Transportation impact on CO₂ emissions of concrete: a case study in Rio Branco/Brazil

Impacto do transporte nas emissões de CO₂ do concreto: um estudo de caso em Rio Branco/Brasil

Abstract

Due to the scarcity of crystalline massifs in the north of Brazil, concrete producers have been using crushed stone and cement from suppliers located hundreds of kilometers away. In this case, CO₂ emissions related to material transportation for concrete production may become significant. Thus, this study aims to analyze the influence of the transportation of the materials in CO₂ emissions of ready-mix concrete production in Rio Branco (Acre). Concrete compositions were obtained from a local concrete producer. Brazilian methods of dosage were not applicable due to the high fineness of the regional sand available; the mix designs were adjusted empirically. Two types of cement (CP V-ARI and CP IV) were considered to create the studied scenarios. Transportation distances of the raw materials (cement and aggregates) ranged from 20 km (local sand supplier) to 3,592 km (cement supplier from Sete Lagoas, MG). CO₂ emissions to produce concrete (f_ck of 25 MPa, cement consumption of 426 kg/m³) ranged from 208 kgCO₂/m³ to 573 kgCO₂/m³. Transportation was responsible for up to 20% of total emissions. The emissions in this study are considerably higher than the national data of concrete production available in the Construction Environmental Performance Information System (Sidac) due to the higher cement consumption and higher transportation distances. Although cement consumption in Acre represents less than 1% of Brazilian consumption, the results reveal the impact of transportation distances in CO₂ emissions of concrete in cities that deal with local scarcity.

Keywords:
concrete; CO₂ emission; transportation; construction materials