Comparative analysis of life cycle inventory of cement and ready-mix concrete production in Indonesia

The development of civil infrastructure in 2016-2021 increased cement and concrete consumption across Indonesia. The reduction of global warming effects can be expedited by providing environmentally friendly cement and concrete alternatives complemented with embodied energy and carbon assessment references. In this study, we investigated the local embodied energy and carbon emission with a boundary of cradle-to-gate for cements and that of cradle-to-site for ready-mix concretes in Indonesia. The production process data were collected from cement manufacturers and ready-mix concrete companies. The analysis starts with the ordinary Portland cement (OPC) and non-OPC cement, and continues to the lightweight OPC concrete and the normal-weight blended concrete. The embodied energy and carbon were quantified. The results showed that those of OPC were the highest, followed by the non-OPC cement of Portland pozzolan cement (PPC), the Portland cement composite (PCC), and the masonry cement. The available low-energy and carbon concrete mixes were found to be a combination of a high-range water reducer admixture, a supplementary cementitious material (SCM), and cement. The lightweight OPC concrete had similar embodied energy with the reference OPC concrete, but its embodied carbon was up to 11.1% lower than the reference OPC. The normal-weight blended PCC concrete with optimum SCM levels reduced embodied energy and carbon by 53.8% and 58.2%, respectively, compared to the reference OPC concrete. The reference PPC concrete is considered an alternative for assessing the embodied energy and carbon of blended concrete in the building design stage.