Development of Composite Cement Reinforced With Coconut Fibre
The Fabrication, Testing and Application of Fibre Cement ...
Transcript of The Fabrication, Testing and Application of Fibre Cement ...
The Fabrication, Testing and Application of Fibre Cement Boards
The Fabrication, Testing and Application of Fibre Cement Boards
Edited by
Zbigniew Ranachowski and Krzysztof Schabowicz
The Fabrication, Testing and Application of Fibre Cement Boards Edited by Zbigniew Ranachowski and Krzysztof Schabowicz This book first published 2018 Cambridge Scholars Publishing Lady Stephenson Library, Newcastle upon Tyne, NE6 2PA, UK British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Copyright © 2018 by Zbigniew Ranachowski, Krzysztof Schabowicz and contributors All rights for this book reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. ISBN (10): 1-5275-0576-6 ISBN (13): 978-1-5275-0576-6
CONTENTS Introduction ................................................................................................ 1 Chapter One ................................................................................................. 7 Fabrication of Fibre Cement Boards By Krzysztof Schabowicz and Tomasz Gorzelańczyk
Introduction ........................................................................................... 7 Primary raw materials ......................................................................... 11 Properties of PVA fibres ..................................................................... 11 Raw materials preparation and mixing zone ........................................ 14 Detailed operation of Hatschek machine and fibre film formation ...... 23 Details of other FCB fabrication process stages .................................. 28
Chapter Two .............................................................................................. 41 Fibre Cement Boards Testing By Zbigniew Ranachowski
Mechanical properties of FCB ............................................................ 41 European Standard EN 12467 .............................................................. 42 Measuring board dimensions, tolerances, straightness
and squareness of edges ................................................................. 44 Measuring apparent density ................................................................. 45 Measuring mechanical resistance ......................................................... 46 Testing water impermeability .............................................................. 56 Testing water vapour permeability by the determination
of the water vapour resistance value µ ........................................... 56 Testing moisture content during FCB production process ................... 58 Durability against warm water ............................................................. 65 Durability against soak–dry cycles ...................................................... 66 Moisture movement test ....................................................................... 66 Durability against freeze–thaw cycles ................................................. 68 Durability against heat–rain ................................................................. 69 Reaction to fire ..................................................................................... 69 Information on parameters determined based on standard tests
and indicated on the product label .................................................. 71 FCB testing using ultrasound ............................................................... 71 Application of Lamb waves for detecting structural defects ................ 78
Contents
vi
By Dariusz Jarząbek Application of advanced optical microscopy ....................................... 89 Examples of application of scanning electron microscopy (SEM) ...... 96 X-ray microtomography (micro-CT) application in visualization
of the fibre distribution and crack detection ................................... 98
Chapter Three .......................................................................................... 107 Applications of Fibre Cement Boards By Krzysztof Schabowicz and Tomasz Gorzelańczyk
Introduction ........................................................................................ 107 Example applications of fibre cement boards .................................... 107 Conclusions ....................................................................................... 121
References ............................................................................................... 123
INTRODUCTION Fibre cement board (FCB) is a versatile green building material, strong and durable. It serves as a substitute for natural wood and wood based products such as plywood or oriented strand boards (OSB). The properties of FCB as a construction material make it preferable for use as a ventilated façade cladding for both newly built and renovated buildings, interior wall coverings, balcony balustrade panels, base course and chimney cladding, and enclosure soffit lining. FCB can be applied to unfinished, painted, or simply impregnated surfaces [1-3].
Fibre cement components have been used in construction for over 100 years, mainly as roofing covers in the form of corrugated plates or non-pressurized tubes. They were invented by a Czech engineer, Ludwik Hatschek (1856-1914) [4]. In 1900, he developed and patented a technology for manufacturing light, tough, durable, and non-flammable asbestos cement sheeting that he called “Eternit.”
Fibre cement composite–compared to the components of concrete–shows improved toughness, ductility, flexural capacity, and crack resistance. A major advantage of the fibre reinforcement is the behaviour of the composite after cracking has started, as the fibres bridge the matrix crack (matrix-bulk material, in which the fibres are dispersed). Then, the stress is transferred to the high-resistance system of fibres, capable of withstanding the load. Post-cracking toughness allows the use of FCBs in construction. Moreover, the fibres can reduce the unwanted free plastic shrinkage within the structure, decrease the thermal conductivity, and improve the acoustic insulation and fire resistance.
For many years asbestos has been regarded as the most suitable material for reinforcing FCBs. White asbestos, a silicate mineral / Mg3(Si2O5)(OH)4 / naturally forms long and durable fibrous crystals with each visible fibre composed of millions of thin microscopic fibrils. It is found in many geological deposits throughout the world.
