of aggregates are bonded by aged asphalt binders, they have lower strength than the physical strength of aggregates used in the manufacture of concrete blocks, which causes quality deterioration. In addition, it is difficult to expect performance improvement through vegetable additives because there is no surface to contact the aged asphalt binder and vegetable additives located inside. Therefore, it is suitable that the maximum particle diameter of the recycled aggregate of waste asphalt concrete used in the manufacture of concrete blocks is 13.2 mm or less. More preferably, it is 8 mm or less.

1 is a view of an embodiment showing that a mixture containing vegetable additives is combined with recycled aggregate of waste asphalt concrete, and lignocellulose 20, which is a vegetable additive, is added to aged asphalt 12 of recycled aggregate 10 of waste asphalt concrete. The constituent lignin [hydrophobic] (21), hemicellulose (22), and cellulose [hydrophilic] (23) components are sequentially combined, and cement paste [hydraulic cement + water] (30) is combined thereto. , This is because the adhesion between hydraulic cement and aged asphalt-coated recycled aggregate is activated by the cross-connection between the cellulose component and lignin component of fine-sized lignocellulose on the surface of the aged asphalt binder covering the asphalt concrete regenerated aggregate, thereby improving the quality of the cement concrete block. increase the compressive strength.

On the other hand, a cement concrete block is formed including cement, vegetable additives, general aggregate, waste asphalt concrete recycled aggregate, and a water reducing agent, but the process of manufacturing the vegetable additive is as follows.

Softening the lignocellulosic particles by putting lignocellulose in an acidic solution containing a sulfate-based inorganic compound, an organic solvent, an emulsion-type silicone antifoaming agent, and water and stirring the same (S1); preparing a suspension by pulverizing the lignocellulose subjected to the softening step while being immersed in an acidic solution (S2); A step (S3) of adding hydroxide to the lignocellulose prepared from the suspension to neutralize it, followed by dehydration and drying to pulverize it (S3).

In the step (S1) of softening the lignocellulosic particles, 0.5 to 2 parts by weight of a sulfate-based inorganic compound, 0 to 10 parts by weight of an organic solvent, 0.1 to 1 part by weight of an emulsion type silicone antifoaming agent, and 85 to 95 parts by weight of water are contained. let it

Examples of the sulfate-based inorganic compound include inorganic compounds including feroxomonosulfate, sulfate, sulfite, feroxodisulfuric acid, disulfate, dithionate, metabisulfite, dithionic acid, thiosulfate, and tetrathionate.

If the amount of the sulfate-based inorganic compound is less than 0.5 parts by weight, lignocellulosic softening does not proceed smoothly, and if it exceeds 2 parts by weight, undissolved inorganic compounds remain and cause expansion of the concrete block.

In addition, it is preferable to use one of acetone, tetrahydrofuran, methyl ethyl ketone, and toluene as the organic solvent, and when the amount exceeds 10 parts by weight, lignin in lignocellulose is lost and crosslinking properties are deteriorated.

40 to 60 parts by weight of lignocellulose is added to 40 to 60 parts by weight of the acidic solution prepared above and immersed, and then immersed and stirred for 10 to 30 minutes at a rotational speed of 300 to 1,000 rpm using an agitator to soften.

The lignocellulosic is leaves, twigs, bark, grasses, hay, reeds, megasasse, sawdust, bagasse ), corn stover, corn cobs, wheat bran, sugar beet press cake, rice hulls, palm, coconut, peat ( peat, sphagnum, rice straw, hemp, kenaf, wheat straw, etc., and also contained in animal waste such as feathers and hair. . Lignocellulose is composed of two types of carbohydrate polymers, cellulose and hemicellulose, and an aromatic polymer called lignin. Each component has a different chemical behavior, so in order to separate it from a composite state into a single material, heat treatment, chemical treatment, enzyme and microbial treatment are required. process is required.

In the process of immersing lignocellulose, when the amount of lignocellulose is less than 40 parts by weight, dehydration and drying time increases and production efficiency decreases, and when it is more than 60 parts by weight, stirring efficiency decreases.

In the step (S2) of preparing the lignocellulose into a suspension, the lignocellulose that has undergone the softening step is pulverized into a size of 10 to 100 μm while being immersed in an acidic solution to prepare a suspension.

If the grinding size of the lignocellulose subjected to the softening step is less than 10 μm, the viscosity of the cement gel increases and the stability of the mixture may deteriorate, and if it exceeds 100 μm, the performance is insufficient.

In addition, the crushing process is performed using a rotary cutter and an in-line mixer while the lignocellulose is immersed in an acidic solution. The crushing process is preferably carried out for 20 to 40 minutes while maintaining the rotation speed of the rotary cutter at 500 to 1,500 rpm and the rotation speed of the inline mixer at 3,000 to 3,600 rpm.

In addition, when the rotational speed of the rotary cutter and the inline mixer used in the grinding process is less than the standard, the grinding time increases and the production efficiency is lowered, and if it exceeds the standard, it is uneconomical.

In addition, if the grinding time is less than 20 minutes, the grinding does not proceed sufficiently, and if it exceeds 40 minutes, it is uneconomical.

In the step of pulverizing the lignocellulose (S3), the lignocellulosic suspension contains a sulfate-based inorganic compound during the softening process, and reacts with the calcium-based compound in the cement when in excessive contact with cement to produce calcium sulfate (CaSO4). It has the property of generating and expanding, and it needs to go through a neutralization process because it affects the durability by making the cement tissue porous.

