YOUR DREAM HOUSE
NEEDS SOME FACTOR TO
DECIDE BEFORE STARTING CONSTRUCTION ACTIVITIES
THE MAJOR PART OF
BUILDING
THE STRUCTURE OF
BUILDING
FRAME STRUCTURE OR LOAD
BEARING STRUCTURE
2ND IS
MATERIALS
BRICKS AS CONVENTIONAL
SYSTEM OF CONSTRUCTION
CONCRETE BLOCKS AS
OTHER CONVENTIONAL SYSTEM OF CONSTRUCTION
AUTOCLAVED AREATED
CONCRETE
A REVOLUTIONARY GREEN
SYSTEM CONSTRUCTION
TODAY’S TRENDS FOR
SAVING EARTH
WE RECOMMEND YOU TO GO
FOR AUTOCLAVED AREATED CONCRETE
MATERIALS
FOR STRUCTURE OF YOUR
DREAM HOUSE
WHY SO
HERE IS A WORKING
COMPARISION
COMPARISION BETWEEN
ALTERNATIVE
WALLING MATERIALS
|
S. No.
|
Parameters
|
Aerated Autoclaved (AAC)
|
Burnt Clay Bricks
|
Fly ash bricks
|
|
|
1
|
Basic raw materials and other inputs
|
Cement, lime, sand, Aeration compound
|
Top agricultural soil, Energy
|
Pond Fly ash , lime, gypsum
|
|
|
2
|
Production process and set-up
|
Produced in well established plant
equipped with steam boiler and high pressure auto-claves
|
Processed in specially erected or
central brick kilns
|
Processed in brick making machine
either operated manually or automatic
|
|
|
3
|
Dry Density Kg/m3
|
551-650
|
Reinforced panel
|
1900
|
1500
|
|
|
Compressive Strength Kg/cm2
|
Minimum 30
|
Minimum 40
|
Minimum 40
|
Minimum 75 kg/cm2
|
|
|
Usage
|
Non load bearing blocks
|
Reinforced panels
|
Load Bearing &
non-load bearing
|
Load Bearing &
non-load bearing
|
|
4
|
Pre cast block size
|
625 x 250 x 100mm to 300 mm in
multiple thicknesses of 25mm
|
229x114x70mm
|
229x114x70mm
|
|
|
5
|
Compaction during production
|
None
|
Yes
|
Yes
|
|
|
6
|
Aging
|
No
|
No
|
Yes
|
|
|
7
|
Thermal Conductivity (W/m.k)
|
0.142-0.161
|
0.7
|
N.A.
|
|
|
8
|
Sound Insulation
|
Superior
|
Normal
|
Normal
|
|
|
9
|
Ease of Working
|
Can be cut, sawn, nailed, drilled
|
Normal
|
Normal
|
|
|
10
|
Eco Friendliness
|
-
Green Building
material
Less energy requires in prodn. Phase
- Saves energy in building
|
-Process creates smoke
- uses high energy and
-wastes agricultural land
|
Green Building material
|
|
|
11
|
Water Absorption
|
Due to its material matrix, very low
water absorption takes place by capillary action. The macro pores and
Micropores are not interconnected in AAC and hence very low level of water
absorption takes place.
|
Being a solid mass, a very high
degree of water absorption takes place due to capillary action
|
Not available
|
|
Some of the basic limitations of Fly
ash bricks are elaborated below for your ready reference :
1)
Bulk
Supplies :
Large volumes cannot be supplied on
projects as the manufacturing process has limitations of quantity and curing
methodology. Also availability of the material is a concerned because the
industry is not so organized. They are mostly air cured and in differential
climatic conditions normal curing cycles would not suffice. AAC in contrast is
factory made and is cured in conditioned steam and has uniform quality.
2)
Finishing
:
Consumption
of cement mortar will be more because of surface undulation and smaller product
size , whereas AAC has only + 5 mm variation only.
