Flowable Fill as Geotechnical Material in Highway Cross-Drain Trenches

Abstract

Abstract Controlled low strength materials (CLSM), also called flowable fills, have widely been used in infrastructure construction due to their inherent merits. However, the procedure of choosing proper constituents and proportions for CLSM is based on such criteria as unconfined compressive strength (UCS), flowability, ability to be re-excavated, and subsidence.A variety of flowable fills are available in design, but few works have been devoted to the soil environment adjacent to trench backfill even though soils' properties are equally important to satisfactory performance of highway cross-drains. A wide range of UCS values existing in CLSM trench backfills causes uncertainties for practitioners in mixture designs. This technical note presents a simple procedure to select an appropriate CLSM for highway cross-drain trenches that will be compatible with adjacent subgrade/embankment soils from perspective of strength and compressibility.A mixture design example illustrates that CLSM with 28-day UCS of 410 kPa is suitable for highway trenches in Louisiana, and such CLSM is also excavatable if sequential excavation is desired.