wr performance on corrugated fiber cement roof sheet

8/2/2019 WR Performance on Corrugated Fiber Cement Roof Sheet

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FLM

Final Progress ReportASSESSMENT OF WATER REPELLENT PERFORMANCEON CORRUGATED FIBER CEMENT ROOF SHEET

USP Team:Prof. Dr. Vanderley Moacyr John, Prof. Dr. KaiLoh, MSc. Flvio Leal Maranho

So Paulo, 2007

ASSESSMENT OF WATER REPELLENT PERFORMANCE ON CORRUGATED FIBER CEMENT ROOF SHEET FINALREPORT


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Contents

Introduction ......................................................................................................................... 4

1.1 Objective: .................................................................................................................. 5

1.2 Project Design ....................................................................................................... 5

1.3 Laboratory Step ..................................................................................................... 5

1.4 Industrial Application ........................................................................................... 6

1.5 Structure ................................................................................................................ 7

Preparation of Specimens .................................................................................................... 9

2.1 Objective .................................................................................................................... 9

2.2 Method ....................................................................................................................... 9

2.3 Materials .................................................................................................................. 12

2.3.1 Water Repellents............................................................................................... 12

First Round ........................................................................................................................ 14

3.1 Objective ............................................................................................................. 14

3.2 Materials and methods ........................................................................................ 14

3.3 Assessment Parameter ........................................................................................ 14

3.4 Specimens ........................................................................................................... 15

3.5 Results ................................................................................................................. 15

3.4.1 Admixture Application ..................................................................................... 15

3.4.2 Post-treatment Application ............................................................................... 16

3.6 Conclusion .......................................................................................................... 18

Second Round .................................................................................................................... 21

4.1 Objective ............................................................................................................. 21

4.2 Materials and Methods ........................................................................................ 21

4.3 Evaluation Parameter .......................................................................................... 22

4.4 Specimens ........................................................................................................... 23

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4.5 Results ................................................................................................................. 23

4.5.1 Application Method .......................................................................................... 23

4.5.2 Superwetter ....................................................................................................... 24

4.5.3 Efflorescence .................................................................................................... 25

4.5.4 Water absorption............................................................................................... 26

4.6 Conclusions ......................................................................................................... 27

Third Round ....................................................................................................................... 30

5.1 Objective ............................................................................................................. 30

5.2 Materials ............................................................................................................. 30

5.3 Specimen Dimension .......................................................................................... 32

5.4 Results and Analysis ........................................................................................... 32

5.4.1 Water Absorption ............................................................................................. 32

5.4.1.1 Conclusions ................................................................................................... 38

5.4.2 MOR ................................................................................................................. 40

5.4.3 Fracture Toughness .......................................................................................... 41

5.5 Conclusions ......................................................................................................... 43

Industrial Application Report ............................................................................................ 46

Conclusions ....................................................................................................................... 51

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Introduction

Cellulose fiber has been used to substitute asbestos on Fiber Reinforced Cement (FRC) roof

tiles, despite the fibers mineralization caused by the wet-and-dry cycles (Dias; John,

2005).

Mould growth is another problem caused by the absorption of water and it influences the

FRC aesthetical and thermal performance.

To improve the FRC performance, hydrophobic products have been used in plants, despite

the little amount of information published so far. Water repellents aim to prevent the

materials degradation and to reduce soiling, which is mainly influenced by mould growth,

thus improving the general appearance of the product and the energy efficiency of the

building.

The water repellent most widely used in building materials is silicone based materials

(mainly silane and siloxane). These products have a good hydrophobic property (by the

non-polar radical) and Si-O and Si-C bond stability.

In FRC there are different ways to introduce water repellent products in plants. The first

one is to treat the cellulose fibres directly (Abdelmowlett et al, 2004). The second is to addthe repellent during the admixture of raw materials (Selley et al, 2006).

The advantage of these methods is that they protect the thickness and edges of all sheets.

However, they modify particle flocculation in plants and cement hydration kinetics, thus

influencing the mechanical properties (mainly MOR) and the sheet layer adhesion.

The third method used to protect FRC sheets is a post-treatment application (Selley et al,

2006), which is the most widely used in other building materials, such as mortar, concrete

and stone. Many factors influence the hydrophobic performance in this method, such as: (i)method of application (spray, paint or dipping), (ii) product concentration and (iii) moment

of application (before or after curing).

It is not easy to compare the different methods because no complete published research has

been identified in the literature.


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For industrial plants, the post-treatment application is easier to put in action but its

performance in service conditions is not well understood and is largely influenced by

cracks (Lunk; Wittmann, 1998).

As other application methods could influence the FRC mechanical properties and the

flocculation process in the hatcheck machine, more researches are required before any

industrial application.

