KR100414901B1 - A concrete composite using slag - Google Patents

Abstract

The present invention relates to a method for producing permeable concrete using the steelmaking slag generated from the steelmaking process to stabilize the steelmaking slag by appropriate treatment to prevent expansion even when contacted with water to use as aggregate for permeable concrete. To provide a method for providing a water-permeable concrete composition using the same, the present invention for achieving the above object is 1500kg aggregate with a maximum dimension of 15mm or 10mm maximum dimension per 1㎥ of concrete To 1700 kg, the amount of water is 90 to 100 kg, the ratio of water to cement (W / C) is 25% to 35% by weight, 0.5% to 2.0% by weight of high-performance AE water reducing agent to cement, colorant 2 to 5% by weight based on the cement, the aggregate is sprayed with water or immersed in water for at least 1 month relative to the total aggregate amount Easing (aging) may be achieved by a steel-making slag for providing the water-permeable concrete joseongmulreul using a steel-making slag, characterized in that contained 10% by volume to 20% by volume.

Description

Water-permeable concrete composition using steel slag {A concrete composite using slag}

The present invention relates to a method for manufacturing permeable concrete using steelmaking slag generated from the steelmaking process, and more particularly, steelmaking, which is a waste resource generated from an electric furnace or converter in the process of refining steelmaking raw materials such as pig iron and scrap metal. A method and composition for producing permeable concrete using slag.

Water-permeable concrete is a paving material that is generally used to pave the surface of roads, parks, etc., which is a problem of the conventional impervious surface pavement, that is, in case of rainfall, lack of drainage or incomplete drainage, By not being able to fall out and sticking to the surface of the road, it not only impedes the passage of traffic, but also reduces the sliding resistance. As the inflow is accelerated, it has been studied to solve various problems presented in terms of protection of the natural environment, such as flooding of rivers and the inability of microorganisms to live in the ground, preventing the growth of roadside trees.

As a way to solve this problem, we have been interested in permeable pavement and developed permeable asphalt in the developed countries in the 1980s and used it for the pavement of life-related roads, plazas and parking lots around the sidewalks. The same water-permeable asphalt pavement has been developed due to the disadvantage that the road surface is deformed when the temperature of the road rises in summer, resulting in the loss of permeability. Therefore, water-permeable concrete has been developed. It is used in roads.

Accordingly, researches for producing permeable concrete having an appropriate level of permeability and strength have been actively conducted. For example, Korean Patent Publication No. 90-4390 discloses water 116kg / ㎥, cement 292kg / ㎥, fine aggregate 87kg / ㎥ Permeable concrete mixed with coarse aggregate 1690kg / ㎥, pigment 7kg / ㎥ admixture 0.58kg / ㎥, and No. 91-6894 provides portland cement and 300 parts by weight of cement per cubic meter of concrete. A water permeable concrete comprising 0.005 to 0.1 parts by weight of binder and 0.35 to 0.45 parts by weight of water and aggregates forming a balance was provided. In Korean Patent Laid-Open No. 97-21018, 120 to 130 kg / m3 of water, 270 to 340 kg / m3 of cement, To provide a water-permeable concrete in which a delay agent is mixed within 0.3% of the amount of cement used in aggregates 1530 to 1920 kg / m 3 and pigments 14 to 20 kg / m 3 having a size of 6 to 10 mm.

In addition, U.S. Patent No. 4,333,765 (Registration No.) describes a technique for efficiently using resources by producing permeable concrete without using clean water by using salty water and mixing coarse aggregate coated with silicon dioxide with cement. Presented.

However, these techniques are for general aggregates, such as aggregates collected from Seoksan as coarse aggregates, which are different from the present invention regarding the manufacturing technology of water-permeable concrete utilizing waste resources as aggregates. Effective utilization of the abandoned aggregate resources is essential not only in terms of cost reduction but also to actively implement environmental protection.

However, as many construction works are carried out every year, the use of concrete is increasing and aggregate resources for concrete are depleted. Already, river sand and steel gravel are almost exhausted. Because of the limited reasons, the development of alternative aggregates, such as the utilization of waste resources, has emerged as an important task.

Blast furnace slag, which can be easily obtained as an alternative aggregate, is produced when making pig iron and is specified in the Korean Industrial Standard for use for concrete. It is prohibited to use concrete as aggregate because it exists in the slag in the state of glass lime, which is not in the state of glass lime, and the volume expands upon reaction with water, causing the expansion of slag to collapse and reducing the strength of the concrete. There is a situation.

