Abstract
In this study, hardened cement paste prepared from an identical Portland cement under environments with various temperatures and humidity were investigated in order to clarify environmental influences on the hardened cement in forensic science. Twelve cement pastes prepared using an identical Portland cement were set as samples at four places such as the indoors, the outdoors, an oven and a freezer. Hardening reaction processes of cement for eight weeks after the preparation were measured by Raman spectroscopy and X-ray diffraction. The reactions of samples at the indoors and the outdoors progressed until the stage of the reaction producing calcium carbonate (calcite). The reaction of samples at an oven progressed only until the early stage producing ettringite. Samples at a freezer showed no reactions. These differences were mainly caused by the stay time of water around the cement. In the hardening reaction processes of cement paste, water is an important element for progress of hardening reaction of cement paste. The result of this study showed that a variety of hardened cement pastes were observed even if the cement pastes were prepared from an identical Portland cement and water. This result was caused by differences of the environment with various temperature and humidity around cement pastes. This study is useful for more detailed identification of hardened cement paste in forensic science.
