WO2011132841A1

WO2011132841A1 - Cured material of soil, industrial waste, sea sand and desert sand and method of preparing the same

Info

Publication number: WO2011132841A1
Application number: PCT/KR2010/009506
Authority: WO
Inventors: Ho Deok Byun; Hee Chang Yang; Kyung Sun Park
Original assignee: Ho Deok Byun; Hee Chang Yang; Kyung Sun Park
Priority date: 2010-04-21
Filing date: 2010-12-29
Publication date: 2011-10-27
Also published as: KR100988151B1

Abstract

The disclosure provides a curing composition including 20 to 32 parts by weight of magnesium chloride, 20 to 32 parts by weight of sodium chloride, 15 to 28 parts by weight potassium chloride, 10 to 19 parts by weight of calcium chloride, 2 to 8 parts by weight of sodium sulfate, 1 to 10 parts by weight of sodium triphosphate, and 1.5 to 7.0 parts by weight of sodium lignosulfonate. The disclosure also provides a cured material including the curing composition, a mixture of one or more selected from the group consisting of soil, industrial waste, sea sand and desert sand, and a cement. The disclosure provides a method of preparing the cured material by mixing the curing composition, the mixture including at least one selected from the group consisting of soil, industrial waste, sea sand and desert sand; and the cement. The disclosure also provides a method of preparing the cured material by using the curing composition. According to the curing method of the disclosure, the density, strength, and elasticity of the cured material are increased,the durability of the cured material are improved, and the curing time for the cured material of the soil, the industrial waste, these a sand and the desert sand is reduced, so that the cured material is used as an alternative material to building stones in construction work or engineering works. In addition, the cured material is prepared by using soil existing at the construction site, so the cured material is efficient in terms of economy and natural environment protection. The cured material is used as a material for construction work or engineering works without limitations. In particular, the cured material is used as a landfill material for a port-hinterland, a material for constructing a wharf, a base material for a road, a sub-base material for the road, a building material for a core wall of a river bank and an earth fill dam, and a soft ground improvement material.

Description

CURED MATERIAL OF SOIL, INDUSTRIAL WASTE, SEA SAND AND DESERT SAND AND METHOD OF PREPARING THE SAME

The present invention relates to a cured material of soil, industrial waste, sea sand and desert sand and a method of preparing the same.

At present, since it is difficult to obtain construction materials having high quality when engineering works and construction work are carried out, construction periods are delayed and construction costs are increased. In order to obtain the construction materials, mountains abundant in rock are exploited, or aggregates are collected from rivers or the sea, so that the natural environment is destroyed or the ecosystem is disturbed. In detail, since granular materials, such as building stones, are used as conventional harbor landfill materials and conventional asphalt and concrete pavement materials, fields and mountains may be destroyed due to stone-quarrying. In addition, construction costs are increased due to the stone-quarry work, transportation work, and stone-breaking work. Further, since regular soil is used in most construction work for river banks, the river banks may lack durability and safety due to the scouring caused by pressure of water currents, and the river banks may collapse. Accordingly, flooding disasters may occur, and disease may spread. In addition, in the case of conventional soft ground improvement schemes, a high construction cost is required and the loss of materials used in the construction work is increased.

To solve the above problems, there have been suggested various schemes for utilizing soil, industrial waste, river-dredge sedimentary contaminant and sea sand, which are extensively distributed throughout Korea, and desert sand extensively distributed throughout the Arabian peninsular as the alterative to building stones in various engineering works and construction works.

For instance, a cement stabilization scheme and an LAC (Lignin Rosin Asphalt Concrete) scheme have been developed and utilized in practice. However, since the above schemes require long curing time for the cement in the finish stage, the sufficient compressive strength may not be obtained within a short period of time. In addition, since the compressive strength is limited to 30kgf/cm²or less, the above schemes are restrictively adopted for sub-base materials used in road construction work. Accordingly, the utility of the above schemes is very low.