Due to the above reasons, steelmaking slag obtained from steelmaking process of about 4 million tons per year in Korea as a by-product of steel production is acted as a cause of environmental pollution as waste, and the method adopted as a method for treating this Although it is processed by a method called landfill, there is a problem that a large area of landfill is required for landfilling, and only a very small amount is used for surface treatment to prevent slipping on the downhill road of a highway.

The present invention is to provide a water-permeable concrete composition using the same to provide a method for using the aggregate for permeable concrete by stabilizing the steelmaking slag with the above problems by appropriate treatment to prevent expansion even when contacted with moisture. It is.

In order to achieve the above object, the present invention uses an aggregate having a maximum dimension of 15 mm or an aggregate having a maximum dimension of 10 mm in an amount of 1500 kg to 1700 kg, and has an amount of water of 90 to 100 kg and a ratio of water to cement ( W / C) is 25% to 35% by weight, 0.5% to 2.0% by weight of the high-performance AE water reducing agent and 2% to 5% by weight of the colorant to the cement, the aggregate is added to the total aggregate amount It can be achieved by providing a water-permeable concrete composition using steelmaking slag, characterized in that it contains 10 to 20% by volume of the steelmaking slag aged by spraying or immersing in water for at least one month.

In this case, the aggregate with the maximum dimension of 15 mm means that the aggregate size passes through all 20 mm sieves, 90 to 100% of the weight of the 15 mm sieve, and 40 to 70% of the weight of the 10 mm sieve, and the passing weight of the 5 mm sieve. Percentage 0 to 15% means the aggregate weight of 5 mm or less of 2.5mm sieve or less, the maximum dimension 10mm aggregate means all the 15mm sieve, passing through the percentage of 10mm sieve 85 to 100%, 5 It means that it is 10 to 30% of the passage weight percentage of mm body, 0 to 10% of the passage weight percentage of 2.5 mm body, and 5% or less of the passage weight percentage of 1.2 mm body.

As mentioned above, the steelmaking slag contains free calcium oxide in the steelmaking slag, absorbs moisture when contacted with water, and changes to calcium hydroxide, and the calcium hydroxide reacts with carbonic acid gas in the atmosphere to produce carbonic acid. As the volume is expanded to calcium, it collapses the binding force of the cement acting as a binder and causes cracking, thereby aging it in advance by water or the like to prevent expansion of the volume after the production of concrete.

If you confirm this by chemical reaction

CaO + H ₂ O → Ca (OH) ₂

2Ca (OH) ₂ + 2CO ₂ → 2CaCO ₃ + H ₂ O

The calcium carbonate produced by the above reaction is a very stable compound, so that unless it comes into contact with the acid component, it does not cause a chemical reaction again, so that no further volume expansion is brought about.

In order to confirm the process as described above, the change in free calcium oxide while aging steelmaking slag having a maximum dimension of 15 mm for one month was shown in Table 1 below.

Method elapsed days Before aging 15th 30 days Neglect in the atmosphere 0.6 0.5 0.5 Waiting and spraying once a day 0.3 0.2 Underwater deposition 0.2 0.2

The aging steel slag as described above is chemically stable as the free calcium oxide is changed into the form of calcium carbonate and some free calcium oxide remains, but the amount of remaining free calcium oxide is extremely small. Since the bonding strength obtained by the glassy component of is changed to a slightly weakened state, it does not have the same strength as general aggregates. Therefore, when the ratio of the total aggregate added exceeds 20% by volume, the strength of the porous concrete is weakened. Since it causes a problem, it is recommended to use 10 to 20% by volume.

The ratio of water to cement (W / C) in the range of 25% to 35% by weight is advantageous because the slump of concrete for producing porous concrete is close to zero, but the ratio of water to cement (W / C) When C) is more than 35% by weight, even when the concrete is mixed, the cement and the aggregate are not evenly mixed, so it is difficult to expect a compressive strength of 200kgf / ㎠ or more after laying curing. A problem arises that the cement role as a binder cannot be expected, and when used at 25% by weight or less, there is no effect on the mixing of concrete, but it becomes a dough and results in poor workability.

