Effect of Curing Methods on the Compressive Strength of Kenaf Stabilised Green Lateritic Mortar

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1 Journl of Civil, Construction nd Environmentl Engineering 2018; 3(3): doi: /j.jccee ISSN: (Print); ISSN: (Online) Effect of Curing Methods on the Compressive Strength of Kenf Stbilised Green Lteritic Mortr Temitope Oyenirn 1, *, Olyink Omotosho 2, Bbtunde Olnrewju 1 1 Deprtment of Agriculturl nd Environmentl Engineering, Obfemi Awolowo University, Ile-Ife, Nigeri 2 Agriculturl nd Environmentl Engineering Unit, Institute of Agriculturl Reserch nd Trining, Obfemi Awolowo University, Moor Plnttion, Ibdn, Nigeri Emil ddress: * Corresponding uthor To cite this rticle: Temitope Oyenirn, Olyink Omotosho, Bbtunde Olnrewju. Effect of Curing Methods on the Compressive Strength of Kenf Stbilised Green Lteritic Mortr. Journl of Civil, Construction nd Environmentl Engineering. Vol. 3, No. 3, 2018, pp doi: /j.jccee Received: April 13, 2018; Accepted: My 7, 2018; Published: August 16, 2018 Abstrct: The study considered the effects of curing methods on the compressive strength of kenf stbilised lteritic mortr t 1:5 nd 1:10 cement-ggregte mix rtio. Composition of the mortr for ech of the cement mix rtios ws lso substituted with kenf fibres t 0, 0.5, 1.0, 1.5, 2.0 nd 2.5% by weight. The effects of these fctors on compressive strength of the green mortr reveled tht t 1:5 cement mix, the vlues obtined from 28 dys compressive strength of wter cured smples reveled tht, the kenf replcement level should not exceed 1.0% while for ir curing it should not exceed 1.5% in order to stisfy the ASTM C279 stndrd for O type mortr. However t 28 dys the compressive strength of the smples t 1:10 cement mix did not meet the ASTM C279 stndrd for O nd N type mortr thus indicting tht binder strength ws indequte. In generl the filure in kenf fibrous mortr smples ws observed to hve been slow nd grdul, compred to the instntneous nture of filure observed in the pure cement-ggregte smples. Keywords: Compressive Strength, Curing Dys, Kenf Content, Lterite, Mix Rtio 1. Introduction As the Nigerin popultion keeps incresing, there is n ccompnying dire need for buildings. This hs led to the incresing demnd for building mterils which re now expensive [1]. [2, 3] reported tht the building industry is suffering from shortge nd high cost of building mterils. According to [4], housing progrmmes in Nigeri nd other developing countries of the world re being executed without the use of trditionl building mterils. This hs resulted in the high cost of building nd the non-reliztion of governmentl housing objectives. The cost of building mterils unilterlly ffects housing. The higher the cost of building mterils, the higher the cost of housing construction nd the fewer the number of people who cn fford their desired houses [5]. According to [6], one of the suggestions for cutting down conventionl building mteril costs hs been the sourcing, development nd use of lterntive, non-conventionl locl construction mterils. Lteritic soils re widely used s building mteril in Nigeri nd mny other developing countries of the world. In ddition to Mud wlls, brick msonry (dried or burnt type), buildings re mde from lteritic soils in both rurl nd urbn res of the country, Nigeri. According to [7], the use of lterite to replce snd component of concrete either wholly or prtilly, is becoming widespred mong the low income erners for building construction. The utiliztion of lterites enbles the provision of low-cost houses nd other rurl infrstructures. Also, studies hve been reported on fibrereinforced lterized concrete by [8]. Wire, grss nd kenf rope were used to improve sher nd tensile strength. When mortr is reinforced with biologicl fibre mterils it is referred to s green mortr in some qurters. Kenf (Hibiscus cnnbinus) fibre hs recently gined

