Thursday, November 24, 2011

Traditional Waterproofing Practice

           1.      Brick Bat Coba:


This involves laying of 80-100 mm thick coba concrete on a prepared surface with graded broken aggregate. This treatment though successful in the damp heat of coastal region; it cracks up completely on contact with the dry heat, besides having the disadvantage of imposing an unnecessary load on the system. Brick being a porous material absorbs more water through the cracks and causing the corrosion of reinforcement which ultimately leads to spalling of concrete of the roof slab.

For more information regarding the disadvantages of BBC go here => http://www.coa.gov.in/mag/Archi_Nov09-Lowres/30-31_Archi%20Nov-09.pdf



Misconceptions




There are few misconceptions regarding this conventional waterproofing by Brickbat Koba. That china mosaic topping helps to create water barrier is wrong. Some times the joints of china mosaic may develop a deboned joint making a vent to seepage.

That brickbats create water barrier is also wrong as bricks are porous. Brickbats are in fact used to maintain the slope. Weathered bricks are good for system which is again a wrong concept.

Good quality new brickbats should be preferred. This system provides a very good heat insulation to terrace slab.

Also, it absorbs the vibration and allows the concrete and mortar to breathe and vapour pressure is defused. The entire burden of creating water barrier lies on cement mortar.



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