'

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. ,.=..:I'!\.JSTRll.r-...... 'J[n"1 ,..li' """'~OLO.r'iY ·ANn rvt ~ ""rAc:."K•_,11T.!NT ~~,.. v1·~ __ __:. ..;..l....,.. ~-· ! J!Q_.:. ... f~ J! ~~_.._.nu~ .! .: '~ -.. ~- ..L~.a..MU~ -J.§LJW.Ii:!JJ.., ..e.

Volume 2 Number l Julv 1999 EDITORIAL

-~=-----·-·~~~~=---~--===---.;.._---------~-=

' \ \ I

Ma~rialsffcclino!agy \

t. The Influence of Anatomv a..nd t.wde of Seasoning on the strength Propejties of Bamboo A Adererni .... ...................... ......... .. ....... ... ..... ... ~---········ · · ··· · - ···· ·· -·-- · · · ·· - ···· · ·- ·· ······ · ···· · · ......... ........ .. ..... .... ... ..... ...... .. !

2. Evaluation of a Solar Heated Drv.er in com~son with Ambient Wood drying M Akpan ............ .. ... .. ... ... .. ... ,"... .. .. .... .. ...... .. ............. ... ........................... ....... .. .............. .. ......... . ... ..... .. .. .. .. B

3. The Relationship between Strength and Nnn-destructive Parameters of Murex - Dye Shell concrete D 0 Adeagbo & Y D lzam ... .. ...... ,......... ........... .... . .. ..... .... ....... ........... ... ... .. .... .. ................... ......... .... .. .... .. .. .. .. .. ! 2

4. Strength Properties ofRevibrated Concrete SA B11stani & E Achuenu .................................. .. ............. .... .. ...... .............. .. ............. .. ............................ .............. . i 7

5. Some Characteristics of AHA/OPC ConCr-etes: A Preliminary Assessment I i Dash all & E E J Kamang .............. .............. ................ ................... .. ... .... ................ .... ....... ....... ................ . ... . 22

6. Characteristic Properties of Jinglin S:md J A Egwurube & A A Omolegbe .................................... ... ............ . ...... .. .... ... .... .. .... ... ..... ..;... .. ..... .. ................. 30

7 Applicability of a Local Pumice stone as Light weight Aggregate for Concrete · G S Olaoye & E E J Kamnng ..................................... .. ........... .. ..................... ... .. ...... ........ .............. ..... ............. .... . 34

8. Avoidance of Condensation in large Panel Construction in Tropical Buildings P 0 Nwanlrwo .. ...... ............................ ...... : ....... : ... .......... . : ...... ................ ............. ......... .. .. ... .... ... .. .... .. ... ... ... ........... . 42

9. Preliminary Study ofthe Properties ofCompressed Straw Slabs 0 G Okoli, J A .4peh wu! M M Ga!'h~ ............. ............. .. ............................................. .... ........ ... ..... ....... ... ... ..... ...... 46

Areltitecture/Planning

10.

• i ! •.

12.

B .

Traditional Housing Forms in Nigeria: A Brief 1\Juiysis of the Regional Styles. I U Hussainr ... .... ....................... ....... ....................... .. ... ...... ~ .......... ................. .. .......... .. ... .. ...... .... .......... .. ......... .... . 53 Y oruba Traditional Residential Designs: The Oi'4er in the Chaotic I A Oliewole ..... .. ................ .. .... .. ..... ...... ... ......... ..... .... ................ ............ .. .............. ........ ... .. ... ........... ................. : .. . 60 Influence of Rural -Urbr.. 1 Migrants ' Attitudes oo Seif Help Housing in Nigerian Urban Centres ZA Uji ................................ ................ .... .. ................... .................... , .............. ..... .. .............. .... ....................... .. .... 67 Strategies for Eradication of Slums from Nigerian Cities SA Sumaila & A A_ lsaiL .......... .. .. ... ....... .. ......................... - ...... .............. ............................................ : ............... i6

Economics/I\Ilanagement

14. Analysis of Major Delay Factors in Building Project Execution. J I C Mbachu & G S O!aoye ...... ... ... .......................................................... .......................................................... 8 1

15 . Productivity Problems of Unskilled Labour on Nigerian Building Sites:· The Case of female Operatives Y D lzam & D 0 A.deagbo ......... ........... .. .. ............ .. ............ ................................... ...... ................. .... .. ...... .................. 87

16. Economics of Alternative Construction Materials: Some Conceptual Issues N A Arzigbogu .. ... ..... ... .. .. ........ .... ........ .. ......................... .. ........... ....... ..................... .. .... ... ......... ... ......................... ... 93

17. Manpower Development in the Building and Construction Industry J 0 Kolawole d: F N FmJ:k ............ .. ...... ........ .. .. .. .......... .. ... ................ .-......... ; ....... .. ... .. ........ .. .. ............. .. .... ........... 97

18. Low-Cost Housing in Nigeria: The Case of Incorporating laterite Bricks, Direct Moulding of Sa'ldcrete Blocks, and Cardboard as Components P 0 Lawai ..... ...... .. ....... ... ........... .. .......... ...................... .. ........................................ .......... .... .. .. ... ................ ...... ...... i 03

\ i i

I I I !

