Compuestos fibrosos de matriz cementícia. Obtención y
procesadoHolmer Savastano Jr.
FZEA USP Brasil
Introduction
The Technology
Reinforcing mechanisms
• 1 & 2: fiber bridging with partial debonding
• 3: slipage, connected to composite toughness
• 4: fiber rupture, connected to composite strength
Coutts (1986)
Fiber attributes
Fiber Alkalinity resistance
Temperat. resistance
Processability
Strength Toughness Price
Wood pulp (chem) 1-3 1 1 1 1 3
Wood pulp (mech) 2 2 2 2 3 3
PP 1 3 3 3 3 2
PVA 1 3 3 3 3 2
Kevlar 1 1 2 1 1 1
Stell 1 1 3 3 3 2
Glass 3 1 3 3 3 2
Mineral fiber
3 1 3 3 3 3
Carbon 1 1 3 1 1 1
1 = high, 2 = medium, 3 = low
Relative cost of the fiber
Fiber Rel. cost per unit weight
Specific gravity (SG)
Tensile strength (ft, MPa)
ft/SG Rel. cost per unit weight/(ft/SG)
Wood kraft pulp
1 1.5 500 333 1
Glass ravings
4 2.5 1400 560 2.2
Steel 1.4 7.9 2100 267 1.6
Kevlar 20 1.5 2800 1867 3.3
Asbestos 1.2 2.6 700 269 1.3
PVA 9 1.3 1600 1231 2.2
Fiber impact
• Pulps with low density in comparison with cement matrix
• Air entrappement during composite fabrication
Composite strength
Composite toughness
Composites production in laboratory small scale
Steps of composite production
Pad preparation
z Fibre fractionsy 12% by mass of dry componentsy pulp previously disintegrated in water
z Addition of water to form a slurry of ~20% of solids
z De-wateringy evacuable 120 x 120 mm chambery initial vacuum 60 - 80 kPa
(...) Pad preparation
z Stack pressingy compaction & additional de-wateringy 3.2 MPa by 5 min
z Wet curey 7 days in saturated air at room temperature
z Sawingy Specimen dimensions 120 x 40 x 6 mm
z 7 additional days in laboratory ambient
Producción de tejas pequeñas
ProduProduçção das telhasão das telhas
Roma Jr. et al. (2003)
Transferência para o molde onduladoTransferência para o molde ondulado
Moldagem das telhas onduladas
Savastano Jr. et al. (2001)
Autoclaving
Dimensional stability
Relative humidity (%)
0.0
0.2
0.4
0.6
0 200 400 600 800Time after placing (h)
Len
gth
varia
tion
(%)
Eucalyptus
Eucalyptusautoclaved
Pinus
5090 50 30 90
Similar shrinkage of the composites in different relative humidity conditions.
Autoclaving: alternative to reduce the dimensional instability of the composites.
Manufacture aspects
Manufacturing
Product manufacture
Industrial scale testsIndustrial scale tests
Hatschek ProcessHatschek Process
Amianto
Produto
Cimento e adições
Prensa cilíndrica
Corte
Caixas de tamises
Vácuo
Preparo do amianto
Misturador
Película de fibrocimento
Feltro sem-fim
Água
Onduladora Manta de
fibrocimento
Cement and additions
Raw MaterialsWater
Mixture VatsFelts
Cut Corrugate
Product
DewateringRoll and
knifeFlat of Fiber Cement
Thin layers of fiber cement
Schematic lay-out of industrial plant
Hatschek machine
Schematic lay-out of industrial plant
Homogeneous material
Infibra Ltd., Brazil
Details of the vat and Details of the vat and sieve cylindersieve cylinder
Sieve cylinder
Steps of the Hatschek processSteps of the Hatschek process
Mixture Felt and Dewatering
Cylinder Flat
Steps of the Hatschek processSteps of the Hatschek process
Steps of the Hatschek processSteps of the Hatschek process
Knife Corrugate
Some other industrial processes
Water tanks
Magnani method
Vacuum drainage and pressing
Demolding
Imbralit Ltda.
