Stone masonry in Civil Engineering – Rubble Masonry & Ashlar Masonry

Stone Masonry in Building Material & Construction Technology

Stone masonry can be classified into two types: 

1. Rubble Masonry 
2. Ashlar Masonry

1. Rubble Masonry

• The type of stone masonry in which either undressed or roughly dressed stone are laid in a suitable mortar is called rubble masonry. 
• In this masonry the joints are not of uniform thickness. 

2.Ashlar Masonry

• It is the type of stone masonry in which finely dressed stones are laid in cement or lime mortar is known as ashlars masonry. 
• In this masonry are the courses are of uniform height, all the joints are regular, thin and have uniform thickness. 
• This type of masonry is much costly as it requires dressing of stones.

Types Of Rubble Masonry

Three types of Rubble Masonry are as follows: 

Un-coursed Random Rubble Masonry

• The random rubble masonry in which stones are laid without forming courses is known as un-coursed random rubble masonry. 
• This is the roughest and cheapest type of masonry and is of varying appearance. 
• It is used for construction of walls of low height in case of ordinary buildings. 

Coursed Random Rubble Masonry

• The random rubble masonry in which stones are laid in layers of equal height is called random rubble masonry. 
• In this masonry, the stones are laid in somewhat level courses. 
• Headers of one coursed height are placed at certain intervals. 
• The stones are hammer dressed. 
• CRRM is used for construction ofresidential buildings, boundary walls etc.  

Squared Rubble Masonry

• The rubble masonry in which the face stones are squared on all joints and beds by hammer dressing or chisel dressing before their actual laying, is called squared rubble masonry.  
• There are two types of squared rubble masonry:

 1. Coursed Square Rubble Masonry:

• The square rubble masonry in which chisel dressed stones laid in courses is called coarse square rubble masonry.  
• It is used for construction of public buildings, hospitals, schools, markets, modern residential buildings etc.  and in hilly areas where good quality of stone is easily available.  

2. Un-coursed square rubble masonry: 

• The squared rubble in masonry which hammer dressed stones are laid without making courses is called un-coursed square rubble masonry.  
• It consists of stones which are squared on all joints and beds by hammer dressing.  
• All the stones to be laid are of different sizes.  
• It is used for construction of ordinary buildings in hilly areas where a good variety of stones are cheaply available.  

Note: Dry rubble masonry: The rubble masonry in which stones are laid without using any mortar is called dry rubble masonry or sometimes shortly as “dry stones”.  It is an ordinary masonry and is recommended for constructing walls of height not more than 6 m.