Reducing environmental impact of earthworks with utilization of crushed concrete aggregate

The aim of this paper is to present the impact of utilizing crushed concrete aggregate in earthworks for reducing environmental emission. In the case studies is calculated the effect of the replacement of natural aggregates... [ view full abstract ]

The aim of this paper is to present the impact of utilizing crushed concrete aggregate in earthworks for reducing environmental emission. In the case studies is calculated the effect of the replacement of natural aggregates with recycled materials (crushed concrete aggregate). Construction and demolition waste (C&DW) are one of the major waste types produced by modern society, and depletion of natural aggregates is the main environmental impact in construction. Additionally, airborne emissions generating from energy consumption and transportations are major consequences from construction activities, contributing approximately 20 to 25 % to global carbon emissions and thus significantly to anthropogenic climate change. Transportation of C&DW to and from the crushing facility has a significant effect on the material total emissions. Long transportation distances increase emissions and noise from traffic and decrease safety. However, concrete is well-known for its carbon dioxide (CO2) uptake by carbonation. The uptake rate becomes higher in a recycling process because the reacting surface area is increased by crushing processes. The carbonation in recycled crushed concrete aggregate is an environmental process during its life cycle. The use of recycled crushed concrete aggregate benefits environment by reducing greenhouse gas emissions and energy consumption and preserving the natural aggregates. However, the emission modeling in earthworks has no standard methods, and the calculation principles and methods can vary. To tackle this matter, some development projects have started. In addition, this paper presents the current situation in emission modeling and the future development works regarding developing the modeling principles for different earthworks materials, machinery and methods in Finland.