KSCE Journal of Civil Engineering (0000) 00(0):1-10 Copyright ⓒ2016 Korean Society of Civil Engineers DOI 10.1007/s12205-016-0258-2

Structural Engineering

pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205

TECHNICAL NOTE

Investigation of the Effect on the Physical and Mechanical Properties of the Dosage of Additive in Self-consolidating Concrete Yuksel Esen* and Eyyup Orhan** Received April 1, 2015/Revised 1st: July 23, 2015; 2nd: October 26, 2015/Accepted December 13, 2015/Published Online February 5, 2016

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Abstract The objective of this study was to investigate the effect of superplasticizer and mineral admixture contents on the properties of Self-Consolidating Concrete (SCC). Silica fume was used as a mineral admixture and polycarboxylate based third generation superplasticizer was used as a chemical admixture. In order to determine the optimum admixture dosages; trial mixes were prepared with varying admixture dosages. Nine concrete mixtures with different admixture dosages were prepared from trial mixes. Hardened concrete properties and self-compactability criteria of these series were determined and test results were compared between these SCC mixtures. It was observed that 10S1.3A (10% Silica Fume, 1.3% Superplasticizer) and 10S1.5A (10% Silica Fume, 1.5% Superplasticizer) mixtures show the best performance with regard to fresh and hardened concrete properties. Keywords: self-consolidating concrete, superplasticizer, silica fume ··································································································································································································································

1. Introduction Self-consolidating concrete is an innovative flowable concrete that can flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement while retaining cohesiveness to overcome segregation and bleeding (Saridemir, 2006; Lotfy et al., 2015). Because of these properties, SCC is a type of concrete which is widely used in the prefabricated industry (Leemann et al., 2006). Although SCC is not widely used in Turkey, it has been used in Europe since the 1970s. Due to declining qualified manpower in Japan, the investigations of SCC have begun in 1986. The investigations of SCC were initiated by some researches (Ozawa et al., 1989; Su et al., 2001; Dehn et al., 2000; Hallal et al., 2010; Behfarnia and Farshadfar, 2013; Uysal and Tanyildizi, 2012; Güneyisi et al., 2010; Brouwers and Radix, 2005; Khatib, 2008; Gencel et al., 2011). The widely used method to provide SCC criteria is to limit the coarse aggregate content and to use the proper mortar properties (Bonavetti et al., 2003). Besides, in order to reduce the internal friction, powder content (smaller than 0.125 mm) should be high in the fine aggregate of SCC mixture. For this purpose, mineral admixtures (fly ash, Stone dust, ground granulated blast furnace slag, silica fume) can be used in SCC mixture (Bosiljkov, 2003). Mineral admixtures considerably increase the workability and prevent the segregation of the concrete (Uysal and Yilmaz, 2011).

Silica fume brings Calcium Silicate Hydrate (CSH) forming nucleating due to amorphous structure. The core also contributes to additional crystal formation is speeded up and, indirectly, increase the early compressive strength. Silica fume has a pozzolanic activity because of the high percentage of silica content and o fineness (Felekoglu et al., 2003). Silica fume use, reduces the effectiveness of the plasticizer to be lead to an increased surface area (Punki et al., 1996). Because of this feature should not be used at high dosages when compared to other filler materials. The highest dosage of silica fume is 15% by weight of cement and the optimum dose is about 10%. If it exceeds these rates, the loss of workability and livable difficulties in implementation due to the rising heat of hydration. (Kadri et al., 2000). To reduce the water content and provide flowability of the SCC mixture, plasticizers are used as chemical admixture. There are different types of admixtures with respect to composition and chemical structure (impulsion type). Recently, most preferred admixtures are the polymer based admixtures. Rather than electrostatic impulsion, there are some other dispersion effects in the polymer based chemical admixtures. Steric impulsion which is formed by bonding of the polymer chains on the cement particles is more dominant than the electrostatic impulsion. The degree of steric impulsion depends on the length of the polymer chain, molecular weight, structure of the side chain and ambient conditions. Among the polycarboxylate based chemical admixtures, steric impulsion is particularly major factor that disperse the

*Associate Professor, Faculty of Technology, Dept. of Civil Engineering, Firat University, 23119, Elazig, Turkey (Corresponding Author, E-mail: [email protected]) **Lecturer, Faculty of Technology, Dept. of Civil Engineering, Firat University, 23119, Elazig, Turkey (E-mail: [email protected]) −1−

Yuksel Esen and Eyyup Orhan o

cement particles (Türkel and Felekog lu, 2004). The objective of this study is to investigate the effects of mineral admixture and superplasticizer contents on the self-compactability, hardened properties and exposure to high temperature of SCC mixtures and to determine the optimum admixture dosages.