1.1 Objective:

To select the most effective water repellent produced by Dow Corning to protect

asbestos-free fibrocement corrugated sheets.

1.2 Project Design

The research was divided in two steps: one in USP laboratories and other in INFIBRA

plant.

The first step aimed to identify the water repellent and the concentration that showed the

best performance in laboratory evaluations, while in the second step a semi-industrial

application was tested.Figure 1 shows the methodology used.

Figure 2

1.3 Laboratory Step

The experimental design was divided in three rounds.

In the first round, nine water repellent products were tested (five applied as post-treatment

and four as admixture) using only one concentration for each product. Water absorption

after immersion for 24 hours was used as parameter for evaluation.

FirstRound

SecondRound

ThirdRound

Industrial

test

Laboratory Step

Figure 1: Methodology used in the Research Program


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In the second round three products (520, 6683 and 16-606) at different concentrations were

investigated using water absorption kinetics along 24 hours as parameter for evaluation.

Superwetter performance, the application method (brush or immersion) and the prevention

of efflorescence were also investigated.

In the third round three products (520, 6683 and 16-606) at different concentrations were

submitted to accelerated aging in laboratory conditions. The evaluation parameters were

water absorption kinetics along ten days, MOR and Fracture Toughness.

Table 1 shows the experimental design used.

Table 1: Methodology used in the laboratory program research

Round Products Objective

first 9 (5 post-treatment and 4 as

admixture)

To screen three with the

best performance

second 3 products (2 post-

treatment and 1 admixture)

To determine the water

repellent concentration;

To obtain information

about the Superwetter

performance;

To develop application

procedure and to determine

efflorescence prevention.

third 3 products (2 post-

treatment and 1 admixture)

To evaluate accelerated

aging

1.4 Industrial Application

The industrial application was conducted in INFIBRA plant. A semi-industrial application

was tested using only the best product and concentration identified in the laboratory steps.

Emulsion absorption and consumption were identified.


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1.5 Structure

This report is divided in seven chapters.

In the first one an introduction about the research is presented. It also contains an overview

about the theme and the methodology used in the project.

In the second chapter the preparation method of the specimens and the raw materials used

in the laboratory steps are presented.

In Chapters 3, 4 and 5 the results and comments obtained in the first, second and third

rounds, respectively, are presented.

In Chapter 6, the industrial application is reported and in Chapter 7 the most important

conclusions are pointed out.


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Chapter 2: Preparation of Specimens


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Preparation of Specimens

2.1 Objective

To present the raw material and procedures used to produce the specimens in the laboratory

steps. The materials, except the cement, used in the different rounds were the same.

2.2 Method

The following steps were followed to produce the specimens:

1. Admixture of raw materials to produce the pulp, using a solid/water ratio of 0.20;

2. Apply vacuum (hatcheck);

3. Compression;

4. Curing in an oven at 65C and 90%RH for 18 hours;

5. Apply the post-treatment water repellents;

6. Curing in a plastic bag for 28 days;

7. Cut the specimens in suitable dimensions;

8. Seal the border;

9. Dry in an oven at 65oC and 50 RH for 2 days;

10.Test.

Figure 3 and Figure 4 show the materials used in the research program.

Figure 3 Raw Materials used to produce the sheets

Weight ( )Cement (~30 bfSlag) 70.2

Limestone 20.0

Silica fume 5.0


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PVA fiber 1.8

Dry cellulose 3.0

Figure 4: Materials used to produce the sheets

The admixture procedure was:

Add water in the barrel;

Add cellulose and mix for 2.0 minutes using a rotation rate of 400rpm (Figure 5);

Figure 5: Mixture barrel and the mixing with water and cellulose fiber.

Add the PVA fiber and mix for one more minute (Figure 6)

Add cement, limestone and silica fume and mix for 3.0 minutes at the same rotation

rate (Figure 7).

Figure 6: Mixture after adding the PVA fiber Figure 7: Mixture of all raw materials

After this procedure the pulp was ready to produce the sheets.


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For each sheet, two liters of pulp were poured into the mold with vacuum until no more

water was eliminated (Figure 8). This process is similar to that used in fiber-cement plant

technology and known as Hatcheck method.

Figure 8: Vacuum application

Finally each sheet was compressed on a Shimatzu Universal Machine with a 0.3MPa for

1.0 minute (Figure 9) and then stored in a plastic bag for 28 days. Only after this time the

sheets were cut to produce the specimens used in each round.

Figure 9: Compression with a Shimatzu universal machine.

.


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2.3 Materials

2.3.1 Water Repellents

Table 2 shows the water repellents used in this project. All concentration and dilution rates

used in the test were based on the emulsion weight and not in the activity materials.

