Experimental Study On Fiber Reinforced Red Clay

Clay is widely used in hydraulic and environmental engineering as the natural impervious material. Low strength, low adaptability to nonuniform and dessication cracks are well known adverse properties for saturated clay. The reinforcement of polypropylene fiber was used to improve mechanical properties of red clay at controlled low permeability. The parameters like varied content and length of fiber were comprehensive and systematically investigated to mechanical properties of clay, the following main research contents were in the thesis:(1) Preparation technology of fiber reinforced red clay is introduced. The slurry was prepared by mixer (water content closeness to liquid limit), added proper amount of fiber with simultaneous stirring, stopped at fixed amount and uniformly mixed with fiber after stirring fully. The prepared sample was consolidated in the vacuum consolidometer.(2) Standard Proctor compaction characteristics of fiber reinforced red clay are studied. The results of different content of fiber in red clay showed that fiber had smaller effect on the maximum dry density, whereas greatly influenced the optimum rate of water content.(3) Permeability characteristics of fiber reinforced red clay are discussed. Falling head infiltration permeability tests of red clay with different content of fiber are done in this paper. The results show that the coefficient of permeability of reinforced clay increased as to the addition of fiber while its order of magnitude was the same as the red clay and the reinforced clay still had low permeability.(4) Mechanical characteristics of fiber reinforced red clay in various test conditions are investigated. Red clay with different content and length of fiber was systematically investigated by shear test, unconfined compressive test and triaxial test, respectively; failure mode is emphatically researched in CU condition. The results suggested that the strength of reinforced clay was significantly higher than nature, the more content or length of fiber made reinforced clay higher strength. Adding fiber to red clay, c has obviously enhanced trend,φalmost remains unchanged and stress-strain curve is typical property of work hardening. Failure mode of reinforced clay is bulging type with lower content of fiber compared with not failure with higher content bearing larger axial strain.