2. Materials and Method 2.1 Materials o Mineral origin river aggregate obtained from Elazig Palu region was used as coarse and fine aggregates. Since fine aggregate Table 1. Gradation and Physical Properties of the Aggregate (Orhan, 2012) Sieve sizes (mm) 0.25 % passing the sieve 6 Dry specific gravity (kg/dm3) Water absorption (%) Abrasion after 500 cycles (%)

1.0 2.0 32 40 2.73 2.1 -

4.0 56

8.0 16.0 80 100 2.67 2.0 5.6

Table 2. Physical and Chemical Properties of Superplasticizer Appearance / Color Chemical Structure Density pH Freezing Point Water Soluble Chloride Ion Content Alkali Content

Liquid / light brown Modified polycarboxylate based polymer 1.07-1.11 kg/l (at 20°C) 3-7 -9 Maximum 0.1%, Does not contain chloride Maximum 4%

Table 3. Physical, Chemical and Mechanical Properties of Cement and Silica Fume Oxide Composition Cement (%) (CEM I 42.5 N) Chemical Compositions 21.12 S (SiO2) 5.62 A (AL2O3) 3.24 F (Fe2O3) C (CaO) 62.94 MgO 2.73 2.30 SO3 Na2O K2O 0.009 CI− Loss on ignition 1.78 Physical Properties 3.13 Density (g/cm3) 3370 Specific surface area (cm2/g) Initial setting (min.) 168 Final setting (min.) 258 Compressive Strength 2 Days (MPa) 25.8 7 Days (MPa) 41.8 28 Days (MPa) 50.7

Silica Fume 91 0.58 0.24 0.71 0.33 1.06 0.38 4.34 0.8-1.0 1.84 2.20 -

content is important to produce a SCC mixture, the fraction of fine aggregate passing 0.125 mm sieve was considered as filler material (Gönen, 2009). The gradation and physical properties of the aggregate have been given in Table 1. The properties of high performance third generation superplasticizer are summarized in Table 2. In the experimental study, an ordinary Portland cement (CEM o I 42.5 N) obtained from Elazig Altinova Cement Plant was used and also silica fume was used as a mineral admixture. The physical, chemical and mechanical properties of cement and silica fume are given in Table 3. 2.2 Mix Proportions and Details In the calculation of the mix proportions of the series, aggregate gradation, dosage and water/powder ratio were kept constant. Nine mixtures with three different silica fume contents (0-1020)% and three different admixture contents (1.3-1.5-1.7)% were prepared. The value before the letter “S” represents the amount of silica fume % in the designation of the series, and the value before the letter “A” represents the superplasticizer content in %. Mix proportions of all mixtures have been given in Table 4. Silica fume and superplasticizer are abbreviated as “SD” and “SA”, respectively. In order to obtain a homogeneous mixture, aggregate, cement and silica fume were placed respectively into a 100 dm3 mixer and mixed for about 1 minute before water was added. After dry mixing, 90% of mixing water was added and mixing was continued for 2 minutes. The remaining water and superplasticizer were then mixed together and added into the mixer. Mixing process was carried out for an additional 2 minutes after the addition of superplasticizer in order to show the effect of the superplasticizer. After mixing, fresh concrete was cast into the molds without vibration. SCC specimens were demoded 2 days after casting and they were cured in the lime-saturated water pool. 2.3 Fresh Concrete Tests and Results Slump flow, T50 cm flow time, V-funnel flow time, L-box passing ratio and segregation resistance tests were performed in

Table 4. Mix Proportions Series 0S1.3A 10S1.3A 20S1.3A 0S1.5A 10S1.5A 20S1.5A 0S1.7A 10S1.7A 20S1.7A −2−

Water/powder SA Cement SD ratio (kg/m3) (kg/m3) (kg/m3) (by weight) 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42

500 450 400 500 450 400 500 450 400

50 100 50 100 50 100

1.3 1.3 1.3 1.5 1.5 1.5 1.7 1.7 1.7

Aggregate (kg/m3) 0-4 4-8 8-16 911.5 390.7 325.4 901.5 386.4 321.8 891.5 382.0 318.4 910.2 390.2 325.1 900.2 385.8 321.6 890.2 381.5 317.8 908.8 389.3 324.5 898.6 385.3 321.0 888.8 381.0 317.5

KSCE Journal of Civil Engineering

Investigation of the Effect on the Physical and Mechanical Properties of the Dosage of Additive in Self-consolidating Concrete

