BLAST-FURNACE SLAG-MODIFIED GROUTS FOR IN-SITU STABILIZATION OF CHROMIUM-CONTAMINATED SOIL

Blast furnace slag-modified grouts were used to stabilize soils contam inated with trivalent and hexavalent chromium. Slag content, grout/soi l ratio and water/cementitious material ratio were varied to determine the effects on leachability of chromium, permeability and compressive strength. Slag-modified grouts successfully stabilized Cr(VI)-contami nated soil to give low leachability, thereby allowing omission of the pretreatment stage to reduce Cr(VI) to Cr(III) necessary with lime and ordinary Portland cement stabilization procedures. Leachability of bo th Cr(III) and Cr(VI) decreased with increasing slag content. The perm anence of leach resistance is enhanced by higher slag levels in grout. Compressive strength of grout-treated soil ranges from 6 to 36 MPa an d permeability is of the order of 10(-11) to 10(-7) cm/s, depending on mix proportions. Slag-modified grouts have potential for in situ stab ilization of Cr(III)- or Cr(VI)-contaminated landfills.