Authors : Edy Sulistianto; Sukiman Nurdin; Syamsul Arifin

Volume/Issue : Volume 8 - 2023, Issue 12 - December

Google Scholar : http://tinyurl.com/5fszhstc

Scribd : http://tinyurl.com/rremadj8

DOI : https://doi.org/10.5281/zenodo.10473317

Abstract : Stabilising expansive road subgrade by adding natural limestone and iron oxide is an efficient and economically valuable way of utilising local materials and solving iron oxide waste in environmental problems. In this study, the composition of the mixture was made with proportions: limestone at the optimum level of 6% and iron oxide with varying levels of 0%, 0.2%, 0.4%, 0.8%, and 1.6%. As support in this study, X-ray Diffraction tests and SEM photographs were also conducted to determine the content and composition of expansive clay minerals before and after mixing with stabilisation materials. The test results showed the CBR value without soaking expansive soil compacted according to standard compaction: 12.31%; after being stabilised with 6% limestone and 1.6% iron oxide additive, the value increases to 25.37% with an increased ratio of 106.09%. For the original soil soaking, the CBR value was 8.65%; after stabilisation with 6% limestone and 1.6% iron oxide additive, the value increased to 20.49% with an increase ratio of 136.87%. The results of X-ray Diffraction testing and SEM photos show the addition of new mineral compounds after the original soil is mixed with limestone and iron oxide stabilisation materials, including mineral compounds C-S-H (Calcium Silicate Hydrate). This chemical compound has cementation properties.

Keywords : Subgrade, Expansive Soil, Limestone, Iron Oxide.