3)
High
Density :
Fly ash
bricks are high density as compared to AAC and by its usage the overall dead
load on the structure increases. AAC is light weight and reduces the impact of
earthquake forces on fixed structures. The provisions of amended ‘IS-1893’ are
very stringent in respect of control of impact and earthquake process on fixed
structures and therefore the use of lightweight material is recommended. This
is a unique feature which gives it an edge over the conventional system keeping
in mind the seismic sensitivity of your region.
4) Quality :
The quality of Fly ash brick is a concern because of the manufacturing
process and the quality of pond ash used in the process whereas the properties
of dry fly ash used in AAC is completely Stable and uniform .
5)
Basis
of evaluation for Green certification :-
AAC products qualifies for better
rating than conventional bricks because of following factors :
·
Utilization
of fly ash(55-60%) in building structure.
·
Reduce
weight and time of construction by adopting efficient technologies
·
Use
of low embodied energy material
·
Ensuring
a most energy efficient building envelope
·
Reduction
in waste during construction.
Brick wall v/s
AAC wall comparison for external walling
|
Aspect
|
Brick wall
|
AAC wall
|
Remarks
|
|
Thickness
|
|
|
|
|
- External
|
230 mm
|
200/150 mm
|
Saving of 13 to 35 % in material cost
|
|
- Partition
|
115 mm
|
100 mm
|
Saving of 13 % in material cost
|
|
Mortar Masonry
|
|
|
|
|
- External
|
0.051 m3/m2
|
0.011 m3/m2
|
Saving of 78 % in material cost
|
|
- Partition
|
0.02 m3/m2
|
0.005 m3/m2
|
Saving of 75 % in material cost
|
|
- Plastering
|
12 + 15 mm
|
8 + 10 mm
|
Saving of 33 % in material cost
|
|
Labour for work
|
100%
|
60%
|
Reduction of 40 % in cost
|
|
Quality
|
Normal
|
Superior
|
Satisfied Client
|
|
- Longevity
|
May deteriorate with time
|
Gains strength with time as ordinary
concrete
|
Better Durability
|
The structural savings in the cost of Steel and Concrete
due to reduced weight of walls would be an additional advantage. Also because
of better insulating properties of
AAC block the operating cost of HVAC shall come down
substantially.
Cost of AAC blocks in Noida = Rs 3600.00 per cum
(appx.)
Sl.No
|
Material
|
Qty
|
Unit
|
Rate
|
Amount in Rs. Per cu.m.
|
|
|
1
|
AAC
|
1
|
Cu.m
|
3200
|
3200.00
|
|
|
2
|
Cement
|
0.5
|
Bags
|
265
|
132.5
|
|
|
3
|
Sand
|
5
|
Cuft
|
25
|
125.00
|
|
|
|
|
|
Sub
total
|
|
||
|
4
|
Labour Rate
|
per
|
Cum
|
153
|
153
|
|
|
With one
1st class mason, one 2nd class mason and 1 coolie
|
||||||
|
|
|
|
Grand
Total
|
3610.5
|
||
Rate per square feet of
AAC Masonry: -
625 mm x
250 mm x 200 mm = Rs 722.1 per sq. m = Rs
67.10 per sq. feet
625 mm x
250 mm x 150 mm = Rs 541.58 per
sq. m = Rs 50.33 per sq. feet
625 mm x
250 mm x 100 mm = Rs 361.05 per
sq. m = Rs 33.55 per sq. feet
Rate Analysis of Bricks
masonry (1cu.m.)