, - .-.-~· .. - . - ;·.·:...: ::??~

The Influence of Anatomy and Mode of Seasoning on the Strength Properties of Bamboo

Bv

A Y Ad~yemi, Department of Building, Obafemi Awolowo University lle-Ife

and

0 I Fagbenle, Dep rrtment of Building, Osun State College of Technology, Esa-Oke.

Standardizati:::n of the application of bamboo as materifll of constructiQn requires indepth knowledge of the geometrical and med -t1ical propoerties of the culm in relation to some physical parameters that affect structural performance of bioi ,1cal materials_ Literatures have concentrated mostly on the application of b.!mboo as ;·einforcement in fm, modulus concrete while treating many other factors affeding its structural performance as .. .Jm5.'ant_ An imesti,c dian was therefore conducted to determine the influence of some parameters such as culm g:.rth, moisture contt>r. and mode of seasoning on variations of strength along the /,~ngth of bam bus a vulgaris culm Analysis showc.i that the girth of matured culm tapers linearly from the grow id level to the tip. The green moiswre content d(:;c: eased along the length of the culm while the density was relat,\.ely constant. Seasoning was found to increase the strength of bamboo and strength depended on the mode of seasoning. The average compres~ ive stress wcs 44. 84Nimrrl for green specimen. 3 6 5Nimm2 for sundri(;d and 61.12Nimm2 for the ambient­temper- ture dried The average flexural stress lvas 52.57Nimm2 for green samples, 35.17Nimm2 for oven-dried, 36.45/V mrt/ for ambtent temperature dried The modulus of elasticity was fairly constant along the length of each culm and ho: ers arow,d 2.5 x 10"1Nimm2 for green samples and 3_0 x IO_,N/mm2 for green samples and 3.0 xl0-IN1mm2 fo! cured·s--.mples. It 1-~·as concluded that the strength of dried bamboo dep.;nded on the mode of seasonmg ,.nd the -'Jmb ent tenmerature is the best mode of seasoning bamboo for improved strength.

INTRODl CTION

Bamboo plays an essential role in the daily life of millions of people in both the developed and developing countries. It has been used fo r centuries for various purposes ranging from consumption of the young ~chools as food, to the application matured clumps as prop for formwork in building construction and as reinforcement in low-cost ::::~using_ Sc ent1fic applications of bamboo species as material of construction in low-cost-housing projects _! 2Ve been subject of research focus wcr!d-wide since ::-:,id-·rwent!eth century in a drive tov;ards se2.:'"1dardisation. Gienn ( 1950) investigated the mechanical prooert!es of bamboo in tension

... .l }

._ ~-~P)ression r.nd fies ... \!e. He co;1jucted tests o;1 ~ .. ~:i.!-_!Zi..!lar ana ~·:::f: j-,f.:aYn sne'.:~~Q.~

by varying the percentage ~f bamboo reinforcement and strength of concrete. Mebra, Uppal and Chadda ( 1951 ) investigated the water absorption and volume change of bamboo. Mentzinger and Plourde ( 1966) carried out tension and bond test in untreated, varnish treated and sealer treated bamboo Francis and Paul ( 1966) su~ested the procedure for selecting and preparing bamboo as reinforcement. Cox ·and Guymayer ( 1969) perform~d tests to determine the tensile strength, bond st!ength, coefficient of therrnal expansion and flexural strength of bamb::o under sustained load. They th;;n investigated _the properi:ies of bamboo re1n.fon::ed concrete by ·varying. the type . volurnr and treat~~'te:r!·l • .. !. U.:lTt;;::<._:_ -:_:

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t.