The fibres reinforce FCB components only when added in a specific quantity (approx. 10% wt.) and are uniformly dispersed throughout the cementitious matrix. A highly complex procedure is required to achieve this goal under efficient industrial conditions. Ludwig Hatschek solved the problem by inventing a machine with a rotating sieve and a vat containing a diluted fibre slurry, Portland cement, and mineral components. A thin
2
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CHAPTER ONE
FABRICATION OF FIBRE CEMENT BOARDS
KRZYSZTOF SCHABOWICZ AND TOMASZ GORZELAŃCZYK
FACULTY OF CIVIL ENGINEERING, WROCŁAW UNIVERSITY OF TECHNOLOGY
Introduction A modern process of FCB fabrication consists in laying thin paper-like films on top of each other until a desired sheet thickness is obtained [13, 14]. The process distributes the reinforcing fibres in planar uniformity, taking the best advantage of the reinforcing fibres to increase the in-plane strength of the sheet. Thus, the strength of sheets made using this process is approximately 50% greater than the sheets formed to full thickness in a single action using a filter press or the extruding processes. In a process detailed below, a thin film formed from a diluted fibre slurry is usually 0.25-0.4 mm thick and each FCB comprises a stack of these films. Thus, the final sheet consists of approx. 20-30 or more thin films. A large number of layers partially suppresses the imperfection of the considered method: the films formed on a sieve are not uniform in composition but due to sedimentation they have a fibre-rich side and a fibre-poor side. Additionally, 2.5-3 mm long fibres bridge the sieve holes, slightly blocking the feed of other particles and forming a fibre-rich layer. The portions formed last can be relatively fibre-poor. On this account, an advanced fibre orientation and distribution devices have been developed and introduced into the actual chain of FCB fabrication.
Fig. 1-1 shows a flowchart of a sample fibre cement board production process. The particular sub-processes named in the flowchart are detailed below.
Chapter One
8
Fig. 1-1. Flowchart of sample fibre cement board production process.
Figure 1-2 shows a sample flowchart of the technological process of fabrication of cellulose fibre cement boards, including seven zones corresponding to the specific production stages [12]. Fig. 1-3 shows a detailed diagram of zones no. 1 and no. 2 in order to outline their complexity. The moisture content of the board varies at each stage and is determined using methods described in the next chapter.
Preparing raw materials
Batching mix components
Mixing until homogenous pulp is obtained
Forming boards in special forming machine(Hatschek machine or flow-on machine)
Natural maturing in climatic chambers and in air for 7-14 days(maximally 28 days)
Taking boards off stacks and carrying
Transferring
Pressing to enhance properties
Wet cutting and stacking
Finishing – dustless cutting with water jet
PREP
ARAT
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ZO
NE
WA
TER
AND
WAS
TE R
ECO
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TEM
Fig. 1-2. Flocement board
The fabr1), where ceuniform dispin specific phomogenousof cellulose autoclave camounts of clays, silica contain less
The mixmachine. Thboards with stage involvsuitable for board) is apcement boarcuring tunneboards can bas quickly aso they shou
Fabr
owchart of tecds.
rication of ceellulose fibrespersion is proproportions ars plastic compfibre cement
cured. Low (Portland cemfume, groundPortland cem
xture describhe Hatscheka fixed thick
ves the pressin the type ofpplied. Warmrds directly afel (zone 4) wbe taken off thas possible sinuld not be allo
rication of Fibre
chnological pro
llulose FCB ss are mixed woduced. Bulk cre added to thpound is obtai: low-tempera(air) cured foment combined limestone, o
ment and morebed above is
or flow-on mkness of 4-14 mng of stacked
f board fabricm (due to cem
fter pressing where they remhe stack and pnce the boardsowed to cool a
e Cement Board
ocess of fabric
starts in the pwith water in a
components (che batched wained. There arature cured anormulations ued with fine-gor fly ash. Aupozzolanic co
s transferredmachine is umm. The next
d boards (zoncated (exterioment hydrationor forming armain for abou
placed on a pals are still quiteand dry too mu
ds
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preparation zoa mixer (pulpecement with aater and mixere two main cnd high-tempeusually contaground fillersutoclaved formomponents an
to a boardused (zone 2)t (optional) pr
ne 3). A pressor or interiorn heat) cellulre transferredut 14 hours. Nllet. This muse warm and duch or too qui
9
ulose fibre
one (zone er) until a additives) ed until a categories erature or ain larger s such as mulations
nd fillers. forming
to form roduction
sing force cladding
lose fibre to a pre-
Next, the st be done damp, and ickly.
Chapter One
10
Fig. 1-3. Diagram of zones no. 1 and no. 2.
