# Behavior of Fiber-Reinforced and Lime-Stabilized Clayey Soil in Triaxial Tests
## 4 Conclusions  
Conventional triaxial tests and SEM analysis were conducted to study the coupling effect of wheat straw fiber reinforcement and lime stabilization on the behavior of Hefei clayey soil. Quantitative estimation of the coupling effect was performed using comparisons of the induced results by fiber  
Figure 10: SEM micrograph showing white cementitious gels produced by the chemical reaction of soil and lime.  
Figure 9: Experimental evidence of friction between fiber and soil showing (**a**) breakage or pullout of fibers and (**b**) a scratch formed on the fiber surface (modified from [PERSON] et al. (2007) [64] and [PERSON] et al. (2010) [65]).  
reinforcement, lime stabilization, and a combination of them in terms of the stress-strain relation, secant modulus, and failure pattern. The microstructural mechanisms involved in the coupling effect were analyzed with the help of SEM micrographs. The following conclusions were drawn.  
(1) The strain-hardening behavior of Hefei clayey soil was retained by wheat straw fiber reinforcement but was changed to strain-softening when the soil was stabilized with lime or treated with a combination of fiber reinforcement and lime stabilization. The addition of even a small amount of wheat straw fiber improved greatly the strain-softening of soil stabilized with lime alone.  
(2) A combination of fiber reinforcement and lime stabilization produced a larger increase in the secant modulus at a 1.2% strain level than did only stabilizing soil with lime at an identical lime content despite the fact that reinforcing soil using only fibers could reduce its secant modulus.  
(3) The addition of fibers into lime-stabilized soil restrained the development of a shear band. The restraint was attributable to the tensile stress induced in the fibers bridging the shear band and was beneficial to the occurrence of brittle failure at a greater strain level compared to the case where only lime was incorporated.  
(4) The microstructural mechanisms by which the coupling effect of fiber reinforcement and lime stabilization occurs were found to be the development of the chemical reaction between soil and lime being quickened by the water channels offered by wheat straw fibers and that the effective physical interaction between fibers and soil particles was strengthened by the dense soil fabric and the cementitious gels created by lime stabilization.  
(5) The shear strength parameters were observably increased by combining wheat straw fiber reinforcement and lime stabilization. The maximum cohesion and angle of internal friction were, respectively, 1.37 and 1.30 times those of untreated soil. With increasing lime content, an asymptotic increase in the cohesion existed, but this was not the case for the angle of internal friction.  
[PERSON] proposed the idea of combining wheat straw fiber reinforcement with lime stabilization for improving the behavior of Hefei clayey soil. [PERSON] prepared the manuscript. [PERSON] performed the triaxial compression tests. [PERSON] performed the SEM tests. [PERSON] discussed the test results. [PERSON] revised the manuscript.  
This research work was funded by the National Natural Science Foundation of China (51774107), the Opening Project of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology (KFJJ19-02M), the Fundamental Research Funds for the Hefei Key Project Construction Administration (2013 CGAZ0771), and the Fundamental Research Funds of the Housing and Construction Department of Anhui Province (2013 YF-27).  
The authors declare no conflict of interest.