Table 5. Fresh Concrete Test Results and Relevant Classes Series 0S1.3A 0S1.5A 0S1.7A 10S1.3A 10S1.5A 10S1.7A 20S1.3A 20S1.5A 20S1.7A

T50 flow time (sec) 1 1.12 0.84 0.84 0.85 0.75 1.3 0.8 0.64

Viscosity Class VS1 VS1 VS1 VS1 VS1 VS1 VS1 VS1 VS1

Slump flow (cm) 80 78 78 73 74 76 55 68 65

Slump flow class SF3 SF3 SF3 SF2 SF2 SF3 SF1 SF2 SF2

V-funnel flow time (sec) 5.3 4.87 5.1 4 4.53 3.04 4.19 3.37 3.91

accordance with EFNARC SCC Specification and Guidelines (see Table 5) (EFNARC, 2005). In the slump flow test, first the inside of the slump cone was wetted and placed on the center of the slump flow table. Fresh concrete was then filled into the slump cone and slump cone which was then vertically raised. As the fresh concrete reached the 50 cm flow value, the time was measured to determine the T50 flow time. After the concrete fully flowed, two orthogonal diameters (one of them being the maximum diameter) of the concrete were measured and their average was expressed as the slump flow. In the V-funnel test, in order to compare the viscosity resistance of the SCC mixtures, V-funnel flow time values of the fresh concretes were measured. V-funnel was fully filled with fresh concrete without vibration and jolting and the surface of the concrete was trowelled. The cap of the V-funnel was opened and the flow time of fresh concrete was determined using a stopwatch. As the silica fume content increases, the workability of the concrete increases provided that the mixture has enough water and admixture dosage. As can be seen in Table 5, 20S1.3A mixture has the minimum slump flow value. The excessive use of the silica fume and the lack of sufficient chemical admixture dosage decreased the flowability and T50 flow time values increased. In other mixtures, since the amount of the superplasticizer was sufficient, T50 flow time values decreased with increasing silica fume content. As the slump flow values increased, T50 flow time values decreased. In the SCC mixtures having no silica fume segregation occurred. SCC mixtures having 10% silica fume has the optimum values and the slump flow values decreased in the mixtures with 20% silica fume due to higher water requirement. Bleeding and segregation were observed in SCC mixtures without silica fume. Due to increase in the internal friction caused by the separation of the coarse and fine particles, V-funnel flow time values increased in the mixtures with high segregation in the V-funnel test. As the silica fume content increased, V-funnel flow time decreased. Due to the low viscosity of the mixtures having 20% of silica fume, flow time values increased in these mixtures. Regarding passing ability, all series are within the limits of compactability; however, passing ability of the mixtures having Vol. 00, No. 0 / 000 0000

Viscosity Class

L-box ratio

VS1 VS1 VS1 VS1 VS1 VS1 VS1 VS1 VS1

1 0.98 1 1 1 0.97 0.8 0.88 0.88

Passing ability class PA1 PA1 PA1 PA1 PA1 PA1 PA1 PA1 PA1

Segregation Segregation resistance resistance (%) class 26 23 32.4 6.8 SR2 8 SR2 18.5 SR1 0.5 SR2 1 SR2 1.2 SR2

20% of silica fume was lower than the other series. This is because the cohesion and the water requirement of this mixture were relatively high. In these series, as the superplasticizer content increased, the passing ability of the mixtures also increased (Karataçs, 2007). The sieve segregation test in the slump, 10 liters of fresh concrete was filled into the sample container and the cap was closed. After waiting for 15 minutes, the cap was opened. By taking the tare of sample container and sieve into account, they were placed on a weighing scale and 4.8 kg of the fresh sample is poured into a sieve with 5 mm2 square apertures from a height of 50 cm. After 120 seconds, the weight of material which has passed through the sieve is recorded. The segregation ratio is then calculated as the proportion of the sample passing through the sieve. Mixtures having high cohesiveness and high silica fume content has low segregation than the other mixtures. On the other hand, superplasticizer content increased with increasing segregation. As can be seen in Table 5, segregation ratio falls out of the compactability limit for mixtures with 0% of silica fume. This is due to the fact that the amount of water is higher than the required content as a result of the lack of silica fume. Mixtures having high cohesiveness and high silica fume content has low segregation than the other mixtures. On the other hand, superplasticizer content increased with increasing segregation. As can be seen in Table 5, segregation ratio falls out of the Table 6. Classes of SCC for Various Types of Application (Walraven, 2003)

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compactability limit for mixtures with 0% of silica fume. This is due to the fact that the amount of water is higher than the required content as a result of the lack of silica fume (EFNARC, 2005). All series of SCC mixtures belong to VS1 viscosity class and PA1 passing ability class in accordance with EFNARC. However, since segregation is high in mixtures without silica fume, they exceed the SCC criteria and do not belong to any class. As the other series of the SCC mixtures provide SCC criteria, they can be used in the application areas shown in Table 6.

