Cost economics of reinforced soil retaining walls with rock flour as fill material

The reinforced soil wall construction has gained momentum with advent of geosynthetic reinforcement, particularly in the approaches of bridges and flyovers. The stability and performance of reinforced soil walls depend mainly on fill material and its interaction with reinforcing material. Frictional fills are used as they are free draining and have good frictional characteristics. The commonly used fills in reinforced soil walls are sand and moorum. Due to scarcity and high cost of sand and moorum, alternate fill materials are to be identified to enable construction of reinforced soil walls. Rock flour, produced as waste material at stone crushing plants, is accepted as an alternate to sand in concrete making as the material has particles of sand size. So, in the present study, reinforced soil retaining walls with rock flour and sand as fill materials are designed and their relative economy is assessed over the conventional retaining walls. The retaining wall designs are carried out for silty sand backfill with uniform surcharge of 20 kN/m2, for backfill heights of 4 to 10 m. The reinforced soil retaining walls are designed considering geotextile and geogrid reinforcements. The study revealed that usage of Rock flour fill in reinforced soil walls results in savings up to 30 to 50 percent in comparison to conventional retaining walls.