As another example, Korean Unexamined Patent Publication No. 1996-29280 discloses a method of curing industrial waste and soli mixture by using a curing agent composition. The curing agent composition includes 25% of sodium carbonate, 25% of potassium chloride, 15% of magnesium carbonate, 10% of ammonium chloride, 8% of potassium silicate, 7% of silicate, 5% of iron sulfate, and 5% of titanium oxide. Although the curing agent has a composition suitable for curing the industrial waste and the soil mixture, since sodium carbonate and titanium oxide are used as main components of the curing agent, ahigh-manufacturing cost is required. In addition, the strength of a cured material prepared by using the composition may not be remarkably improved. Accordingly, it is required to develop the curing agent capable of remarkably improving the strength of the cured material.

As described above, building stones are extensively used in various fields, such as harbors, seashores, roads, airports, water resource development fields, soil fields, and engineering works. However, since resources for the building stones are restricted, a method of recycling soil, industrial waste, river-dredge sedimentary contaminant, sea sand and desert sand as the alterative to building stones is required. And the soil, the industrial waste, the river-dredge sedimentary contaminant, the sea sand and the desert sandcan be easily obtained because of their plenty amounts in construction place.

In this regard, inventors of the present invention have completed the present inventionin order to solve the problems occurring in the prior art. The inventors of the present invention have found through various studies and research that if a cured material is prepared by adding a curing agent having the specific composition and fast curing property to soil, industrial waste, sea sand, desert sand, and a little cement the density, strength, and elasticity of the cured material can be increased, the durability of the cured material can be improved, and the curing time can be reduced, so that the cured material can be used as an alternative material to building stones in construction work or engineering works. In addition, the cured material can be prepared by using soil existing at the construction site, so the cured material may be efficient in terms of economy and natural environmental protection.

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, andan object of the present invention is to provide a curing composition of curing soil, industrial waste, sea sand and desert sand.

Another object of the present invention is to provide a cured material of soil, industrial waste, sea sand and desert sand, which is cured by using the curing composition.

Yet another object of the present invention is to provide a method of preparing the cured material by using the curing composition.

In order to accomplish the above objects, the present invention provides a curing composition including 20 to 32 parts by weight of magnesium chloride, 20 to 32 parts by weight of sodium chloride, 15 to 28 parts by weight of potassium chloride, 10 to 19 parts by weight of calcium chloride, 2 to 8 parts by weight of sodium sulfate, 1 to 10 parts by weight of sodium triphosphate, and 1.5 to 7.0 parts by weight of sodium lignosulfonate.However, the composition and compositional ratio of the curing agent of the present invention may not be limited to the above.

According to the present invention, the curing composition serves as a binder that facilitates the curing of soil, industrial waste, sea sand and desert sand.

The hydration reaction of the curing composition according to the present invention can be promoted by various inorganic ions, so that the surface charge of the soil grain may be neutralizedthrough the density balance of the metal ions, and aggregation, crumbing and solidification reactions may occur. In addition, a crosslinking reaction is performed by an organic metal salt. Thus, the rigid crumb structure may be realized even if the soil includes anti-curing materials and the curing reaction is continuously performed to cure the soil.

For instance, the curing composition accordingto the present invention can be prepared by adding inorganic salts and organic metal salts to calcium chloride.

Hereinafter, the components of the curing composition according to the present invention will be described in detail.

In general, magnesium chloride is a colorless crystalline powder and anhydride thereof is used as a source material for metallic magnesium. The magnesium chloride remains as granules or fragments with high deliquescence. The magnesium chloride reacts with oxygen in the atmosphereor reacts with oxygen and calcium chloride dissolved in water to generate magnesia cements, so that the magnesium chloride serves as a coagulant for improving the stabilityand strength of the cured material. If the amount of the magnesium chloride is less than 20 parts by weight, the magnesium chloride may not be easily reacted withmoisture, so that the anti-freezing effect may be degraded. If the amount of the magnesium chloride exceeds 32 parts by weight, a great amount of anhydrides may be generated, so that the curing agent may not be maintained in a liquid phase when the curing agent reacts with the moisture. Thus, the amount of the magnesium chloride is 20 to 32 parts by weight based on the total weight of the curing composition.