The
landed rates for Class-I Bricks
at this instant considered per thousand for computation purposes are Rs.2500/-
per thousand bricks. (Considering all season’s rate effect)
Sl.No
|
Material
|
Qty
|
Unit
|
Rate
|
Amount in Rs. Per cu.m.
|
|
1
|
Bricks Class-I
|
500
|
Nos
|
5.25
|
2625.00
|
|
2
|
Cement
|
1.50
|
Bags
|
265
|
397.50
|
|
3
|
Sand
|
10
|
Cu.ft.
|
25
|
250.00
|
|
|
|
|
|
|
|
|
4
|
Labour Rate
|
Below
Plinth Level
|
Cum
|
==
|
===
|
|
|
|
Plinth
Level
|
Cum
|
==
|
===
|
|
|
|
Above
Plinth level
|
Cum
|
170
|
170
|
|
|
|
|
Grand
Total
|
3442.50
|
|
Rate per square feet of Brick Masonry :-
T- 230
mm = Rs 791.77 per sq. m = Rs. 73.58 per sq. feet
T- 115
mm = Rs 395.88 per sq. m = Rs. 36.79 per sq. feet
Hence a quick comparative looks as follows:
External
Wall :
AAC
Block Work (200mm thk)
-
Rate per
sq. ft. for AAC block masonry = Rs. 67.10 / sq. ft.
Cost of 6
mm thick Internal Plaster (1:6) =
Rs. 5.50 / sq. ft.
Cost of 12
mm thick External Plaster (1:6) =
Rs. 7.50 / sq. ft.
Total
Cost =>Rs. 80.10 / sq. ft.
AAC
Block Work (150mm thk) -
Rate per
sq. ft. for AAC block masonry =
Rs.50.33 / sq. ft.
Cost of 6
mm thick Internal Plaster (1:6) =
Rs.5.50 / sq. ft.
Cost of 12mm
thick External Plaster (1:6) =
Rs.7.50 / sq. ft.
Total
Cost =>Rs.63.33 / sq. ft.
Further the cost of Rs.5.50 / sq.
ft. on Internal Plastering can be saved as POP work can be directly done on AAC
Block Masonry.
Brick Work (230mm thk) –
Rate per
sq. ft. for brick masonry = Rs. 73.58 / sq. ft.
Cost of 12
mm thick Internal Plaster (1:6) = Rs.7.50 / sq. ft.
Cost of 15
mm thick External Plaster (1:6) = Rs.8.50 / sq. ft.
Total
Cost =>Rs. 89.58/ sq. ft.
Internal
Wall :
AAC
Block Work (100mm thk)
–
Rate per
sq. ft. for AAC block masonry = Rs.33.55 / sq. ft.
Cost of 6
mm thick Internal Plaster (1:6)
Both Sides
= 2 x Rs.5.50 = Rs.11.00 / sq. ft.
Total
Cost =>Rs.44.55 / sq. ft.
Further the cost of Rs. 11.00/ sq.
ft. on Internal Plastering can be saved, ON BOTH SIDES as POP work can
be directly done on AAC Block Masonry.
Brick
Work (115mm thk) –
Rate per
sq. ft. for brick masonry = Rs.36.79 / sqft
Cost of 12
mm thick Internal Plaster (1:6)
Both
Sides = 2 x Rs.7.50 = Rs.
15.00 / sq. ft.
Total
Cost =>Rs.51.79 / sq.
ft.
The analysis to
be rated in conjunction with all other qualitative benefits of AAC blocks as
described in our technical paper. For
your ease of reference we would like to mention it again as follows:
- Increased
carpet area : Option of using
various thickness of block.
- Structural
saving : Due to dead load
reduction
- Reduction
in Energy cost : Due to better thermal insulation
properties
- Seismic
resistance :Requires less steel for countering
seismic induced forces
- Better
productivity :
No seasonal variations and bigger in size.
Note :- This
above exercise is an indicative , all input cost and assumptions to be verified
at actual during budgetary calculation.
AAC Masonry
Laying Tips:
1)
LAYING OF AAC BLOCK MASONRY
·
The
jointing mortar shall be leaner i.e. 1:6. The mortar shall not be spread so
much ahead of the actual laying of the units that it tends to stiffen and lose
it’s plasticity there by resulting in poor bond.
- Consistency of
cement mortar as per requirement of site must be maintained at the time of
laying .
- Laying of
AAC block masonry shall be in accordance with the recommendations of IS
6041 of 1985 and IS 1905 of 1987. The maximum joint thickness (Vertical
and Horizontal) shall be 10-12 mm.
