KR102028612B1 - High strength lightweight concrete composition using sludge - Google Patents

Abstract

The present invention is a high-strength lightweight concrete composition used by replacing at least 25% of the aggregate with artificial lightweight aggregate when mixing the concrete composition by adding admixture to cement, water and aggregate, the dry weight of the unit is less than 1850 kgf / ㎥ While 28 days compressive strength is 27 MPa or more, the artificial lightweight aggregate is characterized in that the artificial lightweight aggregate made of sludge produced by molding the sludge into a spherical body and dried in air and calcined by heating to 1000 ℃. One high strength lightweight concrete composition is provided.

Description

High strength lightweight concrete composition using sludge

The present invention relates to a high-strength lightweight concrete composition using sludge, and more specifically, to make artificial lightweight aggregate with industrial waste, which is generated under various conditions, and to use it in a concrete composition to reduce the weight of the structure and reduce construction cost. It relates to a high strength lightweight concrete composition utilizing sludge that can be.

In other words, the present invention is to replace the aggregates such as gravel, which weighs the most weight among the concrete composition with sludge (sludge), which is an industrial waste, to develop lightweight concrete that reduces the weight of concrete and apply it to the structure by increasing the strength. To a composition.

Concrete, which is used as the main material of the structure in modern architecture, is the most used construction material because of its economic efficiency and excellent performance. However, concrete has a disadvantage of increasing the weight of the structure because the weight is greater than the strength. In addition, the recent structure of the structure is gradually higher and larger, the need for research on the high strength and light weight of concrete has emerged.

However, due to the lack of structural lightweight aggregate, mix design of high strength lightweight concrete, lack of construction technology and lack of awareness of high strength lightweight concrete, lightweight aggregate is manufactured from non-structural lightweight concrete that is used for insulation or sound insulation, rather than being used as structural material. The development of high-strength lightweight concrete is still insignificant.

On the other hand, artificial aggregate has the advantage of controlling the physical properties such as porosity, volume specific gravity, absorption rate, size, shape, etc., compared to natural aggregates, structural aggregates such as concrete for reducing the weight of high-rise buildings, bridges, or soundproofing and moisture proof It can be widely used in the field of non-structural aggregates such as concrete, soil substitute, drainage, ceramic carrier and the like.

Recently, research is being actively conducted to produce environmentally friendly artificial lightweight aggregates from various industrial wastes.

Among them, Patent Document 1 is added to the coal fly ash and stone dust sludge as a waste and molded by four different methods and then sintered in the range of 1100 ~ 1200 ℃ to produce artificial aggregate, the surface structure and body structure changes of the molded body To study the effects on the surface dense layer (shell) and internal reduction zone (black core) formation of pre-sintered artificial aggregate, to manufacture artificial lightweight aggregate to enable the production of artificial aggregate having various properties from one batch composition Molding methods are disclosed.

In addition, Patent Document 2 includes a raw material preparation step of dewatering the sludge collected in the waste water treatment plant to remove water, and pulverize the waste glass to powder; A raw material mixing step of mixing any one selected from dehydrated sludge and waste glass powder as a main raw material, and borax and sodium fluoride as an auxiliary raw material, and then adding water and stirring; A granulation step of preparing the mixed raw material into spherical granules; Drying the prepared spherical granules; Disclosed is a method for producing artificial lightweight aggregate, comprising the step of firing and cooling the dried spherical granules.

However, the above patent documents are related to the manufacture of artificial lightweight aggregate by mixing industrial sludge, which is generated in various environments, with other industrial wastes such as coal fly ash and waste glass. There is no disclosure about manufacturing lightweight aggregates.

In addition, artificial lightweight aggregates disclosed in the above patent documents will satisfy the light weight, but has not been disclosed or suggested at all that can be utilized as a structural material that requires high strength.

Therefore, the use of industrial waste sludge is a situation that requires a breakthrough research on high-strength lightweight concrete composition that can satisfy both light weight and high strength as well as excellent economic efficiency.

Korean Patent Publication No. 10-1153904 Korean Patent Publication No. 10-1123278

The present invention has been made to solve the problems in the prior art as described above, by using an artificial lightweight aggregate utilizing industrial waste to replace natural aggregates such as gravel natural aggregates with light weight to reduce the weight of the concrete structure The object of the present invention is to provide a high-strength lightweight concrete composition utilizing sludge that can contribute to the replacement effect and the protection of nature.

