KR101148916B1 - Solidifying agent and method for solidifying soft ground using the same - Google Patents

Abstract

PURPOSE: An environmentally-friendly soil solidifying agent and a weak ground construction work using thereof are provided to prevent early strength degradation and obtain long term intensity stability. CONSTITUTION: An environmentally-friendly soil solidifying agent comprises 10-80 weight% of pozzolan material, 10-50 weight% of Portland cement, 1-30 weight% of gypsum, 1-5 weight% of alkaline, 1-10 weight% of quicklime or calcium hydroxide, and 3-10 weight% of iron oxide. The gypsum is one selected from a group consisting of anhydrous gypsum, hemihydrate, and gypsum dihydrate. The soil solidifying agent can be used to soil cement wall method of construction, deep aging disposal method, or superficial layer consolidating treatment method of construction.

Description

Eco-friendly soil solidification material and soft ground treatment method using the same {Solidifying agent and method for solidifying soft ground using the same}

The present invention relates to a soil solidifying material and a method for treating rough ground using the same, and more particularly, to prevent initial strength degradation and to achieve long-term strength stability, and to eco-friendly soil solidifying material which significantly reduces heavy metals, and soft ground using the same. It is about a processing method.

In general, the soil solidifying material used to reinforce the soft ground is mainly used portland cement or slag cement. However, there was a problem that a large amount should be used to obtain the target compressive strength when mixing them with soil. In order to solve this problem, recently, solidified materials containing fine blast furnace slag powder, anhydrous gypsum, or alkali metal salt compounds have been provided. However, these materials have difficulty in sufficiently securing initial strength when mixed with soil, and deteriorate long-term strength and durability. There are disadvantages. In order to solve this problem, excessively adding alkali metals has a disadvantage of increasing the amount of material used for solidification because of difficulty in working with fluidity and deterioration of long-term strength and durability.

That is, the general soil solidifying materials used to date, not only have a problem in strength in the early and medium to long term, but also have a disadvantage in that heavy metals such as hexavalent chromium may be contained in large amounts due to the excessive use.

The present invention is to solve the conventional problems as described above, to provide a soil solidified material and a soft ground treatment method using the same that can improve the durability by preventing the initial strength degradation and at the same time secure the long-term strength stability It is main purpose to do it.

Another object of the present invention is to provide an environmentally friendly soil solidified material and a soft ground treatment method using the same to reduce the dissolution of heavy metals such as hexavalent chromium to minimize contamination of soil and groundwater.

Soil solidifying material according to the present invention for solving the above object comprises 10 to 80% by weight of pozzolanic material, 10 to 50% by weight of Portland cement, anhydrous gypsum, hemihydrate gypsum, at least one of 1 to 30% by weight of gypsum, 1 to 5% by weight of alkali metal salt, 1 to 10% by weight of quicklime or slaked lime, and 1 to 10% by weight of iron oxide or ferrous sulfate.

The soil solidifying material according to the present invention can be used in the soil cement month method, deep solidification method or surface solidification method.

According to the present invention as described above, the long-term strength can be sufficiently secured by the pozzolanic material for the foaming cement, and the initial strength by quicklime or slaked lime is also sufficiently secured. In addition, the increase in long-term strength makes it possible to provide soil solidified materials having sufficient durability. In addition, reinforcement of the long-term strength, as well as the elution of hexavalent chromium, is maximized by iron oxide or ferrous sulfate, which is added to reinforce the long-term strength drop that may be lost by the quicklime or slaked lime that is added for initial strength reinforcement. The benefits of being able to provide environmentally friendly soil solidification are expected.

The soil solidifying material according to the present invention comprises 10 to 80% by weight of pozzolanic material and 10 to 50% by weight of portland cement. Here the pozzolanic material and the portland cement are basically used as soil hardeners. In the present invention, the pozzolanic material may be used as long as it is known in the art. In addition, the pozzolanic material may use any one or more selected from the group consisting of, for example, blast furnace chain flag fine powder, fly ash, paper ash and silica fume. And the pozzolanic material is mainly used for reinforcing the long-term strength, Portland cement is to allow the pozzolanic material to mix with the cement and then react with water to cause a hydration reaction.

