KR101583257B1 - Lightweight soil for preventing sinkhole - Google Patents

Abstract

The present invention relates to a lightweight fill material for preventing formation of a sinkhole for backfilling an underground structure buried underground, and more preferably, to a lightweight fill material for preventing formation of a sinkhole, which can prevent a sinkhole from being formed due to occurrence of differential settlement caused by poor compaction of fill material into a sewer pipe, which is an underground structure, and a cavity generated around the sewer pipe. The present invention relates to a lightweight fill material for preventing formation of a sinkhole for backfilling an underground structure buried underground, wherein the fill material comprises a binder, water, and recycled soil, wherein the binder is composed of 20-30 wt% of cement, 10-20 wt% of fly ash, and 50-70 wt% of blast furnace slag.

Description

{Lightweight soil for preventing sinkhole}

The present invention relates to a lightweight embankment for preventing sinkholes for backfilling of an underground structure buried in the ground, and more preferably to a method of manufacturing a lightweight embankment for preventing backfilling of an underground structure buried in the ground, And to a sinkhole-preventing lightweight filler capable of preventing a sinkhole being formed.

The embankment used for backfilling of conventional underground structures mainly uses soil. This is economically advantageous because it is used to backfill with the existing soil. However, it takes a long time to compile, and if the compaction time is not long enough, the volume may decrease after a certain period of time, and an uneven settlement may occur.

Especially, underground structures such as a sewer pipe may be deformed due to deformation of the sewer connection part due to uneven settlement, and the backfilling material around the sewer pipe may be lost due to the leakage, so that a sink hole may be formed around the underground structure.

Therefore, there is an attempt to use cementitious filler to solve these problems.

However, cement used as a binder of cement-based filler has problems such as a large amount of energy consumption during production and environmental pollution due to CO ₂ emission.

Recently, interest in environmental problems such as carbon-reduction type and environment-friendly has increased, and construction companies and remicon companies have made various efforts to use cement in a small amount.

In general, limestone (CaCO ₂ ) is the main material of cement, and it is subjected to calcination process in which limestone is calcined during cement production. To a large amount of CO ₂ during this process, typically 1 ton of cement is CO ₂ 0.7 to 0.9 ton occurs during the production, the amount of CO ₂ discharged from the cement industry, domestic domestic CO ₂ It accounts for about 6 to 8% of total emissions.

Also, the strength of cement-based eutectoids is excessively high, so it is difficult to dismantle them in maintenance and management of underground structures, and the underground structures may be damaged when dismantled.

In addition, blast furnace slag or fly ash is used as a by-product in order to reduce cement, which is a binder of cementitious filler.

However, in this method, the mixing design of the cement-based embankment is not systematic and the experience is dependent on the field mixing and pouring. Therefore, the quality of the concrete is inhomogeneous. As a result, the compression strength and the volume And the like.

In order to solve the above-mentioned problems, the present invention provides cement, fly ash and blast furnace slag as a binder of an embankment for backfilling of an underground structure to reduce the amount of cement used and to provide an environmentally friendly light hole filler for preventing sinkholes.

In addition, the addition of foaming agent to the embankment composed of cement, fly ash, and blast-furnace slag, water and recycled soil makes it easier to dismantle the embankment for maintenance and maintenance of underground structures, To provide a lightweight embedding material for preventing sinkholes.

In order to prevent inhomogeneity and deterioration of concrete quality, it is desired to provide lightweight embankment for sinkhole prevention using systematic blending design of embankment through regression analysis of indoor test results.

According to another aspect of the present invention, there is provided a lightweight filler for preventing sinkholes for backfilling of an underground structure buried in the ground, the filler including a binder, water, and recycled soil, The binder is composed of 20 to 30% by weight of cement, 10 to 20% by weight of fly ash and 50 to 70% by weight of blast furnace slag, and the unit bonding amount, unit water amount and unit recycle amount are determined by the following formula To provide a light-weight filler for preventing sinkholes.

delete

[Mathematical Expression]

In this case, B _{unit is the} unit bonding amount (kg / m ³ ), W _{unit is the} unit water amount (kg / m ³ ), D _{unit is the} unit recycle amount (kg / m ³ ), f _{ck is the} compressive strength , ρ _c : Apparent specific gravity required for embankment, S / B: Recycled soil-binder ratio (weight ratio).