2 Journl of Civil, Construction nd Environmentl Engineering 2018; 3(3): populrity s biologicl reinforcement [9-12]. This is due to its renewbility - ese of cultivtion nd high strength [13]. Utilistion of locl mterils is n importnt step to sustinble construction to reduce trnsporttion cost, sve embodied energy, nd protect the environment [14]. Thus, n understnding of how loclly vilble mterils cn be dpted for buildings nd t the sme time lower cost nd rise stndrds without mteril increse in cost is necessry [15]. This study ws limited to the use of lterite, kenf nd cement for the production of test specimens used for compressive strength, in the Deprtment of Agriculturl nd Environmentl Engineering, Obfemi Awolowo University, Ile-Ife, Osun Stte, Nigeri. The min objective ws to determine the effects of mix rtio, kenf content, curing dys nd method on the compressive strength of the specimens. Findings from this study could supply knowledge on effectiveness or otherwise of green mteril in form of kenf fibre in production of composite mortrs. On the other hnd, this study could provide informtion on environmentlly sustinble prctices which will help to reduce the usge of steel, non-renewble mteril in construction of light weight structures. 2. Mterils nd Methods The fine ggregte (lteritic soil) used for the study ws collected from burrowed pit t Ajebnlele re, long Ife- Ibdn express rod, Ile-ife, Osun stte in Nigeri. The reinforcement (kenf bst fibres) ws procured from the Kenf Improvement Unit, Institute of Agriculturl Reserch nd Trining (IAR&T), Obfemi Awolowo University, Moor Plnttion, Ibdn, Nigeri. The binder (OPC) ws purchsed from building mterils mrket locted t Sbo re in Ile- Ife nd potble wter from the Deprtment of Agriculturl nd Environmentl Engineering, Obfemi Awolowo University Ile-Ife. The sieve nlysis for the lteritic soil ws crried out using the mechnicl sieve in the soil nd wter lbortory in the Deprtment of Agriculturl nd Environmentl Engineering. The mchine ws operted three times for ten minutes. A constnt homogenous soil smple (500 g) ws used in ech cse nd their verge ws used in computtions. The result is shown in Tble 1. To remove debris, stones nd obtin fine soil, only prticles pssing through sieve number 4 (4.75 mm) ws used. Tble 1. Sieve nlysis of the soil used. Sieve Size Mss of Mss of Soil Retined (g) Averge Mss of Percentge Cumultive Percentge (mm) Sieve (g) M 1 M 2 M 3 Soil Retined (g) Retined percentge retined Finer Receiver The btching ws done by weight nd two mix rtios, 1:5 nd 1:10 were dopted s recommended by [16 nd 17]. These mix rtios were kept constnt throughout. The wter/cement rtio ws determined using the slump test. The wter cement rtio ws 0.26 nd 0.22 for 1:5 nd 1:10 mix rtios respectively. This ws to enhnce mix workbility s kenf bst fibres reduce workbility. The kenf bst fibre ws cut to 30 mm length size. The mixing followed chronologicl order; lterite nd cement, wter then finlly, fibres. Kenf bst fibre used for the experiment were dded t the rte of 0%, 0.5%, 1%, 1.5%, 2.0%, nd 2.5% of the weight of specimens used in this study. A cst try consisting of 25 number, 100 mm 100 mm cube units ws used to produce test specimens (Figure 1). After twenty four hours, the specimens were removed from the csts. Ech specimen ws produced in triplictes. Decsting ws done within 24 hours nd curing of the specimens in wter (Figure 2) nd ir (Figure 3) respectively strted. Specimens were cured for 7, 14, 21, nd 28 dys. The bering surfce of the testing mchine ws clened, specimens were then physiclly inspected for visible signs of crcks or ny dmge then selected t rndom nd ligned centrlly on the bse of the universl testing mchine. The lod ws pplied to the side perpendiculr to the finishing surfce of the specimen. The lod t filure ws then recorded. The compressive strength ws clculted thus, Where; = compressive strength (N/mm 2 ) = compressive lod t filure (N) nd = surfce re of specimen before filure (mm 2 ) Figure mm x 100 mm cst try used in producing the test cubes. (1)