,.., l....i~iJU.!!. U1....:... JL"-n.J!AC...:J VH .uiu:lU.u VUt. l iU • ,, .. l.:,! -:; ' - i -.i "t i:i. ~

5._bdui and Rahman, 1962). Egypt1a1 ')0 (Youssef, 1976) and Pen1s. ivan ia bamb. m~:.

and Fay, 1978) showed tha ~ /tJ-, r,·· boo culm IS •', able of absorbing between 20 r' ,;'![(,'.' \\ dter in the first ! c1

hours when soaked in W~;; llci': ::nd \l./ ang ( i 976) . -concluded that the innerf;!lii-f'...l..( · f ' b;':,~·.:-. •r is b\ fer

more sensitive to water 0i~> ·='·~ i7!TI~ ~~ th<"1 th• .-·.llts ide . ' .

fibre. In two separate ..SU.c i :;· "~' ',li i ij \;~,; r i eaLcd bamboo poles (Fang et ~'' ' , ! '77/..•; dnd '>UJf'h' ''treated ban1boo rods forst •tU .r;::l , '.:l torcen··, en~ of roncrete {Fang and Mehta, i 978) , ~+: '·. ol S shown rb <H treated bamboo were les~ ..s;gnsiti ' ~ 1,:; ·. ·· 't ter absorptior, than the untreated one~ }1 was • i.u. t1 1er •.1oserved r'!<H non­treated bamboo had strGJW ,o n ,{ h:rl:t :·,··:•,'i ·;,ith the concrete. Datyle (1976} ;,h_."G(u<,i. h~)n_.;1:", ' ;',-;r. :tura! forms, which do \'Wt , ;~l'"''~i J;;~; :x,.;;J .J.n:J. :::an function satisfactortly i.r.,•!;ht~ r.~~ p, ',.··:· ul!!t :•·ls'"' · ·i

, stability and low elastic i"ft ~;,Jwlus . Jians:;e;; : : ~­- !9.88).fonnulated design ·· ·. H. !wrJ fo •· ., .. ,. " ~li; ,, ':~.

the allowable stresz. for inrnt:" l;·, ctr-r; . ..,,Ji''i at the ratio-shown in Tab'ie 1. 1""'*'-',ee'? --tr.~~ r.:ieve;·f:!; of dry and wet bamboo and tli·-: ir cG;')·~,:; ,"Q;;:s \,.?_ +l i"Xural and . t: '

. shearing strengths.

In Nigeria, the ffll~ $' -.:·t~i."\':7 C-t\1&-,!-able specie of bamboo._,.tiif"§tructural v~!l.i~~::;,; :J:e bambusa vulgaris and little research effo;t•: ·;~il·~ e been 'made towards its standardisation as an e11a,~ru:ering mate hal. Omojola and ' dtnoy.Osi ( 10::· ?6) - 'i..Wdie<l thr;· · 'i~o~~frtiaJ · of · b b " J. n; •. , ~ ;, ~'-·~ ' j·• ', . .,l. ; ·~· J..;• ;;, l am usa vu g.a. ,, ~· , -.t, '"~ t: ... ra. engmc\a .n(o matena for use iri f ;H"rt: -.;·:··, J<":~<~.u:s.. The\1.: 'cnndbde(l that bamboo obG.r Hcc~tt-'s h:n.r for s.,;an strain and that the ·node is J S<iun:e. vfweaknes!' to barnboo., Nwa (1978) dpfcrec t~,~ :.t:-~ of barribbo as. a :drainage material and CO'f'f~ded that ' it could be ·used effectively G:cS F;·.,:.~.cl •irainage. Lucas and Ogedengbe (1987) stu~l,e,.J d·•e.. slu·inkage characteristics of hrunboo :rnd fcuP<~l. that bm'1b0o dumps shrink mainly in the c:,.f;)_(~~~ direction 1md that there was no measurnb!e ~:nr>i.dr. age in i•Jngitudina! direction. Olateju n 9CJTf i:"I2Stigatcd' the use of bambusa vulgari1; (krtVu; .spt.J'!ts as reinforcement in teltacrete &'1d CC\ncl .. ded i·h·,:i ,; "" -;pijnts pe-fQrms bett~r as reinforce:-·~r> ·• "' ,,. '--:· · ~ 'y~ who!e c; :rn is used.

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ti,{\Q.. .tariation of strength along the length of the culm. nl~strength properties ofbfu"'Tlboo like wood, would ~L::-pend on the moisture content, anatomy of the niant, position of the specimen on the plant, specific gravity and age. The object ofthis study is to present add itional experimental infonnation based on :nvestigation of the influence of plant anatomy and mode of seasoning on the compressive and flexumi strength of bamboo culm.

