KM_C554e-20150630104853Dr. N.CHITHARANjAN Assistant Professor of
Structural Engineering
Col!ege of Engineerlng Anna Unlversity Madras 600 025 SOUTH
INDlA
T.P. KALIAPPAN Chief Englneer
Tamil - Nadu Slum Clearance Board Madras 600 005 SOUTH INDlA
ABSTRACf
The Cel!ular Concrete Plant at Madras, set up under the Indo-Polish
col!abora tion, by Tamil Nadu Housing Board, one of the major
housing organisations in India manufactures medium sized '07' type
Celcrete blocks which are used for its construction activitles. In
splte of the strlct quality contraI cracking of Celcrete during
manufacture could not be completely avoided and it is a problem for
the authorities to dispose of this waste material. This article
enumerates the feasibility study of using this waste material as
aggregate for the manufacture of light weight concrete precast wal!
elements. The structura I behaviour of these wal! elements are
experimental!y verifled and their suitabillt y for the proposed
Houslng kit for mass Housing schemes are dlscussed.
INTRODUcnON
Inspite of the untiring efforts of various housing organlsations,
catering the housing demand due to the growlng population in a
developing country like India is a perenniel problem. Considerable
research (1 - 5) has be'cn carried out by variolls research
organisations in India to deve lop new construction techniques
using local material for low cost housing. Many housing projects
are seriously affected by the non predictable scarcity of
conventional building materiaIs, dearth of skil!ed labours and due
to the escalation in the cost of materiaIs and construction. To a
certain extend these problems can be solved by going in for partial
prefabrication techniques and by using iocai materiaIs.
The Government of Tamil Nadu, South India has launched a major
housing scheme for providing shelter for Thirty Lakhs of homeless
poor in three years. Tamil Nadu Housing Roard anel Tamil Nadu Slum
Clearance Board are the two major Governmental organisation wh!ch
are seriously involvcd in this venture
2
and are attemptlng various low cost materiais and construction
techniques (6). One such attempt Is the utlllsatlon of Celcrete
wastes for the manufacture of light welght concrete sultable for
the prefabrlcated wall panels (7). The system conslsts of precast
column and panel elements whlch are jolnted together to assemble
wall panels sultable for the proposed Houslng klt for mass houslng
schemes. The structural behavlour of these wall panels when
subjected to Inplane vertical and horizontal loads and due to
uneven settlement of foundatlons are experlmentally studied. The
method of assembling of the wall panel is brlefed and the
economlcal feaslbIlity is dlscussed.
DESIGN OF LIGHT WEIGHT CONCRETE USING CELCRETE WASTES
CelIular Concrete Plant at Madras, set up by the Tamll Nadu Houslng
Board under Indo-PolIsh collaboratlon Is intended to manufacture
'07' type Cellular Concrete blocks for mass housing schemes.
Inspire of the strict quaIlty control the cracking of Celcrete
durlng the manufacture and handling cou ld not be avolded. This
waste material could be used for the manufacture of IIght weight
aggregate concrete (4).
The strength of light welght aggregate concrete (o) Is related to
the strength of aggregate (o ) and that of the mortar (o ) as
a In
o = (o ) no (1-n) a m
where n Is the volume fractlon of aggregate per unlt volume of
concrete, (5).
The suggested nomograms (Figure 1 and Figure i-) can be used for
design of a IIght welght concrete of strength upto 14 N/mm, u sing
Celcrete wastes as aggregates. F.:arller studies revealed the
sultabillty of thls cüncrete to use in composlte wlth relnforcement
for precast roof panels for mass houslng schemes (8,) and as wall
panels for precast twln type W.C. units for sltes and services
schemes (9). Therefore It Is proposed to use thls concrete for the
load bearlng wall elements üf suggested Housing klt.
HOUSING KIT
The suggested houslng kit conslsts of precast components which can
be procured from a centralised precasting plant, transported to the
site and assembled at a faster rate wlth lesser labc)ur cost. The
plan and sectional elevation of the proposed twln type model house
uslng the sugges ted technlque Is shown In Figure 3. The f10w line
productlon of the proposed housing kl t Is diagramatlcally shown In
Figure 4. The objectlve of the present study is to manufacture
Individual precast wall and column elements uslng celcrete waste
aggregate concrete and to assemble prefabricated walls. These walls
will be tested for the followlng loading condltlons:
-----.
-
~ 12.0 w a:: tii 10.0 w > üi ~ 8.0 a: a.
"" r'\. '\..
'\.. r'\..
"
I 1
8 6.00.6 0.8 1.0 1.2 1.4 1.6 f'... I ./ 1
I ./ w 0.0 w
~ 4.0 4 W/C RA TIO 8Y WEI6HT ! V w ~
FIG.1 RELATlON BETWEEN COMPRESSIVE STRENGTH ANO WATER CEMENT RATIO
FOR CELCRETE WASTE AGGREGATE CONCRETE
r I
~ 9.0 ~ ~ ~O ~ ~ 5.5 8.0 w 4: 6.0 8.0 10.0 12.0 14.0 16.0 "" 8
COMPRESSIVE STRENGTH N/mm2 u.
