GEOPOLYMER STABILIZED CEMENT DEEP MIXING PILES FOR ROAD EMBANKMENT ON RECONSTITUTED SOFT SOILS

Abstract

This study was carried out to utilize fly ash and industrial slag based for constructing deep mixing piles. A total of six combinations with slag and fly ash based geopolymer along with cement were used to improve the strength characteristics of soil samples collected from a catchment area of Padma River at Mawa in the laboratory based experiments. Cylindrical samples prepared with different combinations were cured in four different curing conditions and tested for unconfined compressive strength and split tensile strength. Meanwhile, laboratory scale miniature Deep Mixing Pile (DMP) machine was designed and constructed. Reconstituted soil bed was prepared by consolidation process with one liquid limit of water. Laboratory scale deep mixing piles were constructed in the reconstituted soil bed by the miniature deep mixing pile machine using selected three combinations from the laboratory based experiment results. After curing, the extruded pile samples were tested for unconfined compressive strength and split tensile strength. Moreover, microstructure analysis of the pile samples was conducted by Scanning electronic microscope (SEM) and Energy-dispersive x-ray spectroscopy (EDS). It was found that samples cured in humid condition followed by 24 hours heat before test manifested higher strength among the samples of four curing condition, which was five to ten times of the samples cured only in humid condition. Moreover, with the addition of the geopolymer, compressive strength of the cylindrical samples was found to increase up to 25% of geopolymer content. However, further increment of geopolymer resulted in reduction of strength. The laboratory scale machine worked well and could successfully executed deep mixing piles. Among the three combinations used for deep mixing pile, five percent cement with fifteen percent binder showed highest strength value of 527 kPa.