2.4 Hardened Concrete Tests and Results Flexural tensile strength tests were performed on 75 mm × 75 mm × 300 mm prismatic specimens while the other tests were performed on 100 mm × 100 mm × 100 mm cube specimens. 2.4.1 Water Absorption, Porosity, Unit Weight and Specific Gravity Tests Water absorption and density values of SCC mixtures were determined in accordance with TS EN 12390-7 standard and these tests were performed on 28 day old specimens (TS EN 12390-7, 2010).

Fig. 3. Specific Gravity of SCC Mixtures

Fig. 1. Water Absorption of SCC Mixtures

Fig. 4. Unit Weight of SCC Mixtures

Fig. 2. Porosity of SCC Mixtures

Fig. 5. 7, 14 and 28 day Compressive Strength Values of the Series −4−

KSCE Journal of Civil Engineering

Investigation of the Effect on the Physical and Mechanical Properties of the Dosage of Additive in Self-consolidating Concrete

As can be seen in Fig. 1, the minimum water absorption values belong to SCC mixtures containing 10% of silica fume. Water absorption of the concrete specimen is directly related to the void ratio of the concrete. Silica fume improves the bond between cement paste and aggregate while, also decreasing the void ratio of the concrete due to filler effect of the material. Regarding this information, it is expected that the minimum void ratios would belong to mixtures containing 20% of silica fume. However, as the silica fume is used more than the optimum value, micro cracks can be formed and compactability of the concrete reduces. Therefore, optimum value of the silica fume is 10%. As can be seen in Fig. 2 and Fig. 3, except series of 10% silica fume, as the porosity values increase, water absorption values also increase. As can be seen in Fig. 3, specific gravity values are proportional to the unit weight values of the SCC mixtures (Fig. 4). The specimens having low water absorption or void ratio have high specific gravity and unit weight values. 2.4.2 Compressive Strength Test Compressive strength tests of specimens were conducted at 7, 14 and 28 days in accordance with TS EN 12390-3 standard and test results are presented in Fig. 5 (TS EN 12390-3, 2010). In general, specimens gained 70%, 8% and 22% of their 28day compressive strength in the first 7 days, between 7th and 14th days and between 14th and 28th days, respectively (Fig. 5). Owing to its rapid pozzolanic reaction rate, SD has an indirect contribution to early strength through reaction with calcium hydroxide in moist environment and development of C-S-H gels and crystal structure (Türk et al., 2008). As a mineral admixture SD improves compressive strength due to its both pozzolanic effect and pore-filling characteristic. Therefore, in series with high SD content compressive strength will be higher. Fresh concrete criteria will also have an impact on compressive strength. If desired level of placeability of concrete cannot be obtained or if it remains at the limit values, compressive strength will reduce due to inadequate compaction and filling of the mold. According to the porosity values given in Fig. 2, series without SD will have lower compressive strength values than corresponding SD

including series due to their higher pore volume. Since increase in SD content will result in a higher level of placeability, increase in compressive strength was observed depending on superplasticizer content. The highest compressive strength was obtained in the series having 10% SD and 1.3% super plasticizing admixture. Results are directly related with those obtained in sieve segregation resistance test. Increasing superplasticizer content gradually reduced compressive strength due to higher segregation tendency. Series including 20% SD has a lower segregation level as a result of higher cohesion and segregation resistance; therefore, compressive strength increased with increase in superplasticizer content. As SD content increased in the series, the difference between 7-day and 28-day compressive strength appeared to be higher compared to series not including SD. SD-including series showed increase in compressive strength at later ages when compared to series without SD. This results from development of a stronger bond between SD including cement paste and aggregate phase during the hardening process. 2.4.3 Splitting Tensile Strength Test Splitting tensile strength tests of specimens were conducted at 7, 14 and 28 days in accordance with TS EN 12390-6standard and test results are presented in Fig. 6 (TS EN 12390-6, 2010). In general, splitting tensile strength values were found to be similar to compressive strength figures. As hardening proceeds, the bond strength will increase and consequently, splitting tensile strength will become higher. Half specimens were visually inspected and no segregation was observed. As can be seen from Fig. 6, splitting tensile strength went up with increasing SD content. However, specimens with lower segregation ratio, in other words, 10% SD including mixture had the highest splitting tensile strength. Increase in superplasticizer content resulted in decrease in strength values due to higher segregation level (Abrishambaf et al., 2015). 2.4.4 Flexural Strength Test Flexural strength tests of specimens were conducted at 7, 14

