1

Mechanical behaviour assessement of reinforced concrete

with steel wool

Nuno Alexandre Matos Ferreira

Extend Abstract

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Abstract

This work main objective is to contribute to deepening the knowledge of cement matrix composites

reinforced with steel wool. The use of these composites in the construction industry has assumed

greater importance over time since, without losing the characteristics attributed to conventional

concrete, some of the weakest aspects are improved, such as flexural strength and crack control.

To strengthen the cement matrix it was utilized a commercial steel wool used to prepare wood

surfaces and Portland cement of high initial strength and low setting time.

The formulation, production methods and techniques that enabled the analysis of the properties of the

composite are described.

Production of the composite was based on the concept SIMCON, Slurry infiltrated Mat Concrete, the

main objective being the evaluation of the influence of the percentage of steel wool in mechanical

performance of the composite. 5% to 10% by weight of the quantity of cement were the steel wool

percentages used. The effect of different doses and types of superplasticizers additives in rheological

properties of the cement matrix in fresh state were also studied, in means to determine the best

conditions for infiltration of wool. The influence of different dosages and types of superplasticizers

additives in the composite performance in hardened state was measured.

The slurry used in this work is composed of cement, water (30% of the amount by mass of cement)

and adjuvants. For its characterization the following properties were studied: Spreading by its own

weight and the density in fresh state. In the characterization of the composite in the hardened state,

density, the dynamic modulus of elasticity, tensile strength in bending, resistance to compression, the

open porosity and water absorption by capillary action were studied.

For the evaluation of the increase in flexural strength as a result of the introduction of commercial wool

as a reinforcement material, it was possible to assess that the increased percentage of fiber had a

significant impact, occurring increases of 100% in relation with the reference mixes with the

introduction of 10% fibers, these being the studied compositions that were more interesting.

Key-words: SIMCON, Steel wool, Flexural Strength

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Concrete reinforced with steel fibers

The concrete reinforced with steel fibers (SFRC) is a cementitious matrix composite to which is added

certain percentage of fibers. The use of composites in the construction industry has been rising

continuously. As conventional concretes, the SFRC remains a lower cost material to the potential

competitors in the construction industry. The fragility that characterizes conventional concrete is

decreased by means of share of fibers as a reinforcement element (ACI, 2002).

The fibers when crossing the micro cracks, which exist in the cementitious matrix, offer additional

resistance to degeneration in macro cracks, since it’s necessary to expend additional energy for

sliding the fibers relative to the surrounding matrix. Thus, since the composition and mixing techniques

and application of SFRC are suitable, it is found that the energy absorption capability, fatigue and

impact resistance increases with the percentage of fibers in the mixture (Balaguru and Shah, 1992)

(ACI, 2002) (Bentur and Mindess, 2007). It is also verified improvement in crack control (Barros, 1995)

and resistance under static loads (ACI, 2002) (Balaguru and Shah, 1992).

Applications that mobilize the ability of the material to absorb energy are the most appropriate to be

carried out with SFRC. Moreover, if the fibers replace conventional armor, it may be possible to obtain

a considerable saving in the solution to be adopted. Thus, the ground floors of industrial buildings

(ACI, 2002) and the tunnel walls (Bekaert, 2015) are examples of the proper use of SFRC. The partial

replacement of conventional equipment, particularly the shear strength, is also an example of

application of SFRC (Casanova, 1996). The nodes of gateways are chronic areas of damage due to

intense seismic actions (ACI, 2002). The resistance of such zones, and particularly its ductility can be

significantly enhanced if a suitable percentage of steel fibers are applied. If in areas such as these, it

is usual occur congestion shear strength reinforcement, the fibers effectively replace at least some

percentage of such reinforcement, the concrete conditions can improve, thus enhancing the quality of

the applied concrete in these areas.

In the recent years have seen the reinforcement of concrete of high strength steel fiber, since the

decrease in ductility occurs with increased concrete strength can be overcome by ductility introduced

by the fiber reinforcement (Rossi et al. 1996).

The SFRC technology has become a mature industry in recent decades, but the constant need to

optimize the use of fiber for demanding applications led to the emergence of new technologies. One of

the technologies that came up with this need for improvement was the Slurry infiltrated Fiber Concrete

(SIFCON).