3 80 Temitope Oyenirn et l.: Effect of Curing Methods on the Compressive Strength of Kenf Stbilised Green Lteritic Mortr 3. Results nd Discussion 3.1. Compressive Strength of 1:5 Cement Mix Mortr Results obtined from the study (Tble 2) reveled tht t 1:5 cement mix rtio the compressive strength of the cubes incresed with length of curing in wter nd ir for the 0% replcement level s observed by [18], the 0.5 nd 1.0% kenf replcement levels were lso observed to hve lso offered similr results thus implying tht the kenf replcements t these levels hd no. Noticeble effect on compressive strength of the mortr smples. The trend ws however different for ir cured smples with 2.0 nd 2.5% kenf replcement levels s the increment in compressive strength with length of curing ws observed to hve nosedived fter 21 dys curing this my hve been due to the pronounced shrinkge of the kenf mterils s the cubes dried thereby leding to reduction in weight nd higher loss of moisture (tble 3) s well s formtion of pores within the interstices of the concrete smples thereby incresing filure rte. Wter cured smples were lso observed to hve followed the sme trend fter 21 dys s observed in the ir cured smples, however the loss of compressive strength in this cse my hve been due to reduction in the stbility of the embedded biologicl mteril (kenf) s result of the presence of moisture which could cuse the onset of decomposition. Sttisticlly the result shows tht the effect of the kenf content ws significnt (p 0.05) for both the ir nd wter cured mortr smples. Figure 2. Curing cubes in wter. Figure 3. Curing cubes in ir. Tble 2. Comprison of Compressive Strength (N/mm2) for wter nd ir cured specimens for 1:5 cement mix rtios t different curing dys intervl. 7 Dys Curing Dys nd Medium 14 Dys 21 Dys 2.8 Dys Wter Wter Wter Wter Kenf Content (%)* b b b b b b b 1.18 b 1.70 b 1.13 b 1.92 b 3.23 b 4.00 b 3.10 b * Superscripts with the sme letters long the row re not significntly different t p Tble 3. Weight vrition of cubes with chnge in curing dys nd kenf content t 1:5 cement mix rtio. Kenf Content (%) Cube weight (g) 7 Dys 14 Dys Dys Dys After 7 dys of ir curing it ws observed tht the control nd 0.5% kenf replcement smples were the only ones tht b 0.50 c 1.27 b 0.55 b 1.48 c 2.00 c 2.57 b 2.17 b c 0.21 c 0.62 c 0.50 b 0.81 c 1.80 c 1.50 b 2.75 b c 0.18 c 0.57 c 0.42 c 0.41 c 1.80 c 0.70 b 2.68 c hd compressive strengths greter thn stndrds s specified by [19] for mortr type O while none of the kenf replcement smples met the sme stndrd. At 28 dys ir curing the compressive strength of mortr smples t 0, 0.5, 1.0 nd 1.5 kenf replcement levels were observed to hve conformed to [19] stndrd for minimum compressive strengths for mortr type O. The ir cured smples with kenf replcement levels 0f 0 nd 0.5 were lso observed to hve been bove the minimum requirement for mortr type N ccording to [19] stndrd. This revels tht for ir cure smples kenf replcement levels should not exceed 1.5%. The wter cured smples t 0, 0.5 nd 1.0 kenf replcement levels were observed to hve pssed the [19] stndrd for

