Strength characteristics of modified polypropylene fiber and cement-reinforced loess

Abstract

The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials. To study the strength characteristics of loess soil reinforced by modified polypropylene (MPP) fiber and cement, samples were prepared with six different fiber contents, three different cement contents, three different curing periods and three kinds of fiber length. The samples were tested under submergence and non-submergence conditions for the unconfined compressive strength (UCS), the splitting tensile strength and the compressive resilient modulus. The results indicated that combined reinforcement by PP fiber and cement could significantly improve the early strength of loess to 3.65–5.99 MPa in three days. With an increase in cement content, the specimens exhibited brittle fracture. However, the addition of fibers gradually modified the mode of fracture from brittle to ductile to plastic. The optimal dosage of fiber to reinforce loess was in the range of 0.3%–0.45% and the optimum fiber length was 12 mm, for which the unconfined compressive strength and tensile strength reached their maxima. Based on the analysis of failure properties, cement-reinforced loess specimens were susceptible to brittle damage under pressure, and the effect of modified polypropylene fiber as the connecting “bridge” could help the specimens achieve a satisfactory level of ductility when under pressure.

Keywords

fiber-reinforced soil / cement-stabilized soil / loess / mechanical properties / fracture characteristics

References

[1] YanX, WengX, KouY. Influence of fiber grid on interlayer bond property of airport double-layer pavement [J]. Journal of Reinforced Plastics and Composites, 2013

[2] TangC-s, ShiB, GaoW, LiuJin. Single fiber pull-out test and the determination of critical fiber reinforcement length for fiber reinforced soil [J]. Rock and Soil Mechanics, 2009, 30(8): 2225-2230

[3] HuH J, JiangM J, ZhaoT, PengJ B, HongL. Effects of specimen-preparing methods on tensile strength of remolded loess [J]. Rock and Soil Mechanics, 2009, 30: 196-199

[4] FonsecaA, VD. Voids/cement ratio controlling tensile strength of cement-treated soils [J]. Journal of Geotechnical and Geoenvironmental Engineering, 2011, 137(11): 1126-1131

[5] RanL Z, SongX D, TangC S. Laboratorial investigation on tensile strength of expansive soil during drying [J]. Journal of Engineering Geology, 2011, 19(4): 620-625

[6] PléO, LêT N H. Effect of polypropylene fiber-reinforcement on the mechanical behaviour of silty clay [J]. Geotextiles and Geomembranes, 2012, 32: 111-116

[7] LiuB-s, TangC-s, LiJ, WangD-y, ZhuK, TangWei. Advances in engineering properties of fiber reinforced soil [J]. Journal of Engineering Geology, 2013, 21(4): 540-547

[8] AhmadF, BateniF, AzmiM. Performance evaluation of silty sand reinforced with fibres [J]. Geotextiles and Geomembranes, 2010, 28(1): 93-99

[9] IbraimE, DiambraA, RussellA R, WoodD M. Assessment of laboratory sample preparation for fibre reinforced sands [J]. Geotextiles and Geomembranes, 2012, 34: 69-79

[10] LiJ, TangC, WangD. Effect of discrete fibre reinforcement on soil tensile strength [J]. Journal of Rock Mechanics and Geotechnical Engineering, 2014, 6(2): 133-137

[11] MaheshwariK V, DesaiA K, SolankiC H. Performance of fiber reinforced clayey soil [J]. Electronic Journal of Geotechnical Engineering, 2011, 16: 1067-1082

[12] YangY, ChengS, GuJ, HuX H. Triaxial tests research on strength properties of the polypropylene fiber reinforced soil [C]. Multimedia Technology (ICMT), 2011 International Conference on. IEEE, 20111869-1872

[13] TangC, ShiB, GaoW, ChenF, CaiY. Strength and mechanical behavior of short polypropylene fiber reinforced and cement stabilized clayey soil [J]. Geotextiles and Geomembranes, 2007, 25(3): 194-202

[14] CaiY, ShiB, GaoW, ChenF J, TangC S. Experimental study on engineering properties of fibre-lime treated soils [J]. Chinese Journal of Geotechnical Engineering, 2006, 28(10): 1283-1287

[15] GuanY-huaStability of attenuated strength subgrade and mechanics response of its pavement structure [D], 201199-101

[16] ShiL-g, ZhangM-x, CaoPeng. Triaxial shear strength characteristics of lime-soil reinforced with polypropylene fiber inclusions [J]. Rock and Soil Mechanics, 2011, 32(9): 2721-2728

[17] WangD-y, TangC-s, LiJian. Shear strength characteristics of fiber-reinforced unsaturated cohesive soils [J]. Chinese Journal of Geotechnical Engineering, 2013, 35(10): 1933-1940

[18] WelkerA L, JostenN. Interface friction of a geomembrane with a fiber reinforced soil [C]. Slopes and Retaining Structures Under Seismic and Static Conditions. ASCE, 20051-8

[19] AkbulutS, ArasanS, KalkanE. Modification of clay soils using scrap tire rubber and synthetic fibers [J]. Applied Clay Science, 2007, 38(1): 23-32

[20] MohamedA, EM K. Improvement of swelling clay properties using hay fibers [J]. Construction and Building Materials, 2013, 38: 242-247

[21] PrabakarJ, SridharR S. Effect of random inclusion of sisal fibre on strength behaviour of soil [J]. Construction and Building Materials, 2002, 16(2): 123-131

[22] TangC S, ShiB, ZhaoL Z. Interfacial shear strength of fiber reinforced soil [J]. Geotextiles and Geomembranes, 2010, 28(1): 54-62

[23] ZhangP, LiQ, ZhangH. Combined effect of polypropylene fiber and silica fume on mechanical properties of concrete composite containing fly ash [J]. Journal of Reinforced Plastics and Composites, 2011

[24] YanL, DuchezA, ChouwN. Effect of bond on compressive behaviour of flax fibre reinforced polymer tube–confined coir fibre reinforced concrete [J]. Journal of Reinforced Plastics and Composites, 2013, 32(4): 273-285