The nature of the cementitious matrix, which initially consists of discrete particles makes it difficult to

incorporate a large amount of fibers, or fibers with an aspect ratio (ratio of length to diameter) greater

than 100. In the mix based production technologies, maximum fiber content which may be

incorporated is less than 2% by volume, and when using special techniques, such as the Hatschek

process or spray, this limit can be exceeded to between 5% and 12% using short fibers. These are the

limitations to consider when trying to maximize the potential of reinforcing fibers.

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To produce a reinforced concrete with high volume content of discrete fibers it was developed by

Lankard (Bentur and Mindess, 2007), a method based on pre placing a steel fiber bed which is

infiltrated with a cement slurry. In this system, called SIFCON, the placement of the fibers may be

performed manually or fiber distribution units. The pre placed in fiber is controlled by the length of the

fiber and its aspect ratio, a higher percentage of fibers can be obtained with the aid of vibration of the

mold during filling. Fiber volumes can be achieved in the order of 20% (Bentur and Mindess, 2007).

With these high fiber contents, it is possible to increase by more than an order of magnitude of the

flexural strength and toughness as compared to the unreinforced matrix, or a reinforced matrix with

low volume of discrete fibers, as shown in figure 1.

In the preparation of the composite is necessary to prevent non-uniform distribution of fibers.

However, as result of the nature of the preparation of the fiber bed, exist a tendency for the preferred

orientation which depends on the relationship between the size of the mold, the fiber length and

placement method. The effect of orientation can have a considerable influence on the properties. The

type and size of steel fibers can also affect the properties of the composite (Bentur and Mindess,

2007).

Naaman and Homrich (Bentur and Mindess, 2007) studied the mechanisms to strengthen the SIFCON

and found that the failure occurs by yielding of the fiber / adhesive rupture and not by rupture of the

fiber. The cementitious matrix of the blend composition is particularly important to ensure an efficient

leakage during production, and to control the properties of the hardened concrete.

The cementitious matrix may consist of a slurry or mortar with fine aggregate. Generally

superplasticizers are necessary to enhance their rheological properties so that it can be applied in

SIFCON.

In SIFCON technology, the fibers are pre-placed in the mold to prepare the reinforcing bed. This

operation is time consuming. Thus are continually sought new alternative methods to overcome the

limitations of SIFCON. One of these methods consists in producing a fiber mat, which can then be

easily transported as rolls, easily placed and impregnated with the slurry. With these mats or steel

wool is possible to use higher aspect ratio fibers and have a better control of the orientation, thus

Figure 1 - Comparison of stress-strain curves of SIFCON, SFRC and without any concrete

reinforcement element 3 with bending points (Naaman 1992)

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enabling reduction of the amount of fiber. This mesh of interconnected fibers prevents the free

retraction of the array producing lower values of linear retraction, this advantage comes with the easy

handling and better quality control in the production of such compounds and its local application. This

composite is called SIMCON, Slurry Infiltrated Mat Concrete (Bentur and Mindess, 2007).

In this type of composite, an increase in the fiber volume above a value such that it is impossible to

occur infiltration by cement paste can result in a reduction of mechanical properties due to difficulties

in compression. This critical value, depends on the production process, and can be increased by using

more fluid suspension techniques and more intensive compression.

The high flexural strength obtained with a low percentage of fibers reflects the high efficiency of high

aspect ratio fibers used in such composites.

SIMCON properties such as tensile strength, have been reported by A.M. Krstulovic-Opara and Malak

(Bentur and Mindess, 2007), and showed that SIMCON efficiency is higher than SIFCON. With fiber

content in the range of 3-5%, the obtained tensile strength was 10-16 MPa (figure 2). For the same

values in SIFCON, the use of 14% fibers is required.

Both in SIFCON as in SIMCOM fibers are responsible for increased energy absorption capacity

during pull-out, which results in increased strength compared with normal concrete. As result,

these composites have been applied in rehabilitating structures earthquake-resistant

components, explosion resistant structures and fine pre-molded product (Bentur and Mindess,

2007).

Materials and compositions studied

Cement

In this work is used a Portland cement, high early strength, the Supremo Cimento CP V-ARI, provided

by SECIL to the Brazilian market. It is a gray Portland cement, with initial resistance to compression

greater than 34 MPa at 7 days of age and low setting time (less than 60 minutes) that complies with

Figure 2 - Relationship between the fiber and the mechanical properties of SIMCON (Bentur and

Mindess, 2007).

