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ISSN: 2423-4796

Applied Research Journal Vol.2, Issue, 9, pp.384-393, September, 2016

*Corresponding author: Besma M. Fahad, Email: Eng.Mustafa.Al.Taey@gmail.com Department of Materials engineering, University of Mustansiriya, Baghdad, Iraq.

APPLIED RESEARCH JOURNAL

RESEARCH ARTICLE

INFLUENCE OF DIFFERENT ALIGNMENT OF GLASS FIBERS WITH STYRENE BUTADIENE RUBBER ON SOME PHYSICAL PROPERTIES OF MORTAR

* Besma M. Fahad and Mustafa M. Hamza

Department of materials engineering, University of Mustansiriya, Iraq.

ARTICLE INFO ABSTRACT

Article History:

Received: 20, September, 2016 Final Accepted: 25, October, 2016 Published Online: 03, November, 2016

The effect of reinforcing the mortar with glass fibers in different alignment beside the addition of styrene butadiene rubber (SBR), were investigated in this work to show their influence on some physical properties. Different series were prepared, two of them were reinforced the mortar with glass fibers in two manner (random and layers). The others series were the same with the addition of SBR. These series were immersed in water with controlled conditions for 7 and 28 days. The glass fibers were added in different weight percentages (0, 54, 0.76, 1.1 and 1.42). The SBR was added at 7 % from water. Water absorption, ultrasound velocity and acoustic impedance were measured after preparing the specimens and com [paring them with controlled specimens. The results showed an improvement in mortar properties by reduction of water absorption, ultrasound velocity and acoustic impedance as well as producing lighter weight than conventional mortar. The best results were achieved by reinforcing with glass fibers layers in presence of Styrene Butadiene rubber after curing for 28 days.

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Key words:

Random glass fibers, Glass fibers layers, SBR, Water absorption, Ultrasound velocity, Acoustic impedance.

1. INTRODUCTION

Mortar reinforcing by glass fibers is one type of fibers reinforced concrete which has main use in exterior construction facades and precast concrete. Glass fibers reinforcing mortar is a composite material with cementitious matrix and high strength glass fibers reinforcement embedded in that matrix. The fibers act as load bearer, while the surrounding matrix acts as a load transfer medium, hold the reinforcement in the desired orientation and position, and keeps them from external conditions. The using of glass fiber reinforced concrete system was recognized by Russians in the 1940s [1]. Cementitious structures characterizes by brittleness which causes weak fracture toughness, weak impact strength and low cracks resistance. These properties restrict its application. Reinforcing with glass fibers is one of adopted methods to overcome the brittleness [2]. The recent development in the field of construction tends to produce superior properties with lighter weight. Reinforcing with glass fibers produce lightweight structure with high strength/weight ratio and improve the durability and water absorption. As for the use of synthetic polymers in construction, different kinds of polymers are used. They have good adhesion and bonding with the aggregates. The combination of cementitious materials with polymers could produce better physical and mechanical properties. The first using of synthetic-polymer modified system was applied in the 1940s. The applications involve paving, bridges, anti-corrosives, floorings, adhesives and deck coverings [3, 4]. The combination of synthetic polymers with mortar and concrete was started in the 1950s [3, 5].

Latex modified mortar or concrete has greatly improved properties compared with conventional one. The hardened cementitious materials has an agglomerated structure consisted of Calcium hydroxide and Calcium Silicate Hydrates bonded by weak Vander Waals bonds. This structure make the micro cracks easy to occur under exposure to stresses and causes poor fracture toughness. On contrast, in latex modified system the micro cracks are bridged by the polymer films and strong bond of cement hydrate-aggregate is developed.

