This investigation evaluates the characteristics of alkali-activated controlled low-strength materials (CLSM) that were produced using a mixture of red mud (RM) and ground granulated blast-furnace slag (GGBFS) with different RM-to-GGBFS weight ratios (100/0, 90/10, 80/20, and 70/30). A sodium hydroxide (NaOH) solution of 5M concentration was used as an activator. The effects of GGBFS content on fresh and hardened properties of the CLSM were evaluated through the tests of flowability, setting time, and compressive strength. In addition, a scanning electron microscope (SEM) was used to examine the microstructural properties of the CLSM. Experimental results show that using more GGBFS in the mixture reduces flowability and increases compressive strength of the CLSM. Moreover, setting time of the fresh CLSM is associated positively with GGBFS content. Further, analysis of the optimal mixture was conducted based on the test results. Thus, the properties of the CLSM sample containing 80% RM and 20% GGBFS conformed well to the requirements of the Public Works Department, Taipei Government, Taiwan.