In designing a pavement, aside from the types and properties of the surface layer (flexible or rigid), the soil properties of subgrade, subbase, and base materials are also important parameters. This research study was performed to determine the effects of lime sludge (LS) mixed with cement for use as stabilizers for road subbase course material. Laboratory tests to determine the engineering properties and California bearing ratio (CBR) were conducted on treated and untreated soil samples. There were two (2) sets of treated soil samples, Set 1: (Subbase soil + LS) added with varying percentages of lime sludge of 8, 10, 12, 14 and 16; and Set 2 (Subbase soil + LS + OPC) which contained lime sludge content of 8, 10, 12, 14 and 16 percent each coupled with 2% cement. For Mixture Set 1, laboratory test results indicated that treated samples with LS of 10%, 12%, 14% and 16% showed CBR values higher than the untreated sample. Highest CBR in this set of mixtures was recorded from the treated sample with 14% LS. Moreover, when 2% cement was added for Mixture Set 2, CBR values of subbase soil+LS mixtures increased, obtaining the highest value from the mixture with 10%LS and 2% cement. Therefore, the experimental result showed that the LS combined with cement can effectively improve the CBR value of the subbase course material.












