• attributional life cycle assessment (ALCA);
  • building material;
  • consequential life cycle assessment (CLCA);
  • crushed rock sand;
  • industrial ecology;
  • sustainable development


Using waste copper slag (CS) as a replacement for sand in concrete mixture is becoming popular in Singapore and around the world. What are the consequences of this material substitution? Will this result in lower environmental impact? This work used attributional and consequential life cycle assessments to evaluate the net results of replacing sand with CS. Impacts were assessed with respect to embodied energy and greenhouse gas emissions (global warming potential; GWP). It was found that embodied energy and GWP of using a combination of 0.13 kilograms (kg) of CS and 0.9 kg of sand are higher than those of 1 kg of sand. If CS replaces sand and the leftover sand replaces crushed rock sand, the net embodied energy and GWP may also increase. Landfilling the waste CS is similar to recycling it as a building material, in terms of embodied energy incurred and GWPs. Finally, four lessons from these findings were used to suggest a few integrated sustainable resource management policies for the building material and shipping industries.