- The laying
of block may be started either at the corners first or it may be started
from one end and proceed to the other direction.
- Lay 10 mm
thick cement mortar uniformly over block. Wet the blocks on all sides by
using a tray filled with 20/25 mm water and place them one by one and
press it firmly to have proper bond. Ensure proper spread of mortar in the
joints between the blocks.
- The first
course of the cellular block masonry shall be laid with great care, making
sure that it is properly aligned, levelled and plumbed, as this may assist
the mason in laying succeeding courses to obtain a straight and truly
vertical wall.
- Ensure all
the surfaces of the block which comes in contact with cement mortar are
wet to have proper bonding.
- To maintain
proper cement mortar filling at the sill level, please check the height of
masonry and distribute the same along the joints and if the gap is more
same can be adjusted in the bedding mortar. Later the joint shall be
ideally filled up with jute strips dipped in cement slurry so that
flexible joint can be maintained at that level.
- Before
laying the mortar, two 10 mm square rods can be placed on both the sides of the block to
obtain uniform joint.
- The mortar
joint shall be struck off flush with wall surface and when the mortar
stiffening, it shall be compressed tightly.
- Once the
masonry erected the curing shall be minimum unlike brick masonry. The
curing requires more at the joints.
- Before
plastering, cement slurry may be applied on the walls and only leaner mix
shall be applied. The thickness shall be 10-12 mm in the external and
internal walls and in the internal application in case of dry areas even plastering can also be avoided. In such
case directly P.O.P / Gypsum plaster can be applied.
- Maximum
erection of 5-6 courses is desirable in a day.
2) Chasing and cutting
·
Blocks shall be cut with a saw.
·
Where ever chasing to be done
in AAC Blocks, rotary cutters to be used. After marking the area, AAC material to be scooped out with light
hammer and chisel. If requires standard tools of Fischer, Hilti make may also be used .
·
The chases shall be refilled
with leaner mortar and chicken mesh (as per Consultants recommendation) shall
be applied on that area.
All other structural requirements like placing of joint
reinforcement, bond beams etc. is to be
considered in accordance with the recommendations laid down in I.S. Codes- 6041
& 1905
SPECIFICATION
SHEET
Product
Dimension:
|
Product
|
Length
|
Height
|
Thickness
|
|
AAC Block
|
625
mm
|
250 mm
|
100 mm,
125MM,150 mm ,200 mm,225MM,300MM
|
Properties of AAC
Block:
|
Properties
|
Values
|
|
Density (Oven Dry)
Compressive Strength
Thermal Conductivity ( K Value)
Resistant to Fire
Drying Shrinkage
Design Gross Density
|
551-650
Kg/Cum
Minimum
30 Kg/cm2
0.17 W/mK
( on average)
2 - 6
hrs depending upon Thickness
0.1 %
850 Kg/Cum. (appx.)
|
Specification of AAC Block
work:
|
Providing and
laying of Autoclaved Aerated Concrete
(AAC ) block masonry using blocks having dimensions of 625 mm x 250 mm.
thickness ranging from 100 mm to 300
mm conforming to I.S. :2185(part-III) .The jointing cement sand mortar in the
composition of 1: 6 (Cement: sand) shall be used with suitable plasticizer(optional). Sand
having modulus of fineness 1.1 shall be used. The horizontal and vertical
joint thickness shall be approximately 10 mm. In case of partition walls (100
mm /125 mm thk.) the joint reinforcement shall be placed at every alternate
course to be anchored properly with the main structure. All other structural
requirements like stiffening of masonry , joint reinforcement etc. in the AAC
masonry work strictly be carried out as per instructions laid down in .I.S
6041 – 1985, I.S -1905.
|
HOPE THIS FORCE YOU
TO
THINK
AND YOU HAVE MORE
QUERIES ABOUT THIS
IF SO
JUST MAIL YOUR
QUERIES TO ME
ER. KAMAL
projectconsultantengineers@gmail.com