Table 2: Products used in the first step

Admix Use level General Description Comments

16-606 0.5 octyl functional silicone fluid dispersed directly into water.

6288 0.5 octyl functional silicone fluid dispersed directly into water.

6777 0.5 propyl siliconate soluble in water

772 0.5 methyl siliconate soluble in water

Post-treatment Dilution rate General Description Comments

520 10

silane/siloxane emulsion,

MeH containing dilute in plain water to recommended , based on 40 as-supplied.

6683 10silane/siloxane emulsion

water repellent dilute in plain water to recommended , based on 40 as-supplied.

6341 10 octylsilane dilute in white spirit, such as Shellsol D60

6184 20 water dispersible siloxanewater dispersible -- dilute by adding 1-6184 to water, not by adding

water to 1-6184.

772 5 methyl siliconate dilute in plain water to recommended , based on 40 as-supplied.


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Chapter 3: First Round


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First Round

3.1 Objective

The objective was to evaluate the performance of nine different water repellents produced

by DOW CORNING around the world and screen three with the lowest water absorption.

Moreover, the aim was to investigate the influence of steam curing on the performance of

the water repellents.

3.2 Materials and methods

The products used in this round are presented in Table 3.

For the post-treatment application the concentration was based on the emulsion weight. The

application was by dipping the specimens in the solution for 30 seconds.

The admixture concentration was based on the total water weight used in the production.

Table 3: Materials and concentrations used in the first round.

Product Concentration(%)

Admixture

16-606 0.5

6288 0.5

772 0.5

6777 0.5

Post-treatment

520 10

6341 10

6683 10

772 5

6184 20

3.3 Assessment Parameter

The water absorption result after 24 hours of immersion was used as evaluation parameter.

This parameter was decided by the project team (DCC and USP) in the meeting at

04/11/2006.


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3.4 Specimens

In the first round, round specimens were used, as illustrated in Figure 10. The borders were

sealed with bee wax.

Figure 10: Illustration of the round specimens cut from the sheet.

3.5 Results

3.4.1 Admixture Application

Figure 11 shows the water absorption results for the water repellents used as admixture.

In the figure the continuous lines represent the average value, while the dashed lines mean

the standard deviation. Moreover, the green lines represent the untreated results, while the

red lines, the treated results.

The results clearly show that products 6288 and 16-606 had lower water absorption rates

than the other ones.

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorption(%)

TIME (H^0.5)

6288

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorption(%)

TIME (H^0.5)

16-606


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Figure 11: Water absorption results for the admixture water repellents. All concentrations were

0.5% based on water (W/W).

3.4.2 Post-treatment Application

Figure 12 shows the water absorption results for the water repellents applied as post-

treatment. The dilution rate used for each product is identified in the figures. The

continuous lines represent the average value, while the dashed lines, the standard deviation.

The blue lines represent the after-curing application1 and the red lines, the before-curing

application. The green lines represent the untreated samples.

The figures clearly show that the application after curing yields better results and lower

water absorption than the before-curing application for all products tested. Moreover, alltreated samples show a water absorption increase along three days of immersion, reducing

their performance compared to the untreated samples.

Comparing the results after only one hour and one day of immersion, it is clear that product

6683 applied after curing showed the best result.

One important point is that products 520 and 6683, when applied before curing, showed

some white staining on the surface of the specimens (Figure 13).

1 Curing = 18 hours in ventilated oven at 65C and 95%RH.

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorptio

n(%)

TIME (H^0.5)

772

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5 6 7 8

WaterAbsorption(%)

TIME (H^0.5)

6777


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Figure 12: Water absorption results for the

post-treatment application. Green =

untreated; blue = after curing; red = before

curing; dashed lines = standard deviation.

Figure 13: White staining on the specimen surface after curing

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorption(%)

TIME (H^0.5)

520 (10%)

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5 6 7 8

WaterAbsorption(%)

TIME (H^0.5)

6683 (10%)

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorption(%)

TIME (H^0.5)

6341 (10%)

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption(%)

TIME (H^0.5)

6184 (20%)

0%

5%

10%

15%

20%

25%

0 2 4 6 8

WaterAbsorption(%)

TIME (H^0.5)

772 (5%)


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3.6 Conclusion

Table 4 presents all results obtained in the first round. The best products for each period of

time are identified in green. The worst products are in red.

