Fragmentation Evaluation of Some Selected Mudrock Indiced by Physical and Mineralogical Properties

Abstract

Not many mudrock in Indonesia have been evaluated for slaking characteristics. Mudrock disintegrates rapidly when interacting with the atmosphere and hydrosphere. This research investigates the fragmentation of slaked claystone from the Kerek Formation. These formations are known for causing road, slope, and land-strengthening engineering problems along Jalan Semarang-Bawen, Middle Java, Indonesia. In this research, the method includes quantitative analysis of rock slaking level, which collides with the physical and mineralogical properties of the rocks. The slaking test with natural exposure for four cycles was carried out on as many as five samples. It is found the durability parameter value for all samples generally shows a slight difference. The durability index and Fragment Size Distribution Ratio in the 4-month cycle may be considered to evaluate the degree of fragmentation of material mudrock. RGL.0708.10 have an average DIR of 11.81%, and RGI.0908.1 is 2.18%. The value of FSDRatio for RGI.0908.2, RGL.0908.1, RGI.0908.1, and RGI.0708.3 is 1.00, whereas RGI.0708.10 is 0.9997. The indices in this research can be projected and considered to be used in another formation sample with engineering problems. The mineralogical composition of smectite minerals does not show a significant relationship to affect the fragmentation of mudrock with R2 .0.268 in month-4 for the DIR and 0.1322 for the FSDRatio . On the microscopic texture of the sample, there is the presence of calcite minerals, and a modest relationship exists between calcite content and its effect on the fragmentation of mudrock with R2 for DR and FSDRatio , respectively 0.6797 and 0.4732. In addition, physical properties such as natural water content highly influence mudrock’s durability with R2 for DIR and FSDRatio , respectively 0.8321 and 0.9023.