In addition, the present invention provides a high-strength lightweight concrete composition using sludge that can reduce the overall construction cost because by reducing the weight of the building structure by developing a high-strength lightweight concrete composition for structural reduction and simplifying construction Another purpose is to do it.

High-strength lightweight concrete composition using sludge according to an embodiment of the present invention for achieving the above object is a high-strength lightweight concrete composition having a unit weight of 1850 kgf / ㎥ or less and 28 days compressive strength of 27 MPa or more, Only cement, water, sand, aggregate and admixtures are mixed by weight ratio (kgf / ㎥), cement: water: sand: aggregate: admixture = 7.3: 1.88 ~ 3.08: 19.3: 15.4: 0.04 It is used by replacing at least 25% of the aggregate with an artificial lightweight aggregate on the basis of weight mixing, wherein the artificial lightweight aggregate is an artificial lightweight aggregate made of sludge manufactured by molding sludge into a spherical body, drying in air, and heating and baking to 1000 ° C. And, the artificial lightweight aggregate made of sludge is characterized in that the use after mixing the spherical body of 5 mm, 10 mm, 20 mm in diameter, respectively.

In addition, the high-strength lightweight concrete composition using sludge according to an embodiment of the present invention is characterized in that the artificial lightweight aggregate made of sludge is heated and calcined after being molded into a spherical body wrapped around the core of a combustible material.

In addition, the method of manufacturing a high strength lightweight concrete composition using sludge according to an embodiment of the present invention, as a method of manufacturing a high strength lightweight concrete composition using sludge according to the above embodiment, by molding the sludge into a spherical body and air After drying, heating and firing to 1000 ℃ to prepare an artificial lightweight aggregate made of sludge, and mixing only cement, water, sand, aggregate and admixture, the aggregate artificial lightweight aggregate made of sludge on the aggregate Including the mixing step used to replace more than 25%, the step of preparing an artificial lightweight aggregate consisting of the sludge, characterized in that for producing the spherical body of 5 mm, 10 mm, 20 mm in diameter and then mixed and used .

When using a high-strength lightweight concrete composition using sludge according to the present invention having the configuration as described above, there is an advantage to recycle resources by making artificial lightweight aggregate using industrial waste that can come from all over the country, If high strength lightweight concrete is developed, the construction cost can be reduced as the weight of the structure is reduced.

In addition, when the light weight of concrete reduces the size of the structural member, the construction cost and reinforcement amount of the structure is reduced, and the construction cost is also reduced, thereby reducing about 10% of the total construction cost.

1 is a graph showing the comparison of the weight of the test specimen for compressive strength,
2 is a graph comparing the compressive strength of the test specimen for compressive strength,
3 is a view for manufacturing a concrete beam test specimen,
4 is a laboratory setting diagram for an experiment on a concrete beam specimen,
5 is an experimental photograph of the concrete beam test specimen,
6 is a concrete beam specimen after the experiment,
7 is a graph showing experimental results of concrete beam specimens.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to high-strength lightweight concrete composition using sludge according to an embodiment of the present invention.

First, in the case of high-strength lightweight concrete composition using sludge according to an embodiment of the present invention, by mixing only cement, water, sand, aggregate and admixture, the dry weight of the unit is 1850 kgf / ㎥ or less 28 days compressive strength 27 It should be possible to provide high strength lightweight concrete compositions that are at least MPa. This is because the requirements as lightweight concrete and the requirements as high strength concrete must be satisfied at the same time.

Here, the admixture refers to AE agents, fluidized fires, etc., which are used for the purpose of durability improvement, coagulation hardening control, and fluidity improvement, and are neglected when used in a compounding design (less than 1%). Due to its relatively high usage (more than 5%), it is clearly distinguished from admixtures such as fly ash, blast furnace slag, silica fume, and pozzolane, which are considered in concrete mix design.

Thus, in the present invention, even if only a concrete composition consisting of only admixtures with cement, water, sand, aggregate and admixture, that is, high strength and light weight can be achieved even without using a large amount of admixture such as fly ash, blast furnace slag for the purpose of high strength. It features.