Table 4: Water absorption results in the first round

Water Absorption (%)

30sec. 60 sec. 240 sec. 1 hour 24 hours 96 hours

Untreated 2.03 2.54 5.68 15.96 19.08 19.92

Post-treatment

520BC 0.57 1.56 2.46 8.55 13.45 17.90

AC 0.43 0.93 1.41 5.52 10.14 12.84

6683BC 1.14 1.87 3.41 10.37 16.34 18.61

AC 0.75 0.94 1.50 4.12 8.68 11.62

6341BC 1.63 2.76 4.54 6.62 11.79 13.21

AC 3.05 4.40 5.77 6.80 9.61 10.15

6184BC 9.13 13.88 18.00 21.50 21.75 21.78

AC 8.40 13.33 16.22 17.51 18.28 18.97

772 BC 1.83 3.35 9.35 16.33 19.33 21.16

AC 1.90 2.75 5.77 10.74 15.20 15.39

Admixture

6288 0.25 0.46 0.61 1.06 2.88 5.48

16-606 0.49 0.69 0.65 0.84 2.85 5.89

6777 1.15 1.50 2.54 6.55 15.67 16.77

772 2.17 3.81 6.74 13.87 15.79 17.08

The main conclusions are:

Products 6288 and 16-606 showed the best performance;

For the post-treatment application, 520 and 6683 showed the best performances.

The first one was better to reduce water absorption in the first minutes, while the

other was better for longer exposure times;

The application after curing in the post-treatment application was better than that

before curing;


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Product performance seems to decrease along the time;

Some products applied as post-treatment show a white staining after curing (520

and 6683);

The solvent-base product (6341) showed a strong and undesired smell after curing

and which remained for a long time;

Product 6184 became a gel during the application.


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Chapter 4: Second round


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4.3 Evaluation Parameter

The evaluation parameters used in this round were:

a) Superwetter: hydrophobic solution absorption and water repellency;

The first parameter was obtained by measuring specimen weight before and after

the application of the solution, while the second was obtained by measuring water

absorption along 24 hours of immersion.

b) Application method: compare the water absorption kinetics along 24 hours of

immersion for samples treated by brushing or by immersion.

c) Efflorescence: ice cube test (DCC instructions). According to this method an ice

cube is left to melt and dry on the specimen surface (Figure 14).

Figure 14: Efflorescence test used in the second round

This method is qualitative and gives only comparative data. It is based on the increase of

calcium hydroxide solubility as the temperature decreases (Figure 15). Products that show

higher white staining in this test are more likely to produce efflorescence during service

conditions.


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Figure 15: Solubility of Calcium Hydroxide. Based on Taylor (1990)

4.4 Specimens

For the second round, 4cm square specimens were used and the borders were sealed with

bee wax, similarly to the first round.

4.5 Results

4.5.1 Application Method

Figure 16 compares the water absorption kinetics along 24 hours of immersion for products520 and 6683 at the concentration of 10%. The results show that brushing and immersion

applications have similar results. In both products brushing was a little better (lower water

absorption).

Figure 16: Results from different application methods for the post-treatment water repellent.

0

0,2

0,4

0,6

0,81

1,2

1,4

0,0 20,0 40,0 60,0 80,0 100,0 120,0

Ca(OH)Solubility

Temperature (C)

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption(%)

TIME (H^0.5)

6683

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5TIME (H^0.5)

520Untreated

Immersion

Brushing


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4.5.2 Superwetter

Figure 17 shows the absorption of the hydrophobic solution with (identified as with QI) and

without (identified as without QI) Superwetter. It shows that:

Q2-5211 did not increase the absorption of the hydrophobic solution;

For 6683, Superwetter showed better results. The higher the WR dilution level, the

higher the absorption of the solution;

For 520, the lower the WR dilution level, the higher the absorption of the solution.

Figure 17: Water repellent consumption with Superwetter (identified as QI) for 520 and 6683.

Figure 18 shows the water absorption after 24 hours of immersion.

Figure 18: The influence of Superwetter (Q25211) on water absorption at different concentrations.

It is clear that Superwetter did not increase water repellency performance for the products

in the dilution rates tested.

0%

1%

2%

3%

Without

QI

With QI Without

QI

With QI Without

QI

With QI Without

QI

With QI Without

QI

With QI Without

QI

With QI

3% 5% 10% 3% 5% 10%

520 6683

SolutionAbsorption

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

3% 5% 10%

WaterAbsorptionafter24hours

TIME (H^0.5)

6683

with Q2 5211

without Q2 5211

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

3% 5% 10%

WaterAbsorptionafter24houirs

TIME (H^0.5)

520

with Q2 5211

without Q2 5211


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4.5.3 Effloresce

The main results are:

The untreated samp

The post-treatment

reduced the stains (

white stains;

The admixture wat

Figure 19: Untreated samples

3%

Figure 20: Specimens treated

ce

les showed a lot of white staining (Figure 19

products (520 and 6683), at any concentratio

Figure 20 and 21). The higher the concentra

r repellent (16-606) increased white staining

howed typical white deposits after efflorescence te

5%

ith WR 6683 showed typical white deposits after e

);

n (3%, 5% or 10%),

ion, the smaller the

(Figure 22).

st.

