It is made by crushing the clay bricks into small pieces of approximately 40mm to 50mm in size. Bricks used for crushing are slightly over burnt or left over half cut bricks on site during brickwork masonry. Brick ballast is used for making pads underneath the foundations along with the mixture of cement and sand. It is also used under the floor PCC that is laid on compacted earth-fill. Brick blast should be made from “Awwal” A class bricks, as the strength of foundations and floors is heavily dependent on quality of brick ballast.
Quantity check on site
It is delivered on sites in tractor trolleys that have a normal capacity of carrying 350(3.5 sankra) to 400(4 sankra) cubic ft. of brick ballast when filled to vehicle’s capacity. Calculations for quantity check are carried on same formula that is used for sand and crush. However calculations become impossible when it is delivered on site in form of half or partially cut bricks and the crushing is to be done on site by special brick crushing labor. In this scenario quantity check is carried out after the crushing has been done. Crushing should be carried out in such a way that labor should arrange brick ballast as shown in the picture below. In local language ask the labor to make “dari”.
Once you have brick ballast arranged in this shape, apply the same formula to calculate total quantity.
Total Quantity = Length (ft.) x Width (ft.) x Depth (ft.)
Quality check on site
As stated earlier brick ballast should be of good quality for the strength of foundations and floors. Make sure bricks used for crushing are A class (Awwal). Maximum 20% mix of over burnt bricks (Khinger) is acceptable. Brick ballast should be clean, any kind of dirt, leaves, straw or soil materials indicate that the ballast is old or has been collected from some other site. Size of brick ballast should not exceed 50mm so that the material can make bond when laid and compacted. Larger size means more open spaces will be left between pieces that can affect the strength of foundations and floors.