Utilization of ground tile waste with lime as a cohesive soil stabilizer in road subgrade layer / Mohd Hafizan Md.Isa

Mohd Hafizan , Md.Isa (2024) Utilization of ground tile waste with lime as a cohesive soil stabilizer in road subgrade layer / Mohd Hafizan Md.Isa. PhD thesis, Universiti Malaya.

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Abstract

The subgrade layer is crucial for road safety and durability as it provides the foundation for the pavement structure. Improper construction can lead to issues that compromise structural integrity, like settling, deformation, cracking, and erosion. Prioritising subgrade construction is vital for road maintenance and longevity. Various factors can lead to subgrade failures, such as poor drainage, inadequate compaction, or poor soil quality, a severe concern in construction projects. Soil stabilisation is one of the methods for treating poor soil quality. There has been a growing trend toward utilising waste materials in soil stabilisation. In the past, some waste materials used as stabilisers were fly ash, slag, lime kiln dust, quarry dust, waste glass powder, rice husk ash, etc. In this study, the ground tile waste (TW) with lime has been utilised as a soil stabiliser to improve the mechanical properties and rutting behaviour of the road subgrade layer. In order to understand the interaction between soil and TW, six soil mixtures were prepared with different tile waste contents of 5% to 40%. On the other hand, the performance of TW as an auxiliary additive to lime in subgrade stabilisation was investigated by adding 7% lime together with various portions of TW (10%, 20%, 30%, and 40%). The use of TW and lime was investigated in this study by conducting various laboratory tests, such as compaction, unconfined compressive strength, indirect tensile test, flexural test, and California bearing ratio (CBR) test, as well as microstructure analysis. A wheel tracking equipment was also used as an on-field simulation test to predict the subgrade's performance. The results showed that the TW indicated an increment in strength when an optimum percentage of TW was used as a stabiliser for the soft soil samples. Any additional content of TW beyond the optimum value will decrease strength, with excessive TW contents in soil samples without pozzolanic reaction. Meanwhile, strength was significantly increased when a combination of lime and TW was added to the soil. In addition, the mechanical properties of the soil-lime mixture increased by an increment of TW content. The wheel tracking test results indicated that rutting resistance increased with the addition of TW in lime-stabilised soil. This result was found to correlate with the CBR value obtained. When TW is mixed with lime-stabilised soil, the pozzolanic reaction takes place, forming cementitious compounds. The cementitious compounds produced by the pozzolanic reaction fill the voids in the soil and coat the soil particles, thereby improving the strength and stability of the subgrade. Besides, the pozzolanic reaction particle interaction also plays an essential role in the strength. Using recycled TW in the subgrade stabilisation method can provide a sustainable and cost-effective alternative solution to improve performance and reduce the environmental impact due to road construction.

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