10%

fflorescence test.


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3% 5% 10%

Figure 21: Specimens treated with WR 520 showed typical white deposits after efflorescence test.

0.10% 0.25% 0.50%

Figure 22: Specimens treated with WR 16-606 showed typical white deposits after efflorescence test.

Efflorescence reduction in the samples treated with post-treatment products is expected and

well recorded in the bibliography, mainly because it reduces the cement alkalis dissolution.

For both products (520 and 6683) the concentration of 5% showed very important

reductions.

On the other hand, increase of efflorescence in the admixture waters could not be justified

by the test performed. It is a very important point in future researches focus on the

admixture water repellent products.

4.5.4 Water absorption

Figure 23 shows the water absorption kinetics along 24 hours of immersion. All results

presented do not have Superwetter.


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Figure 23: Water absorption kinetics

along 24 hours of immersion

The product used as admixture at any concentration showed a better performance than that

of the post-treatment. For all products, the higher the concentration, the lower the water

absorption.

For post-treatment application, both products tested showed a very similar performance.

However, WR 6683 was a little better.

4.6 Conclusions

Table 6 shows all water absorption results obtained in the water absorption test during the

second round. The best options for each product are identified in green.

Table 6: Water Absorption results in the second round.

Water Absorption (%)

Time 30sec. 60sec. 240sec. 1hour 24 hours

UNTREATED 3.86 5.53 8.07 15.17 20.46

Post-treatment

6683

10%withQ2 5211 0.24 0.27 0.48 1.40 11.52

10%withoutQ2 5211 0.30 0.26 0.32 0.85 7.09

5%withQ2 5211 1.10 1.09 1.27 4.39 14.32

5%withoutQ2 5211 0.19 0.76 0.69 1.84 12.75

3%withQ2 5211 0.77 0.84 1.12 4.60 16.67

3%withoutQ2 5211 1.10 1.09 1.27 4.39 14.32

520

10%withQ2 5211 0.98 1.54 2.93 7.50 12.91

10%withoutQ2 5211 0.49 1.11 1.19 2.43 7.68

5%withQ2 5211 2.32 3.40 8.70 12.12 15.89

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption

Time (h^0.5)

6683

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5Time (h^0.5)

520

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAb

sorption

Time (h^0.5)

16-606

0%

3%

5%

10%

0%

3%5%

10%

0%

0,05%0,10%0,25%0,50%


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5%withoutQ2 5211 0.62 0.92 2.94 4.66 9.44

3%withQ2 5211 1.05 1.28 2.24 4.08 14.63

3%withoutQ2 5211 1.31 1.84 3.37 7.01 12.76

Admixture

16-606

0.5% 0.40 0.16 0.40 0.75 2.44

0.25% 0.31 0.32 0.42 0.87 2.73

0.1% 0.40 0.64 0.71 0.93 3.15

0.05% 0.45 0.55 0.65 1.40 4.72

The main conclusions obtained in the second round are:

The post-treatment application by brushing and immersion for 30 seconds showed

similar performance for both products tested: 520 and 6683;

Superwetter did not improve water repellent absorption and hydrophobic

performance;

The ice cube test is simple to perform and shows some important information about

the prediction of efflorescence risk;

The products applied as post-treatment reduced white staining in the efflorescence

test, while the admixture increased it;

The admixture water repellent at any concentration showed lower water absorption

results than the post-treatment solutions.


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Chapter 5: Third round


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Third Round

5.1 Objective

To evaluate the influence of accelerated aging on water repellent performance.

5.2 Materials

The products used in the third round are presented in Table 7.

For the post-treatment products, two coats were applied after curing using a foam roller. All

applications were after curing.

After the application of the water repellent the specimens were cured in a plastic bag for 28

days.

Table 7: Water repellents and concentrations used in the third round

Product Concentration Test

Admixture 16-606

0.50%

Water AbsorptionMOR

Toughness150 cycles of accelerated

aging

0.25%

0.10%

0.05%

Post-treatment

520

3%

5%

10%

6683

3%

5%

10%

Accelerated aging was performed at USP laboratories, using an automatic machine (Figure

24). It consists in 150 wet/dry cycles, each one lasting six hours:

6 hours 70C - drying

6 hours around 25C - wetting

During the cycles only one side of the specimens was in contact with water (Figure 25),

similarly to what may be observed in a roof.


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Figure 24: Overview of the equipment used in

accelerated aging

Figure 25: illustration of the water level during

aging. Only one side of the specimens was

wetted.

The modulus of rupture and the fracture toughness were evaluated using a four-point

bending test. A support distance of 13.5cm, a load distance point of 5.0cm and a load rate

of 1mm/min were used (Figure 26).

