Abstract
Problem statement: Peat soil is well known to deform and fail under a light surcharge load and is characterized with low shear strength, high compressibility and high water content. With the rising demand from the construction industry, utilization of these soils is required and suitable technique needs to be found out for stabilizing them. Approach: Model study had been carried to stabilize peat soil using cement as binding agent and polypropylene fibers as additive. Due to high natural water content of the peat soil, the stabilized peat soil samples were kept at normal room temperature and relative humidity for air curing for 90 days. The improvement in the mechanical strength of the stabilized samples was studied by California Bearing Ratio (CBR) test for both, unsoaked and soaked samples. The water-cement ratio of the samples was measured for 180 days to study the improvement in strength over time. Results: The results of CBR tests showed an increase by a factor over 22 for unsoaked condition and 15 for the soaked condition of the stabilized samples. With the addition of the polypropylene fibers to the stabilized peat soil with cement not only improved the strength of the stabilized peat soil but also contributed to considerable amount of uniformity and intactness to the stabilized peat soil samples. It was also observed that as the curing time for the stabilized peat soil continued through 180 days the moisture content continued to decrease as well. Thus the water-cement (w/c) ratio reduced and as a result of cement hydration, the strength stabilized peat soil samples increased in hardness and gained strength through the curing period. Conclusion/Recommendations: Cement and polypropylene fibers can be used to improve the mechanical strength of the soft peat soil by adopting air curing technique.
Highlights
Peat is a soil that contains a significant amount of organic materials
California Bearing Ratio (CBR) soaking test: According to the results shown in Fig. 3, stabilized peat soil sample with 15% cement reached 100% saturation and constant weight at the end of four days of soaking period
Air curing technique has been used to cure the peat soil samples stabilized with cement at normal room temperature and relative humidity and no water is added during the curing period
Summary
Peat is a soil that contains a significant amount of organic materials. It is known to deform and fail under a small surcharge load and is characterized by low shear strength, high compressibility and high water content (Huat, 2004). The different methods (Huat, 2007) available to improve the load carrying capacity of poor soils include; transfer the load to a more stable soil layer without improving the properties of the in situ soil; remove the soft soil and replace it, fully or partially, with better quality fill and; improve the in situ soil properties with different techniques of ground improvement. Sometimes it may be possible to combine different methods to provide a suitable foundation for the imposed loads. Hebib and Farrell (2003) provide a technique of surface stabilization combined with stabilized cement columns for foundation loads support.
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