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E VALUATION APPLICABILITY OF USING NEUTRAL SOIL STABILIZER OF PLASTER AS SOIL IMPROVEMENT MATERIALS. Nagasaki University. R.Suzuki H.Sakanoshita Y.Tanabashi Y.Jiang S.sugimoto. Waste plaster board. Back ground of research. ・ Price is low ・ Excel in sound insulation and adiabaticity.
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EVALUATION APPLICABILITY OF USING NEUTRAL SOIL STABILIZER OF PLASTER AS SOIL IMPROVEMENT MATERIALS Nagasaki University R.Suzuki H.Sakanoshita Y.Tanabashi Y.Jiang S.sugimoto
Waste plaster board Back ground of research ・Price is low ・Excel in sound insulation and adiabaticity Plaster board It is used extensively Scrapped construction
・ Increase of disposal cost ・Heavy metal and the hydrogen sulfide are detected Back ground of research Waste plaster board ・Emission increase 1.38million ton(2005) 1.76million ton(2010) The resource recycling of them is an urgent problem
Purpose of research Recycle plaster Waste plaster board Disposed to harmless Soil mixture Pavement and filling material Mechanical property Chemical property Evaluation of usability
heat CaSO4・1/2H2O+3/2H2O CaSO4・2H2O water calcification Environmentally thoughtful solidification material Baseline characteristic of plaster Chemical equation of plaster Cement Alkaline Recycle plaster Neutral
Experimental overview Several soil Recycle plaster Target strength② 300kPa (banking material) mix・chum product under test (φ=5cm、H=10cm) Target strength① 50kPa (conveyance) Cure (constant-temperature zone) (temperature25℃、humidity90%) uniaxial compression test
28th day case CC(cement) 300(kPa) 7th day 50(kPa) Strength growth Solidification material function PC(cohesive soil) Compressive strength(KPa) 60 additive amount(kg/m3) Additive amount increase
Case CS(cement) 28th day 7th day 300(kPa) Additive amount increase PS(sandy soil) Compressive strength(KPa) 60 additive amount(kg/m3) Strength make no difference
28th day 50(kPa) 7th day Strength is low PA(Ariake cray) Compressive strength(KPa) additive amount(kg/m3) Additive amount is low
28th day case CA(cement) 7th day Strength growth PA (Ariake cray) Compressive strength(KPa) additive amount(kg/m3) The gap between cement and plaster is wide. ・Additive amount increase ・Moisture content down
large small Moisture content have a large effect Moisture content of PA ・170% ・120% ・80% Alteration of unconfined compression strength Results of the uniaxial compression test ・PC(cohesive soil) : solidification material ・PA(Ariake cray) : solidification material
50(kPa) Strength growth Reduced moisture content Moisture content is 80% Reached the 50(kPa) Relation moisture and compression strength 300(kg/m3) • 7th day Compressive strength(KPa) 200(kg/m3) 100(kg/m3) Moisture content(%)
300(kPa) 50(kPa) Long cure Several cases reached 300kPa Relation moisture and compression strength 300(kg/m3) (b) 28th day Compressive strength(KPa) 200(kg/m3) 100(kg/m3) Moisture content(%)
Heavy metals leaching test In all sample and mixture sample, no heavy metals exceeded the reference value. (unit:mg/l、N.D.: Non-Detected)
PS(sandy soil) ・Additive amount of plaster have a small effect ・Plaster (60 kg/㎥ and 100 kg/㎥) on the 28th day is as strong as cement on the 7th day PA(Ariake cray) ・Moisture content have a small effect ・Moisture content has a very large effect ① Mechanical property Conclusions PC(cohesive soil) ・ Solidification material function ・Strength increases as material age length
Conclusions Affirmation of chemical stability The mechanical and chemical properties Solidification material is available by additive amount of recycle plaster and moisture content of soil ② Chemical property No heavy metals exceeded the referencevalue.