Influence of expanded polystyrene size on deformation characteristics of light weight soil

Abstract

Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests. The results show that the confined stress-strain relation curve is in S shape, which has a good homologous relation with e-p curve and e-lgp curve, and three types of curves reflect obvious structural characteristics of light weight soil. When cement mixed ratio and EPS volume ratio are the same for different specimens, structural strength decreases with the increase of EPS size, but compressibility indexes basically keep unchanged within the structural strength. The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement. It has no obvious rheology property, and 90% of total consolidation deformation can be finished in 1 min. Settlement-time relation of light weight soil can be predicted by the hyperbolic model. S-lgt curve of light weight soil is not in anti-S shape. It is proved that there is no secondary consolidation section, so consolidation coefficient cannot be obtained by time logarithm method. Structural strength and unit price decrease with the increase of EPS size, but the reducing rate of the structural strength is lower than that of the unit price, so the cost of mixed soil can be reduced by increasing the EPS size. The EPS beads with 3–5 mm in diameter are suggested to be used in the construction process, and the prescription of mixed soil can be optimized.

Keywords

light weight soil / expanded polystyrene (EPS) / size effect / one-dimensional consolidation theory / compressibility index / structural strength / consolidation test

References

[1] YamadaS., NagasakaY., NishidaN.. Light soil mixture with small pieces of expanded polystyrol and sand [J]. Soil Mechanics and Foundation Engineering, 1989, 37(2): 25-30

[2] YAJIMA J, MARUO S, OGAWA S. Deformation and strength properties of foam composite light-weight soil [J]. Doboku Gakkai Rombun Hokokushu, 1994, (499): 197–205.

[3] OtaniJ., MukunokiT., KikuchiY.. Visualization for engineering property of in-situ light weight soils with air foams [J]. Soils and Foundations, 2002, 42(3): 93-105

[4] OhS. W., LeeJ., KwonY. C., LeeB. J.. Bearing capacity of light weight soil using recycled styrofoam beads [C]. Proceedings of the International Offshore and Polar Engineering Conference, 2002KitakyushuInternational Society of Offshore and Polar Engineers670-674

[5] YajimaJ., MydinS. H.. Mechanical properties of the unsaturated foam composite light-weight soil [C]. 4th International Conference on Unsaturated Soils, 2006United statesAmerican Society of Civil Engineers1639-1650

[6] KikuchiY., NagatomeT., FukumotoH., HigashijimaM.. Absorption property evaluation of light weight soil with air foam under wet sand condition [J]. Zairyo/Journal of the Society of Materials Science, Japan, 2008, 57(1): 56-59

[7] MaS.-dong.. The properties of stabilized light soil (SLS) with expanded polystyrene [J]. Rock and Soil Mechanics, 2001, 22(3): 245-248

[8] GuH.-d., GuX., ShenY., XiaoFeng.. The fundamental properties of light soil mixed with foamed beads [J]. Journal of University of Science and Technology of Suzhou, 2003, 16(4): 44-48

[9] LiuH.-l., DongJ.-m., ZhouY.-d., GaoY.-feng.. Study on the stress-strain characteristics of light heterogeneous soil mixed with expanded polystyrene [J]. Chinese Journal of Geotechnical Engineering, 2004, 26(5): 579-583

[10] ZhuW., JiF.-l., LiM.-d., MaD.-g., TangJun.. Relationships among density, strength and materials of lightweight treated soil [J]. Rock and Soil Mechanics, 2007, 28(7): 1411-1414

[11] HouT.-s., XuG.-li.. Experiment on triaxial pore water pressure-stress-strain characteristics of foamed particle light weight soil [J]. China Journal of Highway and Transport, 2009, 22(6): 10-17

[12] MiledK., LeR. R., SabK., BoulayC.. Compressive behavior of an idealized EPS lightweight concrete: Size effects and failure model [J]. Mechanics of Materials, 2004, 36(11): 1031-1046

[13] LeR. R., ParantE., BoulayC.. Taking into account the inclusions’ size in lightweight concrete compressive strength prediction [J]. Cement and Concrete Research, 2005, 35(4): 770-775

[14] MiledK., SabK., LeR. R.. Particle size effect on EPS lightweight concrete compressive strength: Experimental investigation and modeling [J]. Mechanics of Materials, 2007, 39(3): 222-240

[15] Ministry of Water Resources of People’s Republic of China. GB/T50123-1999, Standard for Soil Test Method [S]. (in Chinese)

[16] CourF. R.. Inflection point method for computing Cv [J]. Journal of the Soil Mechanics and Foundations Division, ASCE, 1971, 97(5): 827-831

[17] ScottR. F.. New method of consolidation coefficient evaluation [J]. Journal of the Soil Mechanics and Foundation Division, ASCE, 1961, 87(1): 29-39

[18] SivaramB.. A computation method for consolidation coefficient [J]. Soils and Foundations, 1977, 17(2): 48-52

[19] PrasadY. V. S. N., RaoS. N.. New two point method of obtaining Cv from a consolidation test [J]. Canadian Geotechnical Journal, 1995, 32(4): 741-746