MATERIALS AND METHODS ...,.., The primary material used in the experiment was bambusa vulgaris culm, the most V~idely available spec ie of bamboo of structural v.;:il.ue in Nigeria. Bamboo clumps were procured from a single large clump m the vicinity of Obafemi Awol.owo University, Ile-lfe. Clu..mps seleqied were those having well grown and developed side branches and fairly straight with external culm diameter and !ntemodes in the range of 6l)mm and 300mm respectively. This was to ensure that test spechT.ens were matured clumps.

A total of 32 culm lengths each nine metres long Nere cut at .a height of 600iThll above ground level, :are fully trimmed to remove the bud outgrowth and transported to the Faculty of Environmental Design 1nd Management laboratory of the University for . Jrocessing. Twency-four culm lengths were finally selected fo r the experiment and were divided into groups C and F of 12 culm lengths each. Group C corresponds to where compressive test specimen were to be taken while group F was for flexural test specimen. Each group was later divided into four sections of three culm lengths per . section. The sections relate to ihe modes of seasoning and control which were oven-drying, sun:-drying, ambient temperature drying and green (control). Twenty 300nun long compressive test specimen were taken from each culm length in group C while ten 600mm long flexural test specimen were taken from each culm length in group F. A total of 60 specimens were tested in each section of the compressive test while 30 specimens were tested in each section of the flexural test. AU specimens were wit.h nodes occurring at approximately 150mm from either ends ·md 'Nere taken serially from the botton'! '='f f'·•ch '1•tn ··r"~gth tr-; -~h? tor). T}1;-; corr.pr::':;si .. · ~

-:-L.- ;_i

~ '

..

I)'

Where k denotes the mode of seasoning (k = I ,2,3,4 represents oven-drying, sun-drying, ambient­temperature drying and green specimen respectively).

J

is the serial number of culm length iri a particular sect ion (i = 1 ,2,3). is the position of the specimen along a culm length U = l ,2, ..... ).

The external and internal diameters of each final specimen were measured with vernier callipers after which they were weighed and their moisture content determined. Specimen for ambient-ternperature seasoning were left to dry under room temperature inside the laboratory for a period of four months and those for sun-drying were spread outside the laboratory for three months. Putting specimen inside ~ oven for 24 hours at a temperature of i OOOC seasoned the oven-drying samples .

Specimens were tested as soon as their seasoning period was over. The green specimens were test~d immediately after preparation. Tnis was followed by the oven-dried specimens and later the sundried and ambient-temperature dried ~ecimens. The compression specimens were carefuliy subjected to compression load one after the other using ELE compression tes~mg madtme. Each sample was positioned such that the bt>ttom part rest on the bottom platen of tht: machine while the top platen fixed the specimen in upright position. This ensured that compress io!1 stress was evenly distributed parallel to the grain of the specimen. A specimen was loaded by ciockwise lightemng of the loading valve. The black pointer on the ~cale then carried along with it the red pointer lrt the point the specimen started to experience compressive stress. Inunediately the material failed, the black pointer moved back to the zero point leaving the red pointer to be read. .The flexurai test was performed using A very Universal testing machine. Here, two strong planks were used as loading platforms. T he base platform which is longer had size 55 x 12 x 1.2cm while the upper platform had size 25 x 12 x 1 .Scm. Two steel supports were f!xed into the base platform and close to each of the ends. Similar steel loading was fixed to the upper platform for one-poi!1t loading. The 600mm long bambcc specimens \.vere o!aced en th::, oase pi~;.~OLH1 o.ne ~-;.~ -··~- i.d:-:: :J,.1LJL ... 1-.l-ie LL..J!~-:tr u>~ ",_. _

.--l~.-~·.·: -i~-;::.·.r: ~;),

.._,

load touched the bamboo specimen when the testing machine was switched on (figure 1).

.._.,

Load P

H ydrot:!lic rom

mboo spqcinwn

Loodino p!atfori 11

r:lg.l: Principle of one points rlexurai loading

RESULTS AND DISCUSSION Studies on the girth of fresh culm showed that bamboo tapers gently from the bottom to the tip. The average variation of the external diameter of bamboo clumps studied between the height of 600mm to 630mm above ground level is shown in Figure 2. The variation ofthe external diameter showed a gentle trend amounting to an average change of O,Smrn between successive internodes . At 600rmT1 above ground level, the average external diameter of the clumps was 83.62mm and the average internal diameter was 68 .37mm. These decreased to 77 .82mm and 64.32mm respectively at the height of 3000mm above ground level. At 6300mm above ground level, the external and internal diameter further decreased to 60.37mm and 45.4lmm respectively. This girth variation gave an average culm thickness of 13.75nun for the ::;pecimens studied. From a structural point of view therefore, bamboo culm is more of tapered structural elements rather than linear prismatic elemen, .