FIG.2 A DESIGN CHART CONNECTING QUANTITlES OF VARIOUS MATERIALS
REQUIRED FOR CELCRETE WASTE AGGREGATE CONCRETE
C.lcr.t. wast. aggrogat. panol roofs
Flooring
R.C.C.l:8.16- ;,";; 1
'" N o
V V =_-:-:.w= _..:.:=-::=-_- = :-.=c==<=-
O o t-o 45_i 100_0 r )(X~ si 1000 ,f 1000 ~ -lõ~j PLA N
-1 W:
FOUNOAnON
Pr~st \Vali Elemenu
joisu or 2. Cela,etc Reln!orc~d
A,r.rel.~t~$te AerO<""..!cte
Cuncrete Panel (lei
SUGGESTED LOW COST
HOUSlNG KIT 1
FlN1SHfNG
Colour
Whlte
Wuh
FIG.4 FLOW lINE FOR ASSEMBlING A TYPICAL HOUSING KIT r a5 A-i
-
(a) WASTE AGGREGATES
(b) COLUMN MOULD
---
Mlx Deslgn
It is proposed to manufacture hal f scale models using Celcrete
waste aggregate concrete. Celcrete wastes obtalned from the
Cellular concrete Plant, Madras Is hand crushed to the require2
slze and used as aggregates (figure 5a). A concrete of strength 7
N/mm is arrlved at uslng figure 1 and figure 2. Locally avallable
river sand and ordlnary Portland cement are used. fo'r mlxlng and
curing potable water Is used. Two types of wooden moulds are used
(Figure 6).
Manufacture of coIumn elements
The details of the reusab!e mould can be seen from figure 5.b. A
central rod of diameter 20 mm Is held vertlcally during the casting
as shown in Figure 5.c and as sooo as the mlx sets, this rod is
removed to induce the duct whlch Is used to provide relnforcernent
for the column durlng the assembling of the panel. Samples are
water cured for 28 days anú each pane! of slze 1.5 m x 1.5 m
requlre 16 column unlts.
Manufacture of wall elements
Same mix Is used for wall elements also. Samples are cast on leveI
ground using detachable wooden forms (figure 5.d). After three
hours the slde forms are removed (figure 5. e) and reused. The
samples are water cureú fOí 28 days.
Castlng of base beam
To simulate the pllnth beam at the slte a reinforced concrete beam
of slze 1600 mm x 100 mm x 30 mm (figure 7) Is used for the
assemb!y of the test samples. At speclfled spacing 10 mm dia meter
rods are extended from the base beam whlch wl11 serve as gulde for
allgning the columns and to serve as column relnforcement. Using
cast Iron plpes of 40 mm dlarneter holes are provlded at speclfled
spaclng to anchor the wall element to the test bed.
Castlng of rlb elements
A seperate relnforced concrete contlnuous ribs of size 1600 mm x 50
mm x 50 mm relnforced wlth 4 numbers of 6 mm diameter ml1d steel
bars as maln reinforcement and 6 mm dlameter rlngs at 150 mm c/c as
Shear reinforcement, are casto This rlb is Inteoded for the pro per
distributlon of load over the panels.
Assembly of prefabrlcated wall elements
Three numbers of Wall Panels of slze 1600 mm x 1600 mm x 50 mm are
assembled as descrlbed below (figure 8).
6
x
-j 1-12
---I 75 t---
T .1 100
PLAN (a)MOULD FOR COLUMN ELEMENT
'--175~
Rings 6mmj1! MS aI 20mm CC
6 nos of 12 mm j1! R T S
D3 I. 1600 .1 ~
--..
.. .. • .. ..
(c) PANELS INSERTED (d) SECOND LAYER (a) ASSEMBLING IN
PROGRESS
• .. (.9) TOP RIB FIXED
FIG.S ASSEMBlING WALL PANELS
8
o Fixed the base beam on the test bed with suitable anchorages.
(Figure 8.a) o Align the vertical rods extended for the base beam
and insert four
numbers of column elements. (Figure 8.b) o Insert the panel
elements through the grooves ava!lable in the column
elements and groutwell uslng 1:3 cement mortar. (Figure 8.c) o
Insert the second and thlrd layer of panels by whlch the panels
extend
over the helght of the column elements. Insert the second layer af
column elements. (Figure 8.d)
o Repear the process tlll the celllng helght Is reached. (Figure
8.e) o If necessary spec!ally cast half wall panels may be used at
the top levei. o Insert the top horizontal rlb through the holes
provlded to accomodate
relnforcement from the column elements. (Figure 8. f and Figure
8.g.) o Check the vertlcallty of individuai elements as well as
panel a whole unlt
and grout the jolnt.
