KR101300867B1 - Mass concrete composition mixed with the sludge of water treatment and the method of preparing it - Google Patents

Abstract

PURPOSE: A mass concrete composition with purified water sludge is adapted to delay the concrete stiffening in the early stages and the generation of hydration heat, so that stress generation can be lowered compared to the general low heat mass concrete and the durability of a structure can be improved by reducing the temperature crack. CONSTITUTION: A mass concrete composition with purified water sludge contains 70-95 weight% of Portland cement and 5-30 weight% of purified water sludge powder with the water content under 5 weight% which is dried without sintering process so the mass concrete composition with purified water sludge differs from a concrete composition consisting of binding material, aggregate, and combined water. The purified water sludge powder is fine powder with the fineness of 5,000-10,000 cm^2/g. A manufacturing method of mass concrete composition with purified water sludge comprises the steps of: drying purified water sludge to have the water content of 5 weight% or lower; pulverizing the dried sludge to the size of the fineness of 5,000-10,000 cm^2/g to obtain purified water sludge fine powder and mixing 70-95 weight% of Portland cement and 5-30 weight% of purified water sludge fine powder to produce mass concrete. [Reference numerals] (AA) Comparative example 1; (BB) Example 2; (CC) Example 3; (DD) Example 5

Description

Mass concrete composition mixed with the sludge of water treatment and the method of preparing it}

The present invention relates to a mass concrete composition, and more particularly, to a mass concrete composition using a purified water sludge and a method of manufacturing the same.

With the development of the construction industry, as civil engineering and building structures become larger and higher, the size of large parts such as dam works, harbor structures, LNG underground storage tanks, huge offshore structures, bridges, foundations and bridges Many mass concrete structures are being built. Such mass concrete structures have been applied to a lot of mat foundation construction due to the enlargement of ultra high-rise structures.

Concrete is a material widely used in the construction field because of its excellent compressive strength and excellent physical properties. As condensation proceeds after casting, concrete produces bond strength and hardens. This condensation and hardening is because the cement is hydrated by reacting with the mixed water. In this process, a large amount of heat of hydration is released and the temperature inside the concrete is increased by the heat of hydration of the cement. In general concrete structures, because the cross-sectional thickness of the concrete member is not large, the heat of hydration is mostly dissipated to the outside, and thermal stress due to the temperature difference between the inside and the outside of the concrete is not a big problem.

On the other hand, in a structure having a large cross section such as mass concrete, the heat of hydration on the concrete surface is radiated to the outside, but the heat of hydration inside the concrete is not radiated to the outside, thereby increasing the internal temperature. As a result, a temperature difference with the outside occurs, and thermal stress is generated due to the temperature difference, and when the thermal stress exceeds the tensile strength of the concrete, the frequency of cracking increases. As a result, cracks generated in the structure become a serious problem that damages the watertightness or durability of the structure.

As a construction method for suppressing cracking of mass concrete by hydration heat, a method of pouring concrete to a certain thickness over several times is applied. However, this method has a problem in that the performance of the concrete deteriorates when viewed in the medium to long term because the bonding force is relatively weak compared to the construction method for placing mass concrete at one time, and the watertightness is weak.

In addition, research has been conducted to develop a cement composition having a low heat of hydration in addition to the construction method as a solution for cracking caused by heat of hydration. For example, low heat cement containing bellite (C ₂ S) is used, A method of using a mixed material such as blast furnace slag powder or fly ash in Portland cement has been proposed. Recently, a method of using calcined and dried sludge from wastewater sludge generated in a wastewater treatment plant has also been proposed.

Korean Laid-Open Patent Publication No. 10-2012-0113476 proposes a method of simultaneously reducing the amount of cement used to reduce CO ₂ emission and hydration heat by using a large amount of blast furnace slag powder and fly ash, which are industrial by-products. . However, in the case of fly ash, there is a heat reduction effect of hydration, but there is a problem that the strength expression of the initial and middle periods decreases as the hydration rate is low and the amount of the additive is increased. In addition, since fly ash contains a large amount of unburned carbon, a problem of adsorbing concrete admixtures and degrading its function has been found. In the case of blast furnace slag, there is an advantage of improving the long-term strength, but when the powder is used to increase the thermal insulation temperature of the concrete increases the risk of cracking in the mass concrete. In addition, blast furnace slag, fly ash, etc. used in the past are generated at specific places such as steel mills and thermal power plants. The material which there is is called for. In this regard, the wastewater sludge of the sewage treatment plant near the city center or the purified water sludge of the water treatment plant is attracting attention as an alternative material.