According to another preferred embodiment of the present invention, there is provided a lightweight filler for preventing sinkholes, wherein the filler further comprises a foaming agent.

According to another preferred embodiment of the present invention, the recycled gypsum has a water content of 38 to 42%.

According to another preferred embodiment of the present invention, there is provided a lightweight filler for preventing sinkholes, which has a water-binding ratio (weight ratio) of 25 to 32.5%.

According to another preferred embodiment of the present invention, there is provided a lightweight filler for preventing sinkholes, which comprises a polycarboxylic acid-based high-performance water reducing agent.

According to another preferred embodiment of the present invention, the underground structure is a sewer pipe, and the embankment material fixes the position of the sewer pipe.

The present invention has the following effects.

First, since it reduces the amount of cement used, it can reduce the amount of CO ₂ generated in the production of cement, which is environmentally friendly.

Second, it is not difficult to dismantle the embankment during the maintenance and maintenance of the underground structure, and minimize damage to the underground structure during dismantling.

Third, the burden of the underground structure can be minimized because it is backfilled with lightweight embankment which is replaced with foamed aggregate or coarse aggregate volume.

Fourth, regression analysis of indoor test results provides a systematic blend design of embankment, so that homogeneous quality can be expected.

Fifth, because of the use of homogeneous quality embedment combined with systematic mixing design, it is possible to prevent sinkholes caused by uneven settlement caused by poor compaction of backfill material and voids formed around sewer pipes.

Sixth, the cost and environmental problems can be solved by replacing the volume of fine aggregate and coarse aggregate with recycled soil such as dredged soil and construction residues.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a mixing design process of a lightweight filler for preventing sinkholes of the present invention. Fig.
2 is a cross-sectional view showing an underground structure to which a light-weight filler for preventing sinkholes of the present invention is applied.
FIG. 3 is an exemplary view showing another embodiment of FIG. 2. FIG.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

The present invention relates to a lightweight filler for preventing sinkholes for backfilling of an underground structure buried in the ground, wherein the filler comprises a binder, water and recycled soil, wherein the binder comprises 20-30 wt% of cement, 10 wt% of fly ash To 20% by weight and blast furnace slag 50 to 70% by weight.

 In the present invention, in order to provide an embankment having a strength such that the volume does not change, the earth pressure is effectively supported, and the deformation during use is minimized while being easily disassembled in maintenance management, a blast furnace slag and fly ash Cement-based cement is used as a substitute for a large amount of cement.

In addition, it is possible to solve the cost and environmental problems by recycling the volume of the aggregate aggregate and the coarse aggregate as the recycled soil such as dredged soil and construction residues which require the processing cost while maintaining the required volume.

Generally, Portland cement is mainly composed of calcium oxide (CaO), silica (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) and has a high degree of powder around 3,300 cm 2 / g.

It is preferable that the cement is used in an amount of 20 to 30% by weight. Generally, when the cement is substituted with the admixture, it is necessary to use at least 20% by weight or more to activate the substituted admixture. It is difficult to dismantle when maintenance and management of underground structures are strong, and it is possible to damage underground structures when dismantled.

Fly ash is a fine particle material that is produced when coal or heavy oil is burned. Its main components are silica (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and vitreous, which are spherical.

The fly ash is inexpensive and economical among materials that can be used as an admixture, and the particles are spherical so that the flowability due to the ball bearing effect can be improved when the concrete is mixed.

If the fly ash content is less than 10% by weight, the fly ash is too small to exhibit its performance. If the fly ash content is more than 20% by weight, the compressive strength of the fly ash is too weak, It is difficult to exert.

Blast furnace slag is a by-product obtained from iron ore, limestone, coke, etc. as a raw material in the blast furnace of the steel industry. It is a combination of limestone and pumice as impurities in iron ore.