The maximum flexural stress a structural memher can be subjected to is a function af the section mc.dulus. Figure 2 also showed that thr; ~~ctitJfi ,>i

bamboo culm decreases along \.he iength of the cuir:: from the bottcm to the tip. For the culm lengths studied~ th;e ~; .... "' :,; ~)f! nl<._;dulus decz-e~s~~.:

~~ppro .\ :rnat~~iy t!r~ear;_y. 1'"..~ ·~Cf,):n:-:1 at,~rve gru~!i!f

:,:~ .. t .. ·;-::G 2.\/':!:..~~'t~ ..::-~-~~~:~·:.:~. ' . :\~.·-~a:..'!~#'~ ·~::..:·r~~~ ! ~~'~

J - .- ,.· ~-· .... > ~ . • -: .,_._ ..

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:f ·"" ·-~:-·· .-.. · ··- .;. ... "'".::~:~ - - ~_..-r.:,'"'~' C -~ ~·J .. :; ,,. i': ,,_ __ . r:

x-;~ irL t:rn.:.l d ;araete.•· funhei dt;.:n:a:sed ro 60 37mm ami 4.J .4 i rmn respectiveiv . This girth variati.flr, l!oVf. an average culm thicJ<..ness of I3 .75mm f,x the specimen~ c::tudied. F~·om .struct~n·a! pci~ ·it of vi\, ·"· ~he:efore, bamboo culrn i5 iiwi"e ohaper~:d strucrurai ~ierut;ui:s raiher than iinear pnsmat1c element.

T~e m~ximurn f'!e;~trr!:i~ .srre2C: ? .. stn,;c~1~i·~ ! i ft~hlL·~! :.;:~. b:; :ubj ;,;;~~i;J LG ~ ~ a fi-lh\...du H uf ihe : : ~_~crion

h-rliV•=iulus. FiW4r~ ~ ~~ shOVied that iht~ scc~~on 0f ba_ITiboo culmeecre$s.w..>-EJong t'w length ofrhe r:nl!'n

from thP bottom_· ID· th~ <11Jp. Fe.~~ tLc c~li-~. lc-igth:; st!l.died, the section modulus uecreaseo. approxiwai:ely iineariy. At 600mm above ground ievel, the average ser:tion modu Ius ".'a~ :; 1 ·/E '~ 1 03mm3 and this decreased to 4.69 ;; l 0\-;;,, ,' "~ ~h e. h':;igbt of6300n ·~.rn abv¥t.. ground icve.i \t'Jg.L j . ~fhe

a·verage densi\y for the specimens wa:c, A -

! ,~.r5.'K.g/m, . This figure could he IISed to est imc:tP the WMtight of fresh ba.mboo culm since dcr.Q:, Joes re·G:t '?ary s:~bstantiaUy· along ihe length of lhe cuiln. Tiie green i1i0isture content of the spectmens ranged T-om i 50% at the ~ottom to 127% at the tir Thts ;howed that bambusa vulgari~ cul.m hc lds subs[a<iiia) '/!Iter and is responsible for its lai·ge rad iai shnnkage •vhen seasone:d . Similar view has been e:xpr,·ssed by· orne other authors (Liese. 1986) rwd !I ~!c": :1:1d )gendengbe. 1987 ). The rang,r:s cf m o i:::.;u; -. :. ~ dl ·; tc ; 1l

n dry basis for the cured sample" \\l'i"c illliJJ i iJ 75 ) 11.20% fOJ oven-dried, i i.3 5 to l Ui 5 ~ ;, for 1ndried and 11.45 to 12.10% f0r ;nn.hi enl :mperature dried. The conespor1dtno,: ,: \ _ . i;: ens ity were 734g/m3

, 74lkg/m3 dnd74:'i-..t tn · tat is tical Hest were performed at 5u" lc\ l' l ":

gnificance to know whether the mf'a'1s "r ti: ·

oisture content on one hand ~nd the means,)! iL. ·nsity on the other hand differ s ignificantly from tc curing method w the other. The resuits showed it there were significant differences i.n the means the moisture content and density of the over-dried npies when compared w ith sundried and amGient nperature dried samples. However, there were no ,Hificam differences in the means of the moisture 1tent and density of the sundried sampl :s \Vh~n

npRr.od with the ambient temperature dned.

