Building Materials Analysis
Contributed by Bill Schneck
Transfer of building materials between individuals, tools, and weapons may occur during the commission of practically any crime. Building materials encountered in casework include friable insulation products, hardened concrete, gypsum-containing plasters, glass, safe insulation, asbestos, paint, wood and engineered wood products and materials which are pliable, soft and easily transferred.
Building materials may transfer to a suspects clothing and hair during a burglary. Particles on discharged bullets can help determine trajectory by defining which wall the bullet traveled through. Tools found in a suspect’s possession may have attached building materials which could offer important clues in an investigation. Motor vehicles involved in an accident may be an excellent repository of building materials from contact with an immovable object such as a concrete barrier or wooden utility pole. Civil litigation may involve an expert’s testimony on asbestos-containing building materials which can often be identified to the manufacturer. Traces of concrete, brick, glass fibers and sawdust can be found reworked into soil and are often encountered as evidence.
The analytical methods employed in the analysis of building materials include polarized light microscopy, micro-chemical tests, infra-red spectroscopy, scanning electron microscopy-energy dispersive spectroscopy and other tools such as x-ray diffraction.
Additional References:
1. ASTM Designation: C 856-95, Standard Practice for Petrographic Examination of Hardened Concrete.
2.Bisbing, R. E. and Schneck, W. M., Particle Analysis in Forensic Science, Forensic Science Review, 18(2), July, 2006.
3.Brown, R. S., Boltin, W. R., Bandli, B. R., Millette, J. R., Light and Electron Microscopy of Mineral Wool Fibers, Microscope, Vol 55:1, p. 37-44, 2007.
4. Campbell, D. H., Microscopical Examination and Interpretation of Portland Cement and Clinker, Portland Cement Association, Skokie, IL., USA, 1999.
5. Carr, D. D., Industrial Minerals and Rocks, 6th Edition, Society of Mining, Metallurgy, and Exploration, Littleton, Colorado, 1994.
6. Double, D. D., and Hellawell, A., The Solidification of Concrete, Scientific American, pp. 82-90, July, 1977.
7. Hoadley, R. B., Identifying Wood –Accurate Results with Simple Tools, Taunton Press, Newton, CT, 1990.
8. McCrone, W. C., Asbestos Identification, McCrone Research Institute, Chicago, Illinois, 1987.
Case References:
1. A boy was sexually assaulted on a baseball field in southern California. The physical evidence left at the scene included several poorly preserved shoe impressions with insufficient marks to identify the brand of shoes. A suspect was arrested and his shoes were examined for trace evidence. Small red brick particles were identified in the soil. Investigations determined the material used for the baseball infield was recycled red brick. Microscopical and instrumental analysis confirmed the red brick on the suspect’s shoes was similar to the red brick used at the baseball field. The suspect pled to the crime (Figure 1a- 1b).
2. A body was found lodged in the back seat of a minivan parked along a street. Soil was observed clinging to the wheel wells of the vehicle. Examination of this soil and comparison soil from the driveway of a run-down dwelling in a distant location revealed similar minerals and botanicals. Mixed in the soils from both the vehicle and the driveway were a variety of red, green, white and gray particles, some with adhering asphalt and fiberglass. The duplex adjacent to the driveway lacked rain gutters. Over time, decaying asphalt roofing granules fell from the roof and mixed with the soil. This unusual association of building materials in soil proved useful to the prosecution of the homicide (Figure 2a-2b).
3. The body of a female victim was found tied up in agricultural sacking and covered with stones and tabular concrete slabs on a ledge adjacent to a river in Ireland. The suspect lived 100 meters from the covert burial. Concrete slabs in the suspect’s garden with similar features were compared to the concrete from the burial site. Methods employed included hand specimen, cut section and petrographic examination of concrete thin-sections, x-ray fluorescence analysis, and disaggregation of concrete in acid which enabled automated particle size analysis of the sieved aggregate. The comparison of the concrete was instrumental in the conviction of the suspect to life in prison without parole. (Figure 3).