4 Journl of Civil, Construction nd Environmentl Engineering 2018; 3(3): mortr type O while none of the kenf replcement smples pssed the [19] stndrd for mortr type N. This result revels tht for wter curing the kenf replcement level should not exceed 1.0% t 1:5 cement mix rtio Compressive Strength of 1:10 Cement Mix Mortr The compressive strength (Tble 4) of the smples were lso observed to hve followed the sme trend s those of 1:5 mix however, comprison of the vlues of observed compressive strength with pproved stndrds showed tht mortr specimens t cement mix rtio 1:10 were ll below [19] stndrd for both N nd O mortr types for both wter nd ir cured smples. The smples were lso observed to hve presented much lighter weight (Tble 5) thn wht ws obtined for the 1:5 cement mix smples (Tble 3), this ws s result of combintion of difference in densities resulting from cement-ggregte composition nd the kenf replcement in the mss of the smples. This vrition in weight/density of biologicl mteril stbilised cement mortr grees with findings mde by [20] on cow dung stbilised erth bricks. In generl the filure in kenf fibrous mortr smples ws observed to hve been slow nd grdul, compred to the instntneous nture of filure observed in the control or 0% kenf replcement smples t both 1:5 nd 1:10 cement mix rtios. This implies tht the fibrous mortr composite exhibited greter ductility nd in essence higher bility to sustin lod for considerble length of time before filure despite the reduction in compressive strength it cuses in the mortr. This lso grees with findings mde by [21]. Tble 4. Comprison of Compressive Strength(N/mm 2 ) for wter nd ir cured specimens for 1:10 cement mix rtios t different curing dys intervl. Curing Dys nd Medium 7 Dys 14 Dys 21 Dys.8 Dys Kenf Content (%)* b 0.36 b 0.30 b 0.19 c 0.14 c Wter b 0.65 b 0.25 c 0.06 c 0.05 c b 0.23 c 0.25 c 0.08 c Wter b 0.05 b 0.00 c b 0.18 b 0.10 b 0.03 c Wter b 0.57 b 0.47 c b 0.17 b 0.08 b Wter b 1.07 b 1.00 b 0.87 c * Superscripts with the sme letters long the row re not significntly different t p Tble 5. Weight vrition of cubes with chnge in curing dys nd kenf content t 1:10 cement mix rtio. Kenf Content (%) Cube weight (g) 7 Dys 14 Dys 21Dys 28 Dys Conclusion The study reveled tht for wter cured smples t 28 dys, the compressive will be within required stndrd if the kenf replcement level does not exceed 1.0% while it should not exceed 1.5% for ir curing t 1:5 cement mix rtio. The 1:10 cement mix smples however did not meet the [22] stndrd for O nd N type mortr lthough the trend of compressive strength vrition ws similr to wht ws obtined in the 1:5 smples thus indicting tht binder strength ws indequte. In conclusion informtion obtined from the study hs reveled tht kenf reinforcement of mortr could offer promising green construction mteril which could potentilly be used in number of different structurl nd non-structurl pplictions. References [1] Ktle, D. P. nd Adedeji, A. A. Investigtion on the Use of Clyey Soil Mixed with Cow Dung to Produce Sustinble Bricks, Trends in Applied Sciences Reserch, (8): [2] Aknni, P. O., Oke, A. E. nd Omotilew, O. J. Implictions of Rising Cost of Building Mterils in Lgos Stte Nigeri, SAGE Open 2014, pp. 1 7 DOI: / [3] Mnsur, S. A., Abdul Hmid, A. R., nd Yusof, N. A. Rising Trend in Construction Cost nd Housing Price, Journl of Advnced Reserch in Business nd Mngement Studies 2016, 3(1) pp , [4] Osunde, J. A., nd Fjobi, A. B. Some Engineering Properties Of Lterite/Cement Msonry Blocks Mde With Hnd Operted Moulding Mchine Grnite Fine And Admixtures, Journl of Agriculturl Engineering nd Technology, : [5] Mnsur, S. A., Abdul Hmid, A. R., nd Yusof, N. A. Rising Trend in Construction Cost nd Housing Price, Journl of Advnced Reserch in Business nd Mngement Studies 2016, 3(1) pp , [6] Olnipekun, E. A., Olusol, K. O., nd At, O. A Comprtive Study of Concrete Properties using Coconut Shell nd Plm Kernel Shell s Corse Aggregtes, Building nd Environment, :

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