Sodium chloride has a colorless crystalline structurewith high deliquescence and contains salts, such as magnesium. The sodium chloride is a source material for sodium salt and promotes the hydration reaction of the cement. If the amount of the sodium chloride is less than 20 parts by weight, the sodium chloride may not be easily reacted with moisture, so that high hydration heat may be generated, causing cracks to the spherical structure of the cured material. If the amount of the sodium chloride exceeds 32 parts by weight, the pozzolan reaction of the cement may be restricted, so that the curing composition does not have sufficient strength. Thus, the amountof the sodium chloride is 20 to 32 parts by weight based on the total weight of the curing composition.

Potassium chloride has a white tetragonal crystal system and is used as a source material for potassium salt. Since the potassium chloride has strong absorption property, the potassium chloride is used as a water reducer. If the amount of the potassium chloride is less than 15 parts by weight, the curing rate and the curing time of the cured material may be delayed so that the cured material may not be prepared within a short period of time. If the amount of the potassium chloride exceeds 28 parts by weight, the pozzolan reaction of the cement may be restricted, so that the curing composition does not have sufficient strength. In addition, the cured material may be subject to premature curing, so that the quality of the cured material may be degraded. Thus, the amount of the potassium chloride is 15 to 28 parts by weight based on the total weight of the curing composition.

Calcium chloride is mixed with the cement and serves as catalyst as well as a coagulant to improve the absorption property while preventing the curing composition from freezing. If the amount of the calcium chloride is less than 10 parts by weight, the calcium chloride may not easily reactedwith moisture, so that the anti-freezing effect may be degraded. If the amount of the calcium chloride exceeds 19 parts by weight, a great amount of anhydrides may be generated, so that the curing agent may not be maintained in a liquid phase when the curing agent reacts with the moisture. Thus, the amountof the calcium chloride is 10 to 19 parts by weight based on the total weight of the curing composition.

Sodium sulfate has a relatively stable colorless crystalline structure and is used to prepare glass or sodium sulfide. In preparation of the cured material, the sodium sulfate is used to dry organic substances of the soil. If the amount of the sodium sulfate is less than 2 parts by weight, the hydration reaction (pozzolan reaction) of the cement may be restricted, so that the curing composition does not have sufficient strength. If the amount of the sodium sulfate exceeds 8 parts by weight, the preparation cost may be increased even though the hydration reaction can be improved. Thus, the amount of the sodium sulfate is 2 to 8 parts by weight based on the total weight of the curing composition.

Sodium triphosphate is a white crystalline powder and has been used as a cement aid and a soft ground improvement agent in engineering works. Sodium triphosphate is a deliquescent solid having a property of blockading metal ions and serves as acoagulant. If the amount of the sodium triphosphate is less than 1 parts by weight, the cured material does not have sufficient strength. If the amount of the sodium triphosphate exceeds 10 parts by weight, it may result in economical and environmental problem. Thus, the amount of the sodium triphosphate is 1 to 10 parts by weight based on the total weight of the curing composition.

Sodium lignosulfonate serves as a water reducer or a distributor for the mixture of soil, industrial waste, river-dredge sedimentary contaminant, sea sand, desert sand and cement. The sodium lignosulfonate binds the cement with the mixture to increasethe strength. If the amount of the sodium lignosulfonate is less than 1.5 parts by weight, grain distribution is interrupted and the cured material does not have sufficient strength. If the amount of the sodium lignosulfonate exceeds 7.0 parts by weight, the sodium lignosulfonate may interfere with the chemical reaction of other material because the sodium lignosulfonate has the three-dimensional net structure. Thus, the amount of the sodium lignosulfonate is 1.5 to 7.0 parts by weight based on the total weightof the curing composition.

According to another aspect, the present invention provides a cured material including the curing composition a mixture of one or more selected from the group consisting of soil, industrial waste, sea sand and desert sand; and a cement.

