Laboratory investigation on the effect of microsilica additive on mechanical properties of deep soil mixing columns in loose sandy soils

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

“…The maximum enhancement in the UCS can be assigned to 15% microsilica additive by 24, 19, 18 and 21% compared to original samples related to DSM columns with 0, 5, 10 and 20% amount of salt respectively. It should be noted that the pervious study carried out by the authors also showed this trend for experimental cement-soil columns [22]. As can be seen from the graph, using microsilica up to 10% shows insignificant improvement of DSM columns in terms of UCS and also the UCS has slightly declined by adding 20% microsilica compared to 15%.…”

“…4(a) to (c)). It is worthy to be mentioned that in this study, a cement slurry with water to cement ratio of 1(w/c = 1) and cement dosage of 200 kg/m 3 is agreed for DSM column execution on the basis of reported results in the previous study of the authors [22]. Although the best microsilica additive percentage in absence of the salt has been reported as 15% of the cement weight for achieving the best strength in deep mixed columns in SP sand, in presence of the salt this parameter is considered to vary as 5, 10 and 20% values.…”

“…According to the physical properties of utilized microsilica and cement, the particles of microsilica are approximately 230 times finer than cement ones. As previously investigated by the authors [22], improvement of mechanical properties of DSM columns is vastly dependent on uniform distribution of microsilica particles in empty space between cement particles as fillers. From the SEM images it can be seen that adding 15% microsilica in cement slurry has created a more uniform and integrated structure compared to 20%.…”

“…Among deep improvement methods, the DSM method with different slurry and additive like cement, microsilica, fly ash, lime and etc. has received much attention from geotechnics and geology researchers [14][15][16][17][18][19][20][21][22][23]. For instance, the effect of salt in loose soil was studied on soil improvement adopting deep soil mixing method with cement slurry.…”

“…In another study, Esmaeili et al [22] conducted a series of laboratory tests to find out the effect of microsilica additive on bearing capacity of DSM columns. To do this many experimental DSM columns installed in a loose sandy soil with different water to cement ratio (W/C) and microsilica percentages.…”