Mechanically stabilised layer by geogrids in road construction as an environmental aspect of sustainable development

Abstract

The purpose of this paper is to focus on the advantages of environmental aspects of mechanically stabilised layer by using geogrids (MSL). MSL is utilised in road construction as a sub-base layer or capping layer for a week sub-soil improvement. The concept of a MSL says that unbound granular layer is stabilized by the non-reinforcing hexagonal geogrid by the way of interlock with the aggregate. The mechanism of interlock means that both geogrid and aggregate interact under applied external load. The beneficial consequence on the serviceability of that layer by the resisting of the movement of the particles is defined as stabilisation. Mechanically stabilised layer by geogrid allows to save both money and time of construction compared to traditional technologies. Moreover, it also substantially supports sustainable development being a successful alternative to traditional solutions in road construction, such as: soil replacement, cement and other hydraulically bound mixtures or granular unbound layers which are non-stabilised by geogrids. MSL gives massive benefits for the environment, allowing for significant reduction of energy usage and greenhouse gases emission (mainly CO2). The paper shows the methodology of carbon footprint approach, which is an equivalent amount of CO2 emission, resulting from all component processes related to a specific technology used in road construction.This paper describes also the basic rules of how to calculate the amount of this reduction by using a special tool, so called Carbon Calculator (CC) designed by one of the leading geogrid manufacturer. CC allows to determine the reduction of CO2 as a result of geogrid utilisation in MSL compared to other well-known and long-standing solutions, mainly traditional granular unbound and cement or other hydraulically bound mixtures. A number of calculations of carbon footprint with MSL and other traditional solutions used as a sub-base or capping layer in the road construction have been done and the results of them have been presented in the further part of this article.