This procedure has long been successfully adopted at USP laboratories.

For the mechanical tests an Instron Universal Machine with a load cell unit of 1KN was

used.

Figure 26: Equipment used in the mechanical evaluations

The modulus of rupture and the fracture toughness were calculated according to the

equations:


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Where:

MOR= Modulus of Rupture (MPa)

P = Maximum load (N)

L = support distance (135mm)

b = specimen width (mm)

e = specimen thickness (mm)

= Fracture Toughness (KJ/m2)

Ap- = area below the curve up to the fracture (N.mm)

5.3 Specimen Dimension

In the third round, specimens measuring 16 cm x 3.7 cm x 0.5 cm were used. The borders

were sealed with liquid rubber (3M product). The difference in dimension and border sealer

was necessary to fit the temperature used in the accelerated aging equipment.

5.4 Results and Analysis

5.4.1 Water Absorption

a) WR 6683


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Figure 27 shows the third round results for product 6683. It clearly shows that the higher

the concentration, the lower the water absorption. After one day (24 hours) of immersion,

for the concentration of 3%, and three days (72 hours), for the concentration of 5%, the

results are similar to that of the untreated specimens.

Figure 27: Specimens treated with WR 6683: water absorption kinetics after aging.

Figure 28 shows the results before and after aging for this product. Here, continuous lines

represent the unaged results, while the dashed lines represent the aged results.

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

W

aterAbsorption

Time (h^0.5)

6683

0%

3% 5%

10%


34/53

Figure 28: Specimens treated with WR 6683: water absorption before (continuous line) and after

accelerated aging (dashed line).

The comparative evaluation shows that:

Accelerated aging has a small influence on 6683 performance;

In first hour of immersion, the aged samples show higher water absorption,

mainly at the highest concentration (Figure 29).

3% - ~0%

5% - +50%

10%- +150%

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption

TIME (H^0.5)

6683

0%

3%

5%

10%


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Figure 29: Specimens treated with WR 6683: water absorption in the first hour before (continuous line)

and after accelerated aging (dashed line).

b) WR 520

Figure 30 shows the third round results for product 520. The higher is the water repellent

concentration, the lower was the water absorption (except at 5%, which probably showed

some experimental error).

One important point in this product is that after aging, all concentrations seem to show

similar water absorption after four days of immersion.

Figure 31 compares the unaged and aged results.

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

0 1

WaterAbsorption\

TIME (H^0.5)

6683

0%

3%

5%10%


36/53

Figure 30: Specimens treated with WR 520: water absorption kinetics after aging.

Figure 31: Specimens treated with WR 520: water absorption before (continuous line) and after


For this product the aging cycles reduce water absorption rates along the first day of

immersion. This reduction was very important in the first hour (Figure 32). There is a 75%

reduction for the highest concentration (10%), and a 55% reduction for the others (3% and

5%).

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

WaterAbsorption

TIME (H^0.5)

520

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorptio

n

Time (h^0.5)

520

3%

5%

0%

10%

4 days

0%

3%

5%

10%


37/53

Figure 32: WR 520 water absorption in the first hour before and after accelerated aging. Continuous

line= unaged, dashed line = aged

c) 16-606

Figure 33 shows the third round results for product 16-606. It clearly shows that all

concentrations had a similar performance, and a continuous increase of water absorption

along the ten days of immersion.

Figure 34

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

0 1

WaterAbsorption

Time (h^0.5)

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

Water

Absorption

TIME (H^0.5)

16-606UNTREATED - after aging

UNTREATED - Before aging

0,50% - after aging

0,50% - before aging

0,25% - after aging


0,10% -After aging


0,05% - after aging

0,05% - befor aging

0%

3%

10%

5%


38/53

Figure 34 Figure 33: Specimens treated with WR 16-606: water absorption kinetics after aging

Contrary to what was expected, and as shown in the unaged results, the highest WR

concentration (0.5%) did not show the best performance. In this case, the lower water

absorption was for the concentrations of 0.10% and 0.25%.For all concentrations water absorption was much lower than that of the untreated samples.

It reaches a 70% reduction during the first 24 hours of immersion and 45% after ten days.

Figure 34 compares the aged and unaged results. It shows that the higher the WR

concentration, the higher the water absorption caused by accelerated aging:

0.50% concentration - 100%




0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption

TIME (H^0.5)



0,50% - after aging


0,25% - after aging


0,10% -After aging


0,05% - after aging

0,05% - befor aging


39/53

Figure 34: Specimens treated with WR 16-606: water absorption before (continuous line) and after


5.4.1.1 Conclusions


Accelerated aging caused an important reduction in the water absorption rates of the

untreated specimens (23% after 24 hours of immersion). According to the literature

this behavior is normal and is caused by the increase in cement hydration, which

reduces the matrix porosity;

All products tested were slightly affected by aging cycles. Water absorption

normally increased;

For the post-treatment application, 520 showed a better performance during the first

24 hours of immersion, while 6683 was better for longer periods of time (Figure

35);

The admixture products showed a better performance than the post-treatment

products (Figure 36) during 24 hours of immersion. During the first four hours,

which is a more likely rain duration, the diference is neglible.

