Equivalency of crushed rock with industrial by-products and geosynthetic-reinforced aggregates used for working platforms during pavement construction

A study was conducted to define an equivalency criterion for five materials used for working platforms during pavement construction on a poor subgrade: conventional crushed rock (referred to as "breaker run") and four alternatives [i.e. Grade 2 granular backfill (referred to as "Grade 2"), foundry slag, bottom ash, and foundry sand]. Total deflection data for the equivalency assessment were obtained from a large-scale model experiment (LSME) simulating a prototype-scale pavement structure and in the field using a rolling wheel deflectometer (RWD). Design charts were developed for selecting the equivalent thickness of alternative working platform materials so that the alternative provides equal deflection as a layer of breaker run. Another phase of the study was conducted to determine the equivalency of geosynthetic-reinforced aggregate working platforms in providing support during pavement construction over soft subgrade. Four reinforcing geosynthetics (a geogrid, a woven geotextile, a non-woven geotextile, and drainage geocomposite) incorporated into two granular materials: Grade 2 and breaker run were used in this study. Design charts were developed for selecting the equivalent thickness of an alternative geosynthetic-reinforced working platform material so that the alternative provides equal deflection as a layer of breaker run.