Korean Unexamined Patent Publication No. 10-2012-0125902 provides a composition in which fine powder pulverized after firing and carbonizing dried wastewater sludge dried at a water content of 10 to 20% by weight is mixed with aggregate, cement and water. By the way, wastewater sludge has a problem of containing harmful substances, the use is limited, there is a problem that additional costs due to the firing at high temperatures. In addition, Korean Patent Laid-Open Publication No. 10-2012-0055219 adds sludge composed of waste sludge discharged from a sewage terminal treatment plant or red mud, a by-product of vogue site, instead of cement, and uses natural materials such as wood starch extract and herbal extract as a mixed material. It provides a high-strength concrete composition using the use of waste sludge as it contains water and using a liquid natural admixture such as wood starch extract to replace the use of water (mixed water).

On the other hand, the recent increase in water quality management (sludge) is increasing due to the interest of water quality management, the figure is about 300,000 tons per year. The purified sludge produced by the purified water treatment contains silica, aluminum oxide, iron hydroxide, etc., which has been used for simple disposal or recycling to landfill, cement, covering agent, chemical analysis, interior board, etc. However, due to the lack of recycling, most of them were discarded, and there was a problem of mass production and disposal of waste, and the cost of disposal. Water purification sludge can be supplied from a water purification plant near the city center, so it is easy to supply and receive water, and unlike sewage sludge, there is no concern about harmful substances, and a method for more effective utilization of the sludge is required.

Republic of Korea Patent Application Publication No. 10-2012-0113476 Republic of Korea Patent Application Publication No. 10-2012-0125902 Republic of Korea Patent Application Publication No. 10-2012-0055219 Republic of Korea Patent Publication 10-2000-0075373

The present invention focuses on the use of purified sludge in place of fly ash or blast furnace slag, which was conventionally used as an admixture for portland cement, in order to reduce the heat of hydration of mass concrete. Conventionally, there have been examples of using purified sludge as a substitute for cement, bricks, blocks, etc., but there have been no examples of mixing mixed with portland cement as a mixed material for reducing the heat of hydration of mass concrete. In order to use purified sludge as a cement admixture for mass concrete to replace fly ash or blast furnace slag, purified sludge should be able to reduce the heat of hydration of cement. Above all, the use of purified sludge uses fly ash or blast furnace slag. There should be more than economics. The conventional method of using purified water sludge as a cement substitute is used by firing the sludge at a high temperature, and this method is accompanied by an increase in cost, so it is difficult to replace fly ash or blast furnace slag due to low economical efficiency.

The present invention is to confirm that the fine powder powdered by drying the purified sludge without firing process to reduce the heat of hydration than fly ash or blast furnace slag when used as a blending material in Portland cement. An object of the present invention is to provide a mass concrete composition having excellent durability by using the fine powder powdered without the sintering process, the heat of hydration is reduced, thereby suppressing the cracks due to the heat of hydration in the mass concrete member. In addition, the initial strength in the mass concrete is suppressed to provide a concrete composition that can improve the integrity of the structure by integrating the hardening of the concrete in the construction by a number of continuous casting.

In the present invention,

In the concrete composition comprising a binder, aggregate, blending water,

Provided is a mass concrete composition using purified sludge, characterized in that the binder comprises 70 to 95% by weight of Portland cement and 5 to 30% by weight of purified sludge powder having a moisture content of 5% by weight or less dried without firing.

Further, in the present invention,

A drying step of drying the purified sludge to 5% by weight or less of water content;

Grinding the purified sludge dried by the drying step to a powder degree of 5,000 to 10,000 cm 2 / g to obtain purified sludge fine powder;

70 to 95% by weight of Portland cement, and 5 to 30% by weight of the fine water sludge fine powder is provided, a method for producing mass concrete using purified water sludge is provided.

