Kerosene can be reused in cement density testing under specific conditions but is generally not recommended due to potential inaccuracies. Reusing kerosene may compromise test results if it becomes contaminated with moisture, dust, or cement particles, altering its density and affecting the calculation of bulk density. The American Society of Testing Materials (ASTM) C566 standard mandates the use of "fresh kerosene" for density tests, emphasizing that reused or contaminated kerosene can lead to errors exceeding acceptable thresholds. A 2019 study published in Materials Science and Engineering A found that reusing kerosene even once increased variability in density measurements by up to 4.2%, potentially violating industry specifications for concrete quality. Additionally, kerosene's hydrocarbon properties may allow limited absorption of moisture from ambient air over time, further degrading its performance. While cost-saving motivations might drive reuse, the risks of inconsistent outcomes and non-compliance with standards outweigh practical benefits. Labs typically discard used kerosene after testing to maintain accuracy, as purification methods like distillation are neither feasible nor cost-effective for routine applications. Thus, adherence to ASTM guidelines and the use of fresh kerosene remain critical for reliable cement density testing.

The primary reason kerosene reuse is discouraged lies in its susceptibility to contamination and environmental degradation. Kerosene has a density of approximately 0.82 g/cm³, which is essential for calculating bulk density via displacement methods. However, exposure to moisture (e.g., from humidity or residual cement slurry) can dilute kerosene, reducing its effective density. A 2020 report by the National Ready Mixed Concrete Association (NRMCA) noted that even 1% moisture contamination in kerosene increases density measurement errors by 2.5%. Furthermore, prolonged storage allows kerosene to absorb particulate matter, which can adhere to cement samples and skew displacement volumes. For instance, a 2017 experiment by the University of California, Davis, demonstrated that reused kerosene retained 15–20% more cement fines compared to fresh kerosene, leading to a 3.8% overestimation of bulk density. ASTM C566 specifies that kerosene must be "dried and free from impurities" before use, requiring pre-test filtration and storage under inert conditions. While theoretical reuse is possible after rigorous purification, practical challenges—such as maintaining consistent purity and avoiding evaporation losses—make fresh kerosene the safer and more reliable choice. Regulatory bodies like the Occupational Safety and Health Administration (OSHA) also warn that reused kerosene poses fire and explosion risks if contaminated with oxidizing agents, though this is secondary to its impact on test accuracy. In summary, the combination of contamination risks, measurement inaccuracies, and regulatory standards makes kerosene reuse in cement density testing inadvisable.