:, result of the compressh'e test showerl o r!ecre>1se h~ ultimate: corrmrAssinf\ bar ·1=r0m the bot:J;·;: tJ ~~: ~ i \ .:-· : ·.; ':':'~~~-=--- ~~:J ~· t~1-- - :;\>:.!.;)vneti o..t·aJ. UHS.thS!J ~~-eo

,~- f~c;-"'~}. {~r?: t: a.nge 01 tne ultliTI{:.tf:

~._-,; )f(~;rr~ " :_: - ~ ~·i~·.L -~ :,;: ;. ~.,ct:. aftf~:i: ,~HF.{:ili: ~,)ei-•n't-_;r.;-:5• "..' •...

!wight of nOOmuo ~v1d 6300mm above L"Wmmd !~d w?s f 00 f. 'i IQ'>.l to c> L! 5 Kl"'L The r;:..nge fb~· li1.:: o-.~rn~ dded s~mr;l.~s was iG5.40Kl~ i.u 48.'-dKN. For ~undried and ambient temperature specimen th~ range was 11 0.50KN to 50 .15K.N and i 12 .75KN t!fl 52. i 5K1'! respectively . The average: ultLmate load fur the g~··eer , specint\,;ll ·was G7.29l( hi· , 7~ . i0K l~4 i0r the uvcu··dned, /<1.1KN for the sundried oild 7.'l.~4~N to;· the ambient tf:mr1r-•~tun" dried

Tb(; .: C:tl'l tJf"CS~,i v'C ~i!-ess COi"t cS~o!JJ.iugiy aecreasec fru11i tht: bottom of me cuim to the tip. The average compressive stress for the '!reef! r•drn 'f.'aS

44.8·4~1/mrn3 , 56.51 1'-Lira.rn3 tO; tLe: v v cu.-Jrie;ri~ 60. J.t N/nm.:' foi the sundried and 6 i . l 2 hi'm>'TI

2 fur the ambient temperature dried (Table 2) The modulus of elasticity in co!npression \YW.: <:::~·t~L"1ed by divid ing !h~ pr~duct of the; L;ad tA~ i ii~lu!~ .. and the g~uf:;•~ kngt:i by ,he produci ui the cross-sectional area <H1U the axiai shorter:ing (E=PI/A A) T~ble 3 showed that the averagF. modu!u:: of el::1sticity fer th~ f.-p~h en ,..;mor. '""r ' 1 R··l04l>J/ ··· · · 2 ·~ 1 : . ·• _ .• :., :, ..: ! '- -~ ·- ...; ;--e ~.-·~~~s· .... ~.. = h ~.;: _ . (;}·,. ... l .. ,Hu.d. ~ lu,::, 1e,:,un. t::S

diffc~·.:;nt, significaiitly frow t!1ose ot the cured sarnpJI:;s, wnich were 3 .1 5:d 04Nirnm2 J.42x 1 04N/mm2 (ln(l 3.47-:1 rp ~r '11:11:? fo:· :he ove11-dried, s~ndded, :lPd the ambi~;itL Ltitlpcratme dried ;-~spedi vdy. The iow~r nwJulus ot eiast icity of the green samples could be D.ttributed to lower failure !oad, higher cro •. :;-sr>ctional are::: (r,o ~;hrinkag~)

higher axial shortcEtilg and more mo i;:,<uic content than th~ cured samples.

ln tl1e flex ura l test, all specimens did · ~O[ go th.mugh ~ignificm't defl~ction bc·fore: sp!ill ing failure started ~;t <ih' putlil vf cippl icatiuil of the !oad and spread to 1lic i ""l' L' Ih.is . The failure load appeared to depend on 1h ~ cro~ <, - ~ c:c ii,,n al area of the specimen being tested. I <1hk ~ c;hnwcd th:1t the a\'Ciage failure !oad for the

g: ·:1: .:.[)tClmen was 4 85KN and_the corresponding ·.:a lues for the cured specimens were: 5 .62KN .. 5.75KN and 5.96KN for the -d,~\,.n -c!r~:cl. sundried and 21mbienHemperatu.r~ clr1cd specimei~S .. . · ·~' '

!"esp~ctively. The corresponcth~ ~~.f"'(S!ge h·, ' img stress vvere 32 . 571-J/mm~ for the eteen soecunens 35.17N/mm2 for the oven-dried , 36.4SN/rn·'1, 2 £'or thE: sunctrieti and 38 ,25N/:n.E?.2 . c-... • Jl:. . .~\·1(~.-~.- . ~ •

i.& n~;, CuHDlen-. &.Vt

t·~rn r: ::z~tur~ dt~t:d .