The neutralization process includes any one or more of potassium hydroxide (KOH), aluminum hydroxide (Al(OH)3), calcium hydroxide (Ca(OH)2), and barium hydroxide (Ba(OH)2), and in the acidic solution After adding hydroxide to the mass of dissolved sulfur trioxide (SO3-), the mixture is stirred for 5 to 20 minutes at a rotational speed of 300 to 1,000 rpm. The suspension after stirring is dehydrated, dried, and powdered to complete the preparation of vegetable additives.

If the stirring time is less than 5 minutes, the time for the hydroxide to dissolve in the solution is not sufficient, so that the reaction is not sufficiently performed, and it is unnecessary to exceed 20 minutes.

(manufacture of vegetable additives)

Water: Calcium Sulfate (CaSO4): Acetone: Aqueous silicone antifoam = 97: 1.5: 1: 0.5 Weight ratio of lignocellulose was added to the mixed acidic solution at a weight ratio of 1: 1, and immersion and stirring at a stirring speed of 450 rpm for 25 minutes and softened it. The softened lignocellulose was pulverized for 35 minutes using a rotary cutter (rotation speed: 1,200 rpm) and an in-line mixer (rotation speed: 3,000 rpm) in a immersed state to prepare a suspension having a particle size of 20 μm. Thereafter, potassium hydroxide (KOH) was added to the suspension at a weight ratio of 82.4% of the weight of calcium sulfate (CaSO4) used in the preparation of the acidic solution, stirred at a stirring speed of 500 rpm for 20 minutes to neutralize it, and then dehydrated and dried to micronize lignocellulose. A vegetable additive with a solids content of 99.05% was prepared.

Manufacture of cement concrete permeable block containing recycled aggregate from waste asphalt concrete

For 1 minute and 30 seconds after adding the ingredients in a 2-ton class twin-screw spiral mixer at a weight ratio of 14 : 1.5 : 29.2 : 50 : 0.3 : 5 A cement concrete mixture for a water permeable block was prepared by mixing, and molding was completed by putting in and compacting a mold having a size of 200 mm * 100 mm * 60 mm. The molded water-permeable block was cured for 3 days at a temperature of 40˚C and a relative humidity of 90%, and then cured for 14 days at ambient temperature to complete the production of the water-permeable block. The water permeable block manufactured in Example 2 satisfied the domestic KS standard (KS F 4419, concrete interlocking block for sidewalks) as shown in Table 1 below.

division unit standard result flexural strength MPa 4.0 or higher 5.5 coefficient of permeability mm/s 0.1 or higher 0.5

Manufacture of cement concrete boundary blocks containing recycled aggregate from waste asphalt concrete

Blast furnace slag cement: vegetable additives: general aggregate: waste ascon recycled aggregate: polycarboxylate-based water reducer: water = 13: 1.5: 40: 40: 0.3: 5.2 After adding materials in a weight ratio of 13: 1.5: 40: 5.2, mix for 1 minute and 30 seconds A cement-concrete mixture for boundary blocks was prepared and molded to the dimensions of SC-type road artificial stone boundary blocks of the concrete boundary block test standard (KS F 4006). The molded boundary block was cured at 25˚C for 20 days to complete the manufacturing of the boundary block.

As shown in Table 1 below, the boundary block of the present invention manufactured according to Example 3 complies with the domestic KS standard (KS F 4006, concrete interlocking block for sidewalks) and the recycled product certification standard (GR F 4006, recycled aggregate concrete boundary block). ) satisfies the performance criteria.

division standard unit standard result breaking load KS F 4006 kN 10.0+ 13.6 absorption rate % within 5 2.3 compressive strength GR-F4006 MPa 23.5+ 35.3 after freezing and thawing
compressive strength MPa 23.5+ 32.2

In the above, the present invention has been described with reference to the above embodiments, but various modifications are possible within the scope of the technical idea of the present invention.

10: waste asphalt concrete recycled aggregate
20: Lignocellulose
30: cement paste [hydraulic cement + water]
S1: Step of softening the lignocellulosic particles
S2: preparing lignocellulose as a suspension
S3: Step of powdering lignocellulose

Claims (4)

In the cement concrete block composition using recycled aggregate including cement, vegetable additives, general aggregate, waste asphalt concrete recycled aggregate, and water reducing agent,
10 to 25 parts by weight of the cement, 0.1 to 2 parts by weight of vegetable additives, 10 to 75 parts by weight of general aggregate, 10 to 60 parts by weight of recycled aggregate from waste asphalt concrete, 0.1 to 1 part by weight of a water reducing agent, and 3 to 12.5 parts by weight of water,
As a vegetable additive bound to the aged asphalt 12 of the recycled aggregate 10 of waste asphalt concrete, the lignocellulosic 20 has a structure in which lignin 21, hemicellulose 22, and cellulose 23 are sequentially combined, ,
The vegetable additive,
Lignocellulose was added to an acidic solution containing 0.5 to 2 parts by weight of a sulfate-based inorganic compound, 0 to 10 parts by weight of an organic solvent, 0.1 to 1 part by weight of an emulsion-type silicone antifoaming agent, and 85 to 95 parts by weight of water, and stirred to lignocellulose. Softening the particles (S1);
preparing a suspension by pulverizing the lignocellulose subjected to the softening step into a size of 10 to 100 μm while being immersed in an acidic solution (S2);
Cement concrete block composition using recycled aggregate, characterized in that produced through the step (S3) of neutralizing by adding hydroxide to the lignocellulose prepared from the suspension, dehydrating and drying to powder.
delete According to claim 1,
The vegetable additive is a cement concrete block composition using recycled aggregate, characterized in that the solid content of the micronized lignocellulose having a particle size of 10 μm to 100 μm is 80% by weight or more.









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