Studying the Effect of Improving the Weak Subgrade by Use ‎Halloysite Nanotubes on the Performance of Pavement Layers ‎Using the Kenpave Program

Abstract

 The highways built on gypseous soil, often experience pavement cracking and early ‎serviceability loss due to volume shifts caused by moisture content changes and traffic loads. ‎This study aims to improve the geotechnical properties of gypseous soil using Halloysite ‎nanotubes. The soil sample obtained from Ayn Al-Tamr in Karbala in southwest Iraq, has an ‎average gypsum content of 30%. This soil is classified as SP according to [4]  USCS and A-3 ‎according to AASHTO. The laboratory experiment was done to evaluate the properties of ‎untreated and treated samples using CBR test. The proportions (1.5, 2.5, 5, 7.5)% of Halloysite ‎were added to the soil, and then these samples were subjected to testing. The laboratory data ‎were analyzed using the Kenpave programme. The findings indicated that using Halloysite is a ‎good and effective alternative to treatment the characteristics of gypseous soil by preventing ‎gypsum from dissolving when it comes in contact with water and by enhancing the soil strength ‎by increasing CBR values. The 2.5% Halloysite is the ideal percentage for enhancing the physical ‎properties by filling voids between soil particles. An analytical method were used to study the ‎behavior of gypseous soil that had been treated with 2.5% Halloysite. The data of the soil ‎samples were fed into the Kenpave program. The analysis results used in the program indicate a ‎decrease in  strains. The fatigue and rutting of modified soil were low compared with natural soil ‎because Resilient Modulus increased which leads to increasing fatigue and rutting life.‎