The cured material may include 0.05 to 0.1 parts by weight of the curing composition based on 100 parts by weight of the mixture including at least one selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand, but the present invention is not limited thereto.

The cured material may include 5 to 10 parts by weight of the cement based on 100 parts by weightof the mixture including at least one selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand, but the present invention is not limited thereto. If the cement is excessively included in the cured material, it may result in economical and environmental problem, so thecement must be employed after performing the test in situ to satisfy the regulations of various countries. According to the presentinvention, the curing composition is more efficient as the amount of the cement is increased. However, the effect of the present invention can be realized if the amount of the cement is 5 parts by weight based on the total amount of the curing composition.

According to the present invention, the soil may include a mixture of one or more selected from the group consisting of granite soil, silt, the river sand, the sea sand, and natural soil, but the present invention is not limited thereto. Various soils can be employed in the present inventionwithout limitations.

According to the present invention,the industrial waste may include a mixture of one or more selected from the group consisting of sedimentary contaminant, remnant, volcanic ash, environmental waste, slag, powdered slag, waste concrete and sludge but the present invention is not limited thereto. In general, the industrial waste refers to unnecessary materials generated from buildings or regions occupied by industrial companies. The industrial waste is generally defined as solid-state waste including waste oil. According to the presentinvention, the industrial waste may include sedimentary contaminant, remnant, volcanic ash, environmental waste, and river-dredge sedimentary contaminant, but present invention is not limited thereto. Various types of waste can be employed in the present invention. Preferably, the industrial waste includes slag generated from a blast furnace, powdered slag, waste concrete, sludge discarded after the mineral processing, and a mixture thereof.

The cured material of the soil, the industrialwaste, the sea sand, and the desert sand may include one selected from the group consisting of a landfill material for a port-hinterland, a material for a containeryard, a base material for a road, a sub-base material for the road, a building material for a core wall of a river bank and an earth fill dam, and a soft ground improvement material.

According to yet another aspect, the present invention provides a method of preparing a cured material by mixing the curing composition the mixture including at least one selected from the group consisting of the soil, the industrial the waste, the sea sand and the desert sand; and the cement.

According to yet another aspect, the present invention provides a method of preparing the cured material by using the curing composition.

According to the method of preparing the cured material, in order to cure the ground environmentally-friendly manner, the curing composition is supplied to the ground by adding the curing composition to the cement in a predetermined ratio. At this time, the hydration reaction occurs due to the inorganic ions of the curing composition, so that the surface charge of the soil grain may be neutralized and aggregation, crumbing and solidificationreactions may occur.

In addition, the curing of the cement may occur due to the ion reaction between calcium and nitrogen, which are main components of the cement, and this is generally known in the art.

Since the present invention results in a superior hydration reaction and surface charge neutralization reaction by using the metal ions contained in the curing composition, such as inorganic salts, chloride, and organicmetal salt, the ground curing can be effectively achieved without causing environmental problems.

If the cured material of the soil, the industrial waste, the sea sand and the desert sand is prepared according to the method of the present invention, the density, strength and elasticity of the curing compositioncan be improved. In addition, the structural durability is improved under high temperature conditions and the curing time can be reduced, so that the curing composition can be used as an alternative to building stones in construction work or engineering works. If an automatic mixing plant is used in the mixing process for the curing composition, the curing composition can be uniformly mixed and the moisture content can be easily managed, so that the high-quality curing composition of the soil, the industrial waste, the sea sand and the desert sand can be prepared.

Hereinafter, the application fieldsof the cured material prepared according to the method of the present invention will be described in detail.