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Polymer films developed in the structure provide an increased waterproofness, chemical resistance, moisture and oxygen transmission, and durability [6]. In the 1960s, using of Styrene Butadiene rubber and other synthetic polymer modified cementitious materials increased in practical applications [7]. The first emulsion polymerized Styrene Butadiene rubber was known in the 1930’s as Buna S. It was prepared by I. G. Farbenindustrie in Germany [8]. In 2014 Shete and Upase, investigated the effect of Styrene Butadiene rubber (SBR) addition on compressive strength and water absorption of concrete. Mixtures of (1:1.3:2) cement/sand/gravel ratio and water/cement ratio (0.4) were prepared. SBR percentages were (10, 15 and 20) % by weight of cement. Cubes of (10x10) cm. were prepared and tested after 7 and 28 days of curing. The results showed that the slump of SBR modified concrete was increased. At early ages the compressive strength was reduced with increasing in SBR presence, on contrast at 28 days of curing the best results were achieved 20% SBR which cause increasing in compressive strength by 14% and he water absorption was reduced by 44% [9]. In 2014, A. Deepak Raj and others studied the effect of addition glass fibers with fly ash and 1% super plasticizer on workability and ductile behavior of self-compaction concrete. Mixture proportions was (1:2.4:2.7) Cement/sand/gravel with 0.5 Water/cement ratio and fly ash of 30% of cement. (0.25, 0.5, 0.75, and 1)% with respect to the binder ratio of discontinuous S-glass fibers with different lengths (1.2, 1.8, and 2.4) mm was added. The results showed that the flow ability is directly proportional to glass fibers length and quantity. 1% of S-glass fibers showed better flow ability in all lengths [10].

2. AIMS

This study investigates the effect of addition glass fibers in two manners layers and random with and without the presence of Styrene Butadiene rubber on water absorption, velocity of ultrasound wave passing through the reinforced mortar and acoustic impedance of mortar with studying of curing effect for 7 and 28 days on these physical properties.

3. EXPERIMENTAL PROCEDURE

3.1. Materials

3.1.1. Cement

Sulfate-resistant Portland cement was used; it was of (Tasluja) Al-Jissir trade mark from Lafarge cement factory. In order to avoid the humidity effect on cement properties it was stored in a dry place. Several chemical and physical tests were carried out in National center for construction labs. & researches (NCCLR) to verify its specification, the cement were identical to the Iraqi standard specification No.5/1984. Table 1 and Table 2 show the chemical composition and physical properties of the cement, respectively.

Table 1 Chemical composition and properties of cement

Table 2 Physical properties of the cement

Chemical composition & properties Tests Results% Limits SiO2 19.74 ـــــــــــــــ Al2O3 4.28 ـــــــــــــــ Fe2O3 5.04 ـــــــــــــــ CaO 64.13 ـــــــــــــــ MgO 2.92 ≤ 5% SO3 2.36 ≤ 2.5% C3A 2.82 ≤ 3.5% Lime Saturation Factor (L.S.F) 0.98 ≤ (1.022-0.66)% Insoluble residue (I.R) 0.96 ≤ 1.5% Loss on ignition (L.O.I) 3.92 ≤ 4%

Physical properties Results limits Fineness (m/kg) (blain’s method) 358 ≥ 250 Setting time (hr : min) (Vicat’s method) -Initial setting -Final setting

2 : 15 4 : 15

≥ 45 min. ــــــــــــــ

Soundness (Autoclave) -0.1 ≤ 0.8 Compressive strength (MPa) -3 days -7days

19.5 25.5

15 23

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3.1.2. Sand

Sand from Al-Ukhaidir region was used as fine aggregate with specific gravity of (2.58) and fineness modulus of (2.17). A sieve analysis was carried out in (NCCLR) to know the grading of the fine aggregate according to the Iraqi standard specification No.45/1984. Table 3 shows the results of sieve analysis and the Fig. 1 shows the upper and lower limits of Iraqi specification and the used sand.

Table 3 The results of sieve analysis.

Sieve aperture Weight in gram Retained % Passed % Limits of third area

% 10 mm 0 0 100 100 4.75 mm 1 0.133 99.9 90-100 2.36 mm 57 7.6 92.4 85-100 1.18 mm 132.5 17.66 82.3 75-100 600 micron 277.5 37 63 60-79 300 micron 506.5 67.53 32.5 12-40 150 micron 655.5 87.4 12.6 0-10 salts% 714 95.2 4.8 5

Figure 1 The upper and lower limits of Iraqi specification and the used sand

3.1.3. Glass fibers

A chopped strand mats glass fibers of CHINA BEIHAI trade mark with 2.58 g/cm3 density was used. It was of thickness (2mm) and fiber length (3cm). It was cut into two shapes layers and random fibers as shown in Fig. 2.

Figure 2 A: Random glass fibers, B: Glass fibers layers.