(John, V.M.)
Curing and water proofing
Fourdrinier forming machine
Flow-on principle processing
The pour-on lay-out
Flow-on principle processing
Wonder board process
The wonder board structure
Some properties of wonder board
Property ASTM Test ½” Wonder Board
Weigth D 1037 1.36 kg/m2
Compressive Strength Wet/Dry
D 2394 > 17.6 MPa
Flexural Strength Wet/Dry
D 947 > 6.3 MPa
Fastener Pull Thru D 1037 > 63.5 kg
Linear Variation with Moisture Change
D 1037 < 0.07%
Surface Burning E 84 0/0
Wind load E 330 1.4 MPa
Particle board process
US Market
Market Considerations
Product attributes
• High fire resistance
• Durability
• Resistance to inset attack
• Capability for aesthetically pleasing products
• Paint stability on finished products
• Reduced waste on job site
• High toughness and good strength properties
• Naiable, sawable, cuts with woodworking tool
• Wide distribution & recognition across the US
Some product opportunities
• Lap siding
• Panel siding
• Fascia
• Underlayment
• Tile Backer
• Wall Board
• Roofing Shingles & Slates
• Fance Panels
• Pipes
• Corrugated Roofing Sheets
• Water tanks
Manufacturers in North America
• James Hardie Building Products
• Certain Teed
• GAF Materials
• Cemplank
• Maxi Tile
• Nichiha
Fiber cement prices in the USA
Source: James Hardie Report
Bio-inspiredFunctionaly graded materials
Functionally graded fiber cement: concept
• Heterogeneous properties distribution designed to a desired performance
• Heterogeneous composition– Fiber content
– Fiber properties and types
– Matrix composition
• Graded structure– Porosity
– Pore size
Bio-inspired Design of Affordable Building Materials (a) Scanned image of the R-C cross section of the bamboo culm (b) Same
area imaged by an optical microscope (c) L-R cut at the culm
Functionally graded fiber cement: example
High fiber content
Low fiber content
High fiber content
Low fiber content
MX
Corrugated sheets under bending
Tensile stress distribution
Functionally graded fiber cement: example
Functionally graded fiber cement by Hatschek process
Different formulations
Slurry de-watering process
for FGM fiber-cement
Method
• Specimens preparation– Distribution of PVA fibers
– Layers with different fiber content
• Mechanical performance– Four-point bending test
• Thermogravimetric analysis
• Optical microscopy and SEM
Materials and formulations
Material Density (g/cm³) Formulations (w/w %)
Portland cement 3.05 60.0
Limestone filler 2.78 30.2 – 32.0
Silica fume 2.22 5.0
Cellulose fibers 1.56 3.0
PVA fibers (6mm in length) 1.36 0 – 1.8
Gradation: layers stacking
Layer 12345
PVA fiber content per layer
Series PVA fibers content (w/w %)Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 Average
FC_1.80% 1.80 1.80 1.80 1.80 1.80 1.80
FC_1.07% 1.07 1.07 1.07 1.07 1.07 1.07
GFC 1.8_0_1.8% 1.80 0.90 0.00 0.90 1.80 1.07
GFC 0.2 to 1.8% 0.20 0.60 1.00 1.40 1.80 1.00
FC Homogeneous fiber cement
GFC Graded fiber cement
Layer 12345
PVA fiber content by layer
0.0 0.5 1.0 1.5 2.0
PVA fibers contenet (w/w %)0.0 0.5 1.0 1.5 2.0
PVA fibers contenet (w/w %)
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
Deflection (mm)
Flex
ural
str
ess
(MP
a)FC 1.8%GFC 0.2 to 1.8%_fibers upGFC 0.2 to 1.8%_fibers down
Fibers up
Fibers down
Mechanical performance
PVA fibers (1.8%)
PVA fibers (1.8%)
Experimental data
Formulation PVA fiber content (%)
MOR (MPa) Toughness (kJ/m²)
Estimated cost reduction (%)
