KR20140111738A

KR20140111738A - Volcanic ash, cement and metakaolin mixed soils and an use thereof

Info

Publication number: KR20140111738A
Application number: KR1020130025948A
Authority: KR
Inventors: 김용성
Original assignee: 강원대학교산학협력단
Priority date: 2013-03-12
Filing date: 2013-03-12
Publication date: 2014-09-22

Abstract

The present invention relates to a mixed soil which mixes volcanic ash, cement and metakaolin in proper capacities to increase the strength and to a use of the same. The mixed soil according to the present invention has properties of increasing compression strength and bending strength to be applied to such as bio-vegetation blocks and artificial fishing banks for water purification. Moreover, if effective microorganism is additionally mixed with the mixed soil, the water purification effect can be more improved.

Description

{Volcanic ash, cement and metakaolin mixed soils and an use thereof}

The present invention relates to a mixture of volcanic ash, cement and meta-kaolin mixed at an appropriate volume to improve the strength thereof, and a composition for water purification using the mixture as described above.

Zeolite (Zeolite) is a kind of natural minerals having a large number of fine gaps on the surface. Due to its unique adsorption property and ion exchange ability, it is widely used in industry as a desiccant, a detergent, a catalyst, and a construction material Material. Zeolite is a general term of minerals in which alkali metals and alkaline earth metals are bonded to anions generated by the combination of aluminum oxide and silicate oxide. It is contained in a great number of rocks throughout igneous rocks, sedimentary rocks, and metamorphic rocks. Water, such as hot springs or pegmatite deposits It is produced in abundant environment and contains a large amount of water in the crystal. The zeolite is based on a skeleton composed of silicon dioxide, and the entire crystal lattice is negatively charged by replacing a part of silicon with aluminum. For this reason, water molecules in the micropores are released and cations such as sodium are received to balance the charge. As a result, when zeolite in a powder state is put into an aqueous solution containing other kinds of cations, Adsorption occurs. Potassium, cesium, and other cations, toxins, and ammonia can also be ion exchanged and adsorbed by zeolites. It is also used as a filter medium in the cultivation of ornamental fishes, which is also used for adsorption of ammonia, organic substances and bacteria in water.

As a material similar to that of zeolite, a volcanic ash can be mentioned. Like volcanic ash, zeolite has considerable pore and specific surface area and is expected to be used as a substitute for zeolite. Especially, the possibility of eruption of Mt. Paektu has been increasing recently due to the elevation of the area around Mt. Paektu. If the Mt. Paektu erupts, many facilities such as aviation and logistics will reach to the disabled state due to the ash, It is necessary to minimize the damage caused by volcanic eruption through the development of effective utilization of volcanic ash treatment and construction materials.

As an overseas study of volcanic ash, the material characteristics and performance of road asphalt mixed with ash have been analyzed and the test construction has been carried out based on the results. Experimental study on square-shaped steel pipe columns filled with concrete using volcanic power - Deformation performance of member was investigated by considering displacement and load - strain characteristics. In order to effectively utilize the volcanic ash produced by the Shinmei 辿 dake eruption into concrete, it was subjected to composition analysis, particle size distribution, density and water absorption rate, alkali-silica reactivity test, stability test and dissolution test. Onoue (2012) analyzed strength properties and drying shrinkage characteristics of ash by mixing ratio of ash for effective utilization of ash through mixing of concrete. In order to obtain basic data for development of eco-friendly and high-functional geotechnical materials using Japanese new municipal tobacco and Sakurajima volcanic eruptions, analysis of uniaxial compressive strength according to grain size, compaction characteristics, shear strength characteristics, .

As a domestic study, the chemical properties, physical properties, particle size characteristics, liquid / plastic limit characteristics, soil classification, compaction characteristics, adhesion and internal friction angle of Hwasan volcanic ash were investigated, After analyzing the physical and chemical properties of the ash and the strength as a structural body, the adsorption effect of heavy metal on sile cement was evaluated. In addition, the mechanical properties of the ash concrete were investigated according to the substitution method and substitution ratio.

However, in Korea, the final differentiation occurred in the past compared to other countries, and the related research is mainly about ash that has undergone a considerable geological change over a long period of time. Therefore, further studies are needed to improve the utilization of volcanic ash immediately after eruption.

The present invention is a basic study to utilize ash as a substitute material of zeolite as a construction material. It analyzes the mixing ratio of volcanic ash or zeolite, compressive strength of cement mixed soil depending on mixing of meta kaolin, microstructure and freezing and thawing characteristics The purpose of this study is to clarify the engineering properties of volcanic ash - cement mixed soil and zeolite - cement mixed soil and to provide basic data necessary to utilize volcanic ash - cement mixture as a construction material in the field.

On the other hand, since the Gangjin (M7.3) occurred in the Wangcheng area of China, which is located downstream of the Tumen River in 2002, the number of earthquakes around Mt. Paektu has increased and the surrounding terrain has been rising. At the end of 2010, referring to the possibility of the explosion of Baekdu Mountain in the geological research center of the China Earthquake Country, the interest of the public including the media began to concentrate on the Baekdu Mountain eruption. In the meantime, domestic volcanic eruption has not been defined as a separate disaster type, but from these trends, government ministries have begun discussing countermeasures against Baekdu Mountain eruption. The Ministry of Unification has announced that it is considering considering the construction of an internal task force (TF) regarding the possibility of a volcano eruption in Baekdusan and considering the possibility of ordering research services. Other ministries are also in the process of preparing countermeasures against the eruption of Baekdu Mountain. If the volcanic eruption of Mt. Baekdu, like the European aviation crisis caused by the volcanic eruption of Iceland in 2010, would cause enormous damage to the Northeast Asian region that is actively engaged in economic activities. Many facilities such as aviation, logistics, Of the world's population. Therefore, it is necessary to minimize the damage caused by volcanic eruption through the treatment of volcanic ash and development of effective utilization methods of construction materials, and it has the ability of absorbing heavy metals and organic materials by utilizing characteristics of ash with large pores and large specific surface area. It is expected to be applied to the environmentally friendly revetment method.

In Korea, rivers are concentrated in the rainy season and have steep slopes. Therefore, except for some periods during the year, the flow rate is very low and it is very vulnerable to pollution due to increase of wastewater due to urbanization and industrialization.

Up to now, the improvement of water quality has been applied to collecting pollutants and discharging them to rivers. However, this method is based on the assumption that residual pollution is discharged into rivers without completely treating sewage or wastewater. Non-point pollution sources in the agricultural land are introduced into the river in a state without treatment measures and depend on the self-purification of the river in fact. However, their ability is limited, and when the pollution load is large, It is a situation that is inevitable.

