## 4 Conclusions  
The challenges in determining the unsaturated hydraulic conductivity gave way for simpler data acquisition, wherein the data acquired also illustrated the soil-water interaction across a wide range of saturation levels and several wet-dry cycles. The changes in the soil structure induced by incorporating polyurethane into the soil mixture had an evident effect on the matric suction. Moreover, the degradation of the soil structure due to the wet-dry cycles was evident based on the findings of the study. The unsaturated hydraulic conductivity predicted using the acquired data also showed that the unsaturated hydraulic conductivity generally decreases as the soil moves to a drier state and as the matric suction increases, inducing a better water-holding capacity of the soil matrix. The findings and relationships established for the clay excavated from a proposed SLF site in Kauswagan, Lanao del Norte, and the polyurethane-clay mixture composed of said clay could be a substantial reference for future studies establishing the progression of desiccation cracks of clay in each wet-dry cycle and how it can be related to the suction as the specimen moves to a drier state. This study provides a simplified approach for estimating unsaturated hydraulic conductivity in compacted polyurethane-clay mixtures using WRC-based models. While direct measurement remains ideal, the proposed method offers a practical alternative for preliminary assessments due to its ease of data acquisition and cost-effectiveness. However, its applicability is less reliable for loose or cracked soils, particularly after repeated wet-dry cycles. Future works should integrate experimental validation to refine predictions and improve modeling accuracy for real-world applications.  
It is recommended that future studies consider the presence of cracks in predicting the unsaturated hydraulic conductivity of a compacted layer through several wet-dry cycles, since cracks increase the hydraulic conductivity or permeability of a material. Thus, the volume change may be analyzed by determining the shrinkage and swelling potential in every wet-dry cycle for a more comprehensive study of the effect of saturation and desaturation on the volume change of the compacted clay specimen and how it affects the development of cracks. Moreover, the study did not determine the water retention curve of the wetting process; thus, it is also recommended for future studies to analyze the hysteresis of the water retention curve by conducting experiments that would determine the matric suction during the wetting process. Thus, the developed models in the study are applicable in determining the matric suction during the drying process of a specimen with a similar soil property for a whole range of saturation levels. It is also recommended to increase the number of specimens and directly measure the matric suction and unsaturated hydraulic conductivity of the compacted polyurethane-clay to compare the results obtained in the study from the filter paper method, which determined the matric suction, and the use of the best fit water retention curve with the empirical model to estimate the unsaturated hydraulic conductivity.  
Experimentation and data analysis were the responsibilities of [PERSON] for her master's thesis under the supervision of [PERSON] as thesis adviser. Conceptualization, checking of the analyses, review, writing, and editing of the paper for journal submission were the responsibilities of [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by the Department of Science and Technology (the Philippines) under the Engineering Research and Development for Technology (ERDT) grant.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflicts of interest.