Fig. 6. 7, 14 and 28 day Splitting Tensile Strength Values of the Series Vol. 00, No. 0 / 000 0000

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Fig. 7. 7-, 14- and 28- day Flexural Strength Values of the Series

Fig. 8. 7-, 14- and 28- day Ultrasound Pulse Velocity Values of the Series

and 28 days in accordance with TS EN 12390-5 standard (TS EN 12390-5, 2010). Third-point loading method was applied to simple beams and strength values in Fig. 7 are obtained. Reduction in unit weight and increase in porosity will lead to drop in flexural strength values of series. Series gained a very big portion of their potential flexural strength within the first 7 days. The difference between 7-day and 14-day strength was comparatively high for only 20% SD including series. In series with SD, reduction in flexural strength was observed as superplasticizer content increased. Series with high SD content have a slow hardening rate. As Schmidt rebound numbers indicate, the lowest surface hardness in 7 days belongs to 20% SD including series. Surface hardness and bond strength after hardening are directly proportional with each other. The low level of flexural strength of 20% SD including series in the first few days is attributed to this fact. 2.4.5 Ultrasound Pulse Velocity Transmission time of sound waves between surfaces of 7, 14 and 28 day old specimens were determined using ultrasound pulse velocity test apparatus. Ultrasound pulse velocity was determined using {V = (S/T) × 106} formula and the values in Fig. 8 were obtained.

V = Ultrasound pulse velocity (meter/second) S = Distance between the transducer and the transmitter ends (meter) T = Transmission time of the wave between the surfaces (microsecond) Ultrasound pulse velocity is inversely proportional with porosity value. As superplasticizer content increased, placeability of the mixtures also increased and as a consequence, transmission time between the surfaces reduced; thereby, ultrasound pulse velocity increased. Since more micro cracks in the internal structure of concrete formed with increasing SD utilization, ultrasound pulse velocities of the series dropped. In other words, transmission time of the wave between the surfaces increased. 2.4.6 Surface Hardness Test Surface hardness values (Schmidt hardness) of 7, 14 and 28 day old specimens were determined according to TS 3260 using concrete rebound hammer and test results are shown in Fig. 9 (TS 3260, 2005). In some series, values dropped due to inadequate compaction resulting from low workability and placeability. Schmidt values increased in parallel to increase in superplasticizer content in 20% SD including series as a result of higher superplasticizer

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KSCE Journal of Civil Engineering

Investigation of the Effect on the Physical and Mechanical Properties of the Dosage of Additive in Self-consolidating Concrete

Fig. 9. 7-, 14- and 28- day Schmidt Values of the Series

surfaces of oven-dried specimens were sealed with paraffin as shown in Fig. 10 and only the bottom surface is exposed to water (Demirel and Keleçs temur, 2011). Water height from the bottom surface of concrete was held constant at 5 mm throughout the entire test period. Weight determination of specimens was conducted in time periods of 0, 5, 10, 20, 30, 60, 120, 180, 240, 360 and 1080 minutes and sorptivity coefficients were calculated using the formula given below (Bozkurt, 2010). Q (1) k = -------------A× t

Fig. 10. Measurement of Capillary Water Absorption

content which leads to a better placeability. The highest value in 10% SD including series is procured in 10S1.3A mixture. As it is clear in Fig. 10, if an excess amount of superplasticizer is used than the required content in 10% SD including series, Schmidt values declined. 2.4.7 Capillary Water Absorption Test After application of curing for 28 days, specimens were dried in an oven until a constant mass is achieved and then, they were cooled to room temperature in laboratory environment. Side

k = Sorptivity coefficient (cm/ sn ) Q = Amount of water absorbed (cm3) A = Area of the bottom surface (cm2) t = Duration of contact with water (sn) According to the sorptivity coefficient results shown in Fig. 11, the mixture that absorbed the lowest amount of water is 10S1.5A mixture. This results from the fact that in this mixture, superplasticizer and SD were both used at their optimum ratios. In mixtures without SD, amount of water absorption rose up. When the amount of SD exceeded its optimum value, water absorption

Fig. 11. Amount of Capillary Water Absorption of Series at 28th day Vol. 00, No. 0 / 000 0000

