Performance Indices for a Simulated Strawbale _sb_ Masonry Sprayed With Fibre Reinforced
Transcript of Performance Indices for a Simulated Strawbale _sb_ Masonry Sprayed With Fibre Reinforced
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
104Websjournal of Science and Engineering Application//Lyon _ AIGEN
cement plastered and unplastered strawbale as well as the unsprayed termitarium plastered strawbale.
The methodology of this project includes production of strawbale specimens of plastered and
unplastered sprayed blocks and prisms. The termitarium plastered strawbale were initially tested and itssimulation carried out at the Department of Civil Engineering, Namibia University of Science and
Technology (Kamara et al, 2012). The result of the present work is hereby compared with that of the
termitarium plastered wall. A typical thermal conductivity of natural (coconut) fibre, due to changes in
temperature, is shown in Table 1.
Table 1. Experimentally determined ()for coconut fibre
Density (kg/m ) Thermal Conductivity (W/mK)
15.6C mean temp. 21.8C mean temp.
40 0.05624 0.0575850 0.05099 0.05184
60 0.05051 0.04970
70 0.04891 0.0488480 0.04800 0.04886
90 0.04869 0.05009
Source: Aridome et al (1998)
2. SPRAYED FIBRE REINFOCED PLASTICS REVIEW
Closed-cell spray polyurethane foam (ccSPF) insulation is a self-adhering, two-component productthat is spray applied on site. The material tenaciously bonds to most construction material substrates(i.e. metal, wood, plastic, masonry) and provides a rigid insulation system that adds structural strength
to buildings. It has the highest level of thermal performance per mm, for commonly used thermalinsulation products. Typically, this performance shows a design R-value of 6.2 for 0.91 kg at 23.89oC
for ccSPF wall insulation, and a design R-value of 6.7 for 1.36 at 23.89oC(ccSPF) roof insulation at a
mean temperature of23.89oC(ASTM C 518 04).Closed-cell spray polyurethane foam also has nearly
zero air permeability and acts as an integral vapor barrier. Because the product is sprayed onto thesubstrate and expands to nearly 30 times its original volume when applied, it conforms too many
irregular spaces and fills voids that other insulation materials leave open. It requires no fasteners and istypically installed in a single application (CES, 2007). The Open-cell spray polyurethane foam (ocSPF)
utilizes carbon dioxide as the sole blowing agent. In ocSPF, the cells burst open and are suspended in
the finished foam in an open form.
In walls, ccSPF insulation can be used throughout the interior or exterior of a structure and may beapplied to nearly any construction surface (i.e. masonry, gypsum board products, wood, metal),including exposed or new construction wall framing. Closed-cell spray polyurethane foam wall-
insulation systems provide a continuous air barrier, improved building strength and significant thermal
performance. The system addresses all key issues associated with insulation and air-barrier systems incommercial insulation performance, because of: Superior effective R-value in a complete assembly. A
monolithic, integral vapor and air barrier that requires no additional products to reduce air andmoisture infiltration and exfiltration, thereby exceeding building codes and standards and meeting
ASTM C1029/SPFA guidelines. Low water vapor permeability, low liquid water absorption and highthermal performance, which combine to minimize condensation and water intrusion into the building
(Banthia, 2002). Complete coverage of the building envelope (i.e. roof, walls, foundation and slab),which minimizes thermal bridging caused by fasteners, joints, cracks, penetrations and framing.Finally, ccSPF insulation and waterproofing systems employed in the building envelope (i.e. roof,
walls, foundation and slab) can substantially improve the structural integrity of the building. In fact,
studies show that using ccSPF insulation in walls increases racking strength two to three timescompared to assemblies using traditional insulation products. Using ccSPF as a wall-insulation system
provides significant energy-related benefits. In addition to significantly higher R-value than other
insulation materials, ccSPF eliminates moisture and air infiltration and exfiltration. Thermal testing
standard of R-13 of SPF cells and other polystyrenes are shown in Table 2.
