Abstract Micropiles have been used in numerous ground improvement applications effectively to increase the bearing capacity and reduce the settlements in general and strengthen the existing foundations in general?and other geotechnical facilities in particular. Frictional resistance between the pile surface and soil and the accompanying group effects of micropiles are considered as the possible improvement mechanism. Literature review reveals that a limited research is available on micropiles regarding field testing and use of alternate material mix for concrete for casting micropile. In this connection, the present study deals with the field testing of micropiles stabilized with fly ash for their pullout load–displacement behavior. Here, micropiles of 178?mm in diameter and 530?mm in length were installed and tested with varying percentage of cement replacement with fly ash. The study attempts to understand the effect of fly ash on pullout load–displacement behavior of micropile by replacing the cement with fly ash in varying percentages viz. 0, 5, 10, 15, 20, 25, and 30 while casting micropiles. Ultimate pullout load increases with fly ash percentage from 5 to 20 and then decreases. Micropile displacements were marginally reduced for a given pullout load, with increase in percentage of fly ash. From the results, it is evident that the pullout load–displacement behaviour clearly considers the micropile–soil interaction i.e., bond strength is influenced by fly ash presence.
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