# A Comparative Evaluation of Cement and By-Product Petrit T in Soil Stabilization
## 3 Results and Discussion
### Water Content and Density  
Figure 3 shows the immediate effects of adding Petrit T and cement on the soil water content. It is seen that the addition of both binders has the same trend of reducing the soil water content from its initial value (30%), but the effect is more marked for the cement rather than the Petrit T. The reduction in moisture content of soil is mainly related to introducing dry solid particles into the soil, as well as the hydration reaction between the binder and water. Cement has a greater effect on reducing the initial water content compared to Petrit T, and this is particularly so when binder content levels exceed 7% (see Figure 3). This can be attributed to the variation in hydraulic properties between the two binders, which relates to the ability of each binder type to reacting with water. A similar observation has been made in previous studies [39; 40; 41]. The curing time effects on the soil moisture content of the treated soil with various amounts of the binder is presented in Figure 4. For both binder types, the soil moisture content is further  
Figure 3: Water content of soil versus binder amount after one hour of treatment. Figure 2: Plasticity index versus curing time. decreased with time, with a more dominated effect for cement treatment during the first 28 days of curing. In contrast, a gradual decrease in soil water content with curing time is observed for Petrit T treatment. This can be attributed to the lower reactivity of the main component C2S (belite) in Petrit T (compared to cement), which has four major components: C3S (alite) and C2S (belle) in addition to C3A (aluminate) and C4 AF (Ferrit). The further reduction in soil moisture content is attributed to the hydration and pozzolanic reactions of binders as the samples were cured in a semi-sealed condition. Small leaks in the plastic caps of the UCS samples can be the reason behind the increase in water content for treated soil with 4% and 7% cement content as shown in Figure 4.  
From Figures 1-4, it can be seen that change the soil consistency limits after treatment is accompanied by a reduction in soil moisture content. Workable soil is a term used to explain how the soil can be easily excavated, loaded, transported, compacted, etc. [18]. The immediate reduction in soil moisture content and plasticity index transfer the soil from being plastic to more granular soil, which facilitates higher workability. As pointed out by [42; 43; 44], the workability of clay has been shown to improve with a reduction in the plasticity index. The majority of researchers compared the improvement in workability of treated soil by reducing the plasticity index after treatment e.g., [17; 39; 45]. The immediate increase in the plasticity index combined with the initial reduction in soil water content due to adding small amounts of binders doesn't mean that the workability of soil did not improve. For this reason, using the plasticity index as an indicator to measure the improvement in workability of the treated soils is of limited reliability. Therefore, the liquidity index (LI), as expressed in Equation (1), can be used to explain the affinity between the consistency limits and moisture content of treated soil with two binder types (cement or Petrit T). For the immediate effect (one hour after treatment), Figure 5 shows the relation between the liquidity index (LI) versus binder content. It is noticed that the liquidity index (LI) reduced from 0.6 (soil without binder) until it becomes very close to the plastic limit (LI = 0) at 3% and 7% of cement and Petrit T content, respectively. As the binder amount is increased, further reduction in the liquidity index is observed below the plastic limit. \[\text{LI}=\frac{(\text{W}_{\text{c}}-\text{PL})}{\text{PI}}, \tag{1}\]  
where: LI: liquidity index, PI: plasticity index, PL: plastic limit and W\({}_{\text{c}}\): soil water content. Figure 4: Soil water content versus curing time and binder type and content.