(1) Harbors and seashores

Granular materials, such as building stones, have been used as landfill materialsfor a port-hinterland and materials for a containeryard. However, fields and mountains are destroyed due to stone-quarrying. In addition, the construction cost is increased and the environment is destroyed due to the stone-quarry work, transportation work, and stone-breaking work. If the cured material of the soils, waste slag, construction waste, volcanic ash, river-dredge sedimentary contaminant, sea sand, desert sand, and industrial waste according to the present invention is used in place of the building stones, the construction cost canbe reduced and the natural environment can be protected. For instance, the cured material including 10 parts by weight of the cement and 0.1 parts by weight of the curing agent based on 100 parts by weight of the soil, industrial waste, river-dredge sedimentary contaminant, sea sand, desert sand, or a mixture including at least two of the above elementscan be used as landfill materials for the port-hinterland. In the harbors and seashores, the cured material prepared according to the method of the present invention may represent superior strength in the early stage. Since the cured material has superior waterproof property and improved strength, the cured material may be scarecely subject to expansion and deformation by the seawater. In addition, the cured material represents a superior property against meteorological conditions, such as freezing, and shrinkage cracks may not be generated in the cured material. Further, the cured material is environmentally stable and easy to handle.

(2) Roads and airports

Granular materials, such as rubble, have been used as asphalt and concrete pavement materials. However, rubble has a problem similar to that of building stones. If the cured material of the soils, waste slag, fossil fuels, construction waste, volcanic ash, environmental waste, and industrial waste according to the present invention is used as a base material for a road, a sub-base material for the road, and a base material for a runway and an airplane movement path, the construction cost canbe reduced and the natural environment can be protected. For instance, the cured material including 10 parts by weight of the cement and 0.1 parts by weight of the curing agent may be used as the base material, and the cured material including 5 parts by weight of the cement and 0.05 parts by weightof the curing agent may be used as the sub-base material. In the roads and airports, the cured material prepared according to the method of the present invention may represent superior strength in the early stage. Since the cured material has superior waterproof property and improved strength, the cured material may be rarely subject to the expansionand deformation by the seawater. In addition, the cured material represents the superior property against the meteorological conditions, such as freezing, and shrinkage cracks may not be generated in the cured material. Further, the cured material is environmentally stable and easy to handle. In addition, when compared with the asphalt-concrete pavement and cement pavement, the eruption of the heavy metal is remarkably reduced. According to results, of experiments which wereperformed by immersing the cured material in seawater, shellfish are inhabit the cured material, which signifies that the cured material has a superior environmental-friendly property. In harbors and seashores, toxic materials harmful to the humanbody are remarkably reduced from the cured material according to the present invention when 3 hours has elapsed after the chemical reaction starts among the curing agent, the soil and the cement.

(3) Water resource development fields

General soils are used in most construction works for river banks, so the river banks may lack durability and safety due to the scouring caused by the pressure of water currents, so that the river banks may collapse. If the cured material according to the present invention prepared by using the soils, waste slag, construction waste, volcanic ash, and industrial waste is used as a material for constructing and repairing the river banks or for constructing earth fill dams, the construction cost can be reduced and the natural environment can be protected. In the water resource developmentfields, the cured material prepared according to the method of the present invention may represent superior strength in the early stage. Since the cured material has superior waterproof property and improved strength, the cured material may be scarcely subject to expansion and deformation by seawater. In addition, the cured material represents a superior property against meteorological conditions, such as freezing, and shrinkage cracks may not be generated in the cured material. Further, the cured material is environmentally stable and easy to handle. In particular, when buildinga core wall of an earth fill dam, the cured material can be used instead of the mud having water tightness property, so that the environmental destruction, which is caused when obtaining the mud, can be prevented.

(4) Soils and basic construction fields

If the cured material according to the present invention prepared by using the soils, waste slag, construction waste, and industrial waste is used as a material for improving the soft ground, the construction cost canbe reduced and the natural environment can be protected. In the soil and basic construction fields, the cured material prepared according to the method of the present invention may represent superior strength in the early stage. Since the cured material has superior waterproof property and improved strength, the cured material may be scarcely subject to the expansion and deformation by seawater. In addition, the cured material represents a superior property against meteorological conditions, such as freezing, and shrinkage cracks may not be generated in the cured material. Further, the cured material is environmentally stable and easy to handle. The desired strength can be obtained in the early stage by curing a surface layer.

