Sand is a commonly used ingradient of mortar. Quality of sand is important to produce good mortar. Followings are the functions of sand as one of the ingradients of mortar.    

  • Generally sand is not used in mortar to increase its strength. Rather it is mainly used as an inert material to increase the volume of mortar for economy. 
  • Using sand in right amount can produce cheap mortar without hampering mortar strength.
  • Sand subdivides the paste of cementing materials into a thine film which is the basic principal involved in using all cementing materials.
  • Sand offers the requisite surface area for the film of cementing materials to adhere and to spread.
  • Sand helps to prevent mortar shrinkage. It also prevents cracking of mortar during setting.
  • Well graded sand increases the density of mortar.
  • Sand allows Carbon-Di-oxide from the atmosphere to reach to some depth in case of ft lime mortars and thereby improves their setting capability. 
  • It is also claimed that some chemical reaction takes place between silica (SiO2) of sand grains and the constituents of the cementing materials to form a harden mass. 

References:

  • A text Book of Engineering Materials by Dr. M.A. Aziz