The mass concrete composition using the purified water sludge according to the present invention and a method for manufacturing the same are new ways to recycle a large amount of purified water waste generated during purification of the water supply, and thus, 100% of the increased purified water waste can be recycled, thereby reducing the disposal cost of the waste. Of course, it is possible to achieve new profits using waste and to solve environmental pollution problems. In addition, the mass concrete composition of the present invention, by delaying the initial curing of the concrete, by delaying the generation of hydration heat to reduce the generated stress compared to the general low heat mass concrete to reduce the temperature crack, thereby improving the durability of the structure have. The mass concrete composition of the present invention has the effect of reducing the heat of hydration compared to the mass concrete composition using the conventional fly ash or blast furnace slag, while securing and supplying materials and having a low procurement cost, thereby greatly reducing the cost. .

1 is a result of comparing the compressive strength of the Examples and Comparative Examples.
2 is a result of comparing the air volume and the slump of the Examples and Comparative Examples.
3 is a result of comparing and testing the simple thermal insulation temperature rise of the Examples and Comparative Examples.

The mass concrete composition using the purified water sludge of the present invention is a mass concrete composition comprising a binder, aggregate, and blending water, wherein the binder has an integer of 70 to 95% by weight of Portland cement and a water content of 5% by weight or less dried without firing. Sludge powder 5 to 30% by weight. The binder, the drying step of drying the water purification sludge to 5% by weight or less; Pulverizing the purified sludge dried by the drying step with a powder degree of 5,000 to 10,000 cm 2 / g to obtain purified sludge fine powder; 70 to 95% by weight of Portland cement, and 5 to 30% by weight of the purified sludge fine powder can be obtained by a method comprising the step of mixing. Each step and configuration will be described in detail.

In the present invention, "water sludge" is defined as sludge generated when drinking water is purified.

In the present invention, "portland cement" is meant to include both medium heat portland cement and ordinary portland cement, unless specifically limited.

In the present invention, the purified sludge is dried to a moisture content of 5% by weight or less and then finely ground. The drying step is not particularly limited, and any drying step can be used as long as it can dry the purified sludge at a water content of 5% by weight or less. Since only drying without firing is possible by indirect heating method, it is preferably dried at a temperature of 60 ~ 150 ℃. Most preferably, it is dried at 90-120 degreeC for 15 to 30 hours.

The purified sludge dried at a water content of 5% by weight or less is finely pulverized using a ball mill or the like. Preferably, the powder is also finely powdered at about 5,000 to 10,000 cm 2 / g, and more preferably, the powder is also finely powdered at about 6,000 to 8,000 cm 2 / g.

5 to 30% by weight of finely powdered purified sludge and 70 to 95% by weight of Portland cement are mixed. The use of purified sludge in less than 5% by weight may reduce the heat of hydration and cost reduction effect in the mass concrete, while the use of more than 30% by weight may lower the amount of cement used to lower the strength of the concrete. The portland cement is preferably ordinary portland cement.

The binder including the purified sludge and the portland cement may further include at least one other admixture such as a water reducing agent, an air-entraining agent (AE) agent, an AE water reducing agent, and the like as a conventional concrete composition.

The mass concrete composition of this invention mix | blends aggregate and a mixing | blending number with the binder formed as mentioned above like a normal concrete composition. Matters concerning aggregate and blending water are the same as in the general mass concrete composition, and the aggregate preferably includes both fine aggregate and coarse aggregate.

[Example]

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, these embodiments are only for describing the present invention more specifically, and the scope of the present invention is not limited by these embodiments.

≪ Example 1 >

Treatment of purified sludge

The collected purified sludge was dried at 100 DEG C for 24 hours using a dryer to obtain dry purified sludge having a water content of about 3% by weight. The dry purified sludge thus obtained was pulverized with a ball mill to obtain a fine powder having a powder degree of about 7,000 cm 2 / g.

<Example 2>

Concrete (binder) composition

Usually 94.3% by weight of Portland cement, 5% by weight of finely divided dry purified sludge obtained in Example 1, and 0.7% by weight of a high performance AE reducing agent (trade name: ROADCON-PEMA HR1000).

<Example 3>

Concrete (binder) composition

Usually 89.3% by weight of Portland cement, 10% by weight of finely powdered dry purified sludge obtained in Example 1, and 0.7% by weight of a high performance AE reducing agent (trade name: ROADCON-PEMA HR1000).