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3.1.4. Styrene Butadiene rubber

SBR is an aqueous dispersion of (25%) Styrene and (75%) Butadiene copolymer when mixed with Cementitious products giving high performance water resistance properties, it is especially suitable for primers, renders, mortars and floors with high abrasion resistance and for patching and bonding onto substrates of low suction. The SBR used in this research was of SBI trade mark in UAE. Table 4 shows the typical properties of SBR that is used and all of the information from the manufacturer data sheet.

Table 4 Typical properties of used SBR

Appearance Fluid liquid Color Milky white change to transparent when dry Density 1050 Kg/ni3 Solid content 36 - 38 % pH 8-9 Temperature resistance -20 up to +90 C

3.1.5. Glass fibers

Water is an essential element of mortar due to its rule in chemical reaction with cement which is known as cement hydration reaction [11]. A tap water was used for mixing process and distilled water for curing process.

3.2. Experimental work

Mixtures of 1:2 cement/sand ratios and 0.5 water/cement ratios were prepared for making mortar. The glass fibers was added by two manners, layers and random with weight percentages of (0.54, 0.76, 1.1 and 1.42). The specimens divided into two series glass fibers reinforced mortar free from SBR and glass fibers reinforced mortar with 7% SBR of mixture water.

Table 5 shows the mix design proportions. The glass fibers were weighed before mixing as shown in Fig.3:A. For achieving a homogenous mixing of the materials, sand, cement, and glass fibers were mixed together by hand for about two minutes in dry state, the water was added to the mixture and mixed for four minutes according to ASTM C305 [12].

Fig.3:B. showing the preparation of random glass fibers reinforced mortar. After the mixing process the resulted mortar was poured in cast iron molds of (15×15×15) cm. dimensions. In glass fibers layers reinforcing a glass fibers mat was cut into squares layers of (15×15) cm. dimensions. The mortar and glass fibers layers were sequentially fed into molds in order to produce a cohesive structure.

Fig.4:A. showing the molding of glass fibers layers reinforced mortar. The layers was well compacted by hand until the mixture water penetrate through it which made better bonding between the cementitious matrix and glass fibers layers reinforcement as shown in Fig.4:B.

After the solidification of specimens they were de-molded and cured at temperature of (20∓5)°C for 7 and 28 days at controllable room of (50∓5)% humidity as it shown in Fig. 5.

Table 5 Mix design proportions

Specimens Cement Kg/m3 Sand Kg/m3 Water L/m3 SBR L/m3

Glass fibers Wt.%

Control mortar 627.9 1255.7 313.93 0 0 Glass fibers reinforced mortar without SBR 627.9 1255.7 313.93 0 0.54

627.9 1255.7 313.93 0 0.76 627.9 1255.7 313.93 0 1.1 627.9 1255.7 313.93 0 1.42

Glass fibers reinforced mortar with 7% SBR 627.9 1255.7 291.96 21.96 0.54

627.9 1255.7 291.96 21.96 0.76 627.9 1255.7 291.96 21.96 1.1 627.9 1255.7 291.96 21.96 1.42

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Figure 3 A: Glass fibers weighing, B: preparation of glass fibers reinforced mortar

Figure 4 A: molding of glass fibers layers reinforced mortar, B: glass fibers layer compacting

Figure 5 Curing at A: controlled temperature and, B: controlled humidity

4. TESTING

4.1. Water absorption

According to ASTM C642-97 [13] the water absorption was determined by drying the specimens in oven with temperature of (100-110) °C for 24 hours, cooled in room temperature and weighed. The specimens were immersed in water at (20∓5°C) for 7 and 28 days. The specimens were weighed after their surfaces were dried by towel. The water absorption was calculated according to equation 1 [13]. Waterabsorption% = ( ) ( )

( ) × 100 (1)

4.2. Ultrasonic test

According to ASTM C597-02 [14] a portable ultrasonic non-destructive indicating tester of (PROCEQ) Switzerland making was used. Two transducers are connected to the apparatus cables, the first transducer acts as transmitter for the ultrasonic pulses and the second acts as the receiver. Both transducers are fixed on the specimen surface by using coupling agent like (oil, grease, rubber, or any other viscous material), in this

P a g e | 389 Besma M. Fahad and Mustafa M. Hamza

work a grease was used as a coupling agent to ensure good pulse transmission, a pulse of longitudinal vibration with resonant frequencies of 54 KHz was produced by an electro-acoustical transducer and then converted into an electrical signal by receiver transducer. Fig.6. shows the ultrasonic apparatus. The transit time velocity was calculated according to equation2 [14].

