STST CO.,LTD

Scientific Approachesto the Soil Enviroment

“ Benefical to man & Enviroment ‘

Inorgabic soil amendment agent Solidifies with powerful compactingAction, yet is friendly to the environmentAnd natural resourdes.

(ECO-CURE²¹=STST)

Solidifies everything fromSoft soil to sludge ECO-CURE²¹Inorganic soil amendment agent. In recent years, civil engineering structures haveIncreasingly been built on soft ground and other poorSubsoil, traditionally consudered incapable ofwithstanding such use, as well as in reclaimed land.A wide variety of methods are employed in such casesto increase the bearing capacity of the ground.Depending on the purpose and the soil in question,There methods include compaction, consolidation bySolidifying agents and replacement with better soils,In addition to accelerated consolidation settlementAnd dewatering. The STST soil amendmentProcess, utilizing an inorganic amendment agent,Overcomes the drawbacks of the soil-cement method,Whereby the setting capacity of cement is used toSolidify the ground and improve its bearing capacity.The STST process is a superior soilAmendment technique that offers outstandingadvantages not seen with other methods.

SEM photo of soildified mixture

Slope stabilization of golf course pond

STST Chemical Composition and Solidification Principle

STST is an inorganic agent added to cement or lime in the soil-cement process or in the lime stabilization process. As indicated in the table below,It is mainly composed of inorganic metal salts( sodium chloride, potassium chloride,

Magnesium chloride, calcium chloride,Sodium sulfate, etc ) and citric acid. It is used in a water solution together with cement or lime.

Component % Component %

Sodium chloride 20 Ferric chloride 2

Potassium chloride 31 Sodium sulfate 3

Magnesium chloride 20 Citric acid 3

Calcium chloride 15 Others 6

Soil Particle (-)

Soil Particle (-)

Cement mixtureHumic acid (R.COOH)

(+)

(+)

Humus (humic acid) adhering to theSurface of soil particles inhibits contact between the calcium cationsof the cement and the anions of theSoil particles.

Laboratory Testing

We will conduct soil and laboratory tests on soil sample received from interested parties and prepare a mix design for a fee

Collection of soil sample(approx. 20kg) at the site

Soil sample

Cement or lime + STSTInorganic soil amendment agent

Laboratory tests

Mixing of soil sample and STST

Laboratory tests are conducted in accordance with criteriaSpecified by your country’s national standards. The optimumMix design is then determined on the basic of the results toMeet the strength requirement and other specification of theIntended application.

Solidification Principle

S T S T

The soil is mixed with cement or lime

The action of the STST components neutralizes the negative effect of humus (humic acid).

The electric charge that inhibited the penetration ofcalcium cations is weakened, allowing the cementSolution components to penetrate among the soilParticles.

Hydration, coagulation and stable solidification

The hydrates produced in the hydration reaction withThe cement form needle-like crystals that grow andConnect the soil particles

The resulting solidified soil has an adsorption property like that of activated carbon or zeolite clay and a deodorizing dffect. It also displays improved air and water permeability.Because its specific surface area is dramatically increased, it can adsorb heavy metal ions. In addition, during the growth process of the needle-like crystals, heavy metal ions are captured in its structure, preventing them from leaching out later.

Many outstanding Features

STST effectively transforms soils previously considered unsuitable for roadbed material into stable, solid ground. This includes silts and clays and soils containing large amounts of organic elements. What is more, the improved soil is eminently suitable for vegetation.• When the STST process is applied to doft subsoils like loam or cohesive soils, the extraordinary penetration ability of the ECO-CURE²¹ agent takes the cement hydrates to the deepest soil particle layers. This results in firm setting and solidification to a uniform strength. In addition, the solidified soil is capable of withstanding vastly larger repetitive loading compared with that formed with conventional methods, and it also displays exceptional stability over time.• The solidified soil, formed with a smaller quantity of cement (less than 200 kg/m³) has continuous porous structure, giving it superior water permeability and elasticity.• Because the treated soil is used, there is no need to replace soil or haul in aggregate.• Water-soluble ECO-CURE²¹ takes well to the soil, permeation and solidifying it firmly to reduce the likelihood of stripping. The mix ratio can also beadjusted to match the nature of the soil, eliminating any wastage.