0%

5%

10%

15%

20%

25%

0 1 2 3 4 5

WaterAbsorption

TIME (H^0.5)



0,50% - after aging


0,25% - after aging


0,10% -After aging


0,05% - after aging

0,05% - befor aging


40/53

Figure 35: 6682/520 Water absorption rate x time

Figure 36: Best product concentration after aging cycles.

5.4.2 MOR

Figure 37 shows the MOR results.

-100%

-50%

0%

50%

100%

150%

200%

0 2 4 6 8 10 12 14WaterAbsorption6683/520

Time (H^0.5)

3%

10%

5%

0%

3%

6%

9%

12%

15%

18%

0 1 2 3 4 5

WaterA

bsorption

Time (h^0.5)

0%

6683 - 10%

520 - 10%

16-606 0,25%


41/53

Figure 37: MOR results


For the untreated samples, aging did not affect the MOR. This result is in

accordance with the bibliography (Savastano, 2006 and Dias, 2005)

Unaged:

Post-treatment WR does not affect MOR (Figure 38)

Admixture WR (16-606): important influence on the MOR (Figure 39)

Figure 38: MOR Results x Post-treatment water repellent concentration left = unaged and right =

0

3

6

9

12

15

Unaged Aged

MOR(MP

a)

Untreated

0

3

6

9

12

15

3% 5% 10%

MOR(MP

a)

6683

Unaged aged

0

3

6

9

12

15

3% 5% 10%

MOR(MP

a)

520

Unaged Aged

0

3

6

9

12

15

0,05% 0,10% 0,25% 0,50%

MOR(MP

a)

16-606

Unaged aged

0

3

6

9

1215

0% 2% 4% 6% 8% 10%

MOR(Mpa)

Unaged - post treatment

6683

520

0

3

6

9

1215

0% 2% 4% 6% 8% 10%

MOR(Mpa)

Aged - post treatment

6683

520


42/53

aged

Figure 39: MOR Results x 16-606 concentration

Aged:

6683 the higher the concentration, the lower the reduction

520 no influence

16-606 increases the MOR

5.4.3 Fracture Toughness

Figure 40shows the results.

Figure 40:Fracture Toughness results

0

3

6

9

12

15

0% 0,05% 0,10% 0,25% 0,50%

MOR(Mpa)

16-606

Unaged

Aged

0

3

6

9

Unaged Aged

kJ/m2

Untreated

0

3

6

9

3% 5% 10%

(KJ/m2

6683

Unaged Aged

0

3

6

9

3% 5% 10%

KJ/M2

520

Una ed A ed

0

3

6

9

0,50% 0,25% 0,10% 0,05%

KJ/M2

16-606

Unaged Aged


43/53

The main conclusions about fracture toughness are:

The untreated specimens showed an important reduction after aging (>70%);

Both products applied as post-treatment showed a slight influence before aging;

16-606 causes an important influence before aging. The higher the concentration,

the lower the fracture toughness;

The water repellents applied as post-treatment reduce the fracture toughness

degradation by aging (Figure 41).

Figure 41: Fracture Toughness results x water repellent concentration left = 6683 and right = 520

Figure 42: Fracture Toughness results x 16-606

concentration

5.5 Conclusions

The main conclusions for the third round are:

Untreated samples:

aging reduces toughness

0

3

6

9

0% 5% 10%

KJ/M2

6683

Unaged Aged

0

3

6

9

0% 2% 4% 6% 8% 10%

KJ/M2

520

Unaged Aged

0

3

6

9

0% 0,05% 0,10% 0,25% 0,50%

KJ/M2

16-606

Unaged Aged


44/53

aging does not affect MOR

aging reduces water absorption

Water repellent treatment

Prevents toughness degradation by aging

MOR can be influenced by aging

Water absorption is much smaller than in the untreated specimens

Accelerated aging: minor effect on hydrophobicity

Post-treatment: higher contents are better Higher hidrophobicity

Increase resistance to mechanical degradation

16-606

Unaged: MOR reduction

After aging: great improvement in the MOR and fracture toughness


45/53

Chapter 6: Industrial Test


46/53

Industrial Applicati

Objective: To test the post

corrugated sheets at INFIB

Date: 07/13/2007

Team: David Selley and

Maranho (USP), Luiz Fer

Materials:

o Water repell

o Asbestos-fr

2.44X0.48X

Report:

Only product 520 was tes

corrugated sheets used in t

a few minutes earlier. The

raw materials used.

