Use of Cement Kiln Dust and Cement for Grouting of Granular Soils

]This paper presents the potential of replacing cement by cement kiln dust (CKD) in grouting of granular soils. The content of CKD in the grout mix was varied from 0 to 100%. The prepared grout was used to grout three granular soils that consisted of poorly graded sand (SP), poorly graded gravel (GP) and a mixture of sand and gravel (SP-GP). The effect of CKD content on the properties of the grout such as density, bleeding, viscosity and unconfined compressive strength was investigated. The bleeding decreases as the amount of CKD increases, indicating that CKD is useful in reducing the bleeding of pure cement grout. The grout mixes with 80% CKD satisfy the limit of < 5% bleeding. The viscosity of the CKD-cement grouts increases with the increase in the CKD content and all mixtures gave acceptable viscosity values (Marsh values < 60 seconds). The unconfined compressive strength of the grout decreases with the increase in CKD content. Values of UCS for grouts with 60% CKD varies from about 2 to 16 MPa, depending on the water/solids ratios. All three soils were grouted using CKD-cement grouts. The unconfined compressive strength of the grouted soils decreases with the increase in the content of CKD in the grout mix, but generally high values were obtained for CKD contents of up to 60%. For a grout with up to 60% of CKD and a water/solids ratio of 0.7%, the UCS of grouted sands were about 3 to 7 MPa, depending on the curing time. The poorly graded gravel showed slightly larger UCS than the other two soils. The study showed the effectiveness of using CKD to partially replace cement in grouting of granular soils.