Laboratory Investigation on the Effect of Microsilica Additive on the Mechanical Behavior of Deep Soil Mixing Columns in Saline Dry Sand

Authors

  • Morteza Esmaeili
    Affiliation

    Department of Track and Structures, School of Railway Engineering, Iran University of Science and Technology, 13114-16846 Tehran, Iran

  • Farshad Astaraki
    Affiliation

    Department of Structural and Geotechnical Engineering, Faculty of Architecture, Civil Engineering and Transport Sciences, Széchenyi István University, Egyetem tér 1, 9026 Győr, Hungary

  • Hamed Yaghouti
    Affiliation

    Department of Track and Structures, School of Railway Engineering, Iran University of Science and Technology, 13114-16846 Tehran, Iran

  • Majid Movahedi Rad
    Affiliation

    Department of Structural and Geotechnical Engineering, Faculty of Architecture, Civil Engineering and Transport Sciences, Széchenyi István University, Egyetem tér 1, 9026 Győr, Hungary

https://doi.org/10.3311/PPci.18126

Abstract

Since loose and salty subgrades consider as problematic barriers while constructing new transportation infrastructures such as railway tracks and roads are required, the current study aims to find a solution to stabilize these kinds of subgrades using the deep soil mixing (DSM) technique and micro silica additive. In the present study a series of experimental DSM columns were executed in a salty sand-filled chamber utilizing a laboratory scale DSM apparatuses. In the first step, by adding three salt percentages of 5, 10 and 20 into the original sand, four different sandy subgrades with a relative density of 70% were prepared. Considering three percentages of 10, 15 and 20 for micro silica additive, the water-to-cement ratio of 1, salt percentages of 0, 5, 10 and 20 totally 150 sand-cement columns were constructed in the lab environment. In continuation, unconfined compression strength (UCS) and elasticity modulus of all capped DSM columns have been determined and interpreted using scanning electron microscope (SEM) images at three ages of 7,14 and 28 days. The results indicated that increasing the salinity of subgrade soil from 0 to 20% resulted in a falling UCS and Young module by 28 and 21% for 28-days specimens. Furthermore, as a solution, adding micro silica in cement-water grout up to 15% resulted in enhancing mechanical characteristics of the DSM columns. So that adding 15% microsilica caused a 21 and 42% increase in UCS and elasticity modulus of 28-days samples respectively, executed in subgrade with 20% salt.

Keywords:

deep soil mixing columns; loose salty-sand subgrades; microsilica additive; unconfined compression strength; elasticity modulus

Published Online

2021-11-02

How to Cite

Esmaeili, M., Astaraki, F., Yaghouti, H., Movahedi Rad, M. “Laboratory Investigation on the Effect of Microsilica Additive on the Mechanical Behavior of Deep Soil Mixing Columns in Saline Dry Sand”, Periodica Polytechnica Civil Engineering, 65(4), pp. 1080–1091, 2021. https://doi.org/10.3311/PPci.18126

Issue

Section

Research Article