The cured material according to the present invention can be utilized in various fields related to construction work and engineering works without limitations.

According to the method of preparing the cured material of the present invention, the density, strength, and elasticity of the cured material can be increased, the durability of the cured material can be improved, and thecuring time for the cured material of the soil, the industrial waste, the sea sand and the desert sand can be reduced, so that the cured material can be used as an alternative material to the building stones in construction work or engineering works. In addition, the cured materialcan be prepared by using soil existing at the construction site, so the cured material may be efficient in terms of economy and natural environment protection. In addition, the cured material according to the present invention can be used as materials for construction work or engineering works without limitations. In particular, the cured material is used as a landfill material for a port-hinterland, a material for constructing a wharf, a base material for a road, a sub-base material for the road, a building material for a core wall of a river bank and an earth fill dam, and a soft ground improvement material.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings. These exemplary embodiments of the present invention are forillustrative purposes, and the present invention is not limited thereto. Documents cited in the specification will be entirely incorporated herein by reference.

Embodiments

Experimental example 1: physical property measurement for soil, industrial waste and sea sand

In order to estimate the strength of the concrete specimen preparedby mixing the curing agent with the soil, the industrial waste, the sea sand and the desert sand, the basic physicalproperty of the granite soil, slag, powdered slag, sludge, waste concrete and sea sand which were used as representative specimens in examples was measured according to the test scheme shown in Table 1. The measurement result is shown in Table 2. The representative specimens are extracted through the method of quartering each material loaded in the laboratory to perform several tests.

Table 1

Basic physical property	Test scheme
Moisture content	KS F 2306
Specific gravity	KS F 2308
Liquid limit	KS F 2303
Plastic limit	KS F 2304
Granularity	KS F 2302
Sieve analysis	KS F 2309

Table 2

Specimen	MoistureContent(W_n)(%)	SpecificGravity(G_s) (ton/㎥)	LiquidLimit(LL)(%)	PlasticLimit(PI)(%)	amount of materials obtained through #200 sieve (%)	Granularity(USCS)
Granite soil	19.6	2.65	29.1	13.6	12.9	Sandy coarse grained soil
Slag	15.8	3.05	-	-	0.60	-
Powdered slag	14.3	3.05	-	-	7.52	-
sludge	16.4	3.01	-	-	62.8	-
Waste concrete	13.4	2.98	-	-	2.07	-
Sea sand	15.8	1.98	-	-	21.3	Sandy soil

Preparation Example 1: preparation of curing composition

Magnesium chloride (Israel, purity: 47%), Sodium chloride (China, refined salt, purity: 99%), Potassium chloride (Korea, Namhae Chemical corp. purity: 60%), Calcium chloride (Japan, Bead Type-TOKUYAMAcompany, purity: 74% or more), Sodium sulfate (China, purity: 99% or more), Sodium Lignosulfonate (South Africa) and Sodium triphosphate (Japan, purity: 99% or more) were input into a storage tank in a predetermined mixing ratio based on the total weight of the curing agent, and the mixture was forcibly stirred by a mechanical stirrer, thereby preparing the curing agent according to preparation examples 1 to 3. The components of the curing agent according to preparation examples 1 to 3 are shown in Table 3.

Table 3

Components (weight part)	Preparation examples
Components (weight part)	1	2	3
Magnesium chloride	26.0	20.0	32.0
Sodium chloride	26.0	20.0	32.0
Potassium chloride	22.0	15.0	28.0
Calcium chloride	13.5	10.0	19.0
Sodium sulfate	5.0	2.0	8.0
Sodium Lignosulfonate	3.0	1.0	10.0
Sodium triphosphate	4.5	1.5	7.0

Embodiments 1 to 12 and comparative examples 1 to 4:preparation of concrete specimen