6

the technical recommendations of the Brazilian Norm - NBR 5733/1991. It is used in situations that

require a quick undercut (Supremo Cimento, 2015)

Steel wool

Is used a commercial steel wool (Figure 3) in order to reduce the production cost of the composite.

The wool is distributed by Productos PROMADE S.A., according to the manufacturer's product

intended for the preparation of wooden surfaces for the subsequent application of products such as

varnishes. Can be seen in the steel wool roll that fibers are not uniform, either in terms of length,

straight section and tensile strength even when requested by human force.

Plasticizer

Two types of superplasticizers of MC-Bauchemie were used. MC-TechniFlow 91 (hereinafter

superplasticizer 1 - SP1) is a concrete superplasticizer adjuvant that reduces surface tension of water

even with small dosages. It facilitates the dispersion of cement particles and thereby obtains a higher

concrete workability with a reduced need for compression. Depending on the type of cement,

temperature and weather may be a slight retarding effect of prey.

The other product was used Muraplast FK 98 (superplasticizer 2 - SP2) which is a dispersing agent for

cement particles avoiding their agglomeration and reducing the surface tension of water from the

mixture as a consequence of the better distribution of the cement particles and the aggregate is

obtained an improvement in cohesion and workability of the concrete.

Studied compositions

This study investigated the effect on the fluidity of the mortars in the fresh state of two different

plasticizers and the percentage of infiltrated fiber. To determine the dosages to use that offering better

workability was tested what dosage that offered more fluidity to the mix without it appeared

segregation or exudation. With initial reference the recommended dosage by the manufacturer tests

were made until, for each plasticizers would arise not the phenomena mentioned above. For a fixed

amount of cement and water, water represents 30% of the amount by weight of cement, were made

varying the fiber percentages and superplasticizer according to the cement mass. The following table

(Table 1) shows the dosages used for each plasticizer.

Figure 3 - Steel wool in the form provided by the manufacturer.

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Table 1 – Dosage of plasticizer applied

SP1 SP2

Amount of plasticizer

(g/ Kg of cement) 6; 7 e 9 3; 3,5 e 4

After performing exploratory mixtures, were studied the mixtures presented in Tables 1 and 2. Was

varied percentage of fiber and superplasticizer, for each type of this material.

The test pieces will be designated by the following criteria: "SP1" and "SP2" as used plasticizer, "-X",

which is the dosage of the superplasticizer and finally said "Y%" represents the percentage of fiber.

For example, "SP1-6 5%" represents the superplasticizer 1 with a dosage of 6% and 5% of fibers.

Table 2 - Composition studied with SP1

Designation Percentage of fibre(%) Percentage of SP(%)

SP1-6 0 6

SP1-7 0 7

SP1-9 0 9

SP1-6 5% 5 6

SP1-6 10% 10 6

SP1-7 5% 5 7

SP1-7 10% 10 7

SP1-9 5% 5 9

SP1-9 10% 10 9

Table 1 – Composition studied with SP2

Designation Percentage of fibre(%) Percentage of SP(%)

SP2-3 0 3

SP2-3,5 0 3,5

SP2-4 0 4

SP2-3 5% 5 3

SP2-3 10% 10 3

SP2-3,5 5% 5 3,5

SP2-3,5 10% 10 3,5

SP2-4 5% 5 4

SP2-4 10% 10 4

Results

This section presents the results is considered as the most relevant, open porosity, Young's modulus,

compressive strength, flexural strength and SEM micrographs.

Open porosity

For SP1, as shown below (figure 5), it is common to all the dosages SP that the lower porosity value is

obtained for the reference mixtures, increasing to 5% fiber and lowering for 10%

8

.

Figure 1 – Open porosity referring to SP1, steel wool evaluation

For SP2, the dosages of 3% and 4%, promote the increase of the porosity with the percentage of

introduced fiber. With 3,5% the porosity increased for 5% of the fiber but decreases to 10%.

Figure 2 – Open porosity related to SP2, steel wool evaluation

Dynamic module of elasticity (ultrasound)

The module of elasticity was only evaluated for superplasticizer 2.

Evaluating the effect of introducing fibers, figure 7, it can be seen that for dosage 3% of SP the

module of elasticity increases with the increasing of the percentage of embedded fiber. For all other

dosages, the module of elasticity decreases with increased amount of incorporated fiber, although the

lowest value is presented by the intermediate dosage of 5%.

