compuestos fibrosos de matriz cementícia. obtención y procesado...

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