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
105Websjournal of Science and Engineering Application//Lyon _ AIGEN
Table 2. Current thermal testing standardsInsulation ASTM Standard Mean Test Temperature
Differential, F (oC)
Temperature, F (oC)
R-13 Fiberglass with
paper facing
ASTM C 653 75 (23.89) 40 (4.44)or 50 (10)
Extruded polystyrene ASTM C 578 25 (-6.67), 75 (23.89) 110 (43.33) Min 40 (4.44)
Polyisocyanurate ASTM C 1289 40 (4.44), 75 (23.89) 110 (43.33) Min 40 (4.44)
Closed-cell sprayfoam insulation
C 1029 40 (4.44), 75 (23.89) 110 (43.33)Min 40 (4.44)
Open-cell spray foaminsulation
None 75 (23.89) Min 40 (4.44)
Source : (CES, 2007)
3. MATERIALS PROPERTIES AND CONSTRUCTION OF SB MASONRY
3.1 Strawbale wall as energy efficient
The use of straw as insulation means that the standard insulation materials are removed from the home
standard fiberglass insulation has formaldehyde in it, a known carcinogen bale walls also eliminate theuse of plywood in the walls. Plywood contains unhealthy glue that off-gas into the house overtime
(Downton 2003, Lancinski and Bergeron 2000), which can endanger the occupants. A house envelopedwith a strawbale wall can save up to 75% on heating and cooling costs intact in most climates, we do
not even install air conditioning unit into strawbale building as the natural cooling cycle of the planet
are enough to keep the house cool all summer long(Downton, 2003). Likewise, Adedeji and Aweda(2013) and Adedeji (2007) postulated that all new buildings must be energy efficient with straw walls,
the insulation (straw) is also the building block. Also Lee (2001) indicated straw compacted into balesoffers much better insulation with its high thermal resistance.
3.2 Materials used for specimen construction
DataBase used for this research work was based on experimental tests on strawbale wall - also reportedherewith - were conducted by Samuel (2012). The following materials were used: Mature straw of
guinea corn stalk (cut to size of three strings), ordinary Portland cement (OPC), fine aggregate, steel
wire/twine. The fine aggregate used was clean, soft, well graded, freed from salt and organic
contaminant of 100% passing through sieve no 5mm was employed in the mix. Two different specimensamples were prepared, one in which strawbale was unplastered and other specimen plastered withSFRP.
3.3 Particle size distribution tests and results
500g of dry fine aggregate sample, which passes through sieve no. 5mm, weighted and complied with
BS 882:1201. This was employed in the mix. The natural sand used was well graded in conformity
with the limit given in the Table 1 of BS 882:1201. The result of the sieve analysis carried out is shownin Table 1 and in Figure1, for the number of different sized particle available, BS410: 1976 was
employed for the production of the block specimens.
Table 1 Sieve analysis result or grading of sand for blockSieveSize (mm)
Sieveweight
(g)
Sieve weight +retained
(g)
Retainedweight (g)
Percentageretained %
Cumulativepercentage
retained
Cumulativepercentage
passing5 100
4 554 558 4 0.8 0.8 99.2
2.36 478 493 15 3 3.8 96.22 520 565 45 9 12.2 87.20.5 496 641 145 29 41.8 58.20.25 472 582 114 22.8 70.8 29.20.063 455 552 97 19.4 90.2 9.5Recording pan 254 303 49 9.8 1 00 0
Percentage retained = (weight retained/total weight of sample) x100%
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
106ebsjournal of Science and Engineering Application//Lyon _ AIGEN
Figure 1 Particle size distribution curve
3.4 Spraying of strawbale
The spray was applied to the strawbale by a compressed pump machine. The polymers were mixed andpoured into the compressed pump machine gun after which the polymer fibre reinforced cement mortar
was sprayed out of the guns nozzle toward the surface of the strawbale. Contained in the mix waspaint DALUX 01202092 with a base, hardener and reducer in ratio 2:1:02 (that is, 2 part base, 1
hardener and 0.2 reducer). The surface of the strawbale was cleaned and free of dirt, grease, oil, wateror other contaminants. A total of sixty coupon specimens of each sprayed FRP were prepared as Type
A test pieces. Thirty specimens were made with carbon fiber (CF), and the other thirty specimens for
glass fiber (GF). The installing procedure of the sprayed FRP strengthening is as follows:i) Base arrangement; other extra fin leaves on surface of strawbale (SB) prism were trimmed using
scissors.ii) Primer resin coating; Primer resin was applied to the surface in order to make highly adhesive
between SB and putty/resin.
iii) Putty arrangement; Dent areas and steps on SB surface are filled with putty and made the surfaceflat in order to prevent partial stresses of FRP and air voids on SB. After putty got dried, the
surface was thoroughly sanded.
iv) Resin coat; In order to make fibers more adhesive, resin was coated first by a spray gun. Maximum
lengths of the carbon and glass fibers are 0.5mm and 0.2mm respectively.
