(e)ISSN 2656-8896 (p)ISSN 2656-890X Journal of Infrastructure and Facility Asset Management – Vol. 6, Issue. 1, January 2024 65 Determination of the Percentage Ca(OH)2 Lime Stabilization Material for Weathered Clay Shale as Road Subgrade on Serang – Panimbang Toll Road Section III STA 57+200 Prince Joy Sormin 1,a) , Trihanyndio Rendy Satrya 2,b) , Mahendra Andiek Maulana 2,c) & Wahyu Supriyo 3,d) 1) Magister Student, Civil Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya 2) Civil Engineering Departement, Institut Teknologi Sepuluh Nopember, Surabaya 3) Central Banten BPJN, Directorate General of Highways, Ministry of Public Works and Housing of the Republic Indonesia Correspondent : a) princejoysormin@pu.go.id, b) trendysatrya@gmail.com c) mahendrasipil@gmail.com & d) winurseto@pu.go.id ABSTRACT Clay shale consists of thin, layered formations with irregular fractions, highly smooth, and easily separable along the layer planes. If Clay shale is exposed to sunlight, air, and water for a relatively short period, it will undergo weathering. The construction of the Serang - Panimbang Toll Road Section III is carried out by cutting the soil according to the planned contours. After the cutting process, the subgrade material undergoes a change in its characteristic properties and mechanics because the subgrade soil is Clay shale material that has weathered, commonly referred to as "Weathered Clay Shale." To transform this soil into a subgrade layer that meets the requirements, stabilization with Ca(OH) 2 lime is necessary; in this case, the percentage of lime and the duration of curing need to be determined to achieve optimum lime content. The soil material used is Weathered Clay Shale obtained from the Serang - Panimbang Toll Road Section III STA 57+200. The research involves identifying the initial soil properties, conducting standard proctor tests on soil mixtures with lime variations of 4%, 7%, and 10% to ascertain the optimal soil-lime mixture with Ca(OH) 2 . Subsequently, soil properties are identified with the most optimum lime mixture, and soaked CBR tests are conducted on the optimum lime-soil mixture with curing time variations of 0, 7, and 14 days. The 7% Ca(OH) 2 lime mixture with weathered clay shale soil at STA 57+200 in the construction of the Serang-Panimbang Toll Road Section III has achieved sufficiently good bearing strength. The bearing capacity attained has exceeded the requirements of the Bina Marga Specifications Revision II, especially during the 14-day curing period, where the achieved bearing capacity significantly surpasses the specified standards. Keywords : Weathered Clay Shale, Stabilization, Lime Ca(OH) 2 , Curing, CBR INTRODUCTION Roads play a crucial role in sustaining the pulse of the economy. This significance is inseparable from their role in facilitating human movement and influencing distribution and logistics activities. Thus, a road should be constructed and managed using infrastructure asset