WORK METHODOLOGY / PROCEDURE OF AAC BLOCK MASONRY
& PLASTER WORK
GENERAL
ØSizes of
blocks available are L-600mm x W-200mm x H-(75 to 300mm )
Ø Blocks
will be stacked on level ground.
Ø Blocks
will be preferably placed in 200mm height ( not width wise ) and the stacks
should not be more than 8 to 10 in numbers in height.
Ø For DPC course a layer of 100 mm thick PCC (1:2:4 hand mix, only
10mm aggregate mixed) will be provided on first layer of AAC block.
Ø Compressive strength of AAC block will be 4 N/sq.mm for Grade-I
and 3 N/sq.mm for Grade-II.
Ø Grade of blocks shall be finalized before procuring and it shall
be approved from client.
Ø RCC bend (Patli beam) will be provided at a height of 1 mt to 1.2 mt from top of DPC
level or as per drawing and specification.
Ø Reinforcement for RCC bend :
2 nos of 10dia. horizontal bar and link bar at 200 mm spacing and drill shall
be done upto 50 mm deep in RCC column or wall for horizontal bars.
Ø Ready mix mortar or any approved material shall be used for filling
the gap between RCC beam bottom and Block wall top.
Ø 10 to 20mm size of aggregate shall be provided for metal packing
at 50mm spacing at RCC beam beam.
MASONARY WITH AAC BLOCKS
(Using jointing mortar)
a. a. Mixing of Jointing Mortar b.
Appling of Jointing Mortar
c. c. Fixing of AAC Blocks d. Thickness of AAC Block Joint
Ø Only
approved Block jointing mortar shall be used for jointing of AAC Block.
Ø Block
jointing mortar shall be approved from client before using.
Ø Block
jointing mortar shall be mixed with approximately 25 to 30% of water (Which is
10 to 15 lts of water for 40kgs of jointing Powder) or as per manufacturer
guideline.
Ø Mixing of
jointing mortar shall be done by using of electrical operated mixture machine.
Ø Mix of
jointing mortar shall be a homogenous, lump free mixture and ensure no powder
is left unmixed at the bottom.
Ø Place the
first line of blocks on concrete slab using ready mix plaster mortar or cement
mortar having 1 : 4 ratio (i.e.- 1 part Cement : 4 part Sand).
Ø Ready mix
mortar will be used as a leveling course of 15 to 20mm thick.
Ø The blocks
will be placed in the direction of 200mm height while doing the masonry work.
Ø Pre-wetting
of blocks is essential and post application no curing is required to the mortar
joints.
Ø Care
should be taken to make sure that adhesive spread on the block uniformly.
Ø Racking
shall be done at joints of blocks for proper bonding of plaster
Ø At the
junction between RCC and AAC block masonry, PVC chicken mesh will be used to
avoid cracks in the corners and junctions.
Ø The height
of Patli beam or distance of Mullions will be provided at as per drawing and
specification or as per advice of Client or consultant.
Ø The work
of concealed plumbing or the electrical wiring fittings, etc. will be done in
proper workman like manner using proper tools to avoid damage to the blocks and
to avoid cracks in masonry work.
Ø The
surface is now ready for plaster, at this stage pre wetting to the blocks is
essential before application of plaster.
Ø Plaster
can be started after 24hrs of constructing the wall if Block jointing mortar is
used.
Ø Mullion is
recommended at both the side of door frame for better holding of door frame.
FIXTURES IN AAC BLOCKS:
For
fixing various fixtures, like door and window frames, wash basins, electrical
fittings, etc., to AAC block walls, wire nails should not be used as they have
low holding power. Use of aluminum cut nails gives satisfactory results. It is
recommended that they be skew driven to obtain a dovetail effect.
1. Door Frame Fixing 2.Window Openings 3. Chasing for MEP Groves
a) Door
and window frames are attached in the surrounding masonry with 7” aluminum or
galvanized iron cut nails hammered directly into AAC blocks. 14 gauge screws
may be used, and they should penetrate at least 75mm into the AAC blocks and
should preferably be driven into rawl plugs. All screws shall be inserted into
the blocks and not along the joints.
b) Wash
Basin shall be fixed to the wall by using 3” x 14 gauge screws in rawl plugs.
Where wash basins are mounted on brackets, use of 4” x 14 gauge screws in rawl
plugs will give sufficient strength and rigidity.
c) Light
fuse boxes and switch boxes should be fixed using 3” x 10 gauge screws in rawl
plugs. Heavier fittings should preferably be mounted on the floor or fixed with
through bolts. Wall brackets, light switches, should be fixed using 8-10 gauge
screws, not less than 3” long in rawl plugs. Where conduit runs are made on
surface the supporting saddles may be fixed with 2” x 10 gauge screws directly
into AAC blocks or where the conduit is likely to be subjected to loads during
the erection, by 8/10 gauge screws in rawl plugs.
d) Wherever
possible handrails should be fixed using 4” x 14 gauge screws in rawl plugs.
Ø Before
taking up plastering work it shall be confirmed whether concealed electrical
and plumbing lines are completed and tested.
Ø The
surface to be plastered shall be chipped off any projection, brushed off for
dirt and efflorescence and hacked off (for RCC only).
Ø All
substrate defects shall be patched up before plastering.
Ø The
surface shall be well soaked and touch dry before starting plaster work to
avoid absorption of water present in the mortar by the dry masonry.
Ø Any
admixture to be used in the mortar to be decided and approved in advance and
used as per manufacturers recommendation.
Ø Quality
of Ready Plaster shall be approved in advance if ready mix plaster is used.
Ø Mix
one bag 40kg ready mix plaster with approximately 7 to 9 liters of water is recommended
or as per manufacturer guideline.
Ø Mix
thoroughly for 3 to 10 mins until the desired homogenous mix is achieved.
Ø For
conventional plaster cement sand ratio of 1 : 4 (1 part Cement : 4 Part Sand)
is recommended.
a. a. Mixing by Mixture b. Mixing Manual
Ø Ensure
the mix is free from lumps before use.
Ø The
mortar shall be prepared on watertight platform and consumed with in 90 minutes
after adding water.
Ø Number
of layers, thickness of each layer and type of final surface finish shall be
decided as per requirement of drawing/specification.
Ø In
case of two coat plaster, top surface of first coat shall be kept 12 mm in
thickness with zigzag lines (but leveled) for proper bond with top coat of 8 mm
in thickness.
Ø Succeeding
coats shall not be applied before 24hrs of first coat plaster. Lines, levels
and corners are to be properly maintained before starting of second coat of
plaster.
Ø When
the work is suspended at the end of the day, the plaster shall be left cut
clean to line both horizontally and vertically.
Ø When
plastering is resumed the edge of the old work shall be scraped, cleaned and
wetted with water before plaster is resumed.
Ø Intermittent
curing for AAC Block Masonry is not required
Ø Curing
for Plastering to be done for a period of 7 days.
Reference
Documents
|
Sr.No |
Document
No |
Title |
|
1 |
IS:2185 |
Block
Specification |
|
2 |
IS:6041 |
|
|
3 |
IS
1542 |
|
|
4 |
IS
8112 |
|
|
5 |
IS
1489 |
No comments:
Post a Comment