KR20060044438A - A composite of consolidation and hardening pile for soft ground - Google Patents

Abstract

The present invention relates to a composition of a consolidated hardening pile for soft ground improvement, and more particularly, to a composition of a soft ground improving consolidation pile that can be used not only for deep foundations but also to increase the strength of the surrounding ground and to prevent settlement. .

The consolidation hardening pile composition for soft ground improvement according to the present invention is a consolidation hardening pile composition used for soft ground improvement work, aggregate: quicklime: additives are made by mixing in a weight ratio of 50 to 60: 20 to 25: 20 to 25 Wherein, the additive is a mixture of blast furnace slag powder or fly ash in cement, the ratio is 65 to 85: 15 to 35 with respect to the total weight of the additive,

It is constructed in the form of vertical piles on the soft ground, causing reactions such as pore water, digestive absorption, hydration reaction, exothermic reaction, expansion reaction, and ion exchange reaction in the ground to improve the surrounding ground by lowering the water content and enhancing the shear strength. The resulting coagulated body expresses strength of more than 50kgf / cm 2 and structurally exerts its effect as support pile for settlement and reinforcement pile for activity.

Soft ground improvement, consolidation, pile, quicklime, uniaxial compressive strength, deep foundation

Description

Consolidation pile composition for soft ground improvement {A composite of consolidation and hardening pile for soft ground}

The present invention relates to a consolidation pile composition used in soft ground improvement work, and more particularly, can be used in deep foundations, such as CIP (CAST IN PLACE PILE) method of placing a pile in the field as well as the creation of chemical material in the hole. The present invention relates to a composition of consolidation hardening piles for soft ground improvement that can obtain strength increase and settlement settlement of surrounding ground, such as a chemical pile method in which ash is filled to form a vertical pile.

In general, various methods are used as methods for improving the soft ground, and among these methods, there is a chemical pile method.

In addition, one of the methods used for deep foundation is C.I.P (CAST IN PLACE PILE) method.

These are the following.

In the chemical pile method, a hole of about 20 ~ 40cm in diameter is formed in the soft ground, and a vertical pile is formed by filling a production ash, which is a chemical material. Thus, due to the chemical properties of the quicklime that constitutes the chemical pile, it reacts with moisture contained in the soft ground, causing exothermic reactions of about 300 ° C and digestive absorption reactions [CaO + H ₂ O → Ca (OH) ₂ ] , Expansion effect and ion exchange reaction (Ca ⁺ ) play the role of reducing the ratio of the surrounding soil and consolidating in the horizontal direction by expansion.

As a result, the strength of the surrounding ground may be increased, and the settlement settlement effect may be brought about.

However, the pile form using only quicklime shows the strength of about 5kgf / ㎠, and as a structural support pile, there is a disadvantage that it is unstable and abruptly suppresses work safety due to rapid expression reaction and requires the use of expensive dedicated equipment.

C.I.P (CAST IN PLACE PILE) is a concrete pile made by injecting coarse aggregate and cement paste into the hole after drilling with EARTH AUGER.

At this time, the diameter is at least 25cm and is constructed in various forms such as 30cm, 45cm, 60cm, 90cm.

This method can be used for decayed soils using casing pipes, but it is difficult to apply to soft soils and it has little effect on soil improvement.

The present invention has been made to solve the problems of the prior art as described above by forming a hole in a soft ground made of viscous soil of high water content and by inputting a composite material consisting of quicklime, additives and aggregates to react with the pore water in the ground It is to improve the strength by reducing the water content of the ground and promoting the consolidation in the horizontal direction, and for improving the soft ground, which can provide reinforcement piles for the supporting piles and the activities of the upper loads through the expression of the strength of the material itself after the reaction. An object of the present invention is to provide a composition of consolidated hardened piles.

In particular, the present invention causes a sudden exothermic reaction of about 300 ℃ high temperature during the quicklime reaction, which is a disadvantage of the chemical pile method, inhibits work stability, and the burden of using expensive equipment, and after the reaction of about 5kgf / ㎠ It solves the problem of not being able to expect the effect as a structural support pile by showing small compressive strength, and it is easy to secure work safety by heating to a temperature of about 40 ℃ during construction, and it is easy to install as a general equipment without using expensive equipment. It is possible, and the pile formed after the reaction to express the strength of about 50kgf / ㎠ to provide a composition of the consolidated hardening pile for soft ground improvement that can fully exhibit the function as a structural support pile.

In addition, it is an object of the present invention to provide a composition of the consolidated hardening pile for soft ground improvement excellent durability compared to the quicklime pile by the solidification action by the additive.