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Fig. 12. Residual Compressive Strength of Series After Exposure to High Temperature

Fig. 13. Ultrasound Pulse Velocity of Series After Exposure to High Temperature

increases again due to higher amount of capillary pores; however, with utilization of superplasticizer water absorption declined due to better placeability of the mixtures. 2.4.8 Exposure to High Temperature After the completion of curing period of 28 days, specimens were dried in an oven. Oven-dried specimens were cooled and ultrasound pulse velocity determination was carried out. After that, specimens were exposed to 100, 300, 500, 700 and 900°C for 1 hour period in a Protherm HLF laboratory type furnace that can heat up to 1200°C (8°C/min). Next, specimens were taken out of the furnace they were cooled to ambient by allowing equal air circulation for all surfaces and compressive strength (Fig. 12) and finally ultrasound pulse velocity (Fig. 13) were determined (Esen, 2010).

As cement hydration proceeds, SD helps to improve compressive strength of concrete through reaction with free calcium hydroxide (Çoçskun et al., 2007). Compressive strength of concrete appears to be similar at 20°C and 100°C. A significant loss in compressive strength of concrete was observed at 300°C. All specimens were tested in the same environment and under same conditions; however, the loss in compressive strength is presumed to arise from high moisture content in specimens which would be exposed to 300°C. Upon exposure to 500°C, residual compressive strength of concrete mixtures increased. This may be attributed to the internal structure of the material resulting from SD. Water evaporates in the capillaries occurred in samples 500°C temperatures. This is caused ultrasound pulse velocity decline. Van Der Waals ties with the effect of temperature caused an increase in strength approaching each other. Since deterioration takes place

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KSCE Journal of Civil Engineering

Investigation of the Effect on the Physical and Mechanical Properties of the Dosage of Additive in Self-consolidating Concrete

in the structure of C-S-H gels beyond 700°C temperature level, mixtures lost around 40-50% of their compressive strength. At 900°C, the series which was affected to the greatest extent was 20% SD including mixtures. For these mixtures, loss in compressive strength was observed depending on the superplasticizer content. Compared to series without SD, SD including mixtures had a greater resistance against high temperature. The highest residual compressive strength belongs to 10% SD and 1.5% superplasticizer bearing mixture. Level of deterioration in specimens upon exposure to high temperature was measured by determining ultrasound pulse velocity. As shown in Fig. 13, ultrasound pulse velocity declined with increasing temperature level. This results from the fact that ultrasonic pulses travel slower between transducer and transmitter ends due to the presence of voids formed upon evaporation of water in the structure of concrete. There was a significant drop in ultrasound pulse velocity beyond 500°C. Because at 700°C and 900°C structural damage in C-S-H gels takes place and ultrasound pulse velocity reduces suddenly. Another reason for the decline in ultrasound pulse velocity is the formation of some cracks in concrete body as capillary water evaporates with increasing temperature.

3. Conclusions The following conclusions were drawn upon conducting tests for determining the effect of superplasticizer and mineral admixture contents on fresh and hardened properties of concrete; 1. According to test results on fresh concrete, the most favorable values belong to 10% SD including series. It was expected to obtain better workability in 20% SD including series, but increased water requirement resulted in lower slump flow and passing ability between the reinforcement. Therefore, the optimum usage ratio of SD is 10% of the dosage of cement. 2. From the viewpoint of superplasticizer utilization, 1.3% admixture content seems not to be sufficient in mixtures. Relatively better results are obtained in 10% SD including series while in 20% SD including series 1.3% admixture content was inadequate. On the other hand, 1.7% admixture content exceeds the required amount of the mixture. Saturation point of the mixture was obtained through the use of 1.5% admixture. Beyond the saturation point segregation problem arose, and below the saturation point it became difficult to gain favorable consistency. 3. Compressive strength increased with SD utilization. High values were reached at 10% SD amount. It is apparent that series incorporating 10% SD and 1.3% superplasticizer had high compressive strength. Strength values dropped as the amount of superplasticizer increased. Although high compressive strength values were obtained with 20% SD utilization, in general, the level of strength didn’t go beyond that of 10% SD including series. At 20% SD utilization, increase in compressive strength was observed with increasing superplasticizer content due to better placeability. Regarding these results, Vol. 00, No. 0 / 000 0000

there is no additional compressive strength gain when the SD ratio goes beyond 10%. 4.Amounts of water absorption are in parallel to fresh concrete properties. Because in mixtures having better placeability, pore volume will be lower. Depending on the pore volume, the level of permeability increased. The coefficient of permeability was minimized through the use of 10% SD. 5. Splitting tensile strength increased as the amount of SD in the mixture increased. SD helps to improve bond and strength by forming additional C-S-H gels. The highest values were obtained by the use of 1.3% superplasticizer. In all series, higher superplasticizing admixture content led to drop in splitting tensile strength values. 6. Since SCC is a well consolidated concrete type, it showed good resistance against high temperature. According to residual compressive strength values upon exposure to high temperature, increase in compressive strength was observed at 500°C which can be attributed to internal structure of the material.

