In this experimental and analytical study, waste fire clay (WFC) was consumed by the use of replacing fine aggregate (FA) in confident amounts. It is targeted to remove the current sustainable complications by confirming the consumption of WFC in reinforced concrete beams (RCBs) as raw materials. For this purpose, FAs were partially replaced with WFC in proportions of 0 %, 10 %, 20 %, and 30 %. Based on this motivation, a series of experimental studies were performed on 12 + 12 small-scale bending and shear RCBs of 100×150×1000mm, considering altered WFC and stirrup spacing. While the percentage of WFC in the RCBs was selected as 0 %, 10 %, 20 %, and 30 % by weight, correspondingly, the longitudinal reinforcement was taken into account as Ф12, Ф10, Ф8. Besides, while the longitudinal tension and compression reinforcements of constant 2Ф12 and 2Ф6, the stirrup spacing was chosen as 160 mm, 200 mm, and 270 mm. As a result of the study, increasing the tensile reinforcement ratio has made the WFC less effective. Similarly, as stirrup spacing decreases, stirrup dominates the behavior, and as stirrup spacing increases, WFC determines the behavior. Finally, while the WFC content for bending RCBs increases the ability at the maximum level for the range of 20 %−30 %, it can be said that the optimum WFC content for shear RCBs is 20 %. The experimental results were obtained with the prediction of ACI-318 and the reason for the difference between the expected and actual values can be explained in detail.