## 3 Research Results--Analysis and Discussion
### Uniaxial Compressive Strength (UCS)
#### 3.1.1 Effects of Conventional Stabilisers on UCS  
Of the conventional reagents, lime and cement were considered in this study. In accordance with the explanations given in Section 2.2, lime was added to the natural clayey soil with a share of 3%, 5%, and 7% relative to the dry weight of the soil, whereas, with respect to cement, samples of the clayey soil mixture with a percentage share of 5%, 10%, and 15% were prepared. The obtained results revealed that the addition of traditional reagents contributes to a multifold increase in the UCS value after the chemical treatment of clayey soil (Figure 2). With the addition of **line**, a significant increase in the UCS value was achieved after the chemical treatment. Regardless of the percentage of the added stabiliser, a significant improvement in this soil property was observed over time. Namely, the tests conducted 3 and 7 days after the chemical treatment resulted in similar UCS values, whereas 28 days after the treatment the registered UCS values were significantly higher--with regard to 3% added lime, 3 days after the chemical treatment the UCS value increased twice (from a value of 205 kPa in the natural condition of the soil to 435 kPa), 7 days after the treatment the UCS value increased 2.5 times (to 533 kPa), and 28 days after the treatment the increase in UCS value was fourfold (896 kPa). An almost identical trend of increasing UCS values over time was observed in samples with 5% (529 kPa, 667 kPa, 1145 kPa) and 7% added lime (622 kPa, 715 kPa, 1178 kPa). What was also observed was that a particularly significant improvement in this soil property was achieved when the lime content in the clay mixture was increased from 3% to  
Figure 4: Change in the soil UCS value for the considered alternative materials (chlorides) with increasing stabiliser content and with time after the treatment. Figure 3: Change in the soil UCS value for the considered waste materials with increasing stabiliser content and with time after the treatment. 5%, whereas the increase to 7% did not induce a more pronounced increase in the value of UCS compared to the results for the case of 5% lime addition. This result is consistent with the research findings of other studies [37,38], according to which soil mixed with lower lime content shows a higher UCS value compared to soil mixed with higher contents of lime. Thus, 28 days after the chemical treatment, the value of UCS with the addition of 3% lime increased almost four times (896 kPa), with the addition of 5% lime the increase was 5.5 times (1145 kPa), whereas the value of UCS with the addition of 7% lime was almost six times higher than the initial natural soil value (1178 kPa). This result points to the conclusion that 5% can be considered the optimal lime content. In contrast to lime, with the addition of a **cement binder**, a trend of increasing UCS values was registered both with the increase in the percentage share of the binder and over time elapsed since the chemical treatment. For the time period after 3 days with the addition of 5% cement, there was an increase in the UCS value by 1.5 times (307 kPa), with the addition of 10% cement the improvement was 2.5 times (511 kPa), whereas with the addition of 15% cement the value increased by almost four times (776 kPa) in relation to the natural soil condition (205 kPa). A similar trend of increase, which is almost linear, was also registered in the tests carried out 7 and 28 days after the treatment with the addition of cement binder. The maximum value was registered by adding 15% cement (1425 kPa) 28 days after the treatment (increasing the UCS value almost seven times), which is at the same time the maximum UCS value is registered by comparing all the materials (conventional, waste, and alternative) considered as stabilisers in this research. This indicates that the optimal content with regard to this stabiliser is 15% for this specific study.