Experimental Study on Effect of Water-Cement Ratio and Sand Grading on Workability and Mechanical Properties of Masonry Mortars in Iran

The main role of mortars in masonry walls is to bind individual units such as brick, stone, and block together, as well as to distribute the stresses uniformly. Knowing the mechanical properties of fresh and hardened mortar is crucial to ensure proper performance of masonry walls and buildings. Water-cement ratio (W/C) and sand grading are among several parameters that affect the behavior of fresh and hardened mortars. This experimental study investigates the effects of common sand grading in Iran and W/C on the flow and workability of fresh mortars and the mechanical properties of hardened mortars. Using fine and coarse sands, cement-sand mortar and cement-lime-sand mortar with three different cement contents were manufactured. Three various W/Cs were considered for each mortar mix; overall, 36 kinds of mortar mixes were studied. Standard samples were tested to determine compressive strength, flexural strength, elastic modulus, and flow of mortars. Results were analyzed to find different practical relationships among compressive strength, flexural strength, elastic modulus, and W/C. Results show that by increasing W/C, usually the strength of the hardened mortar decreases and the flow of the fresh mortar increases. Furthermore, cement-sand mortar with fine sand has less compressive strength, flexural strength, and elastic modules compared to mortar with coarser grading sand. Also, mortar with fine sand needs around 25% more water to attain the same flow and workability compared to the mortar with coarse sand.