Figure 3 – Module of elasticity for SP2, evaluation of steel fibers

12,2 14,5 13,9

25,1 28,0

25,5

20,4 20,7 21,5

0

5

10

15

20

25

30

SP1-6 SP1-7 SP1-9

Op

en

po

ros

ity S

P1 (

%)

SP1 - 0% SP1 - 5%

SP1 - 10%

15,3

22,2 20,2 24,7

28,0 23,8 25,2 24,8 25,1

0

5

10

15

20

25

30

SP2-3 SP2-3,5 SP2-4

Op

en

po

ros

ity S

P2 (

%)

SP2 - 0% SP2 - 5%

SP2 - 10%

51,3 58,7 60,1

53,5 53,4 54,0 55,2 56,0 56,8

0

10

20

30

40

50

60

70

SP2-3 SP2-3,5 SP2-4

Dyn

am

ic m

od

ule

of

ela

sti

cit

y S

P2 [

MP

a]

SP2 - 0% SP2 - 5%

SP2 - 10%

9

Determination of compressive strength

The structural elements of cementitious composites are not only exposed to tensile stresses, these

elements are also exposed to the compression, one property whose results are presented below.

When evaluating the effect of the percentage of fiber, is common to all dosages of SP that a lower

value corresponding to mixtures with 5% fiber and a higher value corresponding to 10% fiber. The

reference mixtures have an intermediate value.

Figure 4 - Resistance to compression referring to SP1, steel wool evaluation

For mixtures of SP2 the dosage of 3 and 3,5% it was observed that the compressive strength

increases with the proportion of fiber. For the dosage of 4% the lowest value corresponds to 5% fiber.

For the reference mixture and the mixture with 10% the compressive strength of the fiber increases

with the percentage of fiber.

Figure 5 - Resistance SP2 related to compression, steel wool evaluation

Determination of tensile strength in bending

The tensile strength in bending is an important property to airframe design and it becomes vital to

evaluate the behavior of the cementitious matrix composites with fiber. In this type of composite steel

fiber function is to increase the flexural strength making the material more ductile.

In the case of mixtures prepared with SP1 is common to all dosages of SP that the composition which

has the highest resistance to bending is one that contains 10% fiber, in these cases the values

83,5 81,0 80,6 76,9 74,5 77,6 84,7 84,0 84,0

0

10

20

30

40

50

60

70

80

90

SP1-6 SP1-7 SP1-9

Co

mp

ressiv

e s

tren

gth

SP

1

[MP

a]

SP1 - 0% SP1 - 5%

SP1 - 10%

75,0 69,6 86,2 81,0 79,4 84,5 83,2 87,6 87,5

0

20

40

60

80

SP2-3 SP2-3,5 SP2-4

Co

mp

ressiv

e s

tren

gth

SP

2

[MP

a]

SP2 - 0% SP2 - 5% SP2 - 10%

10

increase in the order of 50% against the reference mixtures. For the incorporation of 5% of fiber we

didn’t observe significant increases.

Figure 6 - Flexural strength of SP1, steel wool evaluation

For SP2 mixtures the highest values of flexural strength are also provided by the compositions with

10% of fibers. With the exception of mixtures with 3,5% SP values of bending strength increase with

increasing of the percentage of the embedded fiber. For compositions containing 3,5% of SP in the

case of no fiber incorporation, was obtained a higher value than for the 5% fiber, contrary to other

cases.

Figure 7 - Flexural strength for SP1, steel wool evaluation

Scanning electron microscopy

In order to try to understand the mechanisms leading to increased mechanical strength as a

consequence of steel wool incorporation were performed microscopy to fracture surfaces after

bending test of some of the mixtures. Samples for analysis were prepared according to the procedure

described in Guedes et al., 2013, consisting in impregnating the sample under vacuum in a low

viscosity resin which is followed mechanical polishing and subsequent wear. The polishing was

performed using fine abrasives to 1mm. The equipment used was a Scanning Electronic Microscope

FEG-SEM JSM-7001F, JEOL, Tokyo, Japan. Which is coupled EDS Microanalysis Inca PentaFETx3,

Oxford Instruments, Abingdon, Oxfordshire, UK. The choice fell on the SP1 9% blends with 5% and

10% incorporated steel wool.