Light weight aggregates can be divided into natural light weight aggregates and artificial light weight aggregates, but there are various kinds of light weight aggregates, in the high-strength lightweight concrete composition according to an embodiment of the present invention, using artificial sludge, which is an industrial waste generated in various environments, Manufacture and use lightweight aggregate.

In order to use such an artificial lightweight aggregate in a construction structure, the general performance of concrete, such as compressive strength and bending performance and shear performance of the concrete beam, must be satisfied.

In order to check whether the compressive strength, which is the most important factor, is satisfied, concrete specimens were made and confirmed by compressive strength test.

In order to manufacture the artificial lightweight aggregate, industrial waste sludge is made into spherical bodies having a diameter of about 5 mm, 10 mm, and 20 mm in a clay-like state and dried to dryness in the air. The dried artificial lightweight aggregate is calcined and heated to about 1000 ° C. to finally prepare an artificial lightweight aggregate composed of sludge. When prepared by mixing the spherical body with a different diameter as described above, not only is easy to manufacture, but also can be used appropriately substituted by coarse aggregate and fine aggregate, there is an advantage that the pore control according to the mixed use is easy.

At this time, in order to further reduce the weight of the artificial lightweight aggregate artificial lightweight aggregate for a relatively thick aggregate having a diameter of 20 mm, such as paper, newspaper, tissue paper, and combustible materials to create additional pores by burning and removing during the firing step. It is preferable to shape | mold in spherical shape by utilizing as a core in a center. In addition, it is preferable that the granular shape of the artificial lightweight aggregate is molded and manufactured so as to be close to a spherical shape and the particle surface state is smooth without irregularities.

The physical properties tested according to KS F 2503 2002 for artificial lightweight aggregate made of sludge as shown above are shown in Table 1 below.

Test Items Sample classification Test Methods 5 mm 10 mm 20 mm Density in surface dry saturation (g / cm 3) 2.15 1.85 1.93 KS F 2503
2002 Absolute Dry Density (g / cm 3) 1.85 1.59 1.67 Absorption rate (%) 15.77 16.55 15.81

On the other hand, the measurement of the specific gravity and air amount of the crushed stone used as aggregate in the artificial lightweight aggregate and the general concrete composition prepared as described above as shown in Table 2 below.

As cement, portland cement is used in accordance with KS L 5201. Water is the primary influencing factor in hydraulic cement, and water has a great effect on concrete strength development and durability through hydration with cement. In-house tap water was used according to the regulations, which did not include groups such as acid, alkali, salt, organic matter, etc.

The high-performance AE water reducing agent is naphthalene-based, specific gravity of 1.2 ± 0.02, dark brown liquid admixture was used, the characteristics are shown in Table 3.

type color chief ingredient characteristic freezing point importance Liquid bitumen Naphthalene
sulphonate none -2 ℃ 1.2 ± 0.02

In addition, the coarse aggregate size (10 mm, 20 mm), fine aggregate size (5 mm), the specific gravity and the absorption of the fine aggregates used in the present invention were carried out in accordance with KS F 2504, respectively, the unit volume weight and gap test were KS It carried out based on F2505 and KS F2506.

The water cement ratio was 50%, which was found to be effective in the existing studies, and the test factor was set to 25%, 50%, and 100% for the replacement of artificial lightweight aggregates.

The cement, artificial lightweight aggregate, sand, crushed stone, admixture and water prepared as described above were prepared to prepare a concrete specimen, and the weight and compressive strength were measured as shown in Table 4 below. The test mixture ratio is shown in Table 5 below.

Specimen Weight compounding (kgf / ㎥) Specimen weight cement Lightweight aggregate broken stone sand water Admixture General Concrete 7.3 0 15.4 19.3 3.08 0.04 3.62 25% replacement rate 3.47 11.93 1.88 3.49 50% replacement rate 6.94 5.97 1.93 3.30 100% replacement rate 15.4 0 2.49 3.16

The specimens were manufactured in accordance with KS F 2403 with a size of Φ10 x 20 cm for each compressive strength combination, 3 pieces for compressive strength, capping after 24 hours, and demolded for 24 hours after demolding for 20 ± 2 It was cured in water for 28 days in a constant temperature water bath.