FC 1.8% 1.80 13.7 1.1 5.3 1.5 0.0
GFC 0.2_1.8% Fibers up 1.00 9.3 1.2 0.8 0.1 18.3
Fibers down 1.00 13.1 1.4 4.1 1.1 18.3
GFC 1.8_0_1.8% 1.07 11.2 0.9 2.6 0.8 16.5
FC 1.07% 1.07 11.4 1.5 1.8 0.4 16.5
MOR x PVA fiber content
y = 3.5691x + 7.4927R2 = 0.9847
8
9
10
11
12
13
14
15
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
PVA fiber content on the lower half of the specimens' cross sectional area (w/w %)
MO
R (M
Pa)
Toughness x PVA fiber content
y = 3.6325x - 1.4026R2 = 0.9523
0
1
2
3
4
5
6
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
PVA fiber content in the lower half of the specimens' cross sectional area (w/w %)
Espe
cific
ene
rgy
(kJ/
m²)
Comments
• Thermogravimetric analysis– Effective technique to characterize PVA fiber
content distribution
• Fiber content optimization– Cost reduction – Similar mechanical strength
• MOR and toughness versus PVA fiber content
Fiber cement produced by extrusion process
Die
Extrusion Process
ExtrusionDie
Pugmil chamber
Deairing chamber
Compression chamber
Die
Pugmil chamber
Deairing chamber
Compression chamber
Pugmil chamber
Deairing chamber
Compression chamber
Cut Cure Products
Planetary Mixer
Silos
Cellulose Preparation
Water
Dough Feed
•Low water/cement ratio
•Any product configuration
•Low cost to implement
Fibre cement factory
Company13 tons/h production line (variable according to product specification)
FCM (Hatschek)* US$ 3.000.000,00
RAMMIL (Hatschek)* US$ 1.400.000,00
GELENSKI (Extrusion)** US$ 100.000,00
*2004 data
**2007 data
Extrudability
Relevant aspects:
• Extruder type an characteristics
• Die configuration
• Raw-Material proprieties
• Formulation rheology
Rheometry
Benbow parameters:
• initial bulk yield stress
• initial die land shear stress
• die land velocity factor
• die entry velocity factor
P
Die configuration effect
0
0,02
0,04
0,06
0,08
0,1
0,12
0 20 40 60 80 100 120
Stroke (mm)
Extr
usio
n pr
essu
re (M
Pa)
Die D/L=1Die D/L=4Die D/L=8
v=20mm/sv=13,3mm/s
v=8,9mm/s v=5,6mm/s
v=20mm/s
A Concluding Thought
“Fiber cement continues to be a successful business. It is likely that product diversification will continue in the years ahead in addressing market opportunities that are likely to emerge.”
“Fiber cement composites are poised to offer
product replacement as well as new applications as we move into the next decade and beyond.”
CommentsCommentsThe adhesion between cement matrix and the synthetic fiber plays an important role in the fiber cement behavior
The densification of the matrix improves the behavior of the composite before cracking (LOP)
The toughness in the early ages is based in the cellulose pulp and in the synthetic fiber pull out
Aging deteriorates the cellulose pulp and increases adhesion of synthetic fiber with decrease in the toughness
CONCLUSIONS
• This talk presented some of the basic concepts that are guiding our research at USP Brazil on processing of composite materials for affordable infrastructure
• An advanced materials approach is being used to guide the toughening of natural fiber composites
• Transference of technology to private sector is a key issue for the asbestos free products
Thank you very much for your kind attention!
Lectura complementar
• IIBCC Proceedings (2006) & (2008)– Curran Ltd. Publishing
• Special issue of Construction and Building Materials Feb. 2010
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