Velocity(m sec.⁄ ) = ( )

( .) (2)

Figure 6 Ultrasonic test

4.3. Acoustic impedance (Z) measurement

A measures of the opposition that a system presents to the acoustic flow resulting of an acoustic pressure applied to the system is known as acoustic impedance with units of (Kg/s.m2), it can be computed from equation 3 [15,16].

Acousticimpedance(Kg s.m )⁄ = Velocity (m s)× Density(Kg m )⁄⁄ (3)

5. RESULT AND DISCUSSION

5.1. Water Absorption

After curing for 7 and 28 days, the water absorption of glass fibers reinforced mortar was measured and compared with control specimens. Random and layers glass fibers cause a reduction in water absorption. This reduction is attributed to the water proof property of glass fibers.[17] Fig.7. & Fig.8. show the effect of random glass fibers and layers glass fibers, respectively. Layers glass fibers addition showed better results than random addition. The incorporation of reinforced mortar with 7% SBR showed more reduction in water absorption. This reduction is belong to the nature of SBR as water proof material which fills the vacancies in the structure of mortar.[18] The effect of this incorporation is showed in Fig.9. & Fig.10. for random and layers glass fibers addition respectively. The layers glass fibers addition showed best results with addition of SBR after curing for 28 days. A comparison between the addition of glass fibers (random and layers) with and without the presence of SBR is shown in Fig.11. and Fig.12. after curing for 7 and 28 days respectively.

Figure 7 Effect of random glass fibers addition on the

water absorption of mortar. Figure 8 Effect of glass fiber layers addition on the water

absorption of mortar.

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Figure 9 Effect of random glass fibers addition with SBR

on the water absorption of mortar.

Figure 10 Effect of glass fiber layers addition with on the water absorption of mortar.

Figure 11 Comparison between the effect of glass fibers addition with and without SBR on the water absorption at

7 days curing.

Figure 12 Comparison between the effect of glass fibers addition with and without SBR on the water absorption at

28 days curing.

5.2. Ultrasonic Test

Ultrasonic pulse velocity test (UPV) was measured by determine the transmitting time of ultrasonic waves. The transmitted time of ultrasound wave gives an indication about the homogeneity of the interior structure and cracks. The addition of glass fibers was showed a reduction in ultrasound wave’s velocity compared with control specimens after curing for 7 and 28 days as shown in Fig.13 and Fig.14 for random and layers addition, respectively. The reason of this reduction in ultrasound velocity belongs to the fact that the glass fibers are good acoustic insulator Therefore they act as an obstacles to disperse the sound wave [19]. SBR addition to glass fibers reinforced mortar increases the obstacles in the interface against the passed ultrasound waves which disperse the ultrasound wave and consequently caused more and reduction in ultrasound velocity. Effect of Glass fibers addition with 7% SBR is shown in Fig. 15 and Fig.16 for random and layers addition, respectively. A comparison between the effect of glass fibers addition with and without SBR is shown in Fig.17 and Fig.18 for 7 and 28 days of curing, respectively.

Figure 13 Effect of random glass fibers addition to mortar

on velocity. Figure 14 Effect of glass fibers layers addition to mortar

on velocity.

P a g e | 391 Besma M. Fahad and Mustafa M. Hamza

Figure 15 Effect of random glass fibers with SBR

addition to mortar on velocity.

Figure 16 Effect of glass fibers layers with SBR addition to mortar on velocity.

Figure 17 Comparison between the effect of glass fibers

addition with and without SBR on ultrasonic velocity after curing for 7 days.

Figure 18 Comparison between the effect of glass fibers addition with and without SBR on ultrasonic velocity after

curing for 28 days.

5.3. Acoustic Impedance

The addition of glass fibers (random & layers) to the mortar specimens showed a decreasing in acoustic impedance as shown in Fig. 19 and Fig. 20 respectively. The layers glass fibers addition caused better reduction in acoustic impedance than random addition. The addition of SBR to glass fibers reinforced mortar caused more reduction in acoustic impedance as shown in Fig. 21 and Fig. 22 for random and layers addition, respectively. A comparison between the effect of glass fibers with and without presence SBR is shown in Fig. 23 and Fig. 24 after curing for 7 and 28 days, respectively.

Figure 19 Effect of random glass fibers addition on

acoustic impedance. Figure 20 Effect of glass fibers layers addition on

acoustic impedance.

