Road construction with XPS, cellular glass, and crushed rock : An analysis of environmental impact, cost, and work environment

This thesis examines three different road construction solutions with a focus on ground insulation and fill materials: XPS foam, cellular glass (foam glass), and crushed rock. The aim is to compare these alternatives from three main perspectives: environmental impact, cost, and work environment. The study is based on a case study involving the construction of a small road (10 x 5 meters) in Kramfors Municipality. The road is designed for light traffic (BK1, ÅDT 250–500) and requires frost protection down to a depth of 1.95 meters. To achieve the objective, life cycle assessments (LCA) have been conducted using environmental product declarations (EPDs), along with cost calculations. The results reveal clear differences between the three options. For climate impact, two sets of results are presented due to the absence of life cycle stages B–D in the EPD for cellular glass. Result 1 includes stages A1–A3, while Result 2 covers the full life cycle, A–D. Foam glass shows the lowest climate impact at 250 kg CO₂-equivalents per functional unit, largely due to the use of recycled glass. XPS, being a fossil-based and energy-intensive material, has the highest climate impact at 1 800 kg CO₂-equivalents. Crushed rock falls in between at 370 kg, with emissions primarily resulting from extraction, crushing, and transportation. In Result 2, which includes all life cycle stages (A–D), cellular glass accounts for 650 kg CO₂-equivalents, crushed rock for 1 700 kg, and XPS for 2 600 kg CO₂-equivalents. In terms of cost, XPS is the most economical option with a total cost of approximately 27 900 SEK. Foam glass is slightly more expensive SEK 28 300 SEK, while crushed rock is the most costly alternative around 39 000 SEK, primarily due to deeper excavation and increased labor effort. The study thus identifies an interesting conflict: the option with the highest climate impact is also the cheapest, while the most environmentally friendly alternative is only marginally more expensive yet significantly more sustainable in the long run. Work environment aspects have also been considered. Crushed rock and foam glass are advantageous from an ergonomic standpoint, as they are largely handled with machinery reducing physical strain. In contrast, XPS boards must be laid manually which can lead to increased ergonomic stress for workers. The conclusion is that there is no universally best option, instead material choices should be adapted to the specific requirements, goals, and conditions of each project. If sustainability is prioritized, foam glass should be preferred whereas a focus on cost often leads to the choice of XPS. To enable a more sustainable road construction industry, the study suggests that climate requirements and incentives should be incorporated into future procurement processes.