Laboratory tests were carried out to investigate the performance of lime and fly-ash inorganic binder stabilized steel-slag and crushed-stone aggregate mixtures for pavement base. The test results and analyses indicate that the unconfined compressive strengths of the mixtures increase significantly with the increase of slag content. In other words, the slag can reduce the use of the inorganic binder. The moisture induced expansion rate of combined aggregate can be controlled by changing steel-slag content, which must be considered in the material design. The slag can increase the indirect tensile strengths and compressive moduli of the mixtures. A content of 50% slag in the aggregate can increase the strength and modulus by up to 24% and 21%, respectively, resulting in layer thickness reduction in the designed pavement structure. The slag can decrease the dry-shrinking coefficient of the mixtures. A content of 50% slag in the aggregate can decrease the coefficient by up to 27%, resulting in moisture loss induced cracking alleviation in pavement base. The existence of slag has little effect on the water scouring properties of the mixtures, which does not have to be considered in the material design.