8,7 7,8 6,6 8,8 8,9 9,2

16,0 17,0 17,1

0

4

8

12

16

20

24

SP1-6 SP1-7 SP1-9

Fle

xu

ral str

en

gth

SP

1 [

MP

a]

SP1 - 0% SP1 - 5% SP1 - 10%

6,3

14,3

7,6 8,9 9,5 8,9

17,5

22,7 20,0

0

4

8

12

16

20

24

SP2-3 SP2-3,5 SP2-4

Resis

tan

ce t

o b

en

din

g

SP

2[M

Pa]

SP2 - 0% SP2 - 5% SP2 - 10%

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Figure 8. Microscopy: mixture SP1-9% with 5% steel wool (Left) and 10% steel wool (right)

Figure 13. Microscopy: mixture SP1-9% with 5% steel wool after polishing

Discussion of Results

For the module of elasticity, property which was only performed for SP2 in case of 3% dosage SP2,

we observed that this property increases with steel wool embodiment. In other cases the module of

elasticity decreases with wool incorporation and it had more incidence in mixtures with 5% fiber. The

results obtained in this property induce in different conclusions, i.e. we cannot find a link between

other properties already discussed. It’s not possible to conclude what is the effect of the addition of

steel wool in the Module of Young. This may be due to the presence of closed porosity which would

lower the Module of Young.

In relation to compressive strength this we can, in the case of SP1, found that the introduction of steel

wool has a slight effect on the compressive strength. With the exception of mixtures containing 5%,

wherein the compressive strength decreases (which are also the mixtures show the highest porosity)

there is an increase in this property to 10% fiber even with increased porosity. In SP2 case we also

seen compressive strength increases with the introduction of wool, as a result of better control of

cracking caused by fibers. The only exception was in the case of dosage 4% of SP to 5% fiber,

however the reference mixture has a higher standard deviations, which may indicate that the value

could even be lower and thus kept to compressive strength increasing trend with increasing

percentage of incorporated wool.

Regarding the flexural strength of the blends prepared with SP1 it was concluded that the

incorporation of steel wool has a significant impact on the flexural strength of the composites. The

incorporation of 5% of steel wool does not result in a significant improvement of this property, however

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with the addition of 10% wool in relation to the reference mixtures the improvement was of the order of

100%.

In the case of blends prepared with SP2 where the dosage is 3% and 4% SP, the results obtained

were in line with those obtained in the case of SP1. Slight increases occur for the incorporation of 5%

fiber; with 10% fiber the flexural strength increases for more than doubled. It was also found that, for

both SP, are generally mixtures with a 5% steel wool which have higher values of porosity. For

mixtures with 3,5% the trend is not similar, the mixture of reference without fiber added showed a

mechanical resistance higher than the other mixtures without fiber or with 5% fiber.

As previously stated, in order to try to understand the mechanisms leading to the increase of

mechanical strength as a result of the steel wool incorporation were realized some microscopy to

fracture surfaces after the test of bending of some mixtures.

For mixtures of SP1 it was possible to observe that pull-out occurred, as shown in figures 40 and 41.

And it was proved that it was the steel wool present in the composite that resisted to bending stress. It

was observed that the filaments of steel wool which suffered pull-out, i.e. they suffered tearing as a

result of bending stress in the case of the composite with 10% wool rushes incorporated into the same

kind of phenomenon.

Another mechanism mentioned was the better control of cracking introduced by the fiber in the steel

wool. The presence of steel wool filament stopped the propagation of a crack thus proving the

improvement introduced by the steel wool in mechanical performance of composites made with steel

wool.

Conclusion and Future Work

The experimental campaign followed in this work enabled us to understand several important aspects

for the BRFA behavior.

Regarding steel wool embodiment, it was concluded that:

That could cause a very significant increase in tensile strength by bending;

In general, causes an increase in compressive strength;

Increase the amount of pores in the cementitious matrix composite;

Lead to increased capillary coefficients relative to the mixtures without steel wool ;

Although the steel wool has a high variety of types of fibers and that the influence of this variability

have not been considered in the behavior of the produced composite, it was considered that producing

a concrete reinforced with steel wool as a variant of low-cost SIMCON composite.

This work identified that with the introduction of 5% fiber slight gains are obtained in increasing the

flexural strength of the composite. However with the introduction of 10% fiber are significant gains may

submit increments greater than 100% as in the case of mixtures produced with SP2.