Natural remediation techniques by direct contact, which is proposed as a method to improve the water quality of the river and restore the original hydrophilic function, have been applied to actual small watershed and have contributed to the water quality purification to a certain extent. This catalytic oxidation method is widely used in simple rivers because the organic solution is well decomposed by the metabolic action of the microorganisms while the installation cost is low.

However, since the conventional microorganism carrier is a simple adherent inorganic substance, it does not have a special function, and the denitrification process is divided into aerobic denitrification process and anaerobic denitrification process. In the denitrification process, (Oh et al., 2002). As an alternative to this, as an alternative to the BOD removal process itself, the use of shell powder (Moon et al., 1997) and effective microorganism (Effective microorganism, EM) as a microorganism carrier capable of effectively performing denitrification and de- (Lee, 2005; Seo et al., 2008).

A study on vegetation revetment for maximizing the midnight capability of domestic and overseas rivers, Mohamed et al. (2006) investigated the hydraulic and environmental performance of coconut shells, palm shells, and sugar cane shells by joining them to shore blocks. Kim (2007) developed vegetation shore blocks using wet- Respectively. Oh et al. (2002) studied the physical properties of porous concrete and its ability to remove contaminants. Cheong et al. (2009) examined the removal of nitrogen and phosphorus in plating wastewater using a soil reactor, and Lee and Kim (2005) investigated the effect of water purification on aquatic plants through field experiments. Kim et al. (2011) attempted to clarify water purification characteristics by constructing bio-composite vegetation blocks using oyster shells and useful microorganisms with high adsorption capacity for heavy metals and organic matter.

Kim, YT (2009) analyzed the physical and chemical properties and the strength of the ash of the basaltic ash materials in Jeju Pusan Basin, analyzed the far-infrared emissivity and harmfulness of Soil cement using heavy metals, Kim, MY (2009) also studied the use of volcanic ash as a sorbent for heavy metal wastewater treatment. However, the research on this is still insufficient, and many researches are needed continuously.

The purpose of this study is to investigate the bending strength of mixed soil blocks according to mixing ratio of volcanic ash, cement, and meta kaolin as an environmentally friendly construction material of Baekdusan volcanic ash , The microorganisms were applied to the volcanic ash-cement block block and the cage-type volcanic block without the binder, and then immersed in the contaminated water to investigate the effect on the water quality environment. And to provide basic engineering and environmental data to be applied as a drag structure.

On the other hand, the second explosion of the Eyjafjallajokull volcano in southern Iceland in April 2010 resulted in an air turbulence in Europe, and in June 2002, it was 7.3 in the Wangcheng area, The earthquake occurred in the area of Mt. Paektu and the intensity of the earthquake was increased and the ground surface was rising about 10cm. So, many media reported the risk of volcanic eruption of Baekdu Mountain. In Korea, the volcanic eruption has not been defined as a separate disaster type in the Disaster and Safety Management Act and the Natural Disaster Countermeasures Act, so the disaster management measures of the National Security Management Basic Plan 2010-2014 It has been excluded. However, the issue of volcanic eruption has been the subject of question for the first time in the National Assembly due to the interest of the media in June 2010. The government agencies such as Meteorological Agency, National Emergency Management Agency, Ministry of Strategy and Finance and National Intelligence Service, And began to discuss countermeasures. At present, there is no clear indication of the differentiation of Mt. Baekdu, but the countermeasures should be prepared at all times. If Mt. Paektu is erupted, it will be hit by air, transportation, logistics, precision machinery industry, It is necessary to develop a plan for the treatment and utilization of volcanic ash.

The purpose of this invention is to utilize ash as a construction material under such a basis and to provide the basic data necessary to utilize the volcanic ash-cement mixture as a construction material in the field .

Onoue, K, 2012. Effective utilization of volcanic ash into concrete products, International Workshop for Volcanic Risk Assessment and Disaster Preparedness 145-162.

Accordingly, an object of the present invention is to provide a mixed soil in which cement, volcanic ash, and meta-kaolin are mixed to improve compressive strength or flexural strength.

Another object of the present invention is to provide a composition for purifying water comprising the above-mentioned mixture soil.

In order to solve the above problems, the present invention provides a mixed soil in which cement, volcanic ash, and meta-kaolin are mixed to increase compressive strength or flexural strength.

In one embodiment of the present invention, the ash has a particle size of GP or GW.

In an embodiment of the present invention, the ash includes 3 to 5 parts by weight of the cement, and the meta kaolin is 0.01 to 0.5 parts by weight based on 1 part by weight of the cement.

In one embodiment of the present invention, the increase in compressive strength or flexural strength is attributed to the production of ethene zeite.

In one embodiment of the present invention, the mixed soil further comprises a useful microorganism.

The present invention also provides a composition for purifying water comprising the above-mentioned mixture soil.

According to the present invention, the compressive strength and flexural strength of cement, volcanic ash, and meta-kaolin mixed soil increase. Considering such strength characteristics, the present invention can be utilized for receiving vegetation block and artificial fish for water purification, and contributing to effective utilization of volcanic ash that was conventionally disposed of. Further, if the microorganism is further mixed with the mixed soil, the water purification effect of the mixture can be further improved.