0
20
40
60
80
100
0.001 0.01 0.1 1 10
PERCENTAGEFINER(%)
PARTICLE SIZE (mm)
Figure 2 SFRP plasteredStrawbale prism before loading
Figure 3 Failure mode in ruptureand splitting
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
107ebsjournal of Science and Engineering Application//Lyon _ AIGEN
In this study however, it was a goal to obtain sufficient behaviours as applicable to the wall element
by factoring the results of the prism (Adedeji, 2007). Figure 2 shows typical FRP sprayed strawbaleprism, while Figures 3, 4 and 5 show typical failure modes of the prisms subjected to compressive
strength test.
3.5 DataBase
Mechanical properties of carbon and glass fibres are shown in Table 2 and database for specimensare also indicated in Table 3.
Table 2. Mechanical properties of FRP and plastered strawbale and TSB
Identification Tensile Strength(MPa) Elastic Modulus(GPa) Ultimate strain (%)
CF-A1** 4451* 254.1* 1.76
GF-A2** 2378* 127.1* 1.87CF-A3** 117.1 15.24 0.78
GF-A4** 112.9 8.00 1.48
T-SB*** - 6.00 -* For sectional area of only fiber (not included resin)
**(Toshiyuki, c_kanakubo_final_pdf)*** Kamara et al (2012)
T-SB = Termitarium Strawbale composition, thermal conductivity =0.020 0.035
Table 3. Prism specimensSpecimen Section FRP FRP (Specified values)
(mm) Length (mm) Arrangement pFRP(%) Elastic modulus (GPa) Thickness (mm)
CF- A1 254.1 0.5GF- A2 250 *450 1000 Mixed 0.13 127.1 0.16CF-A3 15.2 0.2GF-A4 8.0 0.13
pFRP= Percentage of FRP
3.6 Compressive strength test results
The characteristic values of axial compressive strength of the SFRP masonry prisms are obtained
from the compression test results on full height prism subjected to eccentric loading. In general, it isconservative to assume pinned-pinned condition and it may be noted that for design purposes, the
characteristic values should be divided by partial safety factor 1.7 and maximum of 3.3 (Adedeji, 2000)
Compressive strength applied in this study involved the capacity of the masonry to withstand axialload only. When the limit of compressive strength is reached, materials are crushed. Tables 4 to 7
Figure 4 Sprayed plastered strawbale
prism splitting under loading
Figure 5 Sprayed plastered strawbale prism
crushing under loading
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
108Websjournal of Science and Engineering Application//Lyon _ AIGEN
shows the average compressive strength test results on sprayed and unsprayed plastered strawbale
prisms with their standard deviation.
Table 4. Average compressive strength for sprayed cement plastered strawbale prism
Analysis Plan Area
(mm2)
Crushing load
(N)
Compressive strength (N/mm )
Prism Actual wall
Mean Value 85.6 x140.6 7838.77 0.65 6.5
Standard deviation 1192.75 0.092
Table 5. Average compressive strength for unsprayed cement plastered strawbale prism
.
Table 6.average compressive strength for sprayed cement unplastered strawbale prism
Analysis Plan Area
(mm2)
Crushing load
(N)
Compressive strength (N/mm )
Prism Actual wall
Mean Value 85.6 x140.6 7838.77 0.65 6.5Standard deviation 1192.75 0.092
Table 7.average compressive strength for unplastered strawbale prism without spray
Prism model is factored by 0.1 of the actual wall dimensions
For the height of the strawbale prism, HP = 1m and thickness BP = 0.45m, the maximum stressesallowable and calculated using SAP2000 are also shown in the Tables 8 and 9for both cement
(Adedeji, 2011) and termitarium plaster composition (Kamara et al, 2012).
Table 8.Minimum and maximum stresses (N/mm2) between each of the plaster compositions
and the strawbale material.
Outside plaster Inside plaster
Plaster composition Minimum stressMaximum
stressMinimum stress Maximum stress
*Cement -9.8 9.6 -19.3 18.3
Termitarium -6.0 6.2 -6.3 6.5
*Adedeji (2011), Kamara et al (2012)
Table 9Differences between the allowable and calculated stresses for both plaster compositions.