As a result of comparing the weight and compressive strength of the specimen prepared as described above, as shown in Figures 1 and 2, the high-strength lightweight concrete according to the present invention showed a reduction of about 15% compared to the general concrete in terms of weight, The 20-day compressive strength of the high-strength lightweight concrete according to the invention is in the range of 18 MPa to 33 MPa, and in terms of 28-day compressive strength, it is considered to be 20 MPa to 38 MPa, exceeding the high strength standard value of 27 MPa. It was confirmed that it can be prepared into.

Next, in order to confirm the utility value of the high strength lightweight concrete composition according to the present invention to the concrete structure, in order to confirm the bending performance and shear performance of the concrete beam, five test specimens were manufactured and manufactured by the internationally recognized testing institute ( Note) Structural experiments (bending and shear strength) were conducted at Total E & C (Hanyang University Erica Campus).

The beam specimens were used as test factors to verify the flexural and shear performances. The beams were used as the main root for the bending of the beams, and the shear was the spacing of the roots. The scale of the specimens was 1/2 in consideration of the manufacturing environment and transport conditions. The test specimens of the beam were made of three general concretes, two high-strength lightweight concretes, and a total of five. The specimen specifications are shown in Table 6 and FIG. 3. The high strength lightweight concrete is prepared using a high strength lightweight concrete composition utilizing sludge of 25% crushed stone replacement rate described in the above embodiment.

NO Subject name Freckle Weight Remarks One C @ 200 2-HD13 Φ9 @ 200 General concrete / center Φ9 @ 300 2 LC @ 200 2-HD13 Φ9 @ 200 Lightweight concrete / center Φ9 @ 300 3 C @ 300 2-HD13 Φ9 @ 300 General Concrete 4 LC @ 300 2-HD13 Φ9 @ 300 Lightweight concrete 5 CON Rootless Rootless General Concrete

The laboratory setting status for the experiment on the beam specimen as described above is shown in Figure 4, the specifications of the experimental equipment used in the experiment is shown in Table 7 below.

Volume Quantity 500 kN actuator Stroke: ± 150mm
Force: ± 500kN One Data Logger (TDS-303) 30 CH One LVDT 200 mm
100 mm One
2

Lightweight concrete specimens were confirmed that the construction of the formulation and compaction was made well because the phenomenon such as irregularities due to the aggregate aggregate of the surface was not found, the experimental results are as shown in Figure 7, except for the normal concrete without bending cracks It was destroyed by (see Fig. 5 and 6, the experimental process and the photograph after the experiment) it was confirmed that the bending performance and shear performance of the lightweight concrete is not significantly different from the general concrete.

Claims (3)

High strength lightweight concrete composition with a unit weight of 1850 kgf / ㎥ or less and 28 days compressive strength of 27 MPa or more,
Only cement, water, sand, aggregate and admixtures are mixed by weight ratio (kgf / ㎥), cement: water: sand: aggregate: admixture = 7.3: 1.88 ~ 3.08: 19.3: 15.4: 0.04
25% or more of the aggregates on the basis of the weight of the composite to be replaced with artificial lightweight aggregate,
The artificial lightweight aggregate is an artificial lightweight aggregate made of sludge which is manufactured by molding sludge into a spherical body and drying in air and then heating and baking to 1000 ° C.,
The artificial lightweight aggregate consisting of the sludge is characterized in that the mixture used to produce a spherical body of 5 mm, 10 mm, 20 mm in diameter, respectively, high strength lightweight concrete composition utilizing sludge. The method according to claim 1,
The artificial lightweight aggregate made of sludge is characterized in that the core of the combustible material is molded into a spherical body wrapped around the sludge and then heated and fired, high strength lightweight concrete composition utilizing sludge. A method for producing a high strength lightweight concrete composition using sludge according to claim 1 or 2,
Molding the sludge into a spherical body and drying in air, and calcining it by heating to 1000 ° C. to prepare an artificial lightweight aggregate made of sludge; and
Mixing only cement, water, sand, aggregate and admixture, the aggregate includes a mixing step in which the artificial lightweight aggregate made of sludge is substituted by at least 25% by weight,
The step of preparing an artificial lightweight aggregate made of sludge, characterized in that for producing a spherical body of 5 mm, 10 mm, 20 mm in diameter, respectively, mixed and used, the method for producing a high strength lightweight concrete composition using sludge.

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