Cure for 7 days by spraylng water before load testo
The deta!ls of assembly of the wall panel for settlement study Is
the same as that of the earlier samples, except for the depth of
the base beam is reduced to 100 m m.
TESTING
Three numbers of samples are tested In the Test bed ava!lable in
the Structural Engineerlng Divislon. The samples for lateral load
test Is firlnly connected to the test bed. The disc type of
dlsplacement meters are used to measure the deformatlon.
Rectangular Rosettes are pasted at specifled Intervals on the
surface of the wall panels for measurlng the straln variatlons for
incrementaI loadlng.
Testlng of Wall Panel for Inplane VertIcal Loading
The load Is applied through a loadlng tree to slmulate unlformly
dlstrlbuted load uslng a 20 tonnes Hydraullc jack and a provlng
rlng (Figure 9.a). Panel deformatlons are measured at every 0.25
tonnes Increment of load and the straln varlatlons are noted for
every 2 tonnes Increment of load. The first crack. appeared at a
line load of 25 KN/metre run over the wall panel and the sample
failed at an equlvalent line load of 38.40 KN/metre run. Though the
first crack appeared In the vertical dlrectlon the final fa!lure
was due to horizontal jolnt failure due to the buckllng of the wall
panel (FIgure 9.b). The varlatlon of principal stralns on the
surface of the panel was negllglble. Treatlng as a slngle storey
bullding wlth flat roof but wlth no access, the service load works
out to 13.5 KN/metre run Inclusive of dead loads. Even the observed
cracklng load (25 KN/metre run) is 1.85 times the anticlpated ser
vice load. Thls test revealed the suitablllty of this wall panel to
use In low cost houslng conslderlng the strength cri teria beca use
the panel was Intact even after testlng (Figure 9. b.).
Testlng of Wall Panel for Inplane Lateral Loadlng
The dimenslons of thls test sample Is similar to the earlier one
and is rlgldly anchored to the test bed. Uslng a 5 tonnes hydraulic
jack anel provlng ring lateral load is applied at the top
horizontal rib. Lateral deformations are measured uslng disc type
displacement meters and correctlons are made for the upli ft of the
panel as a whole. The first horizontal crack
, " " l~'
9
FIG.9 TESTED SAMPLES
(o) FAILURE DUE TO BASE BEAM
10
appeared at about 30 percent of the ultimate load levei (8.50 KN).
On further loading subsequent joints failed and at about 88 pe r
cent of the ultimate load levei vertical seperation between the
column a nd panels are wltnessed. Lateral deformatlon behavlour of
the panel Is shown In Figure 10. Rosette readings could not give
substantial information. The fallure is initiated by propogative
horizontal cracks followed by vertical seperation of column and
panei (Figure 9.c). Th is study e nlightened the struc tural safety
of the panel against accedental iate ral ioads.
Testlng of Wall Panel for uneven Settlement
To lnduce uneven settlement thls panel Is supported on rollers with
equal ove r hang on both sides and is subJected to inplane vertical
ioad. The flrst c rack appeared at 0.53 times the ultlmate load
ievel (60.32 KN/metre run). Upto 74 percent of the uitimate load
leveI the buckllng was not so serious (Figure 11). However at about
87 percent of the ultlmate load le veI the lateral buckllng was
predomlnent. The first vertical crack appeared at 0. 38 times the
ultirnate load levei and extended towards the overhang support at
0.83 times the ultlmate load levei and the overhang falled a t the
ultimate levei (Figure 9.d). The settlement of the wall pane l is
shown In Figure 12. The monollthic behaviour of the \vall elements
are evident from the principal stress contours shown in Figure 13.
The behaviour of this panel is similar to the panel tested without
settlement. This test revealed that inspite of the increased number
of joints the provision of base beam which s imulate the ca;:Jplng
beam at the site ellminates the catastrophical failure o f the
structure (Figure 9.e).
Testlng of lsolated Column Elements
A full scaie column of the same mix and of height 3.0 m is cast
uslng the same principIe and tested to destruction. The test sample
could carry 99 percent of the ultimate load that could be carried
by an identical column cast monolithlcally. Thls study also
revealed that the provlsion of reinforce ment at the ce ntre for
the column has not seriously affected stre ngth provided the
eccentricity of load is ellminated.
CONCLUSIONS
Celcrete Wastes as Aggregates for Concrete
o The suggested nomograms can be used wlth confldence for mix
designo o Conventionai brlck work can be replaced by this concrete.
o Earlier studies revealed the suitabillty of this material for
relnforced
structural elements.