The purpose of the present invention as described above is in the consolidation hardening pile composition used in soft ground improvement construction, aggregate: quicklime: additive is made by mixing in a weight ratio of 50 to 60: 20 to 25: 20 to 25, the additive is cement It is a mixture of blast furnace slag powder or fly ash (Fly Ash) in a ratio of 65 to 85: 15 to 35 with respect to the total weight of the additive is made by a soft ground improvement consolidated hardened pile composition.

As the aggregate, any one or a mixture of bottom ash, blast furnace slag aggregate, or a mixture thereof may be used, and the additive may include 4% to 5% more of an ion exchange material, and the zeolite (I) Zeolite) and Lignin (Ca +) can be used.

Hereinafter, an example of the consolidated hardening pile composition for soft ground improvement according to the present invention will be described.

The pile material to be formed on the soft ground according to the present invention is to have the shape of the pile by pouring a mixture of quicklime + additives + aggregate in the ground in the form of powder.

The powdered material absorbs the pore waters in the ground and undergoes a chemical reaction. With this reaction, the surrounding ground is improved, and the strength of the pile itself is gradually expressed.

The optimum ratio is by weight: aggregate: quicklime: additives = 50% to 60%: 20% to 25%: 20% to 25%.

According to the design, the mixing ratio of the material should be adjusted so that it can be up to 50kgf / ㎠, and the appropriate particle size control of the aggregate is required in order for the powdered material to be compacted by vibration.

Aggregate should have a particle size distribution as shown in Table 1.

The mixing ratio of quicklime + additives + aggregate is based on the weight ratio, and can be variously adjusted as shown in Table 2 according to the target strength.

As can be seen in the table above (quick lime + additive): the ratio of aggregate

In the case of 1: 1.5, not only the compressive strength but also the result was the most stable.

As the additive material, blast furnace slag powder or fly ash is used to improve the performance of cement and aggregate, and the material used as the aggregate is bottom ash, blast furnace slag aggregate, and the like. Industrial by-products were used.

Quick lime, which is the main material of the pile composition according to the present invention, is a ground improving material, that is, a material having a water content lowering and consolidation effect, and generates about 300 ° C of heat by reacting with water present in the pores between the ground granules. , Digestion and absorption [CaO + H ₂ O → Ca (OH) ₂ ], expands, Ca ⁺ ions released from Ca (OH) ₂ (calcite) undergoes ion exchange reaction (Ca ⁺ ) with the cations of the surrounding granules In addition, Ca (OH) ₂ (calcined lime) powder reacts with water present in the pores between the ground particles of the surrounding ground to cause a curing reaction, thereby reducing the water content of the surrounding ground and consolidating in the horizontal direction due to expansion. It will play a role.

Additives mixed with the quicklime include cement, blast furnace slag powder / fly ash, ion exchange material, and the like.

When the bottom ash (Bottom Ash) is used as the aggregate, blast furnace slag powder is added, and when the blast furnace slag aggregate is used as the aggregate, fly ash becomes a component of the additive.

The cement is a typical binder that reacts with water to bind solids. The main function is a strength enhancing material of a pile, and the additional function has a water content decrease and a consolidation function. Add 65% to 85% of the additive weight.

The blast furnace slag powder is a by-product of the steel industry, such as CaO, SiO ₂ , Al ₂ O ₃ is a main component and is a material that exhibits bonding strength in an alkaline situation. The reaction rate is considerably slower than that of quicklime and cement, so it can reduce the high heat of 300 ℃ during the initial reaction of quicklime to improve the work safety and to achieve continuous strength improvement corresponding to the consolidation mechanism of the ground.

In addition, when the blast furnace slag is in contact with water, a dense impermeable acidic film is formed on the surface of the slag particles, so that the blast furnace slag is not cured by itself, but the film is destroyed by calcium hydroxide (Ca (OH) ₂ ), which is a reaction product of cement or quicklime. Reactions (potential hydraulics) enhance the long-term strength of solids and form dense solids to inhibit chlorine ion penetration, sulfate and chemical resistance to seawater.

Blast furnace slag powder is a admixture for improving the role of the commonly used cement to reduce the strength of the solids when added over a certain amount. In the present invention, 15% to 35% of the weight of the additive is added.

The fly ash (Fly Ash) is mainly composed of SiO ₂ , Al ₂ O ₃ to reduce the heat of hydration to suppress the cracking of heavy structures, improve the water-tightness of the solidified body, increase the freeze-thawing resistance. In particular, although it does not have its own hydrophobicity, it gradually reacts with Ca (OH) 2 to produce insoluble stable calcium silicate hydrate (pozzolanic reaction), which is effective for long-term strength expression. 15% to 35% of the weight of the additive is added.