The blast furnace slag is a material capable of replacing calcium hydroxide (CaO), which is a limestone component of conventional Portland cement, and contains a large amount of non-glazed glass phase. Such a non-hard phase is a latent hydraulic material which easily reacts with an alkaline substance .

It is preferable that the blast furnace slag is used in an amount of 50 to 70% by weight. When the blast furnace slag is less than 50% by weight, the blast furnace slag is too small to exhibit its performance. When the blast furnace slag is more than 70% by weight, It is hard to expect.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a mixing design process of a lightweight filler for preventing sinkholes of the present invention. Fig.

Conventionally, lightweight foamed concrete has been blended in accordance with experience-based field composition without a systematic blending design, so that homogeneous quality can not be expected, and it may lead to poor construction.

However, in the present invention, it is possible to form a lightweight embedding material of homogeneous quality by using an optimal formulation formula through regression analysis of indoor test results.

As shown in FIG. 1, the unit bonding amount, the unit amount, and the unit recycle amount can be determined by the following equations.

[Mathematical Expression]

In this case, B _{unit is the} unit bonding amount (kg / m ³ ), W _{unit is the} unit water amount (kg / m ³ ), D _{unit is the} unit recycle amount (kg / m ³ ), f _{ck is the} compressive strength , ρ _c : Apparent specific gravity required for embankment, S / B: Recycled soil-binder ratio (weight ratio).

The input values for the blend design are the apparent apparent specific gravity (ρ _c ) and the recycled soil-binder ratio (S / B) of the total embankment.

The above equation can easily and accurately determine the unit bonding discretion (B _unit ), the unit quantity (W _unit ), and the unit recycle amount (D _unit ) by only these two input values.

It is possible to predict the compression strength (f _ck) of the concrete by the input value, and to determine the unit coupled discretion (B _unit) by the predicted concrete compressive strength (f _ck), the unit combining the discretion (B _unit) The unit quantity (W _unit ) can be determined.

In addition, the unit recycling amount (D _unit ) can be determined by the unit bonding amount (B _unit ) and the recycled soil-bonding material ratio (S / B).

On the other hand, an experiment for verifying the mixing design using the above equation was performed as follows.

Table 1 shows the blending details of the lightweight filler for preventing sinkholes and the experimental results based on this blend design.

Input Mixing design Experiment result Error rate (%) Apparent apparent density Recycled soil-binder ratio (weight ratio) Design Compressive Strength (MPa) Mixing details (kg / m3) Apparent specific gravity Compressive strength (MPa) Apparent specific gravity Compressive strength (MPa) Unit binding discretion Unit quantity Unit Recycling Amount Bubble amount (ℓ) 0.7 3 0.36 225.5 73.3 676.6 470.8 0.71 0.36 1.4 0.8 One 3 1.22 307.1 99.8 921.4 279.3 1.05 1.30 5.0 6.4 1.3 3 3.02 385.5 125.3 1156.5 95.4 1.36 3.50 4.6 15.8 0.7 5 0.21 147.3 41.9 736.5 490.8 0.68 0.23 2.9 9.0 One 5 0.79 208.5 67.8 1042.4 279.3 1.00 0.83 0.0 14.9 1.3 5 1.79 269.2 87.5 1346.0 69.4 1.30 1.81 0.0 1.4 0.7 7 0.15 108.8 35.4 761.8 502.9 0.75 0.17 7.1 11.9 One 7 0.51 158.4 51.5 1108.9 276.4 1.03 0.57 3.0 11.6 1.3 7 1.26 208.8 67.9 1461.6 46.3 1.31 1.22 0.8 3.4 Average error rate (%) 2.8 8.4

As shown in Table 1, the desired apparent specific gravity of the embankment and the target value of the recycled soil-binder ratio (weight ratio) can be selected as shown in Table 1, and then the mixing design can be designed through the above equation.

A comparison of the actual apparent density and the design compressive strength of the embankment selected as the target value from the actual experimental results through the above mixing design can be confirmed to be very similar.

In particular, it can be seen that the apparent specific gravity has a mean error rate of 2.8% which is considerably low. Compressive strength is slightly lower than the apparent specific gravity, but the average error rate is 8.4%, which is less than 10%. These results demonstrate that the formulation design formula is very accurate.

