Recycling of concrete from demolished bridges and other engineered structures

Abstract

The Environmental Policy (2014) of the Finnish Transport Agency (now the Finnish Transport Infrastructure Agency) identifies reducing the volume of waste and conserving renewable and non-renewable natural resources as one of the Agency’s environmental goals. The Agency has decided to pursue this goal by various means, including promoting the use of recycled materials, revising legislation and permit and notification procedures, and improving its purchasing practices and guidance. At the beginning of 2018, the Finnish Transport Agency was responsible for 15013 road bridges and 2516 railway bridges. Two thirds of the road bridges are made of concrete, and their total area accounts for approximately 80% of the total area of all road bridges in Finland. The Finnish Transport Agency currently has limited official guidance and few other established procedures for sorting and recycling concrete waste generated from the demolition of engineered structures in connection with road and rail projects. According to circular economy principles, demolition waste should be reused in a manner that adds the most value to the project and is utilized as close to its source as possible. Concrete waste from demolitions often ends up in secondary use such as embankment fills or noise barriers, which is not, from the perspective of the environment or the economy, the most optimal way to use the material. Concrete waste crushed down to the correct size, the resulting crushed pieces make a high-quality construction material. High quality crushed concrete can be used in accordance with the registration procedure set out in the Government Decree on the Recovery of Certain Wastes in Earth Construction or, if the project and/or the material do not satisfy the requirements of the Government Decree, in accordance with the environmental permit procedure. Bridge demolition concrete waste should ideally be treated and processed to add as much value to projects as possible. Pulverisation is relatively expensive and the end product has a relatively low value, which is why, in practice, it almost always makes sense to reduce concrete waste down to, for example, a size that satisfies the quality requirements for the sub-base set out in the Government Decree on the Recovery of Certain Wastes in Earth Construction in a crushing plant or using a crusher bucket.