References Abrishambaf, A., Barros, J. A. O., and Cunha, V. M. C. F. (2015). “Tensile stress-crack width law for steel fibre reinforced selfcompacting concrete obtained from indirect (splitting) tensile tests.” Cement & Concrete Composites, Vol. 57, March 2015, pp. 153-165, DOI: 10.1016/j.cemconcomp.2014.12.010. Behfarnia, K. and Farshadfar, O. (2013). “The effects of pozzolanic binders and polypropylene fibers on durability of SCC to magnesium suffate attack.” Construction and Building Materials, Vol. 38, January 2013, pp. 64-71. Bonavetti, V., Donza, H., Menéndez, G., Cabrera, O., and Irassar, E. F. (2003). “Limestone filler cement in low w/c concrete, a rational use of energy.” Cem. Concr. Res., Vol. 33, No. 6, pp. 865-871, DOI: 10.1016/S0008-8846(02)01087-6. Bosiljkov, V. B. (2003). “SCC mixes with poorly graded aggregate and high volume of limestone filler.” Cem. Concr. Res., Vol. 33, No. 9, pp. 1279-1286, DOI: 10.1016/S0008-8846(03)00013-9. Bozkurt, B. (2010). “Strength and capillary water absorption of lightweight concrete under different curing conditions.” Indian J. Eng. & Mater. Sciences, Vol. 17, No. 2, pp. 145-151. Brouwers, H. J. H. and Radix, H. J. (2005). “Self-compacting concrete: Theoretical and experimental study.” Cem. Concr. Res., Vol. 35, No. 11, pp. 2116-2136, DOI: 10.1016/j.cemconres.2005.06.002 o Coçs kun, A., Tany ildiz i, H., and Yaz ic iog lu, S. (2007). “The effect of 800°C temperature level on bond strength of mineral admixtured concrete.” Pamukkale University, Journal of Engineering Sciences, Vol. 13, No. 3, pp. 347-51. Dehn, F., Holschemacher, K., and Weise, D. (2000). “Self-compacting concrete (SCC) time development of the material properties and the bond behavior.” LACER, Vol. 5, No. 1, pp. 115-124. Demirel, B. and Keleçs temur, O. (2011). “Effect of elevated temperature on the mechanical properties of concrete produced with finely ground pumice and silica fume.” Fire Safety Journal, Vol. 45, Nos. 6-8, pp. 385-391, DOI: 10.1016/j.firesaf.2010.08.002. Esen, Y. (2010). “The effect of cure conditions and temperature changes on the compressive strength of normal and fly ash-added concretes.” Int. J. Phys. Sciences, Vol. 5, No. 17, pp. 2598-2604.

