Does the use of recycled concrete lower the carbon footprint in humanitarian construction?

Purpose: This study investigates the carbon footprint of the alternative structure types and materials used for the reconstruction of schools in Haiti. Are recycled construction materials more environmental than virgin materials? To estimate which alternative construction solution has the smallest carbon footprint, a survey was made for the school model used for the reconstruction programme in Haiti after the 2010 earthquake. Design/methodology/approach: The carbon footprint was calculated using life cycle assessment methodology for five different concrete structure alternatives and five different cement mixes for the same design of a school building. In addition, the uptake of CO₂ through the carbonation of concrete during 50 years was calculated. Findings: The carbon footprint of recycled materials can be either the best or worst option, depending on how the materials are used. The difference to using virgin materials is not big. This is mainly due to the lower structural performance of recycled materials, which needs to be compensated for by using additional reinforcements. Using cement mixes that have high amounts of substitutes for cement seems to lower the carbon footprint of structures considerably. The uptake of CO₂ in carbonation has potential but requires an optimal design and environment. Originality/value: The findings give information for humanitarian project managers and designers on lowering the carbon footprint of their construction projects.