Fig. 1 is a distribution curve of Baekdusan volcanic ash and zeolite particle size.
2 is a graph comparing the uniaxial compressive strengths of Baekdusan volcanic ash-cement admixture with meta-kaolin blend.
3 is a graph comparing the uniaxial compressive strengths of the zeolite-cement mixed soil with and without the meta-kaolin blend.
4 is a graph showing the normalized compressive strength of Baekdusan volcanic ash-cement admixture according to the presence or absence of meta kaolin blend.
FIG. 5 is a graph showing normalized compressive strength of zeolite-cement mixed soil depending on whether meta-kaolin is mixed or not.
6 is a graph comparing the uniaxial compressive strength-axial strain of Baekdusan volcanic ash-cement admixture with meta-kaolin admixture.
FIG. 7 is a graph comparing the uniaxial compressive strength-axial strain of zeolite-cement mixed soil according to presence or absence of meta-kaolin blend.
8 is a graph comparing freeze-thaw characteristics of Baekdusan volcanic ash-cement mixed soil with and without meta kaolin blend.
9 is a graph showing a result of scanning electron microscope analysis according to presence or absence of meta-kaolin (0 day, 2000 times magnification).
FIG. 10 is a graph showing the results of scanning electron microscope analysis according to presence or absence of meta-kaolin mixture (7 days, 2000 times magnification).
FIG. 11 is a graph showing the results of X-ray diffractometer analysis according to presence or absence of meta-kaolin (0 day at age).
12 is a graph showing the results of X-ray diffractometer analysis according to presence or absence of meta-kaolin blend (at 7 days of age).
13 is a distribution curve of particle sizes of Baekdusan ash and Halla ash.
14 is a graph comparing unconfined compressive strengths of Baekdusan volcanic ash-cement admixture with meta-kaolin blend.
15 is a graph comparing the uniaxial compressive strengths of the Mt. Halla ash-cement admixture with and without the meta-kaolin blend.
16 is a graph showing normalized compressive strength of Baekdusan volcanic ash-cement admixture according to presence or absence of meta kaolin blend.
17 is a graph showing the normalized compressive strength of the Hwasan volcanic ash-cement admixture according to the presence or absence of meta-kaolin blend.
18 is a graph comparing the flexural strengths of Baekdusan volcanic ash-cement admixture with meta-kaolin admixture.
19 is a graph comparing the flexural strengths of the Mt. Halla ash-cement admixture according to the presence or absence of meta-kaolin blend.
FIG. 20 is a scanning electron microscope (SEM) chart of the Baekdusan volcanic ash-cement mixed soil and Hallyu volcanic ash-cemented soil according to the presence or absence of meta-kaolin.
FIG. 21 is a scanning electron microscopic (SEM) image of the Baekdusan volcanic ash-cement admixture and the Harakasan ash-cement admixture according to presence or absence of meta-kaolin.
FIG. 22 shows the results of X-ray diffraction analysis of Baekdusan volcanic ash-cement mixed soil and Hwalasan volcanic ash-cement mixed soil according to presence or absence of meta-kaolin.
FIG. 23 shows the results of X-ray diffraction analysis of Baekdusan volcanic ash-cement mixed soil and Hwasan volcanic ash-cement mixture according to presence or absence of meta-kaolin.
24 is a particle size distribution curve of Baekdusan volcanic ash, Halla volcanic ash, and gravel.
25 is a view showing a production process of the ash-cement mixture soil block.
26 is a view showing a cage-type volcanic block without a binder.
27 is a graph comparing the flexural strengths of the Baekdusan volcanic ash-cement mixture soil.
28 is a graph comparing the flexural strengths of the Halla ash-cement mixture soil.
FIG. 29 is a view showing a situation where a useful microorganism (EM) is applied to a volcanic ash-cement mixture soil and soaking the polluted water.
30 is a graph comparing changes in SS, BOD, and COD (Mn) of ash-cement mixed soil using useful microorganisms.
31 is a graph comparing changes in TN, TP, and pH of ash-cement mixed soil using useful microorganisms.

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

< Example 1>

Baekdu Mountain Volcanic Ash - Cement Mixed soil And Characteristics of Zeolite-Cement Mixed Soils

<1-1> Materials to be used

In the present invention, Baekdusan volcanic ash, zeolite, meta kaolin, etc. were used as samples. Table 1 and Fig. 1 show the particle size distribution curves of the Baekjusan volcanic ash and zeolite used in the present invention. The passage amount of Baekdusan ash and zeolite (4.76mm) is less than 50% and classified as Gravel system. The uniformity coefficient (Cu) of Baekdusan volcanic ash is 1.43, the curvature coefficient (Cc) is 0.92, the uniformity coefficient of zeolite is 2.33 and the curvature coefficient is 1.11. Both samples are classified as GP by unified classification method. Cement used ordinary Portland cement of domestic company, and Table 2 and Table 3 show the chemical composition and physical properties of Portland cement, respectively.

Comparison of physical properties of ash and zeolite Type Specific Gravity
(Gs) Uniformity
Coefficient
(Cu) Gradation
Coefficient
(Cc) USCS V.A 0.56 1.43 0.92 GP Zeolite 2.22 2.33 1.11 GP

Chemical Composition of Portland Cement (Unit:%) SiO ₂ Al ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O Fe ₂ O ₃ 21.09 4.84 63.85 3.32 3.09 1.13 0.29 2.39

Water intellectual property of Portland cement Specific Gravity (Gs) Setting time (h-min) Compressive strength (MPa) Initial Final 3days 7days 28days 3.15 5-7 7-20 19.4 21.6 32.3

<1-2> Mixture design and production

<1-2-1> combination

For the mixing design of volcanic ash-cement mixed soil and zeolite-cement mixed soil, various weight ratios were set and mixed to find optimum mixing conditions as shown in Table 4 by referring to the study of Onoue (2012) To form a specimen. That is to say, 16 kinds of experiments were conducted considering the mixture ratio (4 kinds) and meta-kaolin mixture (2 kinds) for Baekdusan volcanic ash and zeolite.

Mixture composition of volcanic ash or zeolite and cement Material Case Material Cement Remark VA
/ Zeolite One 3.5 One without and with metakaolin 2 4.0 One 3 4.5 One 4 5.0 One

<1-2-2> Specification making

In order to investigate the uniaxial compressive strength characteristics of the mixed soil, materials were injected into ø50 × 100 mm molds and compaction was carried out to produce cylindrical specimens. In order to investigate the strength characteristics according to the ages of these specimens, curing was carried out at 3, 7 and 28 days.

<1-3> Comparison of characteristics of mixed soil

<1-3-1> Uniaxial compressive strength exam

Uniaxial compressive strength was measured by using a uniaxial compression tester at a speed of 1 mm / min at a specimen of φ50 × 100 mm at 3, 7, and 28 days of age according to KS F 2314 (unconfined compression test method for soil) Respectively.

As a result, the same conclusions as in FIG. 2 and FIG. 3 were obtained. FIG. 2 and FIG. 3 show the compressive strengths of the cement mixed soil according to the mixing ratio of Baekdusan volcanic ash and zeolite and meta kaolin, respectively. As can be seen from this relationship, as the mixing ratio of the ash and the zeolite increases, the compressive strength tends to be small (Figs. 2 (a) and 3 (a)). As shown in Table 5, the strength of 1.05 MPa at 28 days when mixed with Baekdusan ash and cement at 3.5: 1 was increased as the mixing ratios were increased to 4.0: 1, 4.5: 1 and 5.0: 1, Are 0.78, 0.48, and 0.25 MPa, respectively.