The curing composition of preparation examples 1 to 3 prepared according to the composition and contents shown in Table 3 was previously prepared. Then, the curing composition was mixed with portland cement according to the composition shown in Tables 4 to 6. Then, each specimens(soil, industrial waste, sea sand and desert sand) were input into a cylindrical steel mold having two joints at both lateral sides thereofand the specimens were compacted in the form of 3 layers x 25, thereby preparing the concrete specimen having a diameter of 50mm and a height of 100mm. The joints and upper and lower end portions of the mold were sealed to prevent water leakage or deformation, and an inner surface of the mold was treated with mineral oil such that the concrete specimen canbe easily separated from the mold after the curing has been finished. After that, the mold was immersed in water for seven days to cure the concrete specimen. After seven days elapsed, the concrete specimen was separated from the mold and upper and lower end portions of the concrete specimen were ground to asize of 0.05mm or less when viewed in a plan view. The soil, the industrial waste, the sea water and the desert water were identical to those used in experimental example 1 as representative specimens.

Table 4

Components (weight part)		Embodiments				Comparative examples
Components (weight part)		1	2	3	4	1	2	3
Curing agent	PreparationEx. 1	0.1		-	0.2	0.05	-	-
	preparationEx.2	-	0.1		-	-	0.05	-
	preparationEx.3	-	-	0.1	-	-	-	0.05
Cement	Portland cement	10	10	10	10	10	10	10
Soil or industrial waste	Granite soil	100	100	100	100	100	100	100

Table 5

Components (weight part)		Embodiments				Comparative examples
Components (weight part)		5	6	7	8	4
Curing agent	Preparation Ex. 1	0.1		-	0.2	0.05
	Preparation Ex. 2	-	0.1		-	-
	Preparation Ex. 3	-	-	0.1	-	-
Cement	Portland cement	10	10	10	10	10
Soil or industrial waste	Slag	100	100	100	100	100

Table 6

Components (weight part)		Embodiments
Components (weight part)		9	10	11	12
Curing agent	Preparation Ex. 1	0.1	0.1	0.1	0.1
Cement	Portland cement	10	10	10	10
Soil or industrial waste	Powdered slag	100	-	-	-
	Waste concrete	-	100	-	-
	sludge	-	-	100	-
	Sea sand	-	-	-	100

Experimental example 2: measurement of compressive pressure after curing of concrete specimen

The concrete specimens prepared according to embodiments 1 to 12 and comparativeexamples 1 to 4 were cured for 7 days and 28 days, respectively, and top and bottom surfaces of a rigid pressing plate of a tester were cleaned. Then, the central axis of the prepared concrete specimen was matched with the center of the pressing plate and a load was applied to the concrete specimen at a constant speed such that the impact may not be applied to the concrete specimen according to KS F 2405. At this time, the load was applied such that the compressive pressure can be increased by 2~3 kgf/㎠ per second. After the concrete specimen suddenly started deforming, the load was continuously applied without adjusting the load based on the compressive pressure, and unconfined compressive strength was measured. The result is shown in Table 7.

Table 7

Index	Unconfined compressive strength
	(kgf/㎠)
	7 days curing	28 days curing
Embodiment 1	47.52	87.60
Embodiment 2	47.41	91.26
Embodiment 3	48.67	90.84
Embodiment 4	48.57	91.79
Embodiment 5	32.68	61.38
Embodiment 6	33.38	61.52
Embodiment 7	32.37	60.04
Embodiment 8	38.99	72.78
Embodiment 9	30.26	58.94
Embodiment 10	27.05	49.87
Embodiment 11	20.50	41.38
Embodiment 12	21.68	44.92
Comparative example 1	27.69	53.29
Comparative example 2	30.10	55.84
Comparative example 3	29.42	57.65
Comparative example 4	26.36	50.42

As can be seen from Table 7, in the case of embodiments 1 to 12, the compressive strength was about 41~92 kgf/㎠ when the concrete specimen wascured for 28 days. The compressive strength of the granite soil (embodiments 1 to 4) treated with the curing agent according to the present invention was generally high. When the same amount of curing agent and cement were used, the compressive strength was gradually lowered in the sequence of the granite soil (embodiment 1), the slag (embodiment 5), the powdered slag (embodiment 9), the waste concrete (embodiment 10), and the sludge (embodiment 11). Meanwhile, when considering the compressive strength of the granite soil concrete specimen (embodiment 1 and comparativeexample 1) and the slag concrete specimen (embodiment 5 and comparative example 4), which were obtained when the amount of the curing agent was changed and thesame amount of cement was used, it can be understood that the amount of the curing composition may exert great influence upon the compressive strength improvement.

