Life cycle assessment (LCA) of precast concrete blocks utilizing ground granulated blast furnace slag

Concrete paving block (CPB) has become a popular construction material for pavements subjected to passive loads (parking, toll plazas, gas stations, and street pavements). Due to the short time in the production of CPB, the concrete block industry has experienced tremendous growth over the past decade. In this scenario, the environmental distress cannot be ignored due to the increased extraction of raw materials (fossil fuels, limestone, river sand, and crushed aggregates) in the manufacturing of CPB. The sustainability issues demand the utilization of eco-friendly materials instead of natural ones to minimize the abiotic depletion caused by the construction industry. This study investigates the technical and environmental performance of CPB production incorporating an eco-friendly mineral admixture, i.e., ground granulated blast furnace slag (GGBS), as a cement replacement material. The optimum level of GGBS was decided based on the required engineering performance and minimal environmental impact. For the determination of the engineering performance of CPB, several parameters were considered such as compressive strength (CS), impact toughness (IT), and water absorption (WA). The environmental impact of Global Warming Potential (GWP) was assessed based on a cradle-to-gate LCA analysis. The results suggested that maximum mechanical performance and minimum GWP can be simultaneously achieved at 5-10% replacement of cement with GGBS, while to satisfy the minimum strength requirement, CPB can be prepared using 25% GGBS as a replacement for cement that accounts for 17% lower GWP than that of the conventional CPB manufacturing.

Automated summary

The production of CPB has significant environmental impacts, and using eco-friendly materials, such as GGBS, as a replacement for cement can reduce these impacts. The study found that replacing 5-10% of cement with GGBS can achieve the best mechanical performance and minimal environmental impact. Additionally, using 25% GGBS as a replacement for cement can meet the minimum strength requirement with a 17% lower environmental impact than traditional CPB manufacturing.