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As future work it could be developed the BRFA production technique, which can be improved the wool

infiltration conditions and controlled parameters such as vibration time that this work has not been

quantified and has considerable influence on the final properties of the composite.

It is also important to study the durability of the composite, as well as the steel wool resistance to

corrosion processes.

References

ACI (2002) American Concrete Institute – State of the art – Report on Fiber Reinforced Concrete. Reported by ACI Committee 544. 66p.

Balaguru, P.N.; Shah, S.P. (1992) Fiber Reinforced Cement Composites. McGraw-Hill International Editions. Civil Engineering Series. 531p.

Barros, J. A. O. (1995) - Comportamento do Betão Reforçado com Fibras, Análise Experimental e Simulação Numérica. Tese de Doutoramento, Dep. Engª Civil, FEUP.

Bekaert (2015) – Products and applications: Construction. Disponível em: www.bekaert.com. Acesso: 25.09.2015.

Bentur A.; Mindess, S. (2007) – Fibre Reinforced Cementitious Composites. 2ª Edição. Taylor & Francis. USA. – Ramakrishnan, V.; Coyle, W.V.; Dahl, L.F.; Shrader, E.K., “A Comparative Evaluation of Fiber Shotecrete”, Concrete International: Design and Construction, Vol. 3, Nº 1,1981, pág. 56-59.

BOTAS, S. (2009) – Avaliação do comportamento de argamassas em climas frios. Dissertação para obtenção do grau de Mestre em Engenharia Civil. Caparica,. FCT/UNL.

Casanova, P. (1996) - Bétons Renforcés de Fibres Métalliques, du Matériau à la Structure. Laboratoire Central des Ponts et Chaussées. Février.

Coutinho, A.M. (2006) Fabrico e Propriedades do Betão. Edições LNEC. 646p.

CRAST (2015) Centro Ricerche Archeologiche e Scavi di Torino – Activities of the Institute of Archaeological Sciences and of the Centre for the Restoration of Monuments in Baghdad. Disponível em http://www.centroscavitorino.it/ (Acesso em 03 de Abril de 2015).

Engineer Statistics Handbook (2014) – Estatísticas. Disponível em: http://www.itl.nist.gov/div898/handbook/prc/section1/prc16.htm. Acesso em: 25.09.2015.

Guedes, M.; Evangelista, L.; Brito. J.; Ferro, A. F. (2013) – Microstructural Characterization of Concrete Prepared with Recycle Aggregates. Microscopy and Microanalysis. Pág: 1-9.

LNEC E 393. 1993. Absorção de água por capilaridade. Portugal: Laboratório Nacional de Engenharia Civil.

MARTINS, A. I. (2010) - A influência das condições de cura em argamassas de cais aéreas com e sem adição de metacaulino. Dissertação apresentada para: cumprimento dos requisitos necessários à obtenção do grau de Mestre em Construção Civil. Escola Superior de Tecnologia do Barreiro do Instituto Politécnico de Setúbal.

Naaman, A. E. (1992) - SIFCON: Tailored Properties for Structural Performance, HighPerformance Fiber Reinforced Cement Composites. E & FN Spon. London, UK: 18-38.

Odelson, J.B.; Kerr, E.A.; Vichit-Vadakan, W. (2007) – Young’s modulus of cement paste at elevated temperatures. Cement and Concrete Research, 37: 258-263.

14

Rossi, P.; Renwez, S.; Guerrier, F. (1996) Les bétons fibrés à ultra-hautes performances. L'expérience actuelle du LCPC. Bulletin des Laboratoires des Ponts et Chaussées Nº 204. 87-95.

Simões, A.; Diogo, A. C.; Costa, C. M.; Montemor, F.; Margarido, F.; Flores-Colen, I.; Custódio, J. E.; Correira, J. R.; Fernandes, J. S.; Almeira, J V.; Fernandes, J. C.; Brito, J. M.; Neves, J.; Nunes, L.; Gil, L.; Rosa, L. G.; Vieira, M.; Gonçalves, M. C.; Amaral, P. M.; Pontifice, P.; Colaço, R.; Pires, V. C. (2012) – Ciência e Engenharia de Materiais de Construção. IST Press. 1ªEdição. 1057p.

Vilardell, J.; Aguado, A.; Agullo, L.; Gettu, R. (1998) - Estimation of the modulus of elasticity for dam concrete. Cement and Concrete Research, 28: 93- 101.