The purpose of the lysimeters is to collect water under 'fieldlike' conditions and to examine the quantity and quality of the water percolating through different materials. The lysimeter field at SGI consists of basins of different sizes filled with the alternative material that is going to be examined (a standard size is 3m by 3m by 1m). Preinstalled collection and drainage systems divert the percolating water to a collection station in the cellar of a nearby located building. Here the flow is continuously registered and samples can be taken at chosen intervals. At the same time, the quantity and chemical composition of the water percolating through lysimeters filled with moraine and crushed bedrock (common ground conditions in Sweden) are measured as a reference to the alternative materials. A continuous registration of the climate is done (precipitation, wind, temperature) in order to calculate the water balance of the lysimeters.
In the Alt-Mat project, SGI is primarily studying crushed concrete and blast furnace slag, largely because these materials have already been used in real roads in Sweden and these will be examined as part of the study. To date, blast furnace slag has been investigated in laboratory trials and SGI has opened up pits in the road between Linkoping and Stockholm built in 1986 and 1994 to examine the mechanics and chemical changes that have occurred since then. Two newly built roads containing crushed concrete with installations to collect percolating water provides an excellent opportunity to study leaching in a perspective from laboratory analyses via fieldlike situations such as the lysimeters to the 'real case' an existing road.