Various admixtures such as polycarboxylic acid, melamine and naphthalene are commercially available for the admixture used as a high performance AE water reducing agent. In the compaction process, the unit water is increased to decrease the strength of concrete after pouring, and when it is added more than 2.0% by weight, the loss of slump according to the elapsed time is large and the amount of air is excessively entrained to decrease the strength of concrete. Therefore, it is preferable to add 0.5 wt% to 2.0 wt% with respect to the cement.

As pigments used as colorants, pigments such as synthetic iron oxide, chromium oxide, and phthaloxyan-based pigments are generally used, and when added to 2% by weight or less with respect to cement, the coloring effect cannot be properly exhibited. In order to reduce the workability of the concrete and cause problems such as a decrease in strength and an increase in shrinkage rate, it is generally used within the above range.

Unlike conventional concrete, permeable concrete is affected by compaction as well as water-cement (W / C) ratio. As the porosity increases, the permeability improves in proportion to the increase in the permeability, so it is necessary to make sure that the requirements for strength and permeability are met.

In general, permeable concrete is designed to have a porosity of 10% to 30% of the compaction and the amount of aggregate per cubic meter of concrete is applied 1500kg to 1700kg.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

<Examples 1 to 10>

Aggregate made of steelmaking slag with the maximum size of aggregate was 10mm and sprayed once a day for 1 month in yard. The composition ratio of other components is as per Table 2 below. Prepared and measured the compressive strength according to the coefficient of permeability and curing is shown in Table 3.

No. W / C (%) Slag replacement rate (%) Unit weight (kg / m ³ ) water cement High performance AE water reducer Coarse aggregate Steel slag Crushed stone One 30.0 10 90 300 3.0 198 1406 2 20 396 1250 3 30 595 1093 4 40 793 937 5 50 991 781 6 25.0 10 100 400 4.0 194 1376 7 20 388 1223 8 30 582 1070 9 40 776 917 10 50 970 765

Permeability Test

Using a method of dropping a 2.5 kg ramma at a height of 30 cm, it was compacted 30 times in a single layer to make a specimen having a diameter of 15 cm and a height of 10 cm, and then cured in water at 20 ° C. Permeability test was carried out under the condition of water head difference of 10 cm.

Compressive Strength Test

A specimen of 10 cm in diameter and 20 cm in height was prepared by compacting 20 times in two layers using a method of dropping a 2.5 kg ramma at a height of 30 cm. And the next day was capped by cement paste and cured in water at 20 ℃ for 28 days, 3 months, 6 months and 9 months of age and then subjected to compressive strength test.

No. Permeability coefficient (cm / s) Compressive strength (kgf / cm ² ) 28 days 3 months 6 months 9 months One 0.45 165 178 183 187 2 0.39 173 188 195 198 3 0.52 158 165 170 165 4 0.41 163 173 170 166 5 0.35 159 172 167 150 6 0.15 242 259 265 265 7 0.14 248 268 273 282 8 0.11 251 271 273 265 9 0.20 247 257 249 236 10 0.16 236 255 230 225

As can be seen from Table 3, when the replacement rate of steelmaking slag is 20% or less, the compressive strength tends to increase with age, but when the replacement rate is 30%, the strength of 9 months is 6 months. Steel slag aggregates show a tendency to deteriorate slightly, and when the replacement rate is 40% or more, the compressive strength of 6 months and 9 months is gradually decreased from the compressive strength of 3 months. When the replacement rate of 20% or more of the total aggregate is used, since the strength of the long-term age is lowered, it can be seen that it is preferable to use within the scope of the present invention.

As can be seen from the above description, the present invention can solve the pollution caused by waste by applying to porous concrete by replacing steelmaking slag, which is not useful as aggregate, with a part of aggregate. Losing is a useful invention that can serve to supplement some of the aggregates.

Claims (1)

In the permeable concrete composition composed of cement, aggregate, high-performance AE reducing agent, coloring material, and water, 1500 kg to 1700 kg of aggregate having a maximum dimension of 15 mm or aggregate having a maximum dimension of 10 mm is used per 1 m 3 of concrete. 90 to 100 kg, the ratio of water to cement (W / C) is 25% to 35% by weight, 0.5% to 2.0% by weight of high performance AE water reducing agent, 2% to 5% by weight of colorant Percentage using steelmaking slag, wherein the aggregate contains 10% to 20% by volume of the steelmaking slag, which is aged by sprinkling or immersing in water for at least 1 month. Castle concrete composition.