Laser induced breakdown spectroscopy for strength assessment in Ca binded soils

In this study, two distinct types of soil having different parent mineral (WS: White Soil and RS: Red Soil) is chosen and efforts are made to identify the presence/influence of Calcium (Ca), on these bulk soil solids following chemical processing. The two doped samples are named as “WS_DOPED” where Ca is doped in White Soil and “RS_DOPED” with Ca doped in Red Soil. Laser Induced Breakdown Spectroscopy (LIBS) is performed on the surface of these soil samples to understand the variation in spatial deposition of Ca with different soil matrices. Also, the influence onto the compressive strength of the soil samples is probed using LIBS. Using LIBS the ratio of ionization to the neutral state of the most predominant element “Silicon (Si)” in these samples are compared to the unconfined compressive strength of the WS_DOPED and RS_DOPED soil samples which is found to be 13.6 kPa and 15.7 kPa respectively wherein the virgin soil samples are non-cohesive in nature. Also, a comparison of LIBS with EDX measurements is carried out wherein LIBS found to be more sensitive towards detecting trace elements. Laser induced breakdown spectroscopy (LIBS) performed at various locations on the surface of calcium doped soil samples. LIBS of (a) Sample 1 (WS_DOPED) and (b) Sample 2 (RS_DOPED) showing Ca II emission peaks at 393.3 nm and 396.9 nm collected at different sample locations. [Display omitted] •Virgin and Ca doped soils were characterized using Laser Induced Breakdown Spectroscopy (LIBS).•Trace elements not found in EDX were detectable using LIBS.•For Ca doped soil samples, its unconfined compressive strength were correlated with LIBS signal