When the pozzolanic material is added more than the above-mentioned composition range, it may be advantageous in terms of long-term strength but adversely affects in terms of early strength. In addition, when Portland cement is added more than the composition ratio, it is relatively advantageous in terms of initial strength, but it is not preferable because the long-term strength associated with the pozzolanic material is lowered.

And 1-30 weight% gypsum containing at least one of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum is added to the soil solidification material which concerns on this invention. This gypsum is used as a soil solidifying material to further secure the strength. However, when the gypsum exceeds 30% by weight, the strength and durability is rather deteriorated. If the gypsum is less than 1% by weight, it does not have meaning because the strength is not secured although it does not significantly affect durability.

In the present invention, it is understood that the pozzolanic material is added within the range of the composition ratio as described above, so that long-term strength can be sufficiently secured. In addition to the long-term strength by the pozzolanic material, 1 to 10% by weight of quicklime or slaked lime is added to reinforce the early strength of the soil solidifying material of the present invention. If the addition ratio of quicklime or slaked lime is less than this, there is not enough disadvantage in terms of early strength reinforcement, and if it is added more than this, it may be helpful in early strength reinforcement, but the long-term strength will be remarkably lowered.

In the present invention, it can be seen that in order to sufficiently secure early strength, 1 to 10% by weight of quicklime or slaked lime is added. As described above, since the pozzolanic material is mainly used for long-term strength reinforcement, it is necessary to sufficiently secure the initial strength when used as a soil solidifying material. In the present invention, quicklime or slaked lime is added for reinforcement of initial strength.

And the use of quicklime or slaked lime can sufficiently secure the initial strength, where 1 to 10% by weight of iron oxide or ferrous sulfate is used to more reliably reinforce the lowering of the long-term strength due to their use. When the iron oxide or ferrous sulfate introduced in the present invention is less than 1% by weight, a sufficient effect may not be obtained in terms of strength, in particular, long-term strength, but when it exceeds 10% by weight, the strength is rather lost. As described above, in the present invention, it is possible to further secure long-term strength by injecting iron oxide or ferrous sulfate together with quicklime or slaked lime that are added to secure initial strength, thereby substantially increasing the durability of the soil solidified material. Will be. In addition, by adding iron oxide or ferrous sulfate, the hexavalent chromium can be immobilized to reduce heavy metals.

As a matter of course, other components may be added to the soil solidifying material having the structure according to the present invention as described above. For example, a small amount of a flow agent for improving fluidity with respect to the viscosity of the pozzolanic material may be added. For example, such a flow agent is preferably added in a small amount within the range that the basic properties of the soil solidifying material of the present invention as described above does not change, for example, may be selected from naphthalinsulfonic acid compounds. In addition, it may be possible to use alkali metal salts such as K2SO4 and Na2SO4 as a supplement for early strength reinforcement.

And it is natural that the soil solidifying material according to the present invention having the composition as described above can be used in various types of soft ground treatment methods. For example, it may be applied to the surface layer mixing process for stabilizing by mixing solidified materials on the surface of the soft ground, securing the traffickers of heavy equipment, laying foundations, and improving roadbeds. And it can be applied to in-depth mixing treatment method for improving the soft ground to the columnar, reticulated or full surface by mixing the solidified material of the present invention as described above in the ground. Since such a method itself is widely practiced at present, a detailed description thereof will be omitted, and in addition, it can be applied to any method for solidifying soil, such as a soil cement month method.

Next, an embodiment of the present invention will be described. Table 2 shows the results of evaluating the physical properties after mixing with the soil using the solidified material prepared as shown in Table 1 below. The soil and test methods used for the evaluation of the properties are as follows.

