STABILISATION OF DEGRADED CLAY SHALE WITH THE GEOPOLYMER INJECTION METHOD
Keywords:Geopolymer, Clay shale, Injection, Soil–grout column
Geopolymer injection is a method for increasing the strength of degraded clay shale. Clay shale is a type of mud rock with low durability. Samples of clay shale were exposed to weather changes and in an open field to observe weathering and degradation. A series of laboratory experiments was also conducted on reconstituted clay shale specimens. The primary objective of this research was to investigate the factors influencing the distribution of geopolymer injected into compacted clay shale. The strength index of stabilised clay shale was examined in terms of unconfined compressive strength. Soil density was varied with three relative compaction values, namely, 0.75, 0.85 and 0.95, of the maximum dry density, which correspond to porosity of 0.54, 0.48 and 0.42, respectively. Geopolymer was varied in four activator-fly ash ratios, namely, 0.5, 0.75, 1, and 1.25. An empirical equation was developed for calculating the volume of the injected geopolymer and the radius of the soil–grout column. This equation is a function of injection pressure, duration, geopolymer viscosity and air void porosity. The unconfined compressive strength of the compacted clay shale increased up to five times after geopolymer grouting. The contribution of geopolymer injection is correlated with the size or volume of the soil–grout column.