The ion exchange material is a solidification material for preventing the dissolution of heavy metals, but among the additives used in the present invention, the bottom ash (Bottom Ash), slag and the like is less than the acceptance criteria, but may contain harmful heavy metals, from which heavy metals are eluted. It serves to prevent.

Zeolite, a kind of ion exchange material, is a porous aluminosilicate crystal composed of SiO ₄ , AlO ₄ tetrahedron and reacts with surrounding metal cations to maintain electrical neutrality.

This ion exchange action has the effect of suppressing the dissolution of harmful heavy metals in the surroundings. Add 4% to 5% of the additive weight.

As shown in Table 3, the harmful heavy metal content of the bottom ash to be used as aggregate in the present invention is different depending on anthracite and bituminous coal, and varies depending on the country, coal type, and coal mixing rate, but is generally as follows. These are all below the limit.

The bottom ash is a by-product of coal-fired fly ash (Fly Ash) and coarse particles of bottom ash (Bottom Ash) as a by-product of a coal-fired power plant as physical ash as shown in Table 4 and Table 5 And chemical composition.

The bottom ash having the above characteristics is not suitable for the standard of aggregate aggregate of general concrete, so it is not suitable for use as concrete aggregate, but it can be used for special concrete parts such as lightweight concrete or parts that do not have a great structural effect. In the present invention, by mixing 50% to 60% of the total weight to perform the function as aggregate.

Particularly, in the present invention, each material is mixed and poured in a powder state. Bottom ash has a lighter specific gravity than a general aggregate and is composed of a porous structure generated at a high temperature, thereby separating from other materials. As can be seen from Table 4, the absorption rate is four times higher than that of general aggregates, which is effective in lowering the water content of the surrounding ground.

The blast furnace slag aggregate is an industrial by-product obtained in the manufacturing process of pig iron and is commercialized as a substitute for concrete aggregate. In the present invention, the blast furnace slag aggregate defined in KS F 2544 (blast furnace slag aggregate for concrete) is 50% to 60% of the total weight. Mixing to perform the function as aggregate.

The ground improved paper composition formed by the consolidation hardening pile composition for soft ground improvement according to the present invention is constructed and constructed as described above is as follows.

① It lowers the water content of the surrounding ground within a short time by digestive absorption and exothermic reactions.

② There is ground consolidation effect in horizontal direction by expansion reaction, and it increases density.

③ It increases the shear strength of surrounding ground viscous soil by ion exchange reaction (Ca ⁺ ),

④ In the course of the reaction, the strength of the pile itself is expressed up to about 50kgf / ㎠

By expressing the strength of, the effect as a support pile can be obtained.

As a side effect, by using coal power plant by-products and steel mill by-products as aggregates, waste resources can be used to save natural resources, reduce harvesting costs, and preserve the environment. It has the effect of reducing the transportation cost and improved ground improvement effect by utilizing the characteristics of waste resources superior to natural aggregates such as pozzolanic reaction and latent hydrophobicity during curing.

In addition, the addition of additives and aggregates decreases the chemical reaction rate due to the addition of 100% quicklime, which results in a gradual reaction that can further increase the effect of improving the ground. Can be secured.

Furthermore, the diameter of the pile is smaller than that of the large special equipment used in the construction of the conventional sand compaction pile, and the construction of the general compaction equipment can be performed since the use of the special equipment for the rapid exothermic reaction is unnecessary. This can reduce the economics of the use of the equipment, work safety and environmental problems due to noise reduction.

The configuration and operation as described above are not limited to the claims of the present invention as an embodiment, and various changes and modifications are possible within the scope of not changing the technical spirit of the present invention. It is obvious to those who are engaged.

Claims (3)

In the consolidated hardening pile composition used for soft ground improvement work, Aggregate: quicklime: additive is made by mixing the weight ratio of 50 to 60: 20 to 25: 20 to 25, The additive is a mixture of blast furnace slag powder or fly ash (Fly Ash) in cement, the ratio is 59 to 81: 15 to 35 with respect to the total weight of the additive, the consolidated hardening pile composition for soft ground improvement. The method of claim 1, wherein the aggregate is a bottom ash (Bottom Ash), blast furnace slag aggregates any one or a mixture of these, the consolidated hardened pile composition for soft ground improvement. The method of claim 1 or 2, wherein the additive further comprises an ion exchanger of 4% to 5% of the total weight of the additive, the ion exchanger is characterized in that any one of zeolite (Legin), Lignin (Ca +) Consolidation hardening pile composition for soft ground improvement.