[Use soil]

-Cohesive soil: water content 85%, 1,700g / l

-Sandy soil: Water content 52%, 1,800g / l

[Test Methods]

Uniaxial compressive strength (KSF 2426), fluidity (KSL 5111),

Meat chromium dissolution test (Ministry of Environment Notice 2007-151)

division Pozzolanic substances Portland
cement Slag cement Anhydrous gypsum quicklime Slaked lime Ferrous sulfate Liquid fire Alkali metal salts Example 1 65 27 - 8 - - - - - Example 2 62 27 - 8 3 - - - - Example 3 61 27 - 8 3 - One - - Example 4 60 27 - 8 3 - One One - Example 5 60 27 - 8 - 5 - - - Example 6 - 100 - - - - - - - Example 7 - - 100 - - - - - - Example 8 60 27 8 3 - One - One

use
Fire
Kinds Soil type Fire
usage
(g / l) W / C
(%) Compressive strength (kg /) liquidity Hexavalent chromium elution
(ppm) 1 day 7 days 28 days 90 days Example 1 Clay soil 210 100 Not measurable 2.4 18.6 19.9 169 6 Sandy soil 210 100 Not measurable 3.2 21.3 23.0 174 6 Example 2 Clay soil 210 100 1.1 7.2 26.9 25.3 162 7 Sandy soil 210 100 1.9 8.0 27.3 28.2 168 6 Example 3 Clay soil 210 100 1.3 7.9 28.1 35.6 163 Not detected Sandy soil 210 100 1.9 9.8 29.5 38.2 167 Not detected Example 4 Clay soil 210 100 1.0 5.4 28.2 37.3 186 Not detected Sandy soil 210 100 1.7 10.7 30.0 41.3 193 Not detected Example 5 Clay soil 210 100 1.2 7.5 23.2 23.0 164 7 Sandy soil 210 100 1.7 8.3 26.4 25.9 175 6 Example 6 Clay soil 350 100 1.2 6.7 23.7 26.2 160 21 Sandy soil 350 100 1.8 8.6 25.3 28.9 169 20 Example 7 Clay soil 210 100 0.1 5.9 24.3 28.9 173 11 Sandy soil 210 100 0.3 7.2 28.1 34.0 177 10 Example 8
Clay soil 210 100 1.5 8.1 28.6 38.0 161 Not detected Sandy soil 210 100 2.2 10.9 32.4 41.1 165 Not detected

In the above examples 1 and 2 are only the pozzolanic material, portland cement, gypsum and quicklime in the present invention, Examples 3 and 4 are ferrous sulfate in the composition ratio of the present invention for the initial strength reinforcement and environmental friendliness It was put together. And Example 5 relates to a composition prepared according to the composition ratio of the present invention omitting quicklime for initial strength reinforcement. In addition, it can be seen that Examples 6 and 7 are comparative examples irrelevant to the composition ratio of the present invention. In Example 8, ferrous sulfate and an alkali metal salt were added within the composition ratio range of the present invention.

In Examples 3 and 4, which can be called examples of the present invention, it was found that the elution amount of hexavalent chromium was not detected at all, which was determined by the addition of ferrous sulfate. . In addition, it can be seen that the initial strength is sufficiently secured as well as the long-term strength by the introduction of ferrous sulfate. In addition, it can be seen that the long-term strength by the pozzolanic material also shows a remarkable effect compared to the comparative example.

Of course, many modifications are possible to those skilled in the art within the scope of the basic technical idea of the present invention as described above, and the present invention has the protection scope of the present invention based on the appended claims. It is self-evident that must be decided.

Claims (2)

10 to 80% by weight of pozzolanic material; 10-50% by weight of portland cement; 1 to 30% by weight gypsum comprising at least one of anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum; 1-5% by weight of alkali metal salt; 1-10% by weight of quicklime or hydrated lime; And 3-10 wt% of iron oxide.
The soil treatment method using the soil solidification material of Claim 1.