<Example 4>

Concrete (binder) composition

Usually 83.8% by weight of Portland cement, 15% by weight of finely divided dry purified sludge obtained in Example 1, and 1.2% by weight of a high performance AE water reducing agent (trade name: ROADCON-PEMA HR1000).

<Example 5>

Concrete (binder) composition

Usually 77.9% by weight of Portland cement, 20% by weight of finely divided dry purified sludge obtained in Example 1, and 2.1% by weight of a high performance AE reducing agent (trade name: ROADCON-PEMA HR1000).

&Lt; Comparative Example 1 &

Concrete (plain) composition

Usually 99.3% by weight of Portland cement and 0.7% by weight of a high performance AE reducing agent (trade name: ROADCON-PEMA HR1000) were mixed.

Comparative Example 2

Concrete (binder) composition

Usually 89.3% by weight of Portland cement, 10% by weight of fly ash (FA) and 0.7% by weight of high performance AE water reducing agent (trade name: ROADCON-PEMA HR1000) were mixed.

&Lt; Comparative Example 3 &

Concrete (binder) composition

Usually 77.9% by weight of Portland cement, 20% by weight of blast furnace slag powder, and 2.1% by weight of high performance AE water reducing agent (trade name: ROADCON-PEMA HR1000) were mixed.

&Lt; Comparative Example 4 &

Concrete (binder) composition

Usually 77.9% by weight of Portland cement, 20% by weight of fly ash (FA) and 2.1% by weight of high performance AE water reducing agent (trade name: ROADCON-PEMA HR1000) were mixed.

&Lt; Test Example 1 >

Compressive strength test

Compressive strength tests were carried out on the compositions of Examples and Comparative Examples. Compressive strength test results for the compositions of Examples 2, 3, 5 and Comparative Example 1 (plain) are shown in Table 1 below and FIG. Comparative results of the compressive strength of the compositions of Example 3, Comparative Examples 2 and 3 are shown in Table 2. The composition of the present invention had a low initial strength but increased in strength over time, and the strength after 28 days showed a higher strength than the composition of the comparative example using fly ash or blast furnace slag.

&Lt; Test Example 2 &

Air volume and slump test

The amount of air and slump for the compositions of Examples 2, 3 and 5 and Comparative Example 1 (plain) were compared. The results are shown in Table 3 and FIG. 2 below. The compositions of the present invention all showed titrations in air volume and slump.

<Test Example 3>

Simple insulation temperature rise test

The test which confirms the simple insulation temperature rise about the composition of Examples 2-5 and the composition of Comparative Example 4 was done. As the temperature of concrete is increased by the hydration reaction of cement, the ambient temperature is increased. Therefore, the degree of ambient temperature is increased by the hydration reaction in the concrete insulation state. The results are shown in Tables 4, 5 and 3 below.

The mass concrete composition of the present invention can improve the durability of the structure by preventing cracking due to the heat of hydration of the mass concrete, and at the same time can lower the cost of concrete, it can be used in various fields in place of the existing mass concrete . In particular, the mass concrete composition according to the present invention, can be applied to the construction and civil engineering (dam) construction, the use of ready-mixed concrete, such as road construction, sofa block, artificial reef, large farm water channel, fume pipe, box culvert.

Claims (5)

In the concrete composition comprising a binder, aggregate, blending water,
The binder comprises 70 to 95% by weight of Portland cement and 5 to 30% by weight of purified sludge powder having a moisture content of 5% by weight or less, dried without firing,
The purified sludge powder is a mass concrete composition using purified sludge, characterized in that the fine powder of 5,000 ~ 10,000 cm2 / g powder. The mass concrete composition of claim 1, wherein the binder further comprises at least one of a water reducing agent, an AE agent, and an AE water reducing agent. delete A drying step of drying the purified sludge to 5% by weight or less of water content;
Grinding the purified sludge dried by the drying step to a powder degree of 5,000 to 10,000 cm 2 / g to obtain purified sludge fine powder;
Mixing 70 to 95% by weight of Portland cement with 5 to 30% by weight of the purified sludge fine powder
A method of producing mass concrete using purified sludge, including. The method of claim 4, wherein the mixing comprises further mixing at least one of a water reducing agent, an AE agent, and an AE water reducing agent.

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