?cr. i'' si;np!e suppo::tea eeam "l'i'ith concenrr::~trrllr, ::Jri z~t the middle~ th r~ tTl(H_-hdnc: (rf' ~ ~ -~"t~.~r~y .. :, :~ ~~ -: - k~

~::=- F" -~ :i. f:• -:.

.. . ..

;;,r~fi ~ !~M~i fa~~~~~ ~~ ~o.k-v..:·~ t.~·(~li:!f.~~ ~~~:;; ..

,..,......... ,;,-- ·~· ... ~;..-.·~

~a i ,.,~ tt:f~ .. ~1~414i..c~~~~~ ~-~x~d

, w '!flrne :f:it'C.~mtl! ~11\'U On'lfit;!llt 0{ an::a ,,

The res~r~ of ~ ·~omr;.tut.qt~on in~hcated ~lilt ~!~ c> The strer.gL.'1 resulta sho·.,·ed t.l)at curing signiflt<::u~t •.• increas<:d the strength of bat:nbpo ciumps. o~ .. ~;n­dried clumps were however signifi<:antly weaker irJ compression and flexvre thaP the s•mdried ancl 0!! ambient te1nperature dried ~hnnps. !~here \V2.S r~::

significant difference in the slrr.n~:,~h ol 1.;; umps cured under the sun and those cured unoer ambient temperatme except that ambient-ten ... qi!·erature dried specimer.. hcd slightly highe::- st"ength. ..., j,

differences ~n the strength of the gret:n dumps cHi ,

thOS¥ cured in vario.us modes may be attributec · the foHowtng reasons: 1. The ::>trength ~f biobgh:al m~teria 1 s !

affected by i.li'wir moie:~m'e c.;J>lii;;nt thus big: strength illl <aii.is<X:iatetil \vith low mo1srw •· content for forest products (Cave, i 975).

2 The !ovver strength of oven··dried bar::t culrn specimens in comparison v~iiL ,; , _ sundried and the ambient··tempenmtn' dried, was as a result of fast &'ate of moisture extraction from the material by garililla radiation which led to great~r 4itic­shrinkage. According to Frey-Wys~;iing

( J 968) gamma radiation often ~·~ult .in discontinuity in fibre lengt~ ~:;}!:~~· !r~;,

decrease in strength. 3. fhere is a slower extrac~ion ot W(t!it~r rrom

the fibres of samoles dried in ~hc.: ~~.:m. :~ , , r:

drying involves simultaneo•Js P.'.::tiva[l'"'' bot11 short and long \Vtrve racHat~,.:.~Lt ~;j;.J_,

changes in ~emperature and relative humidity . Hence fibre-shrinkage is less ih stm-drying than in oven-drying and this led to improved strength of the sundried

4. · sarnpies over the oven-dried samples. AmbienHemperature'drying invo lves ontv long wave radiat ion with fluctuating effe·, 1 ~

oftemperamre and relative humidity. ·, :tu~ !:he rate of mo isture extract inn saturated tibre is s lowest and quilt ~:, I·

This led to improved strength ove,· l! i •

over-dried and the sundried sa!n!Jl~s ..

avf;'l~(; mc.dah1s -of ~twti~BlV u1 ill:endiru!, forr tt•;;; gr-ee~ · speci~em: w~~ ? .24x ~ ~ll~]rn2 a.ttiJ fo .. ~!!"' curecl specimens, a~ -,;;;.as 2.70x W4Nmm2

, 2.&5N/iiui f" and 3.08N/mm2 for the oven-dr!w, sundried atw; ambient temperature dried samples respectiveiy (THb!~ 3. ).

CONCLUSiON The result of this investigation revea~ed the loliowing: i) The girth of bamboo culrn tapers linear!y

along its length from thP bottom to the top hence it cannot be andysed as a prismruk element in st~ucrural applicarions.

• ;(i

4 \· ,i

,.\

As a result oftaperi_ng, the density and!oa.d carrybg capacit'j 0f bamboo :-educes along the iengi:h of the cuim fmm Ihe g:rmmri level to the tip. Seasoning i.cncreasecl the strength ofb(lmbQc. and this varied with ~h e :n.Jd .: s f seasoliing. Ambient-temperature seasoniug improveci the strength capacity of bamboo over sundried · and oven-dried mode of :;;~asoning. Huwever, the strength .uf

bam~ seasoned by arnbient temperatwe and the one seasoned by sun-drying were oot s~ificantly different The moduh.1s of elasticity of bamboo culm is reiatively constant throughom the length @.f a culm and it hoveis around J.OO:>t l 04N/nun2

ftli' sundried and ambient remper~rwe dried lh~"'TT.boc.