The boards placed on the pallets are left to mature and are cured in steady thermal-moisture conditions, e.g., in special airtight tarpaulin tents (zone 5) for about 14 days. After that time, the boards obtain the proper bending strength, and some moisture is removed naturally. After the maturation period, the boards are transferred to a final drying oven (zone 6) where they are subjected to three-stage drying at 180°C, 160°C, and
Fabrication of Fibre Cement Boards 11
120°C, respectively at stage 1, 2, and 3. Then, the boards are cooled naturally for about 20-30 minutes depending on their thickness. This is a critical stage of the fabrication process. Boards with excessive moisture content are not fit for further treatment, such as impregnation or painting. At the last fabrication stage, the boards are trimmed, and, if necessary, their surface is ground at the edges (zone 7).
Primary raw materials
Table 1-1 shows the typical primary raw materials used in the fabrication of naturally maturing fibre cement boards. Table 1-1. Typical primary raw materials used in fabrication of fibre cement boards.
Standard ratio
type of raw material approximate composition
Cement ~ 60% Cellulose (dry) ~ 8% PVA ~ 2% Kaolin or lime ~ 30% Total ~ 100% Additives & admixtures Hyperplasticizer ~ 0.1 l/t *) Didecyldimethylammonium chloride (DDAC) or bromide (DDAB)
~ 0.1 l/t *)
Perlite ~ 1 kg/t *) Mica ~ 1 kg/t *) Microsphere ~ 1 kg/t *) Antifoaming agent ~ 0.26 l/t*) *) l/t or kg/t = litres or kilograms per ton of finished product
Properties of PVA fibres
PVA (polyvinyl alcohol) fibres are a major component in the fabrication of naturally maturing cement fibre boards. The basic specifications of PVA fibres, based on the data for Kuralon (manufactured by Kuraray America Inc.) [40], are shown below. Table 1-2 shows the basic specifications of PVA fibres compared to other commercially available fibres.
Chapter One
12
Main advantages of Kuralon fibres: ▪ non-toxic, ▪ long-term presence on the market, ▪ established manufacturing process, ▪ high quality.
Table 1-2. Specifications of PVA fibres compared to other commercially available fibres [40].
Parameter type of fibre
Kuralon PET Nylon PAN PP Aramid Carbon tenacity (cN/dtex) 11-14 6-8 5 2-4 6-8 22 13-23
Young’s modulus 250-300 80-
145 40-80 30-70
30-110
400-700
1190-2370
alkali resistance X X X X
adhesion to cement X X X X X
weather resistance X
= good, = normal, X = bad
Figure 1-4 shows micrographs of the cross-sections of fibre cement boards reinforced with different fibres.
a)
b)
c)
Fig. 1-4. Micdifferent fibre
Fabr
crographs of ces [40]: a) Kura
rication of Fibre
cross-sections oalon fibres; b) p
e Cement Board
of fibre cementpolypropylene fi
ds
t boards reinfofibres; c) ARG f
13
orced with fibres.
14
Figure 1strength of f
Fig. 1-5. Relaboards [40].
R
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17
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Chapter
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machine n
ine. The maineve rotating iforming a filteThe sieve is drng cylinder byorming roller.l roller.
23
n section n contact
ering film riven by a y a couch The felt
24
Fig. 1-17. Ha
The sheefollowing prin the vat, wporous film moves the fis pressed toWhen the reto form a shthe roller anfilms in confilms togeth
Typical particles arethese particlwhereas thefibrous matestructure of
The effimaterial depachieved bydiameter witnetwork of particles. Th
atschek machine
ets are formedrocedure [13]water from th
of fibres andfilm onto the fo the felt. Thequired numbheet of a requind laid out flntact with eac
her and form asieve mesh si
e significantlyles can freely fibres are reterials within ththe fibre layericiency withpends on the
y a special procthout affectinfine fibres ca
his forms an i
Chapter
e diagram.
d in the Hatsch. When the cl
he slurry runsd cement onfelt. The exce
he felt transferber of films isired thicknesslat to form ach other unde continuous soizes are approy smaller (appy pass throughtained on thehe film on thers formed. which the f
e fineness ofcessing, i.e., b
ng their lengthapable of trapinitial filter la
r One
hek machine lean sieve is pthrough the
the surface oess water is rers the film onwrapped aro
, the stack ofboard. The d
er pressure isolid material.x. 0.4 mm, wrox. 50 µm inh the sieve ousieve. Thus, e
e surface of th
filter layer ref the cellulosby crushing thh. High qualitypping at leastayer on the su
in accordancepulled under tsieve to depo
of the sieve. Temoved whennto the formin
ound the formfilms is remodraining of susufficient to
whereas the non diameter). Tut of the formentrapment ofhe sieve depen
etains the nose kraft pulphe fibres to redy kraft pulp cathe larger no
urface of the s
e with the the slurry osit a soft The sieve the sieve ng roller. ing roller
oved from uccessive bind the
on-fibrous Therefore, med layer, f the non-nds on the
on-fibrous . This is duce their an form a
on-fibrous sieve and