Wall composition Maximum allowable stressMaximum calculated stress using
SAP2000*Cement plastered strawbalewall
70.14kN/m2 38.836kN/m
2
Termitarium plasteredstrawbale wall
73.14kN/m2 67.452kN/m
2
*Adedeji (2011), Kamara et al (2012)
Analysis Plan Area(mm
2)
Crushing load(N)
Compressive strength (N/mm )Prism Actual wall
Mean Value 85.7x140.6 7305.7 0.61 6.1
Standard deviation 865.28 0.076
Analysis Plan Area(mm
2)
Crushing load(N)
Compressive strength(N/mm )Prism Actual wall
Mean Value 85.8 x 140.5 5297.4 0.44 4.4Standard Deviation 727.14 0.061
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Websjournal of Science and Engineering ApplicationISSN: 1974-1400-X, Vol 2, No 2, 2013, 103-112
A.A. Adedeji, V. S. Kamara and D. P. Katale
111Websjournal of Science and Engineering Application//Lyon _ AIGEN
5. DISCUSSION OF RESULTS
Due to the tests carried out on strawbale prisms and simulation, the results are presented as follows:In a sprayed fibre reinforced plastics walls, thepeak values for the state of stress and deformation occur
in the same minute cycle of temperatures. So, the results of thesimulation of temperature for the stress
and deformation indicate the rational 'stress and deformation tolerance 'in which the wall situates, The
section of an SFRP of the strawbale (SB)wall plastered with cement mortar has minimum compressive
stress (outside wall-surface) of 8.839, 8.034 and 7.001 N/mm2
at eccentricity, e = 0, e = 6 and e =20mm and the length of 1.0 m respectively, while the compressive stress (inside wall-surface of 0.1
N/mm2 occurred
at 20 hrs respectively. The case is different with a two-sideplastered wall, where the
tensile stress of 1.8N/mm2was recorded at 15 hrs, while the compressive stress of 0.5 N/mm
2occurred
at 24 hrs. The maximum (normal) stress at the contact of the wall and the FRPplaster outside the wallis 1.3N/mm2and it occurred at 20hrs. The shear stress along the contact is in compression with a
maximum value of 0.2N/mm2in the 23hrs. This is not the case with the wall plastered on both sides
where tensile stress occurs in the 14hrs mid the shear stress (compressive) occurs in the 20hrs .The
SFRPplastered wall is very sensitive to thermal movement, from 'all indications,when compared with
both cement plastered and termitarium plastered SB wall and so is the compatibility (bond) between thewall elements and the plasters. The high bond stress is due to the field of stress by the modulus of
elasticity of SFRP plaster and the strawbale surface area. Though, a modular ratio (ESFRP/ESB) of 1.33gives moderate compatibility between the two materials, the time cycle for this rapid change may affectthebond between the two elements as yearspassby. This maybe more damaging at any slight daily
swings of temperature. Temperaturepatterns forboth plastered and unplastered wall arethe same.
6. CONCLUSION
The performance of sprayed fibre reinforced polymer plasters, on strawbale prism, has beenidentified by this research work. The results obtained were factored 0.95 (Adedeji, 2007) to obtain the
values for the wall. Strawbale wall has shown adequate resistance against vertical loading. Comparison
of results was made between plastered and unplastered strawbale with spray, unplastered and plastered
strawbale without spray. Spray-plastered strawbale have stresses of 8.838N/mm2over 8.387N/mm
2of
unsprayed plastered strawbale with the sprayed FRP thermal conductivity ranges between 0.020and0.035.This implies that when higher loading such as the above stresses occur, the response of the
fibre reinforced cement plastered strawbale is high compared to other unsprayed strawbale wall. From
this work however, it could be recommended that strawbale sprayed plastic fibre mortar should beemployed for sustainable, strong and ecosystem compatible buildings; as there is a strong indication of
a moderate bond between the SFRP of both cement and termitarium plaster and the SB surface areaeven, on the west wall, at 700 W/m2solar gain at a temperature of 43.33oC.
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A.A. Adedeji, V. S. Kamara and D. P. Katale
112Websjournal of Science and Engineering Application//Lyon _ AIGEN
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