Precast Elements
---
10 20 30 Deformation in mm
1.00 Pu'
1000 1600 500
1 lf . o o
FIGlO LATERAL DEFORMATION ;:F A WALL PANEL DUE TO INPLANE
LOAD
0. 19 Pu' O.35Pu·
T Bale I beam
( li ) W ithoul slZttlement
p
300 nJ
FIG.11 BUCKLiNG OF WALLS DUE TO INPLANE VERTICAL LOADS
U ltimate load Pu' ~ 95.50 kN
1000 - ---....... ,- 300-.
FIG.12 DEFLECTlON PROFILE OF A BASE BEAM EXPERIENCING UNEVEN
SETTLEMENT
FIG.13 MAXIMUM PRINCIPAL STRESS CONTOUR FOR VERTICAL INPlANE LOAD
(40 kN)
12
Prefabricated Panels
o Panels could be assembled at a faster rate. o Panels and column
elernents could be jointed using 1:3 cement mortar and
the same mortar can be used for grouting the column ducts.
Structural Behaviour
o Inspite of the slenderness the precast wall elements could
withstood without buckling a load equal to 1.85 times higher than
that of the design service load.
o The wall pane! was intact upto 80 percent of the ultimate lateral
load levei.
o Inspite of the uneven settlernent the perfect composite behaviour
of the elements in the wall panel was witnessed upto 80 percent of
ultimate load leveI.
Behaviour or lsolated Column
o The load carrying capacity of the assembled column is comparable
with that of the monolithic one.
o For axial load without eccentricity the provision of
reinforcement in the central core of the column is
permitteri.
Housing Kit
o The required precast components for a twin unit can be easily
transported to the site in a 5 tonnes lorry.
o Complete structure above foundation can be assembled in a weeks
time. o Door and Window openings can be provided by suitably
eliminating the
panels at the requireri spaces. o Precast lintel cum sunshade can
be provided for door and window openings. o By providing suitable
joints plastering can be eliminated.
General
o Suggested technique is 30 percent cheaper than conventional brick
construction.
o Adoption of this technique leads to effective disposal of
CeIcrete waste.
ACKNOWLEDGEMENT
Authorities of Anna University, Madras, South India, are thanked
for extending the laboratory facilities to carry out the
study.
Authorities of Tamil Nadu Housing Board and Tamil Nadu SI um
Clearance Board are acknowledged with thanks for their constant
encourage- ment in this study.
13
REFERENCES
1. Vashneya,] .K. and Mathur,O.N., 'Hand Book of Rural Housing and
Village Plannlng' National Bulldlng Organisation, Mlnlstry of
Works, Houslng and Supply, New Delhl, 1963, pp. 36-44.
2. Chitharanjan,N. , 'Long Span Br!ck Panel Roof for Mass Hous!ng',
the Ind!an Concrete ]ournal Vol.60, No.l, january 1986, pp.
9-14.
3. Chltharanjan,N., 'Development of Llght we!ght Concrete and the!r
Appl!cat!ons to the Reinforced Flexual Members', A Ph.D. Thes!s
approved by the Un!verslty of Madras, May 1980, pp. 16-42.
4. Chltharanjan,N. and Kumaresan,S., 'Design of Llght weight
Concrete using Industrial Wastes', Proceedings of the IAHS
International Conference on Housing Problems In Developing
Countries, Dehran, Vol.II, December 1978, pp. 123-130.
5. • ..................... . , 'Proceedlngs of the Flrst
Internatlonal Congress of Llght ~elght Concrete', Cement and
Concrete Assoc!ation, London, Vol. lI, May 1968, pp. 12-30.
6. Kaliappan,T.P. and Chitharanjan,N., 'A Socio Economic Approach
for Provlding Shelter for the homeless', Proceed!ngs of the IAHS
World Congress on "New Trends on Hous!ng Projects Emphasising
Developlng Countries", Miami, Florida, Dec. 14-20, 1986.
7. Padmanabhan,N., "Development of a Low Cost Hous!ng Kit", A M.E.
Thes!s approved by the Anna University, Madras, j anuary 1988, pp.
1-117.
8. Chitharanjan,N., 'Utillsat!on of Celcrete Wastes for Low Cost
Rooflng Elements', a Research Report submitted to the Tamil Nadu
Housing Board, Madras, ] uly 1986, pp. 1-35.
9. Chltharanjan,N., "Prefabricated Twin Type W.c. Unlts for Sltes
and Servlces Schemes", a Research Report subm!tted to the Tamil
Nadu Housing Board, Madras, jan. 1987, pp. 1-25.
10. Chitharanjan,N., Sundarargan,R., Devadas Manoharan,P.,
'Development and Applicat!on of Aerocrete with Non-metalIic
Fibres', Proceedings of the International Symposium on F!bre
Reinforced Concrete, VoI. lI, Madras, Ind!a, Dec. 16-19, 1987,
pp.7.63-7.74.