Comparison of Compressive Strength according to the composition ratio of Baekdusan ash and cement mixture Items

VA: Cement Days (a) without metakaolin (b) with metakaolin Strength ratio
(b) / (a) Peak
(MPa) Strain
(%) Peak
(MPa) Strain
(%) 3.5: 1 3 0.61 3.76 0.93 2.85 1.52 7 0.68 5.93 1.04 1.88 1.53 28 1.03 3.66 1.21 7.03 1.17 4.0: 1 3 0.35 2.22 0.58 3.96 1.66 7 0.53 3.32 0.65 5.38 1.23 28 0.78 3.35 1.03 4.91 1.32 4.5: 1 3 0.33 3.25 0.34 1.75 1.03 7 0.41 5.06 0.42 3.14 1.02 28 0.48 2.99 0.54 3.43 1.13 5.0: 1 3 0.16 4.97 0.21 4.29 1.31 7 0.16 3.21 0.31 4.59 1.94 28 0.25 6.57 0.37 2.74 1.48

Also, as shown in Table 6, when the zeolite and cement were mixed at a ratio of 3.5: 1, the strength at 28 days was 1.33 MPa. However, as the mixing ratios were increased to 4.0: 1, 4.5: 1 and 5.0: 1, Were 0.93, 0.88 and 0.37 MPa, respectively, indicating the same tendency as the Baekdusan volcanic ash. As the mixing ratio of ash and zeolite increases, the material does not react with the cement, but remains in the cured product and hinders the hydration reaction of the cement.

Comparison of compressive strength according to zeolite-cement mixing ratio Items

VA: Cement Days (a) without metakaolin (b) with metakaolin Strength ratio
(b) / (a) Peak
(MPa) Strain
(%) Peak
(MPa) Strain
(%) 3.5: 1 3 0.89 1.81 1.00 1.71 1.13 7 1.12 3.33 1.26 3.38 1.13 28 1.33 3.00 1.52 2.57 1.15 4.0: 1 3 0.59 2.69 0.65 1.51 1.10 7 0.71 1.81 0.84 2.81 1.18 28 0.93 1.90 1.06 1.08 1.14 4.5: 1 3 0.43 2.18 0.45 2.96 1.05 7 0.53 1.92 0.58 3.30 1.09 28 0.88 0.72 0.93 1.43 1.06 5.0: 1 3 0.21 2.13 0.22 0.89 1.06 7 0.25 1.36 0.27 1.25 1.08 28 0.37 0.22 0.41 1.62 1.11

Therefore, it is considered difficult to incorporate a large amount of volcanic ash and zeolite in order to increase the strength of the cured body using only cement as a binder. Therefore, it is considered that a binder other than cement is necessary for promoting the recycling of ash and strengthening the strength of the ash. In the present invention, the influence of the meta kaolin corresponding to 1/10 of the cement weight on the compressive strength is further analyzed. As a result, it was found that the compressive strength of the mixed soil increased at all mixing ratios (Figs. 2 (b) and 3 (b)), and the quantitative evaluation revealed that the 28 days strength of Baekdusan ash- % And zeolite - cement mixed soil was improved by 6 ~ 15% at 28 days (see Tables 5 and 6), and it was confirmed that the mixing strength of mixed soil could be improved by mixing additional binder.

Figs. 4 and 5 show the normalized compressive strength (fc / f3 at 3 days of age) for each mixing ratio of Baekdusan volcanic ash and zeolite. As shown in this relation, the compressive strength of mixed soil increases with age. The normalized compressive strength (f7 / f3) was 1.06 ~ 1.52 at 7 days, and the normalized compressive strength (f28 / f3) was 1.47 ~ 2.23 at 28 days in Baekdusan volcanic ash - cement mixture. The addition of metakaolin, which is one tenth of the amount of cement, showed a normalized compressive strength of 1.12 ~ 1.45 at 7 days, and a normalized compressive strength of 1.30 ~ 1.78 at 28 days of age.

The normalized compressive strength (f7 / f3) was 1.20 ~ 1.26 at 7 days and the normalized compressive strength (f28 / f3) was 1.49 ~ 2.05 at 28 days in the case of zeolite - cement mixed soil. The addition of metakaolin, which is one tenth of the amount of cement, has a normalized compressive strength of 1.21 ~ 1.29 at 7 days and a normalized compressive strength of 1.52 ~ 2.05 at 28 days of age.

In the present invention, the compressive strength increases with the addition of meta kaolin. The normalized compressive strength at 7 days of age is similar to that of Baekdusan volcanic ash-cement mixture and zeolite-cement as well as meta kaolin, The compressive strength of the Baekdusan volcanic ash - cement mixed soil decreased slightly with the addition of meta kaolin, but the zeolite - cement mixed soil showed similar tendency after the addition of meta kaolin.

FIGS. 6 and 7 show the compressive strength-strain curves of the cement admixture according to the mixing ratio of Baishu Mountain volcanic ash and zeolite and the mixing ratio of meta-kaolin, respectively.

The strain (εf) at fracture of Baekdusan volcanic ash - cement mixture tended to show a rapid brittle fracture at the maximum strength of volcanic ash: cement = 3.5: 1 at 28 days of age. There was no significant difference. On the other hand, in the case of adding meta kaolin with a weight corresponding to 1/10 of the cement to the mixed soil, the strain at fracture was 3.5: 1 in the maximum strength at the age of 3 days and 7 days, But the strain at break was greatly increased to about 7% at 28 days of age.

In the case of zeolite - cement mixed soil, brittle fracture tendency was shown regardless of age and mixing ratio. On the other hand, the addition of meta kaolin to this mixed soil showed a tendency of brittle fracture without significant change of the fracture strain as compared with before addition.

As a result, the fracture strain of Baekdusan volcanic ash - cement admixture and zeolite - cement admixture tends to be brittle fracture at 28th day of age in metakaolin combination. , Which is due to the difference in the material properties of Baekdusan volcanic ash and zeolite, but it needs to be verified through continuous research in the future.

<1-3-2> Freezing and thawing test

The freezing and thawing test was carried out in a freezing cabinet which was not higher than -23 ° C after 7 days of curing in a wet curing chamber after molding the specimen in accordance with KS F 2332 (method of freezing and thawing of aged soil cement mixture) C for 24 hours in a wet curing room with a relative humidity of 100%. The soil-cement loss was measured by the following equation (1).

Loss rate of soil cement (%) =

-------------(One)

From here,

A: The first calculated dry mass minus the final modified dry mass

B: Initial dry mass calculated

Fig. 8 shows the relationship between the loss ratio of the cement mixture soil and the mixing ratio of the material (Baekdusan volcanic ash and zeolite) according to the freeze-thaw cycles. The experimental results showed that the loss rates of 1.27 ~ 3.74% and 1.17 ~ 3.56% of Baekdusan volcanic ash - cement mixed and zeolite - cement ash were 1.76 ~ 4.46% and 2.10 ~ 3.70% respectively. The higher the mixing ratio of ash and zeolite, the higher the loss rate. This indicates that hydration of cement plays an important role in the freeze-thaw resistance of mixed soil.