Because STST hardens over time, it provides improved soil that is subject to less weathering and has long-term stability. It also hardens in water, as it is not eroded by acids or alkalis.• STST protects the natural environment because it is composed mainly of pollition-free inorganic elements. It also hardens without changing the natural color of soils.• Compared with the conventional soil-cement method, compressive, bending and tensile strength properties are approximately 30% greater.• It provides outstanding economy, including significantly shorter process and construction periods owing to its shorter curing time.• STST is transported and stored in a condensed power form, making it easy to handle and reducing overhead. (It is applied in a water solution at the site.)• STST can also be used in the remediation of contaminated sites because it renders pollutants in the soil insoluble• Soil particles are connected by needle-like crystals to from microporous soil that has an adsorption capability like that of activated carbon and provides powerful deodorizing action

Comparison of Uniaxial Compressive Strength

0.8

1.0

1.5

2.0

2.5

3.0

3.5

73 1

Age(days)

Uniaxial compressive strength (kgf/Cm²)

Cement + STST

Ordinary Cement

Solidification test of pond sludge•Test material : pond sludge•Water content L 249%•Moisture density : 1.196g/cm³•lgnition loss : 30.2%•Additive quantity : 150kg/cm³

STST Types and Application

Solidification of soft soilYokohama, japan : Nishida landAdjustment project ; roadbed improvementShonan kokusai village, japan :Slops stabilization and solidification of softGround for road constructionThe Netherlands : Construction ofInternational airport runwaysColimbia : marshland road constructionIndonesia : Industrial road construction in laterite soilHazardous material remediaton, pre-vention of leaching and foul odor controlPusan, korea : Construction of EulsukdoLandfillOkayma, japan : Remediation ofHazardous industrial wasteHokkaido, japan : Remediation ofdewatered sludge from a mineVarious manufacturing companies :Remediation of former plant sites to preventLeaching of hazardous waste ; soil amendmentSludge solidification and production of culture soilOkayama, japan : Solidification ofWastewater sludge for use in greening ofFormer salt fieldsIbaraki, japan : Solidification of sludgedredged from Lake Kanuma for use increating vegetable fieldsMiyagi, japan : Remediation of coppermine slime for use in creating seedling soilTochigi, japan : Slope stabilization andGreening of former Ashio copper mine siteElecric Power Development co. :Solidification of fly ash from coal-firedPower plants to produce culture soilWaste recyclingTaiwan : Manufacture of breakwaterBlocks from ocean sandElectric Power Development Co. :Manufacture of adsorbents and culture soilFrom fly ashShimane, japan : Remediation of sludgeFrom canals ; use of residual excavated soilTo build park

Examples of STST Projects

Application Specific examples

Application utilizing its enhanced water permeability • Amendment of swamp land• Solidification of roads subject to washing away or damage by floods• Stabilization of artificial slopes• Surface solidification of extremely soft soils• Amendment of soft subsoils of roadbeds Application utilizing its enhanced elasticity• Amendment of ordinary roads, airport runways and subgrades.• Simple paving of walking paths and order trails• Soil amendment for tennis courts, cycling tracks and golf course roads• Soil amendment for sports facilities• Amendment of rural or mountain roads Applications for foundation work• Erosion control and sea wall foundations• Stabilization of raised foundations• Raft foundations for structures• Foundations of civil engineering structures• Foundations of steel towers, utility poles and pipes• Prevention of soil liquefaction during earth- quakes Applications for improving farm land• Soil amendment of fields and paddies; prevention of damage due repeated cultivation of same crop• Remediation and greening of poor soil

General soft soilamendment

21

Formation ofnonpermeable layer

31 • Irrigation channels and reservoirs• Ponds at golf dourses

High-strengthSolidification

Manufacture ofSecondary productsFrom cement blockAnd brick waste

Construction offinal disposal sitesfor industrial waste

41

• Recycling of wastewater sludge and incinerator ashes

• Recycling of ashes from ordinary municipal garbage incinerators ( aggregate, etc. )• Solidification of sludge from semiconductor production process

• Recycling of wastewater sludge and incinerator ashes ( artificial reefs, etc.)

Dry

High-strengthSolidification ona par withCement concrete

Solidification ofdredged sludgeQuick solidificationof soft soil

• Canal improvement• Solidification of dredged sludge

“Flow Chart of STST Soft soil amendment Process”

Soil test

A soil test is conductedaccording to yourcountry’s nationalstandards.

Mix design

The mix is designed on the basis of the test results

Site preparation

The site is excavated to the design level.

Spreading of cement

Cement is spread over the site according to the mix design using a small bulldozer or the like

Mixing of cement

The cement is mixed into the soil using a tractor, stabilizer, backhoe or other similar implement.

Spreading of STST

STST powder is dissolved in water and spread on the site.

Flow Chart of STST Soft soil amendment Process

Mixing

Mixing is done again using a tractor, stabilizer, backhoe or other implement.

Provisional compaction

The site lightly compacted using a tire roller, Macadam roller or other implement.

Leveling

The site is leveled to the design level by a grader, bulldozer or other implement.

Final compactionThe site is compacted several times by tire roller, Macadam roller or other implement.

Inspection

The strength of the soil is tested by conducting a plate bearing test according to the CBR (California bearing ratio) test procedure.

STST CO.,LTD