Two hundred kilos of wa

which was then filled with

Figure 44 shows the contai

Figure 43: Water Repellent d

container

n Report

treatment water repellent application proced

RA Industrial Plant

arcos Antonio (DCC); Vanderley John,

ando and Paulo Doniseti (INFIBRA)

ent 520 at a concentration of 10%

e corrugated sheets after steam

0.006m

ed because there was no available time fo

is test were asbestos-free and had been stea

re is no specific information available about

er repellent were deposited in a plastic co

water, reaching a dilution of 10%, as previou

ner dimension.

position in the

Figure 44: Dimensions of the pl

ure on asbestos-free

ai Loh and Flvio

curing - Size

the other one. All

cured for 18 hours

the composition of

tainer (Figure 43),

sly agreed upon.

stic container used in


47/53

the industrial test

In the first stage ten corrugated sheets were immersed manually and individually for four

minutes in the container with the water repellent solution. Then seven stacks, each one with

eleven piled sheets, were dipped in the container for four minutes (Figure 45).

Figure 45: Immersion of the stack of corrugated sheets in the container.

The water repellent consumption was determined by measuring the volume of the solution

before and after the immersion of the sheets. The result was 0.96 dm3/m2.

Therefore, for a single sheet measuring 2.44m x 0.48m, the solution consumption was

112ml.

The dipping time was determined by INFIBRA and corresponds to the time available in the

normal demolding process.

After four minutes of immersion, all sheets piled in the stack show uniformly and totally

wet surfaces (Figure 46), which confirms the good absorption of the solution.

Figure 46: Surface of corrugated sheets after immersion for four minutes.


48/53

Along the first hour after immersion it was observed that the upper corrugation usually

dried first (Figure 47). One hour after the immersion no stain was observed (Figure 48).

Figure 47: Illustration of dry behavior

Figure 48: Surface with no stain one hour after immersion

After the treatment, four stacks were separated for natural aging evaluation. Two of them were

treated with 520 water repellent (manual and stack application) and two were not treated.


49/53

Figure 49: Treated and untreated corrugated sheets

Treated by Stack

Treated manually

Untreated


50/53

Chapter 7: Conclusion


51/53

Conclusions

Water repellent products have a large application potential in asbestos-free products,

mainly because they reduce water absorption, mould growth, cellulose degradation and

color alteration during service conditions.

The Project design performed was effective to evaluate the performance of silicone-base

water repellents and point out the best products.

The water repellents used as admixture were clearly shown to be more efficient to reduce

water absorption than the post-treatment. However, they influence the mechanical

properties, and modify the flocculation kinetics in the hatcheck machine, thus requiring

more researches before any industrial application.

The post-treatment products are easier to introduce in industrial plants and, at a

concentration of 10%, they show a very good performance (especially 520).

The main conclusions obtained in all rounds of this first project are:

Concerning the water repellent application:

Post-treatment applications after steam curing are better than before curing

Brushing and immersion are similar

Superwetter did not work properly

16-606 increases the efflorescence risk, while the products applied as post-treatment

strongly reduce it;

The post-treatment application is easier and faster to introduce in plants;

The products applied as admixture showed the lowest water absorption rates;

150 wet/dry cycles did not cause any important influence on the hydrophobic

performance;

Water repellent products (post-treatment and admixture) improve long-term

toughness performance;

Some WR reduce long-term MOR:

6683 (after aging)


52/53

16-606 (before aging)

The industrial application confirms a good water repellent emulsion absorption;

The water repellent emulsion consumption observed in the industrial plant was

around 10mL/m2.


53/53

Nome do arquivo: final.docxDiretrio: D:\Docs Flavio\empresas\dow

corning\fibrocimento\files\final report\versao finalModelo: C:\Documents and Settings\Flavio\Dados de

aplicativos\Microsoft\Modelos\Normal.dotm

Ttulo: Final Progress ReportAssunto: ASSESSMENT OF WATER REPELLENTPERFORMANCE ON CORRUGATED FIBER CEMENT ROOF SHEET

Autor: USP Team:Prof. Dr. Vanderley Moacyr John, Prof. Dra.Kai Loh, Msc. Flvio Leal Maranho

Palavras-chave:Comentrios:Data de criao: 18/9/2007 11:22:00Nmero de alteraes:10ltima gravao: 18/9/2007 12:39:00Salvo por: Flavio

Tempo total de edio: 85 Minutosltima impresso: 18/9/2007 12:40:00Como a ltima impresso

Nmero de pginas: 52Nmero de palavras: 6.235 (aprox.)Nmero de caracteres: 33.673 (aprox.)