Marine Clay

Marine clay is a type of clay found in coastal regions around the world. In the northern, deglaciated regions, it can sometimes be quick clay, which is notorious for being involved in landslides.
Clay particles can self-assemble into various configurations, each with totally different properties. When clay is deposited in the ocean, the presence of excess ions in seawater causes a loose, open structure of the clay particles to form, a process known as flocculation. Once stranded and dried by ancient changing ocean levels, this open framework means that such clay is open to water infiltration. Construction in marine clays thus presents a geotechnical engineering challenge.

Introduction

The Singaporean Marine Clay (SGMC) produces high viscous gelation in response to the cement milk, which is injected into the ground. The workability greatly decreases due to this high viscous gel. S-Chem is a dispersant, which reduces the viscosity of SGMC, and ensures the quantity of sludge.

Component and Physical Property

S-Chem
Appearance	Light Yellow Liquid
pH	6-8
DensityDensity(g/cm3)	≧1.2
Storage time	６ months (container)
HAZARDOUS MATERIAL CLASSIFICATION	N/A

Characteristics

・Greatly improves the fluidity
・Distribute cement equally and improves the quality of the improved body
・Reduce the amount of slurry generated, and cut down on disposal expenses
・Maintain high ﬂuidity, to ensure better workability without affecting strength.

NEXCO 313 Test

without

with (Dosage:16kg/m3 )

Application

Soil Improvement	・SOIL-CEMENT COLUMN-ROWWALL ・CONSTRUCTION METHOD ・Machine stirring construction method
RECYCLING CONSTRUCTION＊・Backfilling GENERATED SOIL	・Backfilling ・LUIDIZATION TREATED SOIL
Others	・Enhance the fluidity of soil cement

＊By providing the fluidity of the slurry discarded from the construction, it allows you to re-use in the following areas.
・Sield Tunnel(Invert)
・Underground pipe Backfilling
・Dredging
・Filling Cavity
・Others

Recommended Dosgae

・Standard dosage of S-Chem as follow:

S-Chem	1.0 ～ 5.0 % (＊Tests required to determine the most suitable dosage.)

・ Add and mix S-Chem into the water

Results

Experiment Details

MATERIALS

Cement：Portland blast-furnace cement class C Density3.00g/ cm3

＜soil sample：＞

Wet density ρtg/cm3	1.668	Particle size	Gravel(2～75mm)	0.7
Water content Wn %	56.6		Sand(0.075～2mm)	21.5
Liquid limit WL %	75.0		Silt (0.005～0.075mm)	18.7
Plastic limit Wp %	24.8		Clay(less than 0.005mm)	59.1
Plasticity Index Ip	50.2	Maximum grain size mm		4.75

CONDITION

Target Viscosity = 5,000mPa・s or below (30min)
Target Strength = 1,000kN/m or more(28Days)

Dosage /Cement milk 1m3

W/C	S-Chem(kg)	Supporting Agent(kg)	Total(kg)
1.0	9	10	19
1.5	7.5	10	17.5
2.0	6	10	16

＊The effect of the dispersant depends on the application method of construction, Please determine the most suitable dosage through tests, taking the soil conditions and construction conditions into consideration.

Viscosity and Compressive Strength

W/C	Viscosity(mPa.s)			Compressive Strength (kN)
W/C	0min	30min	60min	7day	28day
1.0	107.3	122.7	282	7.899	9.613
1.5	95.3	105.3	218	5.571	8.097
2.0	78.7	84	140	4.563	8.521

* Curing temperature 30℃

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