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) ·'-' " ~ Sy·;ob"' C•lou~ vf ::;"'"'""'~ ~' . ..._ ""..\~.:_., fig .. 4.

·v~"fr:s:~);n ~:tLHtit~"nnte r~--- 'llr •-,,·~.i ~ ... H~~,f rfr"'"&·-· ~'f~q~ Let.~~h o~· i:l31TibO:I Cu~T.

:1 --·-3 C rt'f:n "-. .,_ ,~. ~ 11 . J -~ Oven Ur1~J ... ........._ --, '~ ;-.

1 600 ~1 :: Sua tJ; u:u · ------ .. · .. ---~~~~"'-~ ·- : Amh. ·n~..,t·rldfUrt' :........._ ~, --·:::---..

j ··., · ..... "~ - i ..... ........._ ............... ,

60~~ -t----.... .,-n--, -. ·-...,*~·----:--~-~T""r"1"--:-rrrrr ,......~-,-:--;-,~.--·n•-rr.,.l 1 :-r,·n·T; '; ~-.-r~"<"r":lrr"t"l""" """'"r-·.-n

-·1(? 5'2 60 70 8~) 98 i 00 ' l0 'i 20

·'1~ . 1·

~ r}~\p \.

Dry

rn~·:-.:.sr:.;: c '.J -.~: ,,... ~ '\ .:-.;

Variation of Ult1mate Compressive Load alcllf?. ::h­Length of Bamboo C::t:-,

fhe }~ atio bct·~\ .. ccn the f)ensity (l(f)iH 3 ~a.nU H~~:;

A.llowable Stress (N/mm2) of Bamboo ---- . ----· -------·--···-

Compress ion Bcndmg Sh\~8Y

lno buckl ing)

0.013 0.020 0.003 Bamboo

Green 0.0 1 j G~i5

Bamboo '

l :.1b1e ~:: Cornpre:·iSlv-= :)tre:;s and 1\·1od:.:!t:s ~;::· Sl&::: of Bamboo at Vari ous Iviocies of Seasomng ---- ... . ~~-·~"""' ...... -

Green (unseasoned)

Oven-dried

Sun-dried

Ambient temperature

Compressive Slress N.'mm2

44.84

56 53

60.1 4

6 1. 12

Modulus of Elasticity X 10"

N/mm :::

2 80

3. !5

3.42

3.47

.. . •

Table 3: Flexura l Stress and Modulus of Elastic ity for Various Modes of Seasoning_

F lexural Modulus of E lasticity Stress x 104 N/mm2

(N/mm")

Green 32 .57 2.24 (unseasoned)

Oven-dried 35. !7 2.70

Sun-dried 36.45 2.85

!\mbicnt 38.25 3.08 temoeratur-:

----·--~-..... ____

REFERENCES

l.

2.

3.

9

Cox and Geymaycr. \i"oi,. ·Expendient Reinforcemen t for loncr<:k ivr vS C 111 So uth Eas t As ia· . Technical Rcpon C- o'7 - ~. r\ cf'Vr< :\0. I US Army high way/Water way, E \p<.:r1, ;, ~,; ' J''''l''"'·

Datyle. K.R. ( 1976) ·Sm.;~'~'"· _,;;;;,:;;·Bamboo·, Internat ional Symposium 01·, "'.. Hv«zons 111 Construction Materi als, Leh1gi', "',, .-. ers:;:. .

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Lucas E.B and Ogedengbe, K , ( 1987), ·s hrinkage Characteristics · of Bamboo (Bam busa Vulgaris Schrad)', Nigerian Journal of Forestry, Vol. 17. No. i and 2 pp 7-l l

i'vl ehta , S. R., Uppal. H. G .. and Chadda. L. R. ( 195! ), ·Some Preliminary Investi ga tions in the Use of Bamboo for Reinforcing Concrete·. Judan concrete JournaL Vol. 25, pp20-2l

Memzinger, R. J. And Plourde, R. P.. (1966 ), ' Investigation of Treated and Untreated Bamboo as Reinforcing in Concrete', Vilianova University, V illano~, Pennsylvania.

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Omojola, 0 . 0. And Omoyosi. A. A. (1976), 'Some Strengths of Local Bamboo ' . Proceedings, First Nigerian Congress of 'Theoretical and Applied Mechanics. pp. C86-C9l.

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Youssef, Ivi .A.R .. ( 1976). ·Bamboo as a Substitute for Steel-Reinforcement in Structural Concrete. New Horizons in Construction Materials. Vol L Envo Pubiishing cornpdny inc .. pp525-5)4.