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Figure 21 Effect of random glass fibers addition and7%

SBR on acoustic impedance. Figure 22 Effect of glass fibers layers addition and7%

SBR on acoustic impedance.

Figure 23 Comparison between the effect of glass fibers addition with and without SBR on acoustic impedance

after curing for 7 days.

Figure 24 Comparison between the effect of glass addition with and without SBR on acoustic impedance

after curing for 28 days. 6. CONCLOSION

Reinforcing the cement mortar with glass fibers in both random and layers manner improves the water absorption and causes a reduction in ultrasound velocity and acoustic impedance compared with control specimens after curing for 7 and 28 days. The continues addition of fibers showed more enhancement and the best results was achieved with 1.42 wt. %. The incorporation of 7% SBR to glass fibers reinforced mortar showed more enhancement in physical properties by more reduction in water absorption, ultrasound velocity and acoustic impedance. The glass fibers act as struts which bond the structure and represent obstacles hinder the passing of ultrasound waves and consequently enhance the acoustic insulation of mortar. The SBR particles fill the pores in the mortar specimen and produce a dense structure. The water proof property of SBR Plays a major role in reduction of water absorption. Curing for 28 days showed the best results due to the completion of cement hydration reaction.

7. REFERENCES

[1] Abdullah, M. M., & Jallo, E. K. 2012. Mechanical Properties of Glass Fiber Reinforced Concrete. Al-Rafadain Engineering Journal. 20(5).

[2] Dawood, L. D. E. T., & Hamad, A. J. 2013. High performance lightweight concrete reinforced with glass fibers, AL-Mansour Journal. 20, Special Issue.

[3] Islam, M. A., Rahman, M. M., & Ahmed, M. 2011. Polymer-modified concrete: world experience and potential for Bangladesh. The Indian Concrete Journal. 1: 55-63.

[4] ACI Committee. 1995. State-of-the-Art Report on Polymer Modified Concrete. American Concrete Institute, ACI. 548: 1-47.

[5] Dikeou, J. T. 1978, October. Polymers in concrete: new construction achievements on the horizon. In Proceedings, Second International Congress on Polymers in Concrete, Austin, Texas.

[6] Ohama, Y. 1995. Handbook of polymer-modified concrete and mortars: properties and process technology. William Andrew.

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[7] Shirai, A., & Ohama, Y. 1990. Improvement in flexural behaviour and impact resistance of ferrocements by use of polymers. Journal of ferrocement. 20(3): 257-264.

[8] Chandrasekaran, V. C. 2010. Rubber as a construction material for corrosion protection: a comprehensive guide for process equipment designers (Vol. 43). John Wiley & Sons.

[9] Shete, G. N., & Upase, K. S. 2014. Evaluation of Compressive Strength and Water Absorption of Styrene Butadiene Rubber (SBR) Latex Modified Concrete. International Journal of Emerging Trends in Science and Technology, 1(09).

[10] Deepak Raj A. et. Al. 2014. Experimental Methods on Glass Fiber Reinforced Self Compaction Concrete. IOSR Journal of Mechanical and Civil Engineering. 11(2): 19-23.

[11] ASTM C642. 2006. Standard test method for density, absorption, and voids in hardened concrete. [12] ASTM C305. 2004. Mechanical mixing of hydraulic cement pastes and mortars of plastic consistency. [13] ASTM C642. 2006. Standard test method for density, absorption, and voids in hardened concrete. [14] Lawrence E. Kinsler. 2000. Fundamentals of Acoustics, 4th edition, John Wiley & Sons Inc. [15] Allisy Roberts and Williams. 2007. Farr’s physicals for medical imaging, 2nd edition, Elsevier Inc. [16] Lawrence E. Kinsler. 2000. Fundamentals of Acoustics, 4th edition, John Wiley & Sons Inc. [17] Madan Mehta, Walter Scarborough and Diane Armpriest. 2013. Building construction, principles,

materials and systems, Second Edition, Pearson Education, Inc. [18] Shete, G. N., & Upase, K. S. 2014. Evaluation of Compressive Strength and Water Absorption of

Styrene Butadiene Rubber (SBR) Latex Modified Concrete. International Journal of Emerging Trends in Science and Technology. 1(09).

[19] Everest, F. A., & Pohlmann, K. C. 2001. The master handbook of acoustics (Vol. 4). New York: McGraw-Hill.