Chamberlain et al. (1990), it is known that the loss rate below 10 ~ 15% does not significantly affect the soil strength near the surface after 12 cycles of freezing and thawing, so Baekdusan volcanic ash-cement mixed soil and zeolite- It is judged that the resistance to freezing and thawing is secured. However, it is necessary to adjust the mixing ratio according to site conditions when using this mixed soil in the field.

<1-3-3> Scanning electron microscope observation of mixed soil

In order to analyze the hydration characteristics of the mixed soil, samples were taken from specimens at 0 and 7 days of age and the morphology and distribution of hydration products were compared using Scanning Electronic Microscope (SEM).

9 and 10 are SEM images of S-4300 (manufactured by SEM) for the 0 day and 7 day samples of Baekdusan volcanic ash-cement mixed soil and zeolite-cement mixed soil having a 3.5: 1 mixing ratio, Hitachi), which shows the microstructure inside the material. SEM analysis of the sample surface revealed that the hydration product, Ettringite, was formed by cement hydration at 7 days of age. In general concrete, a large amount of hydration product is formed due to a large amount of cement. On the other hand, a small amount of hydration product is formed due to hydration of the cement filled in the gap of the mixed soil, (Kellsen et al., 1996). The hydration product produced by the cement not only increases the bond strength with the soil but also contributes to the strength enhancement, so that the increase in the strength with the increase in age is explained well in Figs.

<1-3-4> X-ray of mixed soil Diffraction method Identify constituents by

In order to analyze the hydration characteristics of the mixed soil, samples were taken from the specimens at 0 and 7 days of age and X-ray diffraction (XRD) was used to identify the constituents of hydration products.

In order to analyze the constituents of Baekdusan volcanic ash-cement mixed soil and zeolite-cement mixed soil, XRD analysis was performed on the samples subjected to SEM analysis as shown in Figs. 11 and 12. Fig.

11 and 12 show the XRD analysis results for confirming hydration products after 0 day and 7 days of Baekdusan volcanic ash-cement mixed soil and zeolite-cement mixed soil, respectively. The main component of each mixture is a calcium silicate compound. When methacrolein is mixed, the composition of the compound is slightly changed. As a result of XRD analysis, it was confirmed that Ettringite was formed in both of the mixed soil after 7 days, and the hydration product of the present hydration product increased the binding force with the soil, thereby contributing to the strength enhancement with increasing age.

< Example 2> Baekdusan ash - Cement Mixed soil And the characteristics of Halla ash-cement mixture

<2-1> Materials

In the present invention, Baekdusan volcanic ash (China import), Halla ash volcanic ash (collected in Hanrim-eup, Jeju city), Cement, Meta kaolin, etc. were used as samples. 13 and Table 7 show the particle size distribution curves and the physical and chemical properties of the ash used in the present invention, respectively.

Passing amount of # 4 sieve (4.76mm) of Baekdusan and Halla ash is less than 50%. The uniformity coefficient (Cu) of Baekdusan ash is 1.43 and the curvature coefficient (Cc) is 0.92. In addition, the uniformity coefficient of Hallasan ash is 6.03 and the curvature coefficient is 2.08, and it is classified as GW by unified classification method. The content of SiO2 was the highest in the two volcanic ash, although there was a slight difference in the detailed composition.

Table 8 and Table 9 show the physical and chemical properties of Portland cement (manufactured by Domestic H Company) and meta kaolin used in the present invention, respectively.

Physical and chemical properties of meta-kaolin Physical properties Chemical compositions (unit:%) Specific Gravity (Gs) Surface Area
(cm < ² > / g) SiO ₂ Al ₂ O ₃ CaO MgO Na ₂ O Fe ₂ O ₃ 1.53 10,000 52.0 40.0 1.2 0.5 1.0 3.0

<2-2> Specification Mixing design and production

<2-2-1> Specification Mixing design

For the mixing design of volcanic ash-cement mixed soil, the weight ratio is set for each type in order to find the optimum mixing condition as shown in Table 10, and the mixed specimen is collected to obtain a specimen Respectively. In other words, the experiment was carried out on 16 types of volcanic ash (Mt. Paekdusan and Mt. Halla) considering the mixed ratio of volcanic ash (4 kinds) and meta - kaolin mixture (2 kinds).

Mixture composition of ash-cement mixture Material Case Material Cement Remark V.A One 3.5 One without and with metakaolin 2 4.0 One 3 4.5 One 4 5.0 One

<2-2-2> Specification making

To investigate the uniaxial compressive strength characteristics of ash - cement admixture, cylindrical specimens were prepared by injecting materials into ø50 × 100 mm molds and compaction. In order to investigate the bending strength characteristics of the mixed soil, block type specimens were prepared by injecting the material into a mold of 200 × 200 × 50 mm and compaction. In order to investigate the strength characteristics according to the ages of these specimens, curing was carried out for 3 days, 7 days and 28 days.

<2-3> Test method

<2-3-1> Uniaxial compressive strength exam

The uniaxial compressive strength was measured at a rate of 1 mm / min using a uniaxial compression tester in accordance with KS F 2314 (Unconfined Compression Test Method for Soil) at 3, 7, and 28 days of age at a specimen of φ50 × 100 mm Respectively.

Figs. 14 and 15 show the compressive strengths of the mixed soil according to the mixing ratios of Baekdusan volcanic ash and Halsa ash and meta-kaolin, respectively. As can be seen from this relationship, the compressive strength tends to be small as the mixing ratio of the volcanic ash of the volcanic ash-cement mixed soil increases (Figs. 14 (a) and 15 (a)). The compressive strength of mixed soils increased as the amount of volcanic ash increased as the mixing ratio of 4.0: 1, 4.5: 1, and 5.0: 1 at 28 days of mixing with Baekdusan volcanic ash and cement at 3.5: 1 0.78, 0.48, and 0.25 MPa, respectively. In addition, the strength of 28 days of mixing of Halla ash and cement at 3.5: 1 was 0.84 MPa. However, as the amount of volcanic ash increased, such as 4.0: 1, 4.5: Are 0.52, 0.47, and 0.21 MPa, respectively, showing the same tendency as that of Baekdusan volcanic ash. It is considered that the higher the mixing ratio of ash is, the more the volcanic ash does not react with the cement, but remains in the hardened body and hinders the hydration reaction of the cement. That is, in order to increase the strength of the cured product using only cement as a binder, it is difficult to incorporate a large amount of volcanic ash, and therefore, an additional binder is required. Lee (2006) investigated the effect of meta-kaolin on concrete strength by studying the engineering properties of concrete according to the substitution rate of meta-kaolin (10 ~ 30%). In this study, The effect of the addition of the corresponding metakaolin on the compressive strength was analyzed.