The filler may further include a foaming agent.

In the present invention, by adding a foaming agent to the embankment, the weight of the underground structure is minimized by reducing the volume of the remaining aggregate and coarse aggregate while reducing the weight.

It is also possible to allow continuous pores to be formed when water permeability is required, and single pores to be formed if impermeability is required, by controlling the foaming agent.

The foaming agent may be an animal or vegetable foaming agent commonly used in Korea and may be used as a foaming agent used in concrete. It is preferable to use diluted foaming agent. It is preferable that the diluted bubble is foamed at a pressure of about 6 bar through a bubble generator Do.

The recycled gypsum preferably has a water content of 38 to 42%.

When the water content of recycled soil is less than 38%, it may cause volume reduction by inducing vesicle bubbles during concrete pouring. If it exceeds 42%, the compressive strength may decrease due to increase of unit water quantity.

The water-binding ratio (weight ratio) is preferably 25 to 32.5%.

In the present invention, the water-binding material ratio (weight ratio) is preferably not more than 32.5% in order to secure the compressive strength due to the large amount of fly ash and blast furnace slag substitution. .

However, when the water-binding ratio (weight ratio) is less than 25%, the binding force of the binding material can be reduced.

The above-mentioned embedding material may include a polycarboxylic acid-based high-performance water reducing agent.

Since the high-performance water reducing agent adsorbs on the surface of the cement particles and causes mutual reaction between the particles, the aggregated particles are dispersed to increase the flow of the cement particles, thereby enabling homogenization of the strength due to the water reducing effect.

In one embodiment, when the water-binding ratio (weight ratio) is 32.5% and the recycled soil moisture content is 40%, the high-performance reducing material is preferably added in an amount of 1.75%.

FIG. 2 is a cross-sectional view showing an underground structure using the lightweight filler for preventing sinkholes according to the present invention, and FIG. 3 is an exemplary view showing another embodiment of FIG.

The underground structure can fix the position of the sewer pipe (30) by the embankment (10) with the sewer pipe (30).

As shown in FIG. 2, the lightweight filler 10 for preventing sinkholes of the present invention is prepared by adding an additive such as a foaming agent and a high-performance water reducing agent to a binder composed of cement, fly ash and blast furnace slag, 30, it is possible not only to fix the position of the sewer pipe 30, but also to prevent the loss of the embankment 10, thereby preventing the sink hole from sinking into the ground 20.

In addition, since the embankment 10 is light in weight, the load transmitted to the sewer pipe 30 is weak, so that the life of the sewer pipe 30 can be prolonged.

3, the embankment 10 may be applied only to the lower end of the sewer pipe 30 to uniformly fix the height and the position of the sewer pipe 30 have.

10: Lightweight embankment for sink hole prevention
20: Ground
30: sewer pipe

Claims (7)

The present invention relates to a lightweight embankment for preventing sinkholes for backfilling of underground structures buried in the ground,
The embankment (10) is composed of a binder, water and recycled soil,
The binder is composed of 20 to 30% by weight of cement, 10 to 20% by weight of fly ash and 50 to 70% by weight of blast furnace slag,
Unit bonded amount, unit number and unit recycle amount are determined by the following equation.
[Mathematical Expression]

In this case, B _{unit is the} unit bonding amount (kg / m ³ ), W _{unit is the} unit water amount (kg / m ³ ), D _{unit is the} unit recycle amount (kg / m ³ ), f _{ck is the} compressive strength , ρ _c : Apparent specific gravity required for embankment, S / B: Recycled soil-binder ratio (weight ratio).
delete The method of claim 1,
Wherein the embedding material (10) further comprises a foaming agent.
The method of claim 1,
Wherein the recycled soil has a water content of 38 to 42%.
The method of claim 1,
And the water-binding ratio (weight ratio) is 25 to 32.5%.
The method of claim 1,
Characterized in that the embedding material (10) contains a polycarboxylic acid-based high-performance water reducing agent.
The method of claim 1,
Wherein the underground structure fixes the position of the sewer pipe (30) with the embankment (10) as the sewer pipe (30).

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