Haas S.; Hammerschmidt S.; Shtiza A.; Denayer C.; Scutt D. (2019): Soil improvement with quicklime – quantification of the carbonation rate in an embankment after 34 years

ABSTRACT:

In 1979, during the construction of the motorway A3 Regensburg – Passau (Germany) an em-bankment was built using the technique of soil improvement. The soil was treated with quicklime to accelerate the chemical reaction and shorten the execution time for earthworks. Previous studies were not conclusive to address the scale of chemical reactions taking place after these treatments. In 1990 and 2013, samples from this embankment were taken from the same area and studied chemically and geotechnically. Here, the rate of car-bonation and pozzolanic reaction were quantified for the first time to provide evidence for the long-term stability of lime-improved soils for earthworks.

In 2013, samples were collected to investigate the development of compressive strength levels, the rate of poz-zolanic reaction, and the rate of carbonation of lime over a 34 years period. The rate of carbonation, calculated from available data of the building phase and chemical analysis lies between 35-40%. The amount of available lime and total CaO content suggest that compressive strength should increase if enough water and clay are available for ongoing pozzolanic reactions in the long-term.