Unconfined Compressive Properties of Fiber-Stabilized Coastal Cement Clay Subjected to Freeze–Thaw Cycles

Na Li,Wangyi Wu,Sin Mei Lim,Wei Wang,Yalan Zhu,Fang Zhang

doi:10.3390/jmse9020143

Abstract

This study aimed to investigate the feasibility of using polypropylene fiber-cement-stabilized coastal clay as base-course material or foundation material for city sustainable development by assessing its mechanical performance. The influence of the number of freeze–thaw cycles and curing ages on the mechanical properties of ordinary cemented clay (OCC) and polypropylene fiber-cemented clay (PCC) was investigated by using unconfined compressive test. The experimental results show that the addition of fiber with 1% content can increase the strength as well as the ductility of cemented clay by 12.5% and 15.6%, respectively. The strength of PCC and OCC at 22d age was 1.5 times than at 7d age. Under differently timed freeze–thaw cycles, the mechanical performance of PCC is improved, and, better than that, OCC improves by 11.8% in strength, 16.5% in strain and by 5% in degree of damage, indicating that fiber can improve the freeze–thaw resistance of cemented clay. The frost resistance of PCC and OCC increases with the increase in curing age. Finally, the variation of strength of OCC was explained through the change of micro-structure while the strength enhancing mechanism of polypropylene fiber for cemented clay was also revealed.

Highlights

Received: 4 January 2021With the rapid economic growth and continuous development of coastal cities, more and more projects are being built on soft coastal clay foundations
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Summary

Introduction

With the rapid economic growth and continuous development of coastal cities, more and more projects are being built on soft coastal clay foundations. Coastal clay has some disadvantages such as high natural moisture content, high compressibility and poor bearing capacity, restricting sustainable development of the coastal cities. Under the action of freezing, the volume expansion of soft clay with high water content will be caused by the freezing of internal water. This kind of expansion will lead to the destruction of the internal structure of the foundation clay. When the temperature gradually increases, the frozen soft clay begins to melt, resulting in the loss of part of the strength of the soft clay; as the transformation process of solid ice to liquid water advances, part of the water in the clay is gradually discharged, resulting in a large freeze–thaw settlement of the soft soil

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Conclusion