GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 187-7
Presentation Time: 9:00 AM-6:30 PM


ULMER, Kassidy N. and HOUSEN, Bernard, Geology Department, Western Washington University, 516 High Street, Bellingham, WA 98225

Comparison of rock-like materials such as concrete and bricks can be important parts of certain forensic investigations. While some traditional tools used in sedimentary petrology/provenance (point-counting of grains and clast types) can be applied to compare these materials, these analyses have limitations. This study will present comparisons, inspired by modern geochemical applications in sediment provenance, between different concrete blocks and bricks.

For geochemical investigations, concrete is difficult to compare in a forensic context due to its extreme heterogeneity. This project seeks to mitigate the difficulty of analyzing heterogeneous, multi-sourced samples by determining which, if any, methods of analysis (SEM, XRF, XRD, LA-ICP-MS, reflectance spectroscopy, and density) are capable of establishing variation among concrete blocks and bricks that originated from different manufacturers.

Pairs of concrete blocks and bricks purchased from five different manufacturers are the subjects of this study. The data will be evaluated for (dis)similarity using cluster statistics in R. Methods that show significant similarity between materials from the same manufacturer and no similarity between materials from different manufacturers will be considered successful. A manual will then be developed so that future comparisons of this nature can be conducted with the successful methods as efficiently as possible. Once complete, the manual will be applied to a cold case homicide involving one concrete block found at a crime scene and another found on a suspect’s property.