Therefore, the cured material having various degrees of strength can be prepared by adjusting the curing period and the amount of the cement and the curing composition according to the present invention. Thus, the cured materialprepared by using the curing composition according to the present invention can be applied in various fields.

The cured material according to the present invention can be prepared by mixing the curing composition with a mixture of the soil, the industrial waste, the sea sand and the desert sand, and the cement after metering and transporting the curing composition, the mixture and the cement using various devices. If a portable stability soil base mixing plant (Atech General Machinery & PlantLtd., China) is used for the mixing process, the materials can be uniformly mixed and the moisture content can be easily managed because the materials are metered and mixed by the automatic plant. In this case, superior quality control can be accomplished, working efficiency can be improved and the construction work can be simplified, so that the construction period can be reduced. The product capacity of the cured material must be determined based on the construction scale, character, topographic position, and economic efficiency. In general engineering works, a plant having the product capacity of 3.0 to 5.0m³/min is used.

Although exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

A curing composition comprising:

20 to 32 parts by weight of magnesiumchloride;

20 to 32 parts by weight of sodium chloride;

15 to 28 parts by weight potassium chloride

10 to 19 parts by weight of calcium chloride;

2 to 8 parts by weight of sodium sulfate;

1 to 10 parts by weight of sodium triphosphate; and

1.5 to 7.0 parts by weight of sodium lignosulfonate.
A cured material cured by mixing:

a curing composition of claim 1;

a mixture of one or more selected from the group consisting of soil, industrial waste, sea sand and desert sand; and a cement.
The cured material of claim 2, wherein an amount of the curing composition is 0.05 to 0.1 parts by weight based on 100 parts by weight of the mixture of one or more selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand.
The cured material of claim 2, wherein an amount of the cement is 5 to 10 parts by weight based on 100 parts by weightof the mixture of one or more selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand.
The cured material of claim 2, wherein the soil is a mixture of one or more selected from the group consisting of granite soil, silt, the river sand, the sea sand, and natural soil.
The cured material of claim 2, wherein the industrial waste is a mixture of one or more selected from the group consisting of sedimentary contaminant, remnant, volcanic ash, environmental waste, slag, powdered slag, waste concrete and sludge.
The cured material of claim 6, wherein the sedimentary contaminant is river-dredge sedimentary contaminant.
The cured material of claim 2, wherein the cured material is used as a landfill material for a port-hinterland, a material for a container yard, a base material for a road, a sub-base material for a road, a building material for a core wall of a river bank and an earth fill dam, and a soft ground improvement material.
A method of preparing a cured material by mixing a curing compositionof claim 1; a mixture of one or more selected from the group consisting of soil, industrial waste, sea sand and desert sand; and a cement.
The method of claim 9, wherein an amount of the curing composition is 0.05 to 0.1 parts by weight based on 100 parts by weight of the mixture of one or more selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand.
The method of claim 9, wherein anamount of the cement is 5 to 10 parts by weight based on 100 parts by weight of the mixture of one or more selected from the group consisting of the soil, the industrial waste, the sea sand and the desert sand.
The method of claim 9, wherein the soil is a mixture of one or more selected from the group consisting of granite soil, silt, the river sand, the sea sand, and natural soil.
The method of claim 9, wherein the industrial waste is a mixture of one or more selected from the group consisting of sedimentary contaminant, remnant, volcanic ash, environmental waste, slag, powdered slag, waste concrete and sludge.
The method of 13, wherein the sedimentary contaminant is river-dredge sedimentary contaminant.
A method of preparing a cured material by using the curing composition of claim 1.