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EFNARC (2005). “The European guidelines for self-compacting concrete.” SCC European Project Group. o Felekog lu, B., Yardimci, M. Y., and Baradan, B. (2003). A comparative study on the use of mineral and chemical types of viscosity enhancers in self-compacting concrete, 3rd International Symposium on SelfCompacting Concrete, Iceland, 12p. Gencel, O., Ozel, C., Brostow, W., and Martinez-Barrera, G. (2011). “Mechanical properties of self-compacting concrete reinforced with polypropylene fibres.” Materials Research Innovations, Vol. 15, No. 3, pp. 216-225, DOI: 10.1179/143307511X13018917925900 Gönen, T. (2009). Investigation of mechanical and durability properties of self-compacting structural lightweight concrete, PhD Thesis, Firat University Institute of Science, Engineering and Technology, o Elazig . Güneyisi, E., Gesolu, M., and Ozbay, E. (2010). “Strength and drying shrinkage properties of self-compacting concretes incorporating multi-system blended mineral admixtures.” Construction and Building Materials, Vol. 24, No. 10, pp. 1878-87, DOI: 10.1016/j.conbuildmat. 2010.04.015. Hallal, A., Kadri, E. H., Ezziane, K., Kadri, A., and Khelafi, H. (2010). “Combined effect of mineral admixtures with superplasticizers on the fluidity of the blended cement paste.” Construction and Building Materials, Vol. 24, No. 8, pp. 1418-1423, DOI: 10.1016/j.conbuildmat. 2010.01.015. Kadri, E. H., Aggoun, S., Duval, R., and Petruk, M. P. (2000). “Influence of C3A on physico-chemical and mechanical properties of high performance concretes.” Second International Symposium on Cement and Concrete Technology in the 2000, Istanbul, Turkey, Vol. 2, pp. 31-39. Karataçs , M. (2007). The effect of mineral admixture dosage and type on reinforcement bond in self compacting concrete, PhD Thesis, Firat o University Institute of Science, Engineering and Technology, Elazig . Khatib, J. M. (2008). “Performance of self-compacting concrete containing fly ash.” Construction and Building Materials, Vol. 22, No. 9, pp. 1963-1971, DOI: 10.1016/j.conbuildmat.2007.07.011. Lotfy, A., Hossain, K. M. A., and Lachemi, M. (2015). “Statistical models for the development of optimized furnace slag lightweight aggregate self-consolidating concrete.” Cement & Concrete Composites, Vol. 55, January 2015, pp. 169-185, DOI: 10.1016/j.cemconcomp. 2014.09.009. Leemann, A., Munch, B., Gasser, P., and Holzer, L. (2006). “Influence of compaction on the interfacial transition zone and the permeability of concrete.” Cem. Concr. Res., Vol. 36, No. 9, pp. 1425-33, DOI: 10.1016/j.cemconres.2006.02.010. Orhan, E. (2012). The effect of change in admixture content on properties of self-compacting concrete, Master Thesis, Firat University Institute

o

of Science, Engineering and Technology, Elaz ig . Ozawa, K., Mackawa, K., and Okumura, H. (1989). “High performance concrete based on the durability of concrete.” Proc., of the 2nd East Asia Pacific Conference on Structural Engineering and Construction, Vol. 1, pp. 445-456. Punki, J., Golaszewski, J., and Gjorv, O. E. (1996). “Workability loss of high-strength concrete.” ACI Meterials Journal, Vol. 93, No. 5, pp. 427-431, DOI: 10.14359/9846. Saridemir, H. (2006). The effect of mineral and superplasticizing admixtures on workability and compressive strength of self-compacting concrete, Master Thesis, Erciyes University Institute of Science, Engineering and Technology, Kayseri. Su, N., Hsu, K.-C., and Chai, H.-W. (2001). “A simple mix design method for self-compacting concrete.” Cem. Concr. Res., Vol. 31, No. 12, pp. 1799-1807. TS EN 12390-3 (2010). Testing hardened concrete – Part 3: Compressive strength of test specimens, TSE, Ankara, Turkey. TS EN 12390-5 (2010). Testing hardened concrete – Part 5: Flexural strength of test specimens, TSE, Ankara, Turkey. TS EN 12390-6 (2010). Testing hardened concrete – Part 6: Tensile splitting strength of test specimens, TSE, Ankara, Turkey. TS EN 12390-7 (2010). Testing hardened concrete – Part 7 Density of hardened concrete, TSE, Ankara, Turkey. TS EN 3260 (2005). Determination of compressive strength of concrete by surface hardness method, TSE, Ankara, Turkey, 2005. Türk, K., Karataçs , M., and Ulucan, Z. Ç. (2008). “The engineering properties of self-compacting concrete with silica fume replacement in different amounts.” Firat University, Science and Engineering Journal, Vol. 20, No. 1, pp. 165-74. o Türkel, S. and Felekog lu, B., (2004). “The effect of utilization of superplasticizing chemical admixture in excess dosage on some properties of fresh and hardened concrete.” D.E.U. Faculty of Engineering Science and Engineering Journal, Izmir, January, Vol. 6, No. 1, pp. 77-89. Uysal, M. and Tanyildizi, H. (2012). “Estimation of compressive strength of self compacting concrete containing polypropylene fiber and mineral additives exposed to high temperature using artificial neural network.” Construction and Building Materials, Vol. 27, No. 1, pp. 404-414, DOI: 10.1016/j.conbuildmat.2011.07.028. Uysal, M. and Yilmaz, K. (2011). “Effect of mineral admixtures on properties of self-compacting concrete.” Cem. Concr. Composites, Vol. 33, No. 7, pp. 771-76, DOI: 10.1016/j.cemconcomp.2011.04.005. Walraven, J. (2003). Stuctural Aspects of self-compacting concrete, Proceeding of 3rd International Rilem Symposium on Self Compacting Concrete, Iceland.

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