As a result, the compressive strength of the ash-cement mixed soil increased at all mixing ratios (Figs. 14 (b) and 15 (b) 17 ~ 48%, and 28 days strength of Halla ash - cement mixed soil was improved by 14 ~ 67%. It was confirmed that the strength of the ash mixed soil could be improved through the addition of additional binder.

16 and 17 show the normalized compressive strength (fc / f3 at 3 days of age) for each mixing ratio of Baekdusan and Mt. As shown in this relationship, as the age increases, the compressive strength of the ash - cement mixture tends to increase.

The normalized compressive strength (f7 / f3) was 1.06 ~ 1.52 at 7 days, and the normalized compressive strength (f28 / f3) was 1.47 ~ 2.23 at 28 days in Baekdusan volcanic ash - cement mixture. The addition of metakaolin, which is one tenth of the amount of cement, showed a normalized compressive strength of 1.12 ~ 1.45 at 7 days, and a normalized compressive strength of 1.30 ~ 1.78 at 28 days of age. On the other hand, normalized compressive strength (f7 / f3) was 1.10 ~ 1.28 at 7 days, and normalized compressive strength (f28 / f3) was 1.37 ~ 1.69 at 28 days in Hallyu volcanic ash - cement mixture. The addition of metakaolin, which is one tenth of the amount of cement, has a normalized compressive strength of 1.06 ~ 1.43 at 7 days and a normalized compressive strength of 1.33 ~ 1.72 at 28 days of age.

In the present invention, the compressive strength increases with the addition of meta kaolin, and the normalized compressive strength at 7 days of age is similar regardless of whether meta kaolin is added or not, while the normalized compressive strength at 28 days is similar to that of Baekdusan ash In the case of mixed soil, the addition of meta kaolin was slightly decreased, but that of Hwaseong volcanic ash was similar after adding meta kaolin. As a result, the intensity enhancement effect of metakaolin on the mixed soil using Baekdusan volcanic ash with GP granularity can be estimated to be somewhat less than that of the mixture using Hwasan volcanic ash with GW grain size. However, Is required.

<2-3-2> Bending Strength Test

The bending strength is 200 × 200 × 50 mm on the 3rd, 7th and 28th days of the year in accordance with KS F 2408 (Test method for the flexural strength of concrete) The load was measured at the speed.

Figs. 18 and 19 show the bending strengths of the mixed soil according to the mixing ratios of Baekdusan volcanic ash and Halsa ash and meta kaolin, respectively.

Bending strength ratio of compressive strength of Baekdusan volcanic ash Items

VA: Cement Days without metakaolin with metakaolin Flexural strength
(MPa) Comp.
strength
(MPa) Flex./
Comp. Flexural strength
(MPa) Comp.
strength
(MPa) Flex./
Comp. 3.5: 1 3 0.09 0.61 0.15 0.23 0.93 0.25 7 0.16 0.68 0.24 0.32 1.04 0.31 28 0.18 1.03 0.17 0.36 1.21 0.30 4.0: 1 3 0.05 0.35 0.14 0.10 0.58 0.17 7 0.11 0.53 0.21 0.15 0.65 0.23 28 0.11 0.78 0.14 0.19 1.03 0.18 4.5: 1 3 0.04 0.33 0.12 0.05 0.34 0.15 7 0.09 0.41 0.22 0.13 0.42 0.31 28 0.10 0.48 0.21 0.15 0.54 0.28 5.0: 1 3 0.01 0.16 0.06 0.04 0.21 0.19 7 0.07 0.16 0.44 0.06 0.31 0.19 28 0.10 0.25 0.40 0.11 0.37 0.30

The ratio of flexural strength to compressive strength of Halla ash Items

VA: Cement Days without metakaolin with metakaolin Flexural strength
(MPa) Comp.
strength
(MPa) Flex./
Comp. Flexural strength
(MPa) Comp.
strength
(MPa) Flex./
Comp. 3.5: 1 3 0.07 0.52 0.13 0.2 0.67 0.30 7 0.13 0.65 0.20 0.23 0.85 0.27 28 0.16 0.84 0.19 0.25 0.96 0.26 4.0: 1 3 0.04 0.38 0.11 0.07 0.51 0.14 7 0.08 0.42 0.19 0.10 0.57 0.18 28 0.09 0.52 0.17 0.13 0.68 0.19 4.5: 1 3 0.03 0.31 0.10 0.04 0.32 0.13 7 0.05 0.38 0.13 0.07 0.34 0.21 28 0.09 0.47 0.19 0.09 0.50 0.18 5.0: 1 3 0.01 0.13 0.08 0.03 0.20 0.15 7 0.02 0.16 0.13 0.04 0.29 0.14 28 0.04 0.21 0.19 0.04 0.35 0.11

As can be seen from this relationship, as the mixing ratio of the volcanic material of the ash-cement mixture soil increases, the bending strength tends to be small (Figs. 18 (a) and 19 (a)).

As the volcanic ash content increased, the compressive strengths of the mixed soils increased as the amount of volcanic ash was increased such as the mixing ratio of 4.0: 1, 4.5: 1, 5.0: 1, 0.11, 0.10, and 0.10 MPa, respectively. In addition, the strength of the mixture of Halla ash and cement at 3.5: 1 was 0.16 MPa at 28 days. However, as the amount of volcanic ash increased, such as 4.0: 1, 4.5: 0.09, 0.09 and 0.04 MPa, respectively, showing the same tendency as that of Baekdusan volcanic ash.

As with the compressive strength, the flexural strength is also decreased due to the decrease of hydration reaction of cement as the mixing ratio of ash is increased. Therefore, in order to increase the strength of the mixture, the effect of the addition of meta kaolin corresponding to 1/10 of the cement weight on the bending strength is analyzed. In this case, the bending strength of the ash- (Fig. 18 (b) and Fig. 19 (b)), the 28-day bending strength of the volcanic ash-cement mixed soil was 3.5: 1, 4.0: 1, 4.5 1.00 times, 1.00 times, 1.10 times, and 1.00 times, respectively, for Baekdusan ash and 1: 5.0: , And the increasing rate of flexural strength with mixing of meta - kaolin tended to decrease with increasing ash content.

From Table 11 and Table 12, it can be seen that the ratio of 28 day bending strength to 28 days compressive strength of volcanic ash - cement mixed soil is 14 ~ 40% and 18 ~ 30% Ash content was 17 ~ 19% and 11 ~ 26%.

<2-3-3> Scanning electron microscope observation of volcanic ash - cement mixture soil

To analyze the hydration characteristics of volcanic ash - cement admixture, samples were collected from specimens of 0 and 7 days old and the morphology and distribution of hydration products were compared using Scanning Electronic Microscope (SEM).

20 and 21 show SEM (S-4300 Hitachi) with respect to 0 day and 7 day old samples of volcanic ash mixed with volcanic ash: cement = 3.5: 1 mixed ratio analyzed with maximum compressive strength and flexural strength And the microstructure of the inside of the material measured at 2,000 times.

SEM analysis of the sample surface revealed that the hydration product, Ettringite, was formed by cement hydration at 7 days of age. In general concrete, a large amount of hydration product is formed due to a large amount of cement. On the other hand, a small amount of hydration product is formed due to hydration of the cement filled in the gap of the mixed soil, (Kellsen et al., 1996).

The hydration product produced by the cement not only increases the bond strength with the soil but also contributes to the strength enhancement, so that the increase in strength due to the increase in age is explained well in FIGS. 20 and 21.

<2-3-4> X-ray of volcanic ash - cement mixture diffraction Analytical observation

In order to analyze the hydration characteristics of volcanic ash-cement admixture, samples were taken from specimens of 0 and 7 days old and X-ray diffraction (XRD) was used to identify the constituents of hydration products.

To analyze the constituents of the volcanic ash-cement admixture, XRD analysis was performed on the samples subjected to the SEM analysis as shown in FIGS. 20 and 21.

FIG. 23 shows the results of XRD analysis after 7 days of age. The main components of Baekdusan and Hwangra mountain ash-cement mixed soil are calcium silicate compounds, and additional compounds are confirmed when meta kaolin is mixed. After 7 days, it was confirmed that Ettringite was formed in both Baekdusan and Hallyu volcanic ash - cement mixture soil, and this hydration product increased the bonding strength with soil and contributed to the increase in strength with increasing age

< Example 3> Purification Characteristics of Ash-Cement Mixed Soil Using Microorganisms

<3-1> Materials used

In the present invention, Baekdusan volcanic ash (Chinese import), Hallyu volcanic ash (collected in Hanrim-eup, Jeju), gravel for aggregate less than 40mm in maximum size, cement, meta kaolin were used as samples. 24 and Table 13 respectively show the particle size distribution curves and physical properties of the volcanic ash and gravel used in the present invention, and Table 14 shows the chemical characteristics of the volcanic ash.

Physical properties of Baekdusan volcanic ash, Halla ash, and aggregate gravel Type Specific
Gravity (Gs) Uniformity
Coefficient (Cu) Gradation
Coefficient (Cc) USCS Baekdusan 0.56 1.43 0.92 GP Hallasan 1.09 6.03 2.08 GW Gravel 2.65 3.65 0.96 GP

Chemical properties of ash Type SiO ₂ Al ₂ O ₃ CaCO ₃ MgO KCl Na K Fe Ca Ti Baekdusan 81.66 4.53 0.91 - 0.46 3.06 4.06 5.32 - - Hallasan 63.52 6.38 2.71 2.79 - 2.15 0.47 13.04 7.28 1.66

Passing amount of # 4 sieve (4.76mm) of Baekdusan and Halla ash is less than 50%. The uniformity coefficient (Cu) of Baekdusan ash is 1.43 and the curvature coefficient (Cc) is 0.92. In addition, the uniformity coefficient of Hallasan ash is 6.03 and the curvature coefficient is 2.08, and it is classified as GW by unified classification method. The aggregate gravel used as control was also less than 50% in # 4 sieve passage, and the uniformity and curvature coefficients were 3.65 and 0.96, respectively. In terms of chemical composition, the content of SiO2 was the largest in Baekdusan and Halsa ash, though the difference was somewhat different.

Tables 15 and 16 show the physical and chemical properties of Portland cement (manufactured by Domestic H Company) and metakaolin used in the present invention, respectively.

Physical properties Chemical compositions (unit:%) Specific Gravity (Gs) Surface Area (cm ² / g) SiO ₂ Al ₂ O ₃ CaO MgO Na ₂ O Fe ₂ O ₃ 1.53 10,000 52.0 40.0 1.2 0.5 1.0 3.0

<3-2> Specification Mixing design and production

<3-2-1> Specification Mixing design

For the mixing design of volcanic ash-cement mixed soil, various weight ratios were set and mixed in order to find the optimal mixing conditions as shown in Table 17 with reference to the study of Onoue (2012), and a certain amount of mixed samples were collected to form specimens . In other words, the experiment was carried out on 16 types of volcanic ash (Mt. Paekdusan and Mt. Halla) considering the mixed ratio of volcanic ash (4 kinds) and meta - kaolin mixture (2 kinds).

Material Case Material Cement Remark V.A One 3.5 One without and with metakaolin 2 4.0 One 3 4.5 One 4 5.0 One

<3-2-2> Specification making

In order to investigate the bending strength characteristics of the ash - cement mixed soil block, a block type specimen was prepared by loading the material into a 20 × 20 × 5 cm mold and compaction. In order to investigate the strength characteristics according to the ages of these specimens, curing was carried out for 3 days, 7 days and 28 days. 25 shows a production view of an ash-cement mixed soil block. Fig. 26 shows a cage-type volcanic block without a binder. The cage type volcanic block was constructed with the same volume (V = 2,000 cm ³ ) as the ash-cement mixture block.

<3-3> Characteristics of volcanic ash - cement mixture

<3-3-1> Ash - cement Mixed soil Block Warp sensitivity Characteristic study

The bending strength was 20 × 20 × 5 cm at 3 days, 7 days, and 28 days of age in accordance with KS F 2408 (Test Method for Bending Strength of Concrete) The load was measured at the speed.

27 and 28 show the bending strengths according to the ages of the mixed soil depending on the mixing ratio of Baekdusan volcanic ash and Halla ash and meta kaolin, respectively.

As can be seen from this relationship, the bending strength tends to decrease as the mixing ratio of the volcanic ash of the volcanic ash-cement mixture soil increases (Figs. 27 (a) and 28 (a)). The bending strength of mixed soil was 0.11 MPa as the amount of volcanic ash increased as the mixing ratio was 4.0: 1, 4.5: 1, 5.0: 1, while the 28 day bending strength was 0.18 MPa when the Baekdusan volcanic ash and cement were mixed at 3.5: , 0.10 and 0.10 MPa, respectively. Also, the bending strength of mixed soil was increased as the amount of volcanic ash increased as the mixing ratio of 4.0: 1, 4.5: 1, 5.0: 1, 0.09, 0.09 and 0.04 MPa, respectively, showing the same tendency as that of Baekdusan volcanic ash. This is because the hydration reaction of cement decreases as the mixing ratio of ash increases.

Therefore, in order to increase the strength of the mixture, the effect of the addition of meta kaolin corresponding to 1/10 of the cement weight on the bending strength is analyzed. In this case, the bending strength of the ash- (Fig. 27 (b) and Fig. 28 (b)), the 28-day bending strength of the volcanic ash-cement mixed soil was 3.5: 1, 4.0: 1, 4.5 1.00 times, 1.00 times, 1.10 times, and 1.00 times, respectively, for Baekdusan ash and 1: 5.0: , And the increasing rate of flexural strength with mixing of meta - kaolin tended to decrease with increasing ash content.

Based on these experimental results, in the present invention, the combination of volcanic ash and cement at a ratio of 3.5: 1 and meta kaolin corresponding to 1/10 of the weight of cement is additionally mixed at an optimum mixing ratio, - It was applied to the production of cement mixed soil block. The mixing ratio was also applied to the preparation of the gravel - cement mixed soil block as a control.

<3-3-2> Water quality analysis

In order to analyze the water purification effect of the microbial block, SS, BOD, CODMn, and TN were sampled at 0, 7, and 28 days after soaking. TP, and pH were analyzed according to the water pollution process test method. FIG. 27 (a) shows an application of effective microorganism (EM) application (using 500-fold dilution water) to the block, and FIG. 27 (b) shows a soaking process of the block in the contaminated water. In this experiment, the amount of polluted water was set at 48L.

Water quality analysis scale and method Parameter Method Suspended solids (SS) Filtration, Gravimetric method,
Electric dry oven (103-105) Biochemical Oxygen Demand (BOD) Azide modification of Winkler method Chemical Oxygen Demand (COD _Mn ) Photometric method Total Nitrogen (T-N) Ultraviolet Spectrophotometric method Total Phosphorus (T-P) Ultraviolet Spectrophotometric method Hydrogen ion concentration (pH) Portable pH meter

Figs. 30 and 31 show the concentration changes when the cement mixed soil block and the cage-type block to which the useful microorganisms are applied are soaked in the contaminated water.

The concentration of initial influent in each treatment was measured as SS 3.5 mg / L, BOD 1.0 mg / L, COD 3.2 mg / L, T-N 7.91 mg / L, T-P 0.37 mg / L and pH 7.9. After 0, 7, and 28 days, the concentration range was 0.3 to 6.7 mg / L for SS, 0.3 to 6.1 mg / L for BOD, 3.2 to 21.8 mg / L for COD and 3.94 L of BOD, 1.0 ~ 4.8mg / L of BOD, pH of 7.9 ~ 11.5, and pH of 7.9 ~ 11.5, respectively. , The pH was changed from 7.0 to 8.5, and the concentration of CO was 3.2 to 9.8 mg / L, TN: 5.48 to 7.91 mg / L, TP: 0.07 to 0.37 mg /

SS (Suspended solid) suspended in water was insoluble in water. Concentration at 28 days showed 91% and 37% removal efficiency in Baekdusan volcanic ash-cement mixed soil block and Hallyu volcanic ash-cement mixture soil block respectively And the removal effect was not observed in the gravel - cement mixed soil block. In the cage type block, Baekdusan volcanic block and Hallyu volcanic block showed removal efficiencies of 94% and 77%, respectively, but the removal effect was not observed in the gravel block.

BOD, which is a biochemical oxygen demand, and COD, which is a chemical oxygen demand, increased during 7 days as a whole in the cement mixed soil block and cage type block, but decreased after 28 days, but no significant removal effect was observed.

Total nitrogen (TN) decreased to 4.88 mg / L and 4.80 mg / L in Baekdusan volcanic ash - cement mixture block and Hallyu volcanic ash - cement mixture block after 28 days, respectively. And decreased to 3.94 mg / L in gravel - cement mixed soil block. Also, in the cage type blocks, the removal efficiency was confirmed to be 6.40 mg / L and 5.90 mg / L in the Baekdusan volcanic block and the Hallasan volcanic block, respectively, and the gravel block was reduced to 5.48 mg / L.

In the case of T-P, the removal efficiency was 92% in Baekdusan volcanic ash-cement mixture block and Hallyu volcanic ash-cement mixture block, and 81% in gravel-cement mixture block. Also, in the cage type blocks, Baekdusan volcanic block and Hallyu volcanic block showed high removal efficiency of 78% and 68%, respectively, and 81% efficiency in the gravel block showed similar removal efficiency as the ash block.

Hydrogen ion concentration (pH) increased in the volcanic ash - cement block and gravel - cement block after 7 days, but decreased until 28 days after the volatilization - cement block and gravel - cement block. . Therefore, it is considered that the cement used as a binder of the cement mixed soil block is a factor for increasing the pH.

As a result, the removal efficiency of total nitrogen (TN) and total phosphorus (TP) was found to be excellent in the cement mixed soil block and the cage type block. In the case of using the gravel as the medium, The removal efficiency of suspended solids (SS) due to adsorption was superior. In addition, since the volcanic ash-cement mixed soil block using cement as a binder may cause an increase in pH, it is preferable to apply a cage-type block as a water quality purification block to a portion that is not significantly affected by pH, .

As a result of this study, it is necessary to further verify the performance of the water purification block using ash by deepening the research such as field test.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

V.A .: Baekdusan ash

Claims

Cement, volcanic ash and meta kaolin are mixed to improve the compressive strength or bending strength.

The method according to claim 1,
Wherein said volcanic ash has a GP or GW particle size.

The method according to claim 1,
Wherein the volcanic ash comprises 3 to 5 parts by weight of the cement based on 1 part by weight of the cement, and the meta kaolin comprises 0.01 to 0.5 parts by weight of the cement based on 1 part by weight of the cement.

The method according to claim 1,
Characterized in that the increase in compressive strength or flexural strength is due to the formation of ethene zeit.

The method according to claim 1,
Wherein the mixed soil further comprises a useful microorganism.

A composition for purification of water quality comprising the mixture of any one of claims 1 to 6.