|Sat Oct 04, 2014||Post #1|
|S L Gupta (Civil Engg)|
Join date: Mar 2008
ROOF WATERPROOFING BY BRICK BAT COBA
Roof slabs constructed either by RC or RCC needs insulation for thermal
comfort and waterproofing treatment to prevent leakage of water. Both
these requirements are effectively full fill by brick bat coba
treatment, the details of which are being below:
All existing treatment, coatings on roof slab top is to be removed
and surface cleaned by hard wire brush and washed with water. The
surface should be free from any oil, grease, dust etc. Remedial measured
by provided to all structural cracks. Expansions joints should be
treated as per standard practice.
All non-structural cracks more than 0.5 mm wide and construction
joints if any, should be cut in “V” shape, cleaned with wire brush and
washed, the cracks are then filled by polymer modified cement or mortar
using acrylic polymer, with addition cement slurry mix is spread upon
cleaned SSD roof surface. Over this 15 mm thick cement, sand mortar, 1:4
admixed, with water proofer is laid.
BRICK BAT LAYING
On the above green mortar, a layer of brick bats, soaked over night in
water, is laid, having an average thickness of about 110 mm, about 70 mm
near rain water pipe and 150 mm at ridge.
The gaps between the brick bats are generally kept between 15 and 20
mm. These gaps are filled with cement sand mortar, 1:4, admixed with
waterproofer. In hot and dry weather, the surface should be covered with
wet gunny bags immediately after finishing. Curing should start next
day and continued for 7 days.
The top surface is then finished smooth with 20 mm thick cement sand
mortar, 1:4, admixed with a waterproofer. All liquid admixtures